Hobs

SuperDry III Hob

Beyond the limit of high speed processing… "SuperDry III" Coating hob
High-speed hobbing at a cutting speed of 250 m/min. or more reduces the cycle time, extends tool life and achieves precision processing.

Features

1. The coating strength, boding power and adhesion with base material are increased thanks to the improved coating structure.
2. Improvement in coating structure raises coating strength and bonding power by increasing adhesion with the base material.

Samples

Work	Module 2.25
Pressure angle	17.5°
Number of teeth	52
Helix angle	23°LH
Material	18CrMo4(HB180)
Hob	Outer diameter 75 mm, Material MACH7
Number of start	3 starts
Number of gash	14
with cutting face coating
Cutting condition	Cutting speed 250m/min
Axial feed	2.4mm/rev
Coaxial winding climb, no shift

Comparison graph of tool wears

Picture illustrating wear after hobbing 80 units of work pieces

SuperDry III

SuperDry II

Tooth profile chart X 500 X 4

Lead chart X 500 X 2

Processing by hobbing

Mount a hob on the hobbing machine, position the hob and the work piece in rack and pinion order, perform synchronous rotation, and feed the hob to work piece’s gear width direction; this enables highly efficient and accurate gear processing.

Hob identifies itself either as numerous number of teeth or as a single tooth.
One tooth of a work piece is generated per one rotation.

Feeds the hob to a work piece' s gear width direction Efficiency in processing may improve if the number of starts for the hob is increases but the number of blade will decrease and polygonal error may be formed at the same time.
Machine must have sufficient rigidity and strength.

Gear cutting method in hobbing

Conventional hobbing

Hob rotates from the top face to the bottom face of a work piece.

Climb hobbing

Hob rotates from the bottom face to the top face of a work piece.

Precaution for sharpening

Hob needs grinding as cutting edge surface may become worn; this process is called "Resharpening". Improper resharpening may affect the precision of the hob. Following indicates the typical example of errors in the cutter form:

Influence from cutting load fluctuation

Hob setting angle error and tooth thickness

Number of starts and polygonal error