List of automobile manufacturers of Canada

This is a list of notable automobile manufacturers with articles on Wikipedia by country. It is a subset of the list of automobile manufacturers for manufacturers based in Canada. It includes companies that are in business as well as defunct manufacturers.


Micrometer adjustment nut

On a manual milling machine, the micrometer adjustment nut limits the depth to which the cutting tool may plunge into the workpiece.
The nut is located on a threaded rod on the mill head. The machine operator moves it up or down by rotating it clockwise (to move it down) or counter-clockwise (to move it up). Moving the nut down increases the depth to which the cutting tool may plunge into the workpiece. Moving the nut up reduces the depth to which the cutting tool may plunge into the workpiece.


Partnerized inventory management

Partner-optimized inventory management, also known as partnerized inventory management or sometimes just the abbreviation PIM is an inventory management technique or model often used in deterministic inventory systems in which a significant portion of the total inventory regularly becomes stochastic in nature, due to slowing and/or low demand such as is typical in heavy machinery and construction equipment where the products themselves are extremely durable and have long lives in the field. Inventory in these cases needs to be maintained for an extended time to allow for repairs and product support perhaps as much as two or more decades after a manufacturer has ceased production.
Traditional inventory management techniques break down in cases where a manufacturer maintains inventory to supply future maintenance of their in-service equipment. As demand for goods approaches zero, liquidation of inventory is indicated in most revenue management models. Zero inventory to service products in the field, however, fails the organization in other business areas. Possible costs to manufacture replacement inventory and the harder-to-calculate costs of customer confidence erosion can be greater over time than the immediate financial concerns that are remedied by liquidating inventory entirely by scrapping or discarding it as waste.
While scrapping returns inventory to a state of raw materials, Partner-Optimized Inventory Management (PIM) returns inventory to the market as intermediate goods to be used in production of other goods or non-capital spare parts. An organization that uses the PIM model mitigates the immediate pinch point caused by inventory reduction by retaining as-needed mutual access to inventory through the marketplace for an indeterminate time rather than losing access immediately and irrevocably through scrapping or discarding the inventory as waste.


Milling (machining)

Milling is the process of machining using rotary cutters to remove material by advancing a cutter into a workpiece. This may be done by varying directions on one or several axes, cutter head speed, and pressure. Milling covers a wide variety of different operations and machines, on scales from small individual parts to large, heavy-duty gang milling operations. It is one of the most commonly used processes for machining custom parts to precise tolerances.
Milling can be done with a wide range of machine tools. The original class of machine tools for milling was the milling machine (often called a mill). After the advent of computer numerical control (CNC) in the 1960s, milling machines evolved into "machining centers": milling machines augmented by automatic tool changers, tool magazines or carousels, CNC capability, coolant systems, and enclosures. Milling centers are generally classified as vertical machining centers (VMCs) or horizontal machining centers (HMCs).
The integration of milling into turning environments, and vice versa, began with live tooling for lathes and the occasional use of mills for turning operations. This led to a new class of machine tools, multitasking machines (MTMs), which are purpose-built to facilitate milling and turning within the same work envelope.
Process.
Milling is a cutting process that uses a milling cutter to remove material from the surface of a work piece. The milling cutter is a rotary cutting tool, often with multiple cutting points. As opposed to drilling, where the tool is advanced along its rotation axis, the cutter in milling is usually moved perpendicular to its axis so that cutting occurs on the circumference of the cutter. As the milling cutter enters the work piece, the cutting edges (flutes or teeth) of the tool repeatedly cut into and exit from the material, shaving off chips (swarf) from the work piece with each pass. The cutting action is shear deformation; material is pushed off the work piece in tiny clumps that hang together to a greater or lesser extent (depending on the material) to form chips. This makes metal cutting somewhat different (in its mechanics) from slicing softer materials with a blade.
The milling process removes material by performing many separate, small cuts. This is accomplished by using a cutter with many teeth, spinning the cutter at high speed, or advancing the material through the cutter slowly; most often it is some combination of these three approaches. The speeds and feeds used are varied to suit a combination of variables. The speed at which the piece advances through the cutter is called feed rate, or just feed; it is most often measured as distance per time (inches per minute [in/min or ipm] or millimeters per minute [mm/min]), although distance per revolution or per cutter tooth are also sometimes used.
There are two major classes of milling process:
Milling cutters.
Many different types of cutting tools are used in the milling process. Milling cutters such as end mills may have cutting surfaces across their entire end surface, so that they can be drilled into the work piece (plunging). Milling cutters may also have extended cutting surfaces on their sides to allow for peripheral milling. Tools optimized for face milling tend to have only small cutters at their end corners.
The cutting surfaces of a milling cutter are generally made of a hard and temperature-resistant material, so that they wear slowly. A low cost cutter may have surfaces made of high speed steel. More expensive but slower-wearing materials include cemented carbide. Thin film coatings may be applied to decrease friction or further increase hardness.
There are cutting tools typically used in milling machines or machining centers to perform milling operations (and occasionally in other machine tools). They remove material by their movement within the machine (e.g., a ball nose mill) or directly from the cutter's shape (e.g., a form tool such as a hobbing cutter).
As material passes through the cutting area of a milling machine, the blades of the cutter take swarfs of material at regular intervals. Surfaces cut by the side of the cutter (as in peripheral milling) therefore always contain regular ridges. The distance between ridges and the height of the ridges depend on the feed rate, number of cutting surfaces, the cutter diameter. With a narrow cutter and rapid feed rate, these revolution ridges can be significant variations in the surface finish.
The face milling process can in principle produce very flat surfaces. However, in practice the result always shows visible trochoidal marks following the motion of points on the cutter's end face. These revolution marks give the characteristic finish of a face milled surface. Revolution marks can have significant roughness depending on factors such as flatness of the cutter's end face and the degree of perpendicularity between the cutter's rotation axis and feed direction. Often a final pass with a slow feed rate is used to improve the surface finish after the bulk of the material has been removed. In a precise face milling operation, the revolution marks will only be microscopic scratches due to imperfections in the cutting edge.
Gang milling refers to the use of two or more milling cutters mounted on the same arbor (that is, ganged) in a horizontal-milling setup. All of the cutters may perform the same type of operation, or each cutter may perform a different type of operation. For example, if several workpieces need a slot, a flat surface, and an angular groove, a good method to cut these (within a non-CNC context) would be gang milling. All the completed workpieces would be the same, and milling time per piece would be minimized.
Gang milling was especially important before the CNC era, because for duplicate part production, it was a substantial efficiency improvement over manual-milling one feature at an operation, then changing machines (or changing setup of the same machine) to cut the next op. Today, CNC mills with automatic tool change and 4- or 5-axis control obviate gang-milling practice to a large extent.
Equipment.
Milling is performed with a milling cutter in various forms, held in a collet or similar which, in turn, is held in the spindle of a milling machine.
Types and nomenclature.
Mill orientation is the primary classification for milling machines. The two basic configurations are vertical and horizontal – referring to the orientation of the rotating spindle upon which the cutter is mounted. However, there are alternative classifications according to method of control, size, purpose and power source.
Mill orientation.
Vertical.
In the vertical milling machine the spindle axis is vertically oriented. Milling cutters are held in the spindle and rotate on its axis. The spindle can generally be lowered (or the table can be raised, giving the same relative effect of bringing the cutter closer or deeper into the work), allowing plunge cuts and drilling. The depth to which blades cut into the work can be controlled with a micrometer adjustment nut. There are two subcategories of vertical mills: the bed mill and the turret mill.
Turret mills are generally considered by some to be more versatile of the two designs.
A third type also exists, a lighter, more versatile machine, called a mill-drill. The mill-drill is a close relative of the vertical mill and quite popular in light industry; and with hobbyists. A mill-drill is similar in basic configuration to a very heavy drill press, but equipped with an X-Y table and a much larger column. They also typically use more powerful motors than a comparably sized drill press, most are muti-speed belt driven with some models having a geared head or electronic speed control. They generally have quite heavy-duty spindle bearings to deal with the lateral loading on the spindle that is created by a milling operation. A mill drill also typically raises and lowers the entire head, including motor, often on a dovetailed (sometimes round with rack and pinion) vertical column. A mill drill also has a large quill that is generally locked during milling operations and released to facilitate drilling functions. Other differences that separate a mill-drill from a drill press may be a fine tuning adjustment for the Z-axis, a more precise depth stop, the capability to lock the X, Y or Z axis, and often a system of tilting the head or the entire vertical column and powerhead assembly to allow angled cutting-drilling. Aside from size, the principal difference between these lighter machines and larger vertical mills is that the X-Y table is at a fixed elevation; the Z-axis is controlled by moving the head or quill down toward the X,Y table. A mill drill typically has an internal taper fitting in the quill to take a collet chuck, face mills, or a Jacobs chuck similar to the vertical mill.
Horizontal.
A horizontal mill has the same sort but the cutters are mounted on a horizontal spindle, or arbor, mounted across the table. Many horizontal mills also feature a built-in rotary table that allows milling at various angles; this feature is called a "universal table". While endmills and the other types of tools available to a vertical mill may be used in a horizontal mill, their real advantage lies in arbor-mounted cutters, called side and face mills, which have a cross section rather like a circular saw, but are generally wider and smaller in diameter. Because the cutters have good support from the arbor and have a larger cross-sectional area than an end mill, quite heavy cuts can be taken enabling rapid material removal rates. These are used to mill grooves and slots. Plain mills are used to shape flat surfaces. Several cutters may be ganged together on the arbor to mill a complex shape of slots and planes. Special cutters can also cut grooves, bevels, radii, or indeed any section desired. These specialty cutters tend to be expensive. Simplex mills have one spindle, and duplex mills have two. It is also easier to cut gears on a horizontal mill. Some horizontal milling machines are equipped with a power-take-off provision on the table. This allows the table feed to be synchronized to a rotary fixture, enabling the milling of spiral features such as hypoid gears.
Universal.
Is a milling machine with the facility to either have a horizontal spindle or a vertical spindle. The latter sometimes being on a two-axis turret enabling the spindle to be pointed in any direction on desires. The two options may be driven independently or from one motor through gearing. In either case, as the work is generally placed in the same place for either type of operation, the mechanism for the method not being used is moved out of the way. In smaller machines, "spares" may be lifted off while larger machines offer a system to retract those parts not in use.
Comparative merits.
The choice between vertical and horizontal spindle orientation in milling machine design usually hinges on the shape and size of a workpiece and the number of sides of the workpiece that require machining. Work in which the spindle's axial movement is normal to one plane, with an endmill as the cutter, lends itself to a vertical mill, where the operator can stand before the machine and have easy access to the cutting action by looking down upon it. Thus vertical mills are most favored for diesinking work (machining a mould into a block of metal). Heavier and longer workpieces lend themselves to placement on the table of a horizontal mill.
Prior to numerical control, horizontal milling machines evolved first, because they evolved by putting milling tables under lathe-like headstocks. Vertical mills appeared in subsequent decades, and accessories in the form of add-on heads to change horizontal mills to vertical mills (and later vice versa) have been commonly used. Even in the CNC era, a heavy workpiece needing machining on multiple sides lends itself to a horizontal machining center, while diesinking lends itself to a vertical one.
Alternative classifications.
In addition to horizontal versus vertical, other distinctions are also important:
Alternative terminology.
A milling machine is often called a mill by machinists. The archaic term miller was commonly used in the 19th and early 20th centuries.
Since the 1960s there has developed an overlap of usage between the terms milling machine and machining center. NC/CNC machining centers evolved from milling machines, which is why the terminology evolved gradually with considerable overlap that still persists. The distinction, when one is made, is that a machining center is a mill with features that pre-CNC mills never had, especially an automatic tool changer (ATC) that includes a tool magazine (carousel), and sometimes an automatic pallet changer (APC). In typical usage, all machining centers are mills, but not all mills are machining centers; only mills with ATCs are machining centers.
Computer numerical control.
Most CNC milling machines (also called "machining centers") are computer controlled vertical mills with the ability to move the spindle vertically along the Z-axis. This extra degree of freedom permits their use in diesinking, engraving applications, and 2.5D surfaces such as relief sculptures. When combined with the use of conical tools or a ball nose cutter, it also significantly improves milling precision without impacting speed, providing a cost-efficient alternative to most flat-surface hand-engraving work.
CNC machines can exist in virtually any of the forms of manual machinery, like horizontal mills. The most advanced CNC milling-machines, the multiaxis machine, add two more axes in addition to the three normal axes (XYZ). Horizontal milling machines also have a C or Q axis, allowing the horizontally mounted workpiece to be rotated, essentially allowing asymmetric and eccentric turning. The fifth axis (B axis) controls the tilt of the tool itself. When all of these axes are used in conjunction with each other, extremely complicated geometries, even organic geometries such as a human head can be made with relative ease with these machines. But the skill to program such geometries is beyond that of most operators. Therefore, 5-axis milling machines are practically always programmed with CAM.
The operating system of such machines is a closed loop system and functions on feedback.
These machines have developed from the basic NC (NUMERIC CONTROL) machines. A computerized form of NC machines is known as CNC machines. A set of instructions (called a program) is used to guide the machine for desired operations. There are over 100 different G-codes and M-codes. Some very commonly used codes, which are used in the program are:
 G00 – rapid traverse
 G01 – linear interpolation of tool
 G02 - circular arc clockwise (cw)
 G03 - circular arc counter-clockwise (ccw)
 G20 - dimensions in inch
 G21 – dimensions in mm
 G28 - return to reference point
 G40 - Tool compensation cancel
 G41 - Tool compensation left
 G42 - Tool compensation right
 G43 - Tool length compensation
 G54 - Select coordinate system #1
 M03 – spindle start (clockwise)
 M04 – spindle start (counter-clockwise)
 M05 - spindle stop
 M06 - tool change
 M08 - coolant on
 M09 - coolant off
 M30 – program end
Various other codes are also used. A CNC machine is operated by a single operator called a programmer. This machine is capable of performing various operations automatically and economically.
With the declining price of computers and open source CNC software, the entry price of CNC machines has plummeted.
Tooling.
The accessories and cutting tools used on machine tools (including milling machines) are referred to in aggregate by the mass noun "tooling". There is a high degree of standardization of the tooling used with CNC milling machines, and a lesser degree with manual milling machines. To ease up the organization of the tooling in CNC production many companies use a tool management solution.
Milling cutters for specific applications are held in various tooling configurations.
CNC milling machines nearly always use SK (or ISO), CAT, BT or HSK tooling. SK tooling is the most common in Europe, while CAT tooling, sometimes called V-Flange Tooling, is the oldest and probably most common type in the USA. CAT tooling was invented by Caterpillar Inc. of Peoria, Illinois, in order to standardize the tooling used on their machinery. CAT tooling comes in a range of sizes designated as CAT-30, CAT-40, CAT-50, etc. The number refers to the Association for Manufacturing Technology (formerly the National Machine Tool Builders Association (NMTB)) taper size of the tool.
An improvement on CAT Tooling is BT Tooling, which looks similar and can easily be confused with CAT tooling. Like CAT Tooling, BT Tooling comes in a range of sizes and uses the same NMTB body taper. However, BT tooling is symmetrical about the spindle axis, which CAT tooling is not. This gives BT tooling greater stability and balance at high speeds. One other subtle difference between these two toolholders is the thread used to hold the pull stud. CAT Tooling is all Imperial thread and BT Tooling is all Metric thread. Note that this affects the pull stud only; it does not affect the tool that they can hold. Both types of tooling are sold to accept both Imperial and metric sized tools.
SK and HSK tooling, sometimes called "Hollow Shank Tooling", is much more common in Europe where it was invented than it is in the United States. It is claimed that HSK tooling is even better than BT Tooling at high speeds. The holding mechanism for HSK tooling is placed within the (hollow) body of the tool and, as spindle speed increases, it expands, gripping the tool more tightly with increasing spindle speed. There is no pull stud with this type of tooling.
For manual milling machines, there is less standardization, because a greater plurality of formerly competing standards exist. Newer and larger manual machines usually use NMTB tooling. This tooling is somewhat similar to CAT tooling but requires a drawbar within the milling machine. Furthermore, there are a number of variations with NMTB tooling that make interchangeability troublesome. The older a machine, the greater the plurality of standards that may apply (e.g., Morse, Jarno, Brown & Sharpe, Van Norman, and other less common builder-specific tapers). However, two standards that have seen especially wide usage are the Morse #2 and the R8, whose prevalence was driven by the popularity of the mills built by Bridgeport Machines of Bridgeport, Connecticut. These mills so dominated the market for such a long time that "Bridgeport" is virtually synonymous with "manual milling machine". Most of the machines that Bridgeport made between 1938 and 1965 used a Morse taper #2, and from about 1965 onward most used an R8 taper.
CNC pocket milling.
Pocket milling has been regarded as one of the most widely used operations in machining. It is extensively used in aerospace and shipyard industries. In pocket milling the material inside an arbitrarily closed boundary on a flat surface of a work piece is removed to a fixed depth. Generally flat bottom end mills are used for pocket milling. Firstly roughing operation is done to remove the bulk of material and then the pocket is finished by a finish end mill.
Most of the industrial milling operations can be taken care of by 2.5 axis CNC milling. This type of path control can machine up to 80% of all mechanical parts. Since the importance of pocket milling is very relevant, therefore effective pocketing approaches can result in reduction in machining time and cost.
NC pocket milling can be carried out mainly by two tool paths, viz. linear and non-linear.
Linear tool path.
In this approach, the tool movement is unidirectional. Zig-zag and zig tool paths are the examples of linear tool path.
Zig-zag.
In zig-zag milling, material is removed both in forward and backward paths. In this case, cutting is done both with and against the rotation of the spindle. This reduces the machining time but increases machine chatter and tool wear.
Zig.
In zig milling, the tool moves only in one direction. The tool has to be lifted and retracted after each cut, due to which machining time increases. However, in case of zig milling surface quality is better.
Non-linear tool path.
In this approach, tool movement is multi-directional. One example of non-linear tool path is contour-parallel tool path.
Contour-parallel.
In this approach, the required pocket boundary is used to derive the tool path. In this case the cutter is always in contact with the work material. Hence the idle time spent in positioning and retracting the tool is avoided. For large-scale material removal, contour-parallel tool path is widely used because it can be consistently used with up-cut or down-cut method during the entire process. There are three different approaches that fall into the category of contour-parallel tool path generation. They are:
Curvilinear.
In this approach, the tool travels along a gradually evolving spiral path. The spiral starts at the center of the pocket to be machined and the tool gradually moves towards the pocket boundary. The direction of the tool path changes progressively and local acceleration and deceleration of the tool are minimized. This reduces tool wear.
History.
1780-1810.
Milling machines evolved from the practice of rotary filing—that is, running a circular cutter with file-like teeth in the headstock of a lathe. Rotary filing and, later, true milling were developed to reduce time and effort spent hand-filing. The full story of milling machine development may never be known, because much early development took place in individual shops where few records were kept for posterity. However, the broad outlines are known, as summarized below. From a history-of-technology viewpoint, it is clear that the naming of this new type of machining with the term "milling" was an extension from that word's earlier senses of processing materials by abrading them in some way (cutting, grinding, crushing, etc.).
Rotary filing long predated milling. A rotary file by Jacques de Vaucanson, circa 1760, is well known.
In 1783, Samuel Rehe invented a true milling machine. In 1795, Eli Terry began using a milling machine at Plymouth Connecticut in the production of tall case clocks. With the use of his milling machine, Terry was the first to accomplish Interchangeable parts in the clock industry. Milling wooden parts was efficient in interchangeable parts, but inefficient in high yields. Milling wooden blanks results in a low yield of parts because the machines single blade would cause loss of gear teeth when the cutter hit parallel grains in the wood. Terry later invented a spindle cutting machine to mass produce parts in 1807. Other Connecticut clockmakers like James Harrison of Waterbury, Thomas Barnes of Litchfield, and Gideon Roberts of Bristol, also used milling machines to produce their clocks.
1810s–1830s.
It is clear that milling machines as a distinct class of machine tool (separate from lathes running rotary files) first appeared between 1814 and 1818. The centers of earliest development of true milling machines were two federal armories of the U.S. (Springfield and Harpers Ferry) together with the various private armories and inside contractors that shared turnover of skilled workmen with them.
Between 1912 and 1916, Joseph W. Roe, a respected founding father of machine tool historians, credited Eli Whitney (one of the private arms makers mentioned above) with producing the first true milling machine. By 1918, he considered it "Probably the first milling machine ever built—certainly the oldest now in existence […]." However, subsequent scholars, including Robert S. Woodbury and others, have improved upon Roe's early version of the history and suggest that just as much credit—in fact, probably more—belongs to various other inventors, including Robert Johnson of Middletown, Connecticut; Captain John H. Hall of the Harpers Ferry armory; Simeon North of the Staddle Hill factory in Middletown; Roswell Lee of the Springfield armory; and Thomas Blanchard. (Several of the men mentioned above are sometimes described on the internet as "the inventor of the first milling machine" or "the inventor of interchangeable parts". Such claims are oversimplified, as these technologies evolved over time among many people.)
Peter Baida, citing Edward A. Battison's article "Eli Whitney and the Milling Machine," which was published in the "Smithsonian Journal of History" in 1966, exemplifies the dispelling of the "Great Man" image of Whitney by historians of technology working in the 1950s and 1960s. He quotes Battison as concluding that "There is no evidence that Whitney developed or used a true milling machine." Baida says, "The so-called Whitney machine of 1818 seems actually to have been made after Whitney's death in 1825." Baida cites Battison's suggestion that the first true milling machine was made not by Whitney, but by Robert Johnson of Middletown.
The late teens of the 19th century were a pivotal time in the history of machine tools, as the period of 1814 to 1818 is also the period during which several contemporary pioneers (Fox, Murray, and Roberts) were developing the planer, and as with the milling machine, the work being done in various shops was undocumented for various reasons (partially because of proprietary secrecy, and also simply because no one was taking down records for posterity).
James Nasmyth built a milling machine very advanced for its time between 1829 and 1831. It was tooled to mill the six sides of a hex nut that was mounted in a six-way indexing fixture.
A milling machine built and used in the shop of Gay & Silver (aka Gay, Silver, & Co) in the 1830s was influential because it employed a better method of vertical positioning than earlier machines. For example, Whitney's machine (the one that Roe considered the very first) and others did not make provision for vertical travel of the knee. Evidently, the workflow assumption behind this was that the machine would be set up with shims, vise, etc. for a certain part design, and successive parts did not require vertical adjustment (or at most would need only shimming). This indicates that early thinking about milling machines was as production and not as toolroom machines.
In these early years, milling was often viewed as only a roughing operation to be followed by finishing with a hand file. The idea of "reducing" hand filing was more important than "replacing" it.
1840s–1860.
Some of the key men in milling machine development during this era included Frederick W. Howe, Francis A. Pratt, Elisha K. Root, and others. (These same men during the same era were also busy developing the state of the art in turret lathes. Howe's experience at Gay & Silver in the 1840s acquainted him with early versions of both machine tools. His machine tool designs were later built at Robbins & Lawrence, the Providence Tool Company, and Brown & Sharpe.) The most successful milling machine design to emerge during this era was the , which rather than being a specific make and model of machine tool is truly a family of tools built by various companies on a common configuration over several decades. It took its name from the first company to put one on the market, George S. Lincoln & Company (formerly the Phoenix Iron Works), whose first one was built in 1855 for the Colt armory.
During this era there was a continued blind spot in milling machine design, as various designers failed to develop a truly simple and effective means of providing slide travel in all three of the archetypal milling axes (X, Y, and Z—or as they were known in the past, longitudinal, traverse, and vertical). Vertical positioning ideas were either absent or underdeveloped. The Lincoln miller's spindle could be raised and lowered, but the original idea behind its positioning was to be set up in position and then run, as opposed to being moved frequently while running. Like a turret lathe, it was a repetitive-production machine, with each skilled setup followed by extensive fairly low skill operation.
1860s.
In 1861, Frederick W. Howe, while working for the Providence Tool Company, asked Joseph R. Brown of Brown & Sharpe for a solution to the problem of milling spirals, such as the flutes of twist drills. These were usually filed by hand at the time. (Helical planing existed but was by no means common.) Brown designed a "universal milling machine" that, starting from its first sale in March 1862, was wildly successful. It solved the problem of 3-axis travel (i.e., the axes that we now call XYZ) much more elegantly than had been done in the past, and it allowed for the milling of spirals using an indexing head fed in coordination with the table feed. The term "universal" was applied to it because it was ready for any kind of work, including toolroom work, and was not as limited in application as previous designs. (Howe had designed a "universal miller" in 1852, but Brown's of 1861 is the one considered a groundbreaking success.)
Brown also developed and patented (1864) the design of formed milling cutters in which successive sharpenings of the teeth do not disturb the geometry of the form.
The advances of the 1860s opened the floodgates and ushered in modern milling practice.
1870s to World War I.
In these decades, Brown & Sharpe and the Cincinnati Milling Machine Company dominated the American milling machine field. However, hundreds of other firms also built milling machines at the time, and many were significant in various ways. Besides a wide variety of specialized production machines, the archetypal multipurpose milling machine of the late 19th and early 20th centuries was a heavy knee-and-column horizontal-spindle design with power table feeds, indexing head, and a stout overarm to support the arbor. The evolution of machine design was driven not only by inventive spirit but also by the constant evolution of milling cutters that saw milestone after milestone from 1860 through World War I.
World War I and interwar period.
Around the end of World War I, machine tool control advanced in various ways that laid the groundwork for later CNC technology. The jig borer popularized the ideas of coordinate dimensioning (dimensioning of all locations on the part from a single reference point); working routinely in "tenths" (ten-thousandths of an inch, 0.0001") as an everyday machine capability; and using the control to go straight from drawing to part, circumventing jig-making. In 1920 the new tracer design of J.C. Shaw was applied to Keller tracer milling machines for die sinking via the three dimensional copying of a template. This made die sinking faster and easier just as dies were in higher demand than ever before, and was very helpful for large steel dies such as those used to stamp sheets in automobile manufacturing. Such machines translated the tracer movements to input for servos that worked the machine leadscrews or hydraulics. They also spurred the development of antibacklash leadscrew nuts. All of the above concepts were new in the 1920s but became routine in the NC/CNC era. By the 1930s, incredibly large and advanced milling machines existed, such as the Cincinnati Hydro-Tel, that presaged today's CNC mills in every respect except for CNC control itself.
Bridgeport milling machine.
In 1936, Rudolph Bannow (1897–1962) conceived of a major improvement to the milling machine. His company commenced manufacturing a new knee-and-column vertical mill in 1938. This was the Bridgeport milling machine, often called a ram-type or turret-type mill because its head has sliding-ram and rotating-turret mounting. The machine became so popular that many other manufacturers created copies and variants. Furthermore, its name came to connote any such variant. The Bridgeport offered enduring advantages over previous models. It was small enough, light enough, and affordable enough to be a practical acquisition for even the smallest machine shop businesses, yet it was also smartly designed, versatile, well-built, and rigid. Its various directions of sliding and pivoting movement allowed the head to approach the work from any angle. The Bridgeport's design became the dominant form for manual milling machines used by several generations of small- and medium-enterprise machinists. By the 1980s an estimated quarter-million Bridgeport milling machines had been built, and they (and their clones) are still being produced today.
1940s–1970s.
By 1940, automation via cams, such as in screw machines and automatic chuckers, had already been very well developed for decades. Beginning in the 1930s, ideas involving servomechanisms had been in the air, but it was especially during and immediately after World War II that they began to germinate (see also Numerical control > History). These were soon combined with the emerging technology of digital computers. This technological development milieu, spanning from the immediate pre–World War II period into the 1950s, was powered by the military capital expenditures that pursued contemporary advancements in the directing of gun and rocket artillery and in missile guidance—other applications in which humans wished to control the kinematics/dynamics of large machines quickly, precisely, and automatically. Sufficient R&D spending probably would not have happened within the machine tool industry alone; but it was for the latter applications that the will and ability to spend was available. Once the development was underway, it was eagerly applied to machine tool control in one of the many post-WWII instances of technology transfer.
In 1952, numerical control reached the developmental stage of laboratory reality. The first NC machine tool was a Cincinnati Hydrotel milling machine retrofitted with a scratch-built NC control unit. It was reported in "Scientific American", just as another groundbreaking milling machine, the Brown & Sharpe universal, had been in 1862.
During the 1950s, numerical control moved slowly from the laboratory into commercial service. For its first decade, it had rather limited impact outside of aerospace work. But during the 1960s and 1970s, NC evolved into CNC, data storage and input media evolved, computer processing power and memory capacity steadily increased, and NC and CNC machine tools gradually disseminated from an environment of huge corporations and mainly aerospace work to the level of medium-sized corporations and a wide variety of products. NC and CNC's drastic advancement of machine tool control deeply transformed the culture of manufacturing. The details (which are beyond the scope of this article) have evolved immensely with every passing decade.
1980s–present.
Computers and CNC machine tools continue to develop rapidly. The personal computer revolution has a great impact on this development. By the late 1980s small machine shops had desktop computers and CNC machine tools. Soon after, hobbyists, artists, and designers began obtaining CNC mills and lathes. Manufacturers have started producing economically priced CNCs machines small enough to sit on a desktop which can cut at high resolution materials softer than stainless steel. They can be used to make anything from jewelry to printed circuit boards to gun parts, even fine art.
Standards.
National and international standards are used to standardize the definitions, environmental requirements, and test methods used for milling. Selection of the standard to be used is an agreement between the supplier and the user and has some significance in the design of the mill. In the United States, ASME has developed the standards B5.45-1972 "Milling Machines" and B94.19-1997 "Milling Cutters and End Mills".
General tolerances include: +/-0.005" (~0.1mm) for local tolerances across most geometries, +/-0.010" (~0.25mm) for plastics with variation depending on the size of the part, 0.030" (~0.75mm) minimum wall thickness for metals, and 0.060" (~1.5mm) minimum wall thickness for plastics.


Mill finish

Mill finish is the surface texture (or finish) of metal after it exits a rolling mill, extrusion die, or drawing processes, including sheet, bar, plate, or structural shapes. This texture is usually rough and lacks lustre; it may have spots of oxidation or contamination with mill oil. Most mill finish surfaces are machined or treated with polishing, industrial etching, or some other surface finishing process before they are considered complete.
The quality and characteristics of mill finish can vary widely from one mill to another, and even from one lot (set of similar parts all processed consecutively or in a short time) to another. Hot rolled parts are usually dark and dull, their surface oxidized from being hot worked. Extruded products may have die marks running the length of the stock. Other mill finishes are surprisingly smooth and uniform.
It is possible for a mill to influence the finish of produced stock. Carefully maintained and polished rollers can increase the smoothness and lustre of their product, and some rolling mills will follow rolling with an annealling process to give the stock a matte finish.


Grinding machine

A grinding machine, often shortened to grinder, is a power tool (or machine tool) used for grinding. It is a type of machining using an abrasive wheel as the cutting tool. Each grain of abrasive on the wheel's surface cuts a small chip from the workpiece via shear deformation.
Grinding is used to finish workpieces that must show high surface quality (e.g., low surface roughness) and high accuracy of shape and dimension. As the accuracy in dimensions in grinding is of the order of 0.000025  mm, in most applications, it tends to be a finishing operation and removes comparatively little metal, about 0.25 to 0.50  mm depth. However, there are some roughing applications in which grinding removes high volumes of metal quite rapidly. Thus, grinding is a diverse field.
Overview.
The grinding machine consists of a bed with a fixture to guide and hold the workpiece and a power-driven grinding wheel spinning at the required speed. The wheel’s diameter and the manufacturer’s rating determine the speed. The grinding head can travel across a fixed workpiece, or the workpiece can be moved while the grinding head stays in a fixed position.
Fine control of the grinding head or table position is possible using a vernier calibrated hand wheel or using the features of numerical controls.
Grinding machines remove material from the workpiece by abrasion, which can generate substantial amounts of heat. To cool the workpiece so that it does not overheat and go outside its tolerance, grinding machines incorporate a coolant. The coolant also benefits the machinist as the heat generated may cause burns. In high-precision grinding machines (most cylindrical and surface grinders), the final grinding stages are usually set up so that they remove about 200  nm (less than 1/10000  in) per pass - this generates so little heat that even with no coolant, the temperature rise is negligible.
Types.
These machines include the:


Back end of line

The back end of line (BEOL) is the second portion of IC fabrication where the individual devices (transistors, capacitors, resistors, etc.) get interconnected with wiring on the wafer, the metalization layer. Common metals are copper and aluminum.
BEOL generally begins when the first layer of metal is deposited on the wafer. BEOL includes contacts, insulating layers (dielectrics), metal levels, and bonding sites for chip-to-package connections.
After the last FEOL step, there is a wafer with isolated transistors (without any wires). In BEOL part of fabrication stage contacts (pads), interconnect wires, vias and dielectric structures are formed. For modern IC process, more than 10 metal layers can be added in the BEOL.
Steps of the BEOL:
Before 1998, practically all chips used aluminium for the metal interconnection layers.
The four metals with the highest electrical conductivity are silver with the highest conductivity, then copper, then gold, then aluminium.
After BEOL there is a "back-end process" (also called post-fab), which is done not in the cleanroom, often by a different company.
It includes wafer test, wafer backgrinding, die separation, die tests, IC packaging and final test.


Developable surface

In mathematics, a developable surface (or torse: archaic) is a smooth surface with zero Gaussian curvature. That is, it is a surface that can be flattened onto a plane without distortion (i.e. it can be bent without stretching or compression). Conversely, it is a surface which can be made by transforming a plane (i.e. "folding", "bending", "rolling", "cutting" and/or "gluing"). In three dimensions all developable surfaces are ruled surfaces (but not vice versa). There are developable surfaces in four-dimensional space which are not ruled.
The envelope of a single parameter family of planes is called a developable surface.
Particulars.
The developable surfaces which can be realized in three-dimensional space include:
Formally, in mathematics, a developable surface is a surface with zero Gaussian curvature. One consequence of this is that all "developable" surfaces embedded in 3D-space are ruled surfaces (though hyperboloids are examples of ruled surfaces which are not developable). Because of this, many developable surfaces can be visualised as the surface formed by moving a straight line in space. For example, a cone is formed by keeping one end-point of a line fixed whilst moving the other end-point in a circle.
Application.
Developable surfaces have several practical applications.
Developable Mechanisms are mechanisms that conform to a developable surface and can exhibit motion (deploy) off the surface.
Many cartographic projections involve projecting the Earth to a developable surface and then "unrolling" the surface into a region on the plane.
Since developable surfaces may be constructed by bending a flat sheet, they are also important in manufacturing objects from sheet metal, cardboard, and plywood. An industry which uses developed surfaces extensively is shipbuilding.
Non-developable surface.
Most smooth surfaces (and most surfaces in general) are not developable surfaces. Non-developable surfaces are variously referred to as having "double curvature", "doubly curved", "compound curvature", "non-zero Gaussian curvature", etc.
Some of the most often-used non-developable surfaces are:
Applications of non-developable surfaces.
Many gridshells and tensile structures and similar constructions gain strength by using (any) doubly curved form.


Punching

Punching is a forming process that uses a punch press to force a tool, called a "punch", through the workpiece to create a hole via shearing. Punching is applicable to a wide variety of materials that come in sheet form, including sheet metal, paper, vulcanized fibre and some forms of plastic sheet. The punch often passes through the work into a die. A scrap slug from the hole is deposited into the die in the process. Depending on the material being punched this slug may be recycled and reused or discarded.
Punching is often the cheapest method for creating holes in sheet materials in medium to high production volumes. When a specially shaped punch is used to create multiple usable parts from a sheet of material the process is known as blanking. In metal forging applications the work is often punched while hot, and this is called hot punching.
Slugging is the operation of punching in which the punch is stopped as soon as the metal fracture is complete and metal is not removed but held in hole.
Process.
Punch tooling (punch and die) is often made of hardened steel or tungsten carbide. A die is located on the opposite side of the workpiece and supports the material around the perimeter of the hole and helps to localize the shearing forces for a cleaner edge. There is a small amount of clearance between the punch and the die to prevent the punch from sticking in the die and so less force is needed to make the hole. The amount of clearance needed depends on the thickness, with thicker materials requiring more clearance, but the clearance is always less than the thickness of the workpiece. The clearance is also dependent on the hardness of the workpiece. The punch press forces the punch through a workpiece, producing a hole that has a diameter equivalent to the punch, or slightly smaller after the punch is removed. All ductile materials stretch to some extent during punching which often causes the punch to stick in the workpiece. In this case, the punch must be physically pulled back out of the hole while the work is supported from the punch side, and this process is known as stripping. The hole walls will show burnished area, rollover, and die break and must often be further processed. The slug from the hole falls through the die into some sort of container to either dispose of the slug or recycle it.
Punching characteristics.
The characteristics of punching are:
Geometry.
The workpiece is often in the form of a sheet or roll. Materials for the workpiece can vary, commonly being metals and plastics. The punch and die themselves can have a variety of shapes to create an array of different shaped holes in the workpiece. Multiple punches may be used together to create a part in one step.
Usually, the punch and die are close to the same dimensions, creating a sheared edge when they meet. A punch that is significantly smaller than the die can be used to produce an "extruded hole" where the punch displaces the punched material to the sides, forming a tube perpendicular to the punched sheet.
Equipment.
Most punch presses are mechanically operated, but simple punches are often hand-powered. Major components of this mechanical press are the frame, motor, ram, die posts, bolster, and bed. The punch is mounted into the ram, and the die is mounted to the bolster plate. The scrap material drops through as the workpiece is advanced for the next hole. Most common in industry are large computer-controlled punch press, called a CNC. These most commonly are of the 'turret' or 'rail' variety. A turret punch press houses punches and their corresponding dies in a revolving indexed turret, while a rail type punch stores tooling on a back rail out of the way of the workpiece. These machines use hydraulic as well as pneumatic power to press the shape with enough force to shear the metal.
Forces.
The punch force required to punch a piece of sheet metal can be estimated from the following equation:
Where "t" is the sheet metal thickness, "L" is the total length sheared (perimeter of the shape), and "UTS" is the ultimate tensile strength of the material.
Die and punch shapes affect the force during the punching process. The punch force increases during the process as the entire thickness of the material is sheared at once. A beveled punch helps in the shearing of thicker materials by reducing the force at the beginning of the stroke. However, beveling a punch will distort the shape because of lateral forces that develop. Compound dies allow multiple shaping to occur. Using compound dies will generally slow down the process and are typically more expensive than other dies. Progressive dies may be used in high production operations. Different punching operations and dies may be used at different stages of the operation on the same machine.
Related processes.
Other processes such as stamping, blanking, perforating, parting, drawing, notching, lancing and bending operations are all related to punching.
Plastics.
Punching in plastics fabrication usually refers to the removal of scrap plastic from the desired article. For example, in extrusion blow molding it is common to use punching dies to remove tails, molding flash (scrap plastic) and handle slugs from bottles or other molded containers.
In shuttle machinery, the containers are usually trimmed in the machines, and finished containers leave the blow molding machine. Other blow molding equipment, such as rotary wheel machinery, requires the use of downstream trimming. Types of downstream trimming equipment include detabbers for tail removal, rotary or reciprocating punch trimmers, and spin trimmers.


Chassis cab

A chassis cab, also called a cab chassis or half truck, is a type of vehicle construction, often found in medium duty truck commercial vehicles.
Instead of supplying the customer with a factory pre-assembled flatbed, cargo container, or other equipment, the customer is given the vehicle with just chassis rails and a cab. This allows the customer to add any desired aftermarket equipment, such as fire apparatus, ambulance, or a recreational vehicle conversion package, which can be customized for the specific needs of the customer.
Cutaway van chassis are similar vehicles, but have specific components at the rear whereas chassis cabs usually do not have additional components.
Vehicles of this type are produced by Ford, Chevrolet/GMC, and Ram Trucks.


Calo tester

The Calo tester, also known as a ball craterer or coating thickness tester, is a simple and inexpensive piece of equipment used to measure the thickness of coatings. Coatings with thicknesses typically between 0.1 to 50 micrometres, such as Physical Vapor Deposition (PVD) coatings or Chemical Vapor Deposition (CVD) coatings, are used in many industries to improve the surface properties of tools and components.
The Calo tester is also used to measure the amount of coating wear after a wear test carried out using a Pin-on-Disc Tester.
The Calo tester consists of a holder for the surface to be tested and a steel sphere of known diameter that is rotated against the surface by a rotating shaft connected to a motor whilst diamond paste is applied to the contact area. The sphere is rotated for a short period of time (less than 20 seconds for a 0.1 to 5 micrometre thickness) but due to the abrasive nature of the diamond paste this is sufficient time to wear a crater through thin coatings.
Calculating coating thickness using the Calo tester.
An optical microscope is used to take two measurements across the crater after the Calo test and the coating thickness is calculated using a simple geometrical equation.
formula_1
Where
t = coating thickness,
d = diameter of the sphere
x = difference between the radius of the crater and radius of the part of the crater at the bottom of the coating
x+y = diameter of the crater


Matsuura Machinery

 is a machine tool manufacturing company based in Fukui, Fukui Prefecture, Japan, in operation since August 1935.
Matsuura Machinery began as a manufacturer and distributor of lathes in 1935. Production of milling machines began in 1957, and the company went public in 1960. Production of automatic-controlled milling machines began in 1961 and numerically controlled milling machines from 1964. Production of automatically controlled drilling machines began in 1972, and vertical machining centers from 1974.
The company began exporting to the United States from 1975. In 1981, Matsuura Machinery began production of high-speed machining centers and twin-spindle vertical machining centers, and horizontal machining centers from 1983. The total number of machining centers shipped surpassed 10,000 units in 1993 and 20,000 in 2015.
The company's machining centers are used in a variety of industries, among them aerospace equipment manufacturers. Machine tools manufactured by Matsuura were used by NASA on the Space Shuttle Discovery's fuel tanks in 1998, making them four tons lighter than before.


Downstream (manufacturing)

Downstream in manufacturing refers to processes that occur later on in a production sequence or production line.
Viewing a company "from order to cash" might have high-level processes such as Marketing, Sales, Order Entry, Manufacturing, Packaging, Shipping, Invoicing. Each of these could be deconstructed into many sub-processes and supporting processes.
The Manufacturing process consists of such sub-processes as Design, Tooling, Inventory Management, Receiving, Assembly, and others. The products being manufactured are created in a sequence of processes. Any process occurring after another is considered to be downstream.


1997–98 UEFA Cup

The 1997–98 UEFA Cup was won by Internazionale in an all-Italian final against Lazio. It was their third title in eight years in the competition.
It was the first instance of the UEFA Cup final being a one-game contest at a neutral stadium, having previously being decided over two legs with each team having one home game.
For first time, one nation (France) was represented by seven teams: Strasbourg, Auxerre, Bastia, Nantes, Lyon, Bordeaux and Metz.
Format.
According to 1996 UEFA ranking, Spain took a slot to Germany (but this one took the place of the holders), the Netherlands took a place from Russia, while Ukraine, Czech Republic, and Hungary took a slot from Israel, FR Yugoslavia and Poland (but this one took the place of troubled Albania).
The access list was finally decreased to 102 clubs, because only the 16 best national champions excluded from the Champions League group stage entered in the UEFA Cup.
Teams.
The labels in the parentheses show how each team qualified for the place of its starting round:
Notes
First qualifying round.
Second leg.
"2–2 on aggregate; Dinamo Minsk won on away goals."
"Hapoel Petah Tikva won 3–1 on aggregate."
"Dnipro Dnipropetrovsk won 8–1 on aggregate."
"Boby Brno won 7–4 on aggregate."
"Apollon Limassol won 4–1 on aggregate."
"Celtic won 8-0 on aggregate."
"Neuchâtel Xamax won 10–1 on aggregate."
"Hajduk Split won 6–1 on aggregate."
"Grasshoppers won 10–1 on aggregate."
"2–2 on aggregate; Viking won 5–4 on penalties."
"KR Reykjavík won 4–1 on aggregate."
" Ferencváros won 6–0 on aggregate."
"FK Jablonec 97 won 8–0 on aggregate."
"Spartak Trnava won 4–1 on aggregate."
"Odra Wodzisław won 4–2 on aggregate."
"Vorskla Poltava won 5–2 on aggregate."
"4–4 on aggregate; Brann won on away goals."
"Dundee United won 17-0 on aggregate."
"4–4 on aggregate; Gorica won on away goals."
"Újpest won 9–2 on aggregate."
Second qualifying round.
Second leg.
"Hajduk Split won 5–2 on aggregate."
"Anderlecht won 4–0 on aggregate."
"Neuchâtel Xamax won 4–2 on aggregate."
"Rotor Volgograd won 6–3 on aggregate."
"Trabzonspor won 2–1 on aggregate."
"Rapid Wien won 6–3 on aggregate."
"Celtic won 7–5 on aggregate."
"1–1 on aggregate; Ferencváros won 4–3 on penalties."
"Hapoel Petah Tikva won 1–0 on aggregate."
"Grasshoppers won 3–2 on aggregate."
"Club Brugge won 8–3 on aggregate."
"PAOK won 6–3 on aggregate."
"OFI Crete won 3–1 on aggregate."
"1–1 on aggregate; Örebro won on away goals."
"Excelsior Mouscron won 3–0 on aggregate."
"Lillestrøm won 3–0 on aggregate."
"AGF Aarhus won 3–2 on aggregate."
"Alania Vladikavkaz won 6–2 on aggregate."
First round.
Second leg.
"Auxerre won 2–1 on aggregate."
"Anderlecht won 7–6 on aggregate."
"PAOK won 2–1 on aggregate."
"Udinese won 3–1 on aggregate."
"Ajax won 10–2 on aggregate."
"Lyon won 7–3 on aggregate."
"Dinamo Tbilisi won 2–1 on aggregate."
"Real Valladolid won 2–1 on aggregate."
"Lazio won 6–1 on aggregate."
"Strasbourg won 4–2 on aggregate."
"MTK Hungária won 4–1 on aggregate."
"Schalke won 5–2 on aggregate."
"Bastia won 1–0 on aggregate."
"Spartak Moscow won 6–1 on aggregate."
"The original 2nd leg game finished 2–2 (scorers: Shirko, Alenichev – Lota 2x) on 30 September (Report), but had to be replayed because the goal posts were 8 cm short of the prescribed height."
"OFI Crete won 4–2 on aggregate."
"Athletic Bilbao won 4–1 on aggregate."
"Aston Villa won 1–0 on aggregate."
"Steaua București won 2–1 on aggregate."
"Rotor Volgograd won 6–1 on aggregate."
"1860 Munich won 7–1 on aggregate."
"Bochum won 6–5 on aggregate."
"Croatia Zagreb won 9–4 on aggregate."
"Braga won 3–2 on aggregate."
"Rapid Wien won 2–1 on aggregate."
"Internazionale won 4–0 on aggregate."
"2–2 on aggregate; Liverpool won on away goals."
"Metz won 6–1 on aggregate."
"2–2 on aggregate; Twente won on away goals."
"Club Brugge won 4–2 on aggregate."
"Atlético Madrid won 4–1 on aggregate."
"AGF Aarhus won 3–2 on aggregate."
"Karlsruhe won 3–2 on aggregate."
Second round.
Second leg.
"Strasbourg won 3–2 on aggregate."
"Internazionale won 4–3 on aggregate."
"Braga won 5–0 on aggregate."
"Schalke 04 won 3–1 on aggregate."
"2–2 on aggregate; Ajax won on away goals."
"Bochum won 4–2 on aggregate."
"Karlsruhe won 3–1 on aggregate."
"Spartak Moscow won 4–1 on aggregate."
"Croatia Zagreb won 2–1 on aggregate."
"Atlético Madrid won 9–6 on aggregate."
"3–3 on aggregate; Steaua București won on away goals."
"Aston Villa won 2–1 on aggregate."
"Rapid Wien won 4–2 on aggregate."
"Lazio won 3–0 on aggregate."
"1–1 on aggregate; Twente won on away goals."
"Auxerre won 5–4 on aggregate."
Third round.
The draw for the third round was held on 7 November 1997.
Second leg.
"Internazionale won 3–2 on aggregate."
"Schalke 04 won 2–0 on aggregate."
"Ajax won 6–4 on aggregate."
"Spartak Moscow won 1–0 on aggregate."
"Atlético Madrid won 2–1 on aggregate."
"Aston Villa won 3–2 on aggregate."
"Lazio won 3–0 on aggregate."
"Auxerre won 3–0 on aggregate."
Quarter-finals.
Second leg.
"Internazionale won 2–1 on aggregate."
"Spartak Moscow won 4–1 on aggregate."
"2–2 on aggregate; Atlético Madrid won on away goals."
"Lazio won 3–2 on aggregate."
Semi-finals.
Second leg.
"Internazionale won 4–2 on aggregate."
"Lazio won 1–0 on aggregate."


Multi-pack

A multi-pack also known as multipack is packaging that combines or holds multiple items or smaller packages.
Functions.
Multi-packs can be used to:
Methods.
A wide variety of materials and procedures are available to combine items or packages into a multi-pack. This can include shrink film, pressure sensitive tape, paper overwrap, adhesives, paperboard carriers, plastic clips, etc.
Beverages.
Beverage cans and bottles are sold in multi-packs such as six packs, twelve packs, and cases of 24. These can be paperboard baskets, paperboard overwraps and cartons, corrugated fiberboard boxes, HDPE plastic handles, six pack rings, and shrink packs.
Other uses.
A wide variety of items and packages are combined into multi-packs for sale.


Low pressure molding

Low pressure molding (LPM) with polyamide and polyolefin (hot-melt) materials is a process typically used to encapsulate and environmentally protect electronic components (such as circuit boards). The purpose is to protect electronics against moisture, dust dirt and vibration. Low pressure molding is also used for sealing connectors and molding grommets and strain reliefs.
Process.
Key to this process are the raw materials and specialized molding equipment. Dimer acid based polyamide materials, better known as hot-melts, are used as molding compounds. They are thermoplastics i.e. the material, when heated, becomes less viscous and is able to be reshaped, then hardens to keep the desired form upon cooling down. These polyamide materials differ from other thermoplastics in two main areas:
The mainly used amorphous thermoplastic polyamides combine a favourable viscosity spectrum with a wide application temperature range from . The material is heated until liquid (typically at ) and then injected at very low pressure, typically into a relative cold mold-set. The low viscosity polyamide material flows gently into the mold-set cavity and around the electronics to be encapsulated. It also starts cooling down as soon as it touches the mold-set cavity and the electronics. A mold-set cavity is typically filled in a few seconds but a typical full molding cycle is 20 to 45 seconds. As the polyamide material starts to cool down it also starts to shrink. Continuous injection pressure is therefore applied to the cavity, even after its initial fill. This is done in order to compensate for the shrinkage that naturally occurs when the polyamide material goes from liquid to solid (i.e. hot to cold). The polyamide temperature is not too hot for the electronics and does not re-melt or re-flow the solder. This is simply because the relative cold mold-set will absorb the brunt of the heat, thereby reducing the temperature that a circuit board may see. Millions of circuit boards are successfully over-molded without causing any harm in the process. A low injection pressure does not stress a fragile solder joint.
Use.
The low pressure molding process was initially used in Europe in the 1970s to seal connectors and create strain reliefs for wires. The first commercial use of the low pressure molding process was in the automotive industry. The driving force was to replace toxic and cumbersome potting processes, faster cycle times, lighter parts and environmentally safe components and for some applications to replace heat shrink tubings.
Since then low pressure molding has spread out to other areas such as industrial products, medical, consumer products, military, wire harness and any unique product that needs to be sealed and protected against the environment, like Automotive sensors in-cabin and even under hood, USB thumb drives, RFID tags, moisture sensors, motor control boards, consumer products. In essence the process acts as a middle ground between plastic injection molding which subjects components to high pressure and temperatures that can often damage them and potting with resin a process that involves waste and lengthy curing times.


E-four

E-Four (short for Electrical 4WD System), eFour, AWD-i, or AWD-e was developed by Toyota. Front wheels are powered directly by the hybrid powertrain, rear wheels are powered by a dedicated electric motor with its own power control unit, reduction gear and differential. Amount of torque transferred to the rear wheels is automatically adjusted by the vehicle's electronic control unit according to driving conditions. E-Four also adds additional regenerative braking. In North America, Toyota uses the term "AWD-i" (All-Wheel Drive with Intelligence). There is no drive shaft between the front combustion engine and rear wheels. The rear wheels only receive power and torque from the rear electric motor(s).
E-Four was first implemented in the 2001 Toyota Estima Hybrid and is used in several Toyota and Lexus cars, e.g. 2016 Toyota RAV4, Lexus NX 300h, Lexus RX 450h, and Toyota Prius AWD-e, and in the future may be used in the standard fifth generation Toyota Prius. In Japan, the all-wheel-drive Prius has been available since 2015 and bumps the price by about $1700. The compact HV4WD E-Four used for the Prius adds little weight and doesn't reduce the fuel economy or interior storage. A few weeks before the November 2018 Los Angeles Auto Show, Toyota issued a press release with text and images featuring the car in snowy conditions, suggesting the E-Four package would likely debut in the 2019 U.S. model at the show.


Proportional share scheduling

Proportional Share Scheduling is a type of scheduling that preallocates certain amount of CPU time to each of the processes. In a proportional share algorithm every job has a weight, and jobs receive a share of the available resources proportional to the weight of every job.


Lathe center

A lathe center, often shortened to center, is a tool that has been ground to a point to accurately position a workpiece on an axis. They usually have an included angle of 60°, but in heavy machining situations an angle of 75° is used.
The primary use of a center is to ensure concentric work is produced; this allows the workpiece to be transferred between machining (or inspection) operations without any loss of accuracy. A part may be "turned" in a lathe, sent off for hardening and tempering and then ground "between centers" in a cylindrical grinder. The preservation of concentricity between the turning and grinding operations is crucial for quality work.
When turning between centres, a steady can be used to support longer workpieces where the cutting forces would deflect the work excessively, reducing the finish and accuracy of the workpiece, or creating a hazardous situation.
A center lathe has applications anywhere that a "centered" workpiece may be used; this is not limited to lathe usage but may include setups in dividing heads, cylindrical grinders, tool and cutter grinders or other related equipment. The term "between centers" refers to any machining operation where the job needs to be performed using centers.
A center is inserted into a matching hole drilled by a center drill. The hole is conical near the surface and cylindrical as it gets deeper.
Dead center (and live center).
A dead center (one that does not turn freely, i.e., "dead") may be used to support the workpiece at either the fixed or rotating end of the machine. When used in the fixed position, a dead center produces friction between the workpiece and center, due to the rotation of the workpiece. Lubrication is therefore required between the center and workpiece to prevent friction welding from occurring. Additionally the tip of the center may have an insert of cemented carbide which will reduce the friction slightly and allow for faster speeds. Dead centers are typically fully hardened to prevent damage to the important mating surfaces of the taper and to preserve the 60° angle of the nose. As tungsten carbide is much harder than steel, a carbide-tipped center has greater wear resistance than a steel center.
When turning between centres, a 'dead centre' is used in the headstock as well as the tailstock. As the one in the headstock revolves with the work, this centre is known as a live centre.
Soft center.
Soft centers are a special version of the dead center in which the nose is deliberately left soft (unhardened) so that it may be readily machined to the correct angle prior to usage. This operation is performed on the headstock center to ensure that the center's axis is aligned with the spindle's axis.
Running or revolving center.
A revolving center, also known as a rotating center or running center in some countries, is constructed so that the 60° center runs in its own bearings and is used at the non-driven or tailstock end of a machine. It allows higher turning speeds without the need for separate lubrication, and also greater clamping pressures. CNC lathes use this type of center almost exclusively and they may be used for general machining operations as well. Spring-loaded centers are designed to compensate for center variations, without damage to the work piece or center tip. This assures the operator of uniform constant tension while machining. Some live centers also have interchangeable shafts. This is valuable when situations require a design other than a 60° male tip. A live center, which may be hard or soft, is a plain center placed in the revolving mandrel; it moves and is therefore live.
Pipe center.
A pipe center, also known as a bull nose center is a type of live center which has a large diameter conical nose rather than a sharp point. This allows the center to be used in the bore of a pipe or other workpiece with a large interior diameter. While a pipe center ensures the workpiece remains concentric, its main advantage is that it supports the workpiece securely, and can be used for parts whose larger inner diameter prevents the use of a normal pointed center. Thin-walled material such as pipes easily collapses if excessive force is used at the chuck end.
Cup center.
There are two types of cup centers. The woodworking variety is a variation of the traditional live center. This type of cup center has a central point like a normal live center and also has a ring surrounding it. The ring supports the softer material around the center point and prevents the wood from splitting under pressure from the central point. A different variety of cup center is used for metalworking. The metalworking variety of cup center has a tapered hole rather than a conical point. It supports the part by making contact with the outside diameter of the end of the part, rather than using a center hole.
Drive center.
A drive center, also known as a grip center, is used in the driving end of a machine (headstock). It is often used in woodworking or where softer materials are machined.
It consists of a dead center surrounded by hardened teeth, which bite into a softer workpiece allowing the workpiece to be driven directly by the center. This allows the full diameter of the workpiece to be machined in a single operation, in contrast with the usual requirement where a carrier is attached to the workpiece at the driven end. The use of modified shell end mills in a drive center, instead of hardened pins, enables better gripping and prevents breakdown time due to pin stop.
Spring center.
A spring center is a metalworking lathe center for maintaining a cutting tool like a reamer or a tap, in axial alignment with a hole being worked on. It consists of a point backed by a spring to push the cutting tool into the workpiece.