High-speed hobbing

High-speed hobbing:

Competitive global market requires gear manufacturers to reduce production costs while increasing productivity. This means that the hob hobbing to achieve higher speed and feed rate. This requires the help of high-quality materials, high-performance coatings. Because high-quality tools usually means high prices, and some Machine Shop in not analyzing all aspects of the production process to determine the really important factors - the production cost of each part of the total cost - to reject the case of high-performance roll knives.

To achieve a higher gear cutting tool productivity requirements have led designers to develop high-performance, multi-threaded, shank-type hobs. Shank-type hobs material manufactured using the whole tool steel bars. Usually smaller in diameter, generally longer than the hole cutter. When installed on a hobbing machine, by the journal in both ends fixed, rather than hole cutter mounted on a mandrel so.

Shank-type tool commonly used in the overall processing of worm, the worm requires hob diameter close to the diameter. Shank-type hobs best optimized for high volume production applications. Large diameter, large module gear, such as truck transmissions, or for mining machinery, etc., usually hole cutter production.

Shank-type hobs form the length of the rotation may want to cut a large area, each of the hob can cut a lot of parts. Reduced shank-type hobs and female factors, including cutting time increased feed rate and cutter speed and the number of threads on the hob. Test the tool designer "shank cutter reason is because the production rate in each channel along the hob cutting more rotation position, due to the hob and tool coating wear resistance of materials to improve the cutting frequency increased, so More parts can be processed.
Hobbing process can be with or without coolant in the circumstances. However, many users tend to be dry roll, because it avoids environmental problems and eliminate clean-up costs related to the cooling fluid. Dry cutting requires that they have high-quality coated hob, with high temperature stability and low thermal conductivity, in order to protect the dry, high-speed hobbing conditions of the cutting edge.
As for the integral shank-type hobs, and installed in the machine parts used in fewer components compared to the hob with the hole, their higher rigidity. Installed on the hob for the Brothers, installation and testing between the top, it can be detected. Compared with the hole cutter, shank-type hobs eliminates spindle hole and beating between the cumulative tolerance as a result of gaskets and mounting nut vibrations caused the error.Shank-type hobs quality steel and have high wear resistance, both in the cutting room shower or at high temperatures have high hardness. Despite the high quality steel and coated material costs higher than the low performance, but with a smaller diameter shank-type hobs generate higher cutting speed can ensure that each part has a faster cycle times and lower processing costs (see table .) For the application of occasions, this one-piece processing cost of benefits beyond the one-piece general tool to increase the amount of cost. This saves a single piece of the total cost. Single cost comparison summary Gleason hobbing Genesis shank and hole cutter moreApplications: Automotive pinion, 36.46mm diameter, 22 teeth, materials, 8620, hardness 180HB, production of 800,000 piece quantities.
Hob Material / Finish: handle type - carbon / vanadium / cobalt high speed steel / AlNite
Hole - Cobalt bearing high speed steel / AlNiteGenesis shank (baseline) female (compared with the shank)Hob price 100 58One-piece tool costs (including purchase and maintenance costs) 100 57.1Hob speed 10 062Feed rate 100 1.5Total production time and costs 100 214100 216 cutting cycle timeSingle-piece production costs 100 178Coating is the key
In the hob on the use of appropriate coatings can increase productivity and reduce processing costs. Depending on the application, use of appropriate coatings, tool life may be doubled, so the tool can save costs, reduce the number of tool changes, reduce machine downtime.
As hobbing cutting speed and depth of cut in the workpiece with the tensile strength decreased with the increase, and a suitable choice of coating can achieve a higher speed. In some cases, can achieve a higher feed rate. Almost all of the hob is used through a physical vapor deposition (PVD) coating the coating process protection. Standard titanium nitride (TiN) coated with a lubricant in the case of low effective. Titanium carbonitride (TiCN) coating to improve the hardness and wear resistance for abrasive materials. Titanium aluminum nitrogen (TiAlN) coating is used for dry machining, because they have high strength and heat resistance. Recently developed a dry machining of aluminum coated chromium nitrogen (AlCrN), wear resistance, heat resistance and oxidation resistance even higher.