 | New
Concepts in Milling Handbook A practical approach and illustrated guide to milling cutter selection and use <Table of Contents © 1973 Niagara Cutter Inc. |
| New
Concepts in Milling Handbook A practical approach and illustrated guide to milling cutter selection and use <Table of Contents © 1973 Niagara Cutter Inc. |
Basic Cutter Styles and Their Application - ( «Back )
(LD Series) The Light Duty Plain Mill
Light duty plain mills are used for slab milling and for light slotting applications. They have 10 degree positive radial rake and 0 degree axial rake (straight gashed) angles, on cutters less than 3/4- in width. They do not have side teeth and are therefore limited to milling parts that are less than the width of the cutter when plain milling. Light duty plain mills 3/4" and greater have an 18 degree left hand helix angle. The right hand cut, left hand helix draws the cutting forces into the spindle for better rigidity, which improves surface finish and tool life.When the cutter teeth are straight gashed, the cutting edge engages the work along the full width of cut at the same moment. The cutting pressure drops suddenly as the tooth leaves the work. The sudden change in tooth load reacts through the drive and may cause chatter or chipping. This problem is compounded if machine and fixture are not rigid.
Smoother operation is generally obtained when two teeth are simultaneously engaged in the work, because as one tooth leaves the work, the load change on the cutter is not as great as when only one tooth is engaged at a time. When milling with a helix angle, the length of cutting edge engaging the work increases gradually to a maximum and continues for a considerable part of the tooth travel gradually decreasing until zero load is reached as the tooth leaves the cut. The higher the helix angle, the longer and more constant the engagement, and generally the better the surface finish.
