There are two types of helical broaches : one consists of cutting edge for radial part only and the other consists of circumference and cutting edge for tooth thickness. The former is used for machining helical holes of general automobile parts and electrical components. The latter is used for internal gear cutting of ring gears inside automatic transmission for automobile. This ring gear-intended type of broach is generally called "Large-diameter helical broach". Because this Large-diameter helical broach requires extremely high precision and its size makes machining and tooth profile precision measurement difficult, it has normally been made into an assembly type, in which the rough tooth profile part (body) and finish tooth profile part (shell) are composed of cutting edge for radial part and cutting edge for tooth thickness, respectively. Our company has developed high precision tooth grinder with onboard measuring instrument to manufacture an integrated type of Large-diameter helical broach integrating the body and shell parts, making it possible to meet higher precision requirements.

① Assembly type for internal gear
It is a helical broach for internal gear, consisting of a main body for roughing and a shell for finishing. It is mainly used for ring gears of an automatic transmission system.

  

② Integrated type for internal gear
The tooth thickness finishing stock is reduced and cutting accuracy of gears improves since this broach is manufactured with a main body and a shell integrated. Load per cutting edge can be reduced, therefore total wear also decreases and larger number of gears can be produced per re-grinding. In addition, complex works such as decomposition and assembly of the shell, or a minor adjustment of the phase have become unnecessary, and running cost is reduced.