Click on the image below to see a perspective view of a broach tooth, where you can note the main areas beyond the chip-breaking flutes. The distance between a tooth and another is set to P, the pitch of the teeth. The height measured from the bottom of the tooth (background) and the cutting edge is h. It is also possible to view the angles of the emitting surface (g) and the clearance surface (c). The difference between the heights of the cutting edge (a) is the advancement.
The R and r radius (respectively the background radius and clearance radius) agreement should be defined, because this area is responsible for the formation of a chip, seeking to fold and not break it, or otherwise it can cause quality problems. The well-formed chip folds and does not have sharp edges in contact with the tool. A chip that generates several edges can damage the finish of the part being machined and also the tool itself.
Changing the clearance surface angle will also change the radii R and r, which ultimately influences another important detail, which is the calibration of the teeth. This is evidenced by the presence of a platform parallel to the longitudinal axis of the broach, length (f), which allows the regrinding without loss of height (h).
As a general rule, the greater the clearance angle, the greater the angle of the background (also known as back-pocket) for the accumulation and disposal of chips will be.