Tapping depth problem on Japanese make HMC at Bosch Chassis Systems Pvt. Ltd.
Customer: Bosch Chassis Systems Pvt. Ltd.
Problem Description: A complaint was received from a customer that the tapping depth is coming undersized.
Following was the tapping data:
Machine: Horizontal machining center
Attachment used: Tapping attachment with axial length compensation of +/- 7.5 mm
Tapping size: M 8 x 1.25
Spindle RPM: 200 RPM
Material of the component: Cast Iron.
The tapping depth was coming undersized after tap re-sharpening. Such problem was not observed when the tap was new. Customer also claimed when such tap is used on rigid tapping holder on the machine having rigid tapping facility, the under size depth problem is not observed.
Solution: The tapping cycle was observed carefully. It was seen that while taking the start the compression was getting pressed and the tapping was starting after full compression is compressed and that is the reason the depth was coming undersize.
That means the tapping requires a rigid start, when the cutting edges are ground. Hence the with the help of setting screw the pressure on the compression is increased. This helped to start the tap immediately on touching the drilled hole.