KHK USA - Supplier of Premium Metric Spur Gears
Metric Spur Gears - One Type of Cylindrical Gears
Spur gears are cylindrical disks which have involute shaped teeth cut into their face. To meet your requirements, KHK's spur gears are made in a variety of styles. Our spur gears are offered in many materials, configurations, modules and numbers of teeth. Many of the products that we offer allow for secondary operations such as opening the bore, adding of keyways, adding of tapped holes, or reduction of the hub diameter to be performed. Our offering also includes products which have already had some of these secondary operations completed. These products are identified by a "J" in their part number and they are available within 10 calendar days.
Among gears, spur gears which have simple forms and are easy to manufacture are one type of cylindrical gears used with parallel shafts. The meshing of spur gears are almost rolling contacts producing high efficiency of about 95 - 98%. In the pair of meshing gears, the larger one is called a gear while the smaller is called a pinion.
The main materials used to make spur gears are, in terms of JIS Standard, structural carbon steel S45C, structural alloy steels SCM440 (medium carbon steel) and SCM415 (low carbon steel), gray cast iron FC200, stainless steels SUS303 and SUS304, nonferrous metal C3604 (free cutting brass), engineering plastics MC901 and MC602ST, etc. Of course, in different countries other material standards are adopted, such as AISI, SAE, ASTM, AGMA, etc. in the US.
The production process of cylindrical gears, represented by spur gears, depends on consideration of tooth size expressed in module or DP (diametral pitch), configuration, material, heat treating, method of finishing tooth surface, precision of the gears and manufacturing quantity. The typical production sequence when accuracy and strength are not needed is; cutting off material, blank making on a lathe, tooth cutting on a hobbing machine and deburring. For typical gear cutting, we can name hobbing and gear shaper cutting, etc. Also, in gear cutting, it can be with cutting oil or without oil (called dry cutting which is more environmentally friendly). The methods are determined by the form of the ending finish and the production lot size. Also for heat treating, tooth surface induction hardening and carburizing are often performed.
In recent years, instead of using hobbing machines, a new method is being developed in which a 5-axis machining center is used in combination with a gear manufacturing software which generates the NC data from inputted number of teeth and module of desired gears (spur and bevel gears).