J&M Retention Knobs are shot peened to relieve stress in the material, remove burrs, radius corners, and improve the finish of the knob. This process improves the durability, extends the life and reduces the likelihood of the Retention Knob cracking.

If the Retention Knob breaks when roughing with an end mill, the down time may be from 2 to 10 weeks depending on the severity of the damage. The repair may be as simple as replacing the tool holder and Retention Knob and regrinding the spindle in-house to clean up any damage that has been done. Or it may require the replacement of the spindle by factory repairmen. The repair cost may run from $3,500 to as high as $40,000 per crash.

You can see that it is more cost effective to keep track of the Retention Knob's time in use and the type of duty cycle they have had. For this reason, J&M has Laser-Marked Retention Knobs with the month and year manufactured and serial number on the flange (S/N 03/02- 000323).

This information can be used in a safety log to record the length of time and the type of duty that the Retention Knob has seen in its life span. (For example, light duty situations such as center drilling, or in heavy duty situations such as rough end milling.)

By monitoring the data from the magnetic particle inspection of the Retention Knob, a manufacturer can deterine the life span of the Retention Knob in the different types of duty cycles in their facility.

Serial Number and Work Order:
These numbers are marked on the parts to maintain traceability and good manufacturing practice.
S/N 03/02-00323
Part Number:
Part Number is marked on Knob making it easy to identify part number when Retention Knob is in the tool holder.