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gears. Depending on the tooth size, gears and splines are hobbed in a single pass or in a two-pass cycle consisting of a roughing cut followed by a finishing cut. State-of-the-art hobbing machines have the capability to vary cutting parameters between first and second cut so that a different formula is used to calculat... |
purchase our first CNC gear hobbing machine, what questions should we ask about the software? What do we need to know to correctly specify the system requirements? Question: We are interested in purchasing our first gear hobbing machine. What questions should we ask the manufacturer, and what do we need to know in orde... |
Since we are a high volume shop, we were particularly interested in Mr. Kotlyar's article describing the effects of hob length on production efficiency which appeared in the Sept/Oct issue of Gear Technology. Unfortunately, some readers many be unnecessarily deterred from applying the analysis to their own situations b... |
evaluation of the constant terms. A brief introduction to the subject of Thin Film Coatings and their application to gear hobs and shaper cutters is followed by a detailed description of the Chemical Vapor Deposition Process and the Physical Vapor Deposition Process. Advantages and disadvantages of each of these proces... |
laboratory and field test results. Recommendations are suggested for tool design improvements and optimization of gear cutting operations using coated tools. Productivity improvements potentially available by properly utilizing coated tools are considered in terms of both tool cost and machining cost. New material tech... |
gear tooth surfaces—based on the optimal corrections of the profile and diameter of the head cutter, and optimal variation of machine tool settings for pinion and gear finishing—is presented. The goal of these tooth modifications is the achievement of a more favorable load distribution and reduced transmission error. T... |
in one of two camps: the face hobbing/lapping camp, and the face milling/grinding camp. The quality of the finished gear is influenced by the very first machining operations of the blank. Since the gear tooth geometry is generated on a continuously rotating blank in hobbing or shaping, it is important that the timed re... |
is disturbed by eccentricities of the blank to its operating centerline, the generated gear teeth will not be of the correct geometry. During the blanking operations, the gear's centerline and locating surfaces are established and must be maintained as the same through the following operations that generate the gear te... |
manufacturing. By offering higher cutting speeds, reduced cycle times, enhanced coatings, custom configurations and a diverse range of sizes and capabilities, ICI tools have proven invaluable for finishing and pre-grind applications. They continue to expand their unique capabilities and worth in the cutting tool market... |
gears and is growing in popularity. This article is part four of an eight-part series on the tribology aspects of angular gear drives. Each article will be presented first and exclusively by Gear Technology, but the entire series will be included in Dr. Stadtfeld’s upcoming book on the subject, which is scheduled for r... |
about sophisticated gear manufacturing methods and how they can help solve common gear-related problems. Sandvik presents the latest in gear milling technologies. Indexable carbide insert cutting tools for gears are nothing new. But big gears have recently become a very big business. The result is that there's been a r... |
cutting bevel gear teeth on a gear of the following specifications: 14 teeth, 1" circular pitch, 14.5 degrees pressure angle, 4 degrees pitch cone angle, 27.5" cone distance, and an 2.5" face width? The complete Product News section from the May 2009 issue of Gear Technology. Question: I have just become involved with ... |
the procedure specifies that four involute checks must be made on each side of the tooth of the gear being produced, where one tooth is checked and charted in each quadrant of the gear. Why is this done? These particular gears are checked in the pre-shaved, finish-shaved, and the after-heat-treat condition, so a lot of... |
of gearing systems available to the gear application engineer is the versatile and unique worm and worm gear set. In the simpler form of a cylindrical worm meshing at 90 degree axis angle with an enveloping worm gear, it is widely used and has become a traditional form of gearing. (See Fig. 1) This is evidenced by the ... |
in or supplying such gear sets in unassembled form or as complete gear boxes. Special designs as well as standardized ratio sets covering wide ratio ranges and center distanced are available with many as stock catalog products. Helical gears can drive either nonparallel or parallel shafts. When these gears are used wit... |
requirements are less critical than for gears driving parallel shafts. The forming of gear teeth has traditionally been a time-consuming heavy stock removal operation in which close tooth size, shape, runout and spacing accuracy are required. This is true whether the teeth are finished by a second forming operation or ... |
the distortion of gear teeth caused by quenching must be removed by precision cutting (skiving) and/or grinding. In the case of large gears with large modules, skiving by a carbide hob is more economical than grinding when the highest accuracy is not required. High-speed machining using carbide has been used for some d... |
cutting process has delayed the use of carbide tools in gear manufacturing. Carbide was found at first to be too brittle for interrupted cutting actions. In the meantime, however, a number of different carbide grades were developed. The first successful studies in carbide hobbing of cylindrical gears were completed dur... |
carbide cutting tools for gear production. Since the carbide was quite expensive and the tool life was too short, a TiN-coated, high-speed steel hob was more economical than an uncoated carbide hob. Bodine Electric Co. of Chicago, IL., has a 97-year history of fine-and medium-pitch gear manufacturing. Like anywhere els... |
and obstacles to further improvements. We were producing a high quality product, but our goal was to become more cost effective. Carbide hobbing is seen as a technological innovation capable of enabling a dramatic, rather than an incremental, enhancement to productivity and cost savings. Recent trends in gear cutting t... |
coating, and process technology will afford the best quality at the lowest total cost. Applying the new technologies can have associated risks that may override the potential cost savings. The many interrelated variables to be considered and evaluated tend to cloud the issue and make hobbing process development more di... |
in the hobbing process. In addition, certain gears can be manufactured by shaping, which also needs to be taken into account in the search for a more cost-effective form of production. Traditionally, profile and lead inspections have been indispensable portions of a standard inspection of an involute gear. This also ho... |
inspection of the profile and the lead is rarely performed on a worm wheel. One of the main reasons is our inability to make good definitions of these two elements (profile and lead) for the worm wheel. Several researchers have proposed methods for profile and lead inspections of a worm wheel using CNC machines or regu... |
using CNC machines or regular involute measuring machines. Hu and Pennell measured a worm wheel's profile in an "involute" section and the lead on the "pitch" cylinder (Ref. 2). This method is applicable to a convolute helicoid worm drive with a crossing angle of 90 degrees because the wheel profile in one of the offse... |
involute on the generated worm wheel. Unfortunately, because of the hob oversize, the crossing angle between the hob and the worm wheel always deviates from 90 degrees by the swivel angle. Thus, this method can be implemented only approximately by ignoring the swivel angle. Another shortcoming of this method is that th... |
scanned points deviated from this curve, it produced unreal profile deviation. Octrue discussed profile inspection using a profile checking machine (Ref. 3). Conical involute gears, also known as beveloid gears, are generalized involute gears that have the two flanks of the same tooth characterized by different base cy... |
had to be resharpened on three faces. Those three faces formed the active part of the blade. In face hobbing, the effective cutting direction changes dramatically with respect to the shank of the blade. Depending on the individual ratio, it was found that optimal conditions for the chip removal action (side rake, side ... |
major parameters independently. This, in turn, results automatically in the need for the grinding or resharpening of the front face and the two relief surfaces in order to control side rake, hook angle and the relief and the relief angles of the cutting and clearance side. Quality gear manufacturing depends on controll... |
treat process of choice for many gear manufacturers. The primary reasons for this are: 1. The process is performed at low temperatures, i.e. less than critical. 2. the quench methods increase fatigue strength by up to 125% without distorting. Ferritic nitrocarburizing is used in place of carburizing with conventional a... |
CrC, etc. In addition, the process can also be applied to hobs, broaches, drills, and other cutting tools. In 1961 I presented a paper, "Calculating Conjugate Helical Forms," at the semi-annual meeting of the American Gear Manufacturers Association (AGMA). Since that time, thousands of hobs, shaper cutters and other me... |
This article presents the math of that paper without the formality of its development and goes on to discuss its practical application. This article summarizes the development of an improved titanium nitride (TiN) recoating process, which has, when compared to conventional recoat methods, demonstrated tool life increas... |
called Super TiN, surpasses the performance of standard TiN recoating for machining gear components. Super TiN incorporates stripping, surface preparation, smooth coating techniques and polishing before and after recoating. The combination of these improvements to the recoating process is the key to its performance. I'... |
the latest machine tools and processes; compare hobbing machines, gear grinders and inspection equipment; see turning, milling or grinding machines in action; and ask questions of the various vendors all in one place. This year's IMTS promised to be the biggest ever, and I have no doubt that it will be a valuable exper... |
the way they manufacture products. The hob is a perfect example of how a little manufacturing ingenuity can make a reliable, highly productive cutting tool. It's an engineering specimen that creates higher cutting speeds, better wear resistance and increases rigidity. The cutting tool alone, however, can't take all the... |
Tools and Cemecon helps improve cutting tools by reducing overall costs, increasing tool life and maintaining the highest levels of productivity. The following is a quick recap of new technologies and the latest information in the coating market. The capabilities and limitations of manufacturing gears by conventional m... |
manufacturing methods have extended beyond chip-cutting - hobbing, broaching, shaping, shaving, grinding, etc. and their inherent limitations based on cutting selection and speed, feed rates, chip thickness per tooth, cutting pressure, cutter deflection, chatter, surface finish, material hardness, machine rigidity, too... |
an economical means of producing spur and helical gears with involute tooth profiles. Richard Spens has a hobby that leads him onto the Internet, through magazines, to auctions and into farmers' back yards. The traditional way of controlling the quality of hypoid gears' tooth flank form is to check the tooth flank cont... |
flank form quality by the contact pattern. In recent years, it has become possible to accurately measure the tooth flank form of hypoid gears by the point-to-point measuring method and the scanning measuring method. But the uses of measured data of the tooth flank form for hypoid gears have not yet been well developed ... |
tooth flank form measurement of generated face-milled gears, face-hobbed gears and formulate/generated gears are reported. The authors discuss the advantages and disadvantages of scanning and point-to-point measuring of 3-D tooth flank forms of hypoid gears and introduce some examples of uses of measured data for high-... |
gear-cutting industry in the United State." He built the first hobbing machine for cutting spur gears. He founded the companies that are now Boston Gear and Philadelphia Gear Corp. Imagine the $10 bill with the face of Edwin R. Fellows on it and on the back, a picture of his invention: the gear shaping machine. Or the ... |
a picture of the first hobbing machine, which he built. When parts you manufacture pass through numerous processes such as deep hole drilling, machining, hobbing and grinding, a CMM is essential when your customers require 100 percent in-process and final inspection. There are several methods available for improving th... |
Rotary gear shaving and roll-finishing are done in the green or soft state prior to heat treating. A treasure trove of gear and power components for aspiring engineers and dedicated hobbyists. Dollhouses may be toys for children, but an old-time working miniature machine shop is the ultimate toy for a self-proclaimed h... |
design is the knowledge of their running temperature. Of special interest is the bulk temperature of the tooth to predict the fatigue life, and the peak temperature on the surface of the tooth to avert surface failure. This paper presents the results of an experimental method that uses an infrared radiometer to measure... |
in operation. Measurements are made on 5.08, 3.17, 2.54, 2.12 mm module hob cut gears made from nylon 6-6, acetal and UHMWPE (Ultra High Molecular Weight Polyethylene). All the tests are made on a four square testing rig with thermoplastic/steel gear pairs where the plastic gear is the driver. Maximum temperature predi... |
to data available from literature. Two major processes used for cutting gears, hobbing and shaping. This article describes advanced machine design and cutter materials for gear shaping. A universal gear is one generated by a common rack on a cylindrical, conical, or planar surface, and whose teeth can be oriented paral... |
can be parallel or crossed, non-intersecting or intersecting, skewed or parallel, and can have any angular orientation (See Fig.1) The taper gear is a universal gear. It provides unique geometric properties and a range of applications unmatched by any other motion transmission element. (See Fig.2) The taper gear can be... |
tilting the cutter or work axis and/or coordinating simultaneous traverse and infeed motions. Traditional methods of manufacturing precision gears usually employ either hobbing or shaper cutting. Both of these processes rely upon generating the conjugate tooth form by moving the work-piece in a precise relation to the ... |
a process include reduced production time, material savings, and improved performance characteristics. Drawbacks include complicated tool designs, non-uniformity of gears produced throughout the life of the tooling, and lengthy development times. After shaping or hobbing, the tooth flanks must be either chamfered or du... |
of the gear, because during hardening, the secondary burr will straighten up and, due to its extreme hardness, will lead to excessive tool wear. Grinding is a technique of finish-machining, utilizing an abrasive wheel. The rotating abrasive wheel, which id generally of special shape or form, when made to bear against a... |
a precision spur or helical gear. In most instances the workpiece will already have gear teeth cut on it by a primary process, such as hobbing or shaping. There are essentially two techniques for grinding gears: form and generation. The basic principles of these techniques, with their advantages and disadvantages, are ... |
machines, machining cells, etc., is there a niche somewhere for power brushes? Let me answer by asking another question. What tool does the gear manufacturer have in his arsenal that allows him to deburr green gears, hardened gears, hobbed gears, ground gears and shaved gears? What tool allows him to deburr powder meta... |
gears made of exotic materials such as inconel, waspaloy, or hastaloy, and fiber and plastic gears? How about spur gears, helical gears, sprockets, both internal and external splines, clutch teeth and pump gears? Hobs, broaches, shaper cutters, shaver cutters, milling cutters, and bevel cutters used in the manufacture ... |
properties, such as toughness or manufacturability, that are difficult to achieve with carbide, despite the developments in carbide cutting tools for end mills, milling cutters, and tool inserts. News Items About hob 1 Bourn and Koch Hobbing Machine Offers Single Setup Options (May 3, 2012) The Bourn and Koch 100 H hor... |
in diameter. Mount tools in ... Read News 2 Koepfer's Heavy Duty Hobbing Machine Offers Extended Part Size Capacity (June 6, 2007) The Heavy-duty Model 300 from Koepfer America provides for a bigger part diameter, coarser diametral pitch, and bigger hob capacity than ... Read News 3 Koepfer America Launches Large Capac... |
KFS250 CNC hob sharpening machine, which is based on its KFS100 series. The KFS250 series h... Read News 4 Gleason Debuts Opti-Cut Tools for Gashing, Shaping and Hobbing (November 9, 2007) A new family of cutting tools was recently introduced by the Gleason Corporation for the gashing, shaping and hobbing of gears. Thi... |
Gear Hobbing and Worm Milling (January 10, 2007) Koepfers MZ130 hobbing and worm milling CNC machine from Monnier + Zahner was designed with versatility and ease of use in mind. ... Read News 6 New Clamping Devices for Tool and Hob Manufacturing from Toolink (February 9, 2005) The K?nigdorn hydraulic expansion mandrels... |
The system... Read News 7 New Hob Sharpening Machine from Doimak (January 28, 2005) The AF-75 is a new grinding machine designed for sharpening hobs. Among the various features of this model are high accuracy and an op... Read News 8 New Face Drivers for Gear Hobbing from Logansport (February 2, 2005) The FDNC face dri... |
operations. According to the companys press releas... Read News 9 DTR Offers Hobs for Cutting Wind Turbine and Heavy Industrial Gears (January 21, 2010) DTR Corporation recently announced its full line of high-performance, large coarse pitch hobs for cutting wind turbine and heavy industri... Read News 10 Gleason Intro... |
a design that optimizes dry machining, reduces floor space and improves cycle ... Read News 11 Cutting Tool Sharpener Handles Large Diameter Hobs (February 11, 2010) In response to market demand for a machine capable of sharpening large, heavy hobs, J. Schneeberger has developed the Corvus C500 Coarse ... Read News 12 ... |
the Titan 1200H Hobbing Machine, the first of a new series of Titan hobbers designed for larger cylindrical gears ... Read News 13 Exsys Tool Provides Roughing/Gear Hobbing on Single Machine (August 16, 2011) A special compact gear hobber system from Exsys Tool, Inc. allows shops to generate splines, spur or helical ge... |
Gear Hobbing Line (October 11, 2010) MAG, a manufacturing technology company, has acquired the gear hobbing and chamfering/deburring product line of Samputensili GmbH in Chem... Read News 15 New Gear Hobbing Center from Koepfer EMAG (February 24, 2005) The VSC 250/400 DUO WF from EMAG Koepfer allows complete soft machi... |
H 400 CNC Hobs Small or Large Batches (May 9, 2012) Run small lots or mass produce straight and helical gears; crowned and tapered gears; worm gears; chain sprockets and toothed belt discs;... Read News 17 Zoller Offers Inspection for Hob Cutters (January 14, 2013) Gear cutting is a challenging task. Only perfect and r... |
low downt... Read News 18 SpeedCore Allows for More Efficient and Flexible Hobbing (October 21, 2011) In today's gear manufacturing environment, flexibility and efficiency are key factors in modern machine tool technology. Productivity... Read News 19 LMT-Fette Opens Illinois Hob Facility (April 23, 2006) LMT-Fette est... |
Read News 20 Ingersoll Introduces 2-Start Insert Hob (February 10, 2011) Ingersoll recently introduced a 2-Start Indexable Carbide Insert Hob, which nearly doubles productivity for machining gears with large nu... Read News 21 Gleason Invests in Coarse Pitch Hob Production Cell (August 2, 2011) In response to unprecede... |
Read News 22 Gleason Installs 10 Meter Capacity Gear Hobber in China (April 2, 2013) Gleason Corporation recently announced the successful installation of a P 8000/10000 Gear Hobber at Changzhou Tianshan Heavy Industry Mac... Read News 23 Luren Introduces Hob Sharpening Machine (January 7, 2011) Luren Precision Co., Lt... |
An independent Republic of Armenia was proclaimed at the end of the 1914-1918 War but it lasted only until the beginning of the 1920s when the Bolsheviks incorporated it into the Soviet Union. Armenia's return to independence in 1991 was |
overshadowed by the conflict over Nagorno-Karabakh, the predominantly Armenian-populated region in Azerbaijan (see Current conflicts section). Full-scale war broke out the same year as ethnic Armenians in Karabakh fought for independence, supported by troops and resources from Armenia proper. A |
ceasefire in place since 1994 has failed to deliver any lasting solution. Russia, France and the US co-chair the OSCE's Minsk Group, which has been attempting to broker an end to the dispute for over a decade. In 1997, the |
group tabled settlement proposals seen as a starting point for negotiations by Azerbaijan and Armenia but not by the de facto authorities in Nagorno-Karabakh itself. When the then-Armenian-president Levon Ter-Petrosyan tried to encourage Nagorno-Karabakh to enter into talks he was |
forced to resign amid cries of betrayal. Azerbaiijan declared illegitimate a referendum held in the region in December 2006. Armenia's president Serzh Sarkisian and Azerbaijan's Ilham Aliyev agreed in November 2008 to intensify their efforts to find a political settlement |
to the dispute over Nagorno-Karabakh. They claimed to have made significant progress at talks in Prague in May 2009 on the sidelines of the EU's Eastern Partnership summit. This overview is based on the BBC online country profile for Armenia. |
About Joseph Curran Joseph Curran (March 1, 1906 - August 14, 1981) was a merchant seaman and an American labor leader. He was founding president of the National Maritime Union |
(or NMU, now part of the Seafarers International Union of North America) from 1937 to 1973, and a vice president of the Congress of Industrial Organizations (CIO). Curran was born |
on Manhattan's Lower East Side. His father died when he was two years old, and his mother boarded with another family. He attended parochial school, but when he was 14 |
he was expelled during the seventh grade for truancy. He worked as a caddy and factory worker before finding employment in 1922 in the United States Merchant Marine. He worked |
as an able seaman and boatswain, washing dishes in restaurants when not at sea and sleeping on a Battery Park bench at night. It was during this time that he |
received his lifelong nickname "Big Joe." Curran joined the International Seamen's Union (or ISU; the remnants of which would become the Seafarers International Union), but was not active in the |
union at first. "SS California" strike Main article: S.S. California strike In 1936, Curran led a strike aboard the ocean liner S.S. California, then docked in San Pedro, California. Curran |
and the crew of the Panama Pacific Line's California went on strike at sailing time and refused to cast off the lines unless wages were increased and overtime paid. The |
strike was essentially a sitdown strike. Curran and the crew refused to leave the ship, for the owners would have simply replaced them with strikebreakers. The crew remained aboard and |
continued to do all their duties except cast off the lines. The California remained tied up for three days. Finally, United States Secretary of Labor Frances Perkins personally intervened in |
the California strike. Speaking to the crew by telephone, Perkins agreed to arrange a grievance hearing once the ship docked at its destination in New York City, and that there |
would be no reprisals by the company or government against Curran or the strikers. During the California's return trip, the Panama Pacific Line raised wages by $5 a month to |
$60 per month. But Perkins was unable to follow through on her other promises. United States Secretary of Commerce Daniel Roper and the Panama Pacific Line declared Curran and the |
strikers mutineers. The line even took out national advertising attacking Curran. When the ship docked, Federal Bureau of Investigation agents met the ship and began an investigation into the "mutiny." |
Curran and other top strike leaders were fined two day's pay, fired and blacklisted. Perkins was able to keep the strikers from being prosecuted for mutiny, however. Seaman all along |
the East Coast struck to protest the treatment of the California's crew. Curran became a leader of the 10-week strike, eventually forming a supportive association known as the Seamen's Defense |
Committee. Formation of NMU The S.S. California strike was only part of a worldwide wave of unrest among American seamen. A series of port and shipboard strikes broke out in |
1936 and 1937 in the Atlantic and Gulf of Mexico. In October 1936, Curran called a second strike, in part to improve working conditions and in part to embarrass the |
ISU. The four-month strike idled 50,000 seamen and 300 ships. Curran, believing it was time to abandon the conservation International Seamen's Union, began to sign up members for a new, |
rival union. The level of organizing was so intense that hundreds of ships delayed their sailing time as seamen listened to organizers and signed union cards. In May 1937, Curran |
and other leaders of his nascent movement formed the National Maritime Union. The Seamen's Defense Committee reconstituted itself as a union. It held its first convention in July, and 30,000 |
seamen switched their membership from the ISU to the NMU. Curran was elected president of the new organization. Elected secretary-treasurer of the union was Jamaican-born Ferdinand Smith. Thus, from its |
inception NMU was racially integrated. Within six years, nearly all racial discrimination was eliminated in hiring, wages, living accommodations and work assignments. A hallmark of the new union was the |
formation of hiring halls in each port. The hiring halls ensured a steady supply of experienced seamen for passenger and cargo ships, and reduced the corruption which plagued the hiring |
of able seamen. The hiring halls also worked to combat racial discrimination and promote racial harmony among maritime workers. Within a year, the NMU had more than 50,000 members, and |
most American shippers were under contract. Stripped of most of its membership, the ISU became almost moribund. In July 1937, Curran and other seamen's union leaders were invited by John |
L. Lewis to come to Washington, D.C., to form a major organizing drive among ship and port workers. The unions comprising the CIO had been ejected by the American Federation |
of Labor (AFL) in November 1936, and now Lewis wanted to launch a maritime union. His goal was to create, out of the 300,000 maritime industry's workers, a union as |
large and influential as the Steel Workers Organizing Committee. Although Lewis favored Harry Bridges, president of the Pacific Coast District of the International Longshoremen's Association, to lead the new maritime |
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