Manufacturing Solutions, Inc Model C3A and the older Model C3 ChamferMate
machines are supplied standard with a tool holder designed to utilize a ½” square insert in either a SPG-422 or SPU-422 size.
S=Square
P=Positive Rake
G=Ground
U=Utility.
There are many manufacturers of these inserts and each manufacture has many grades and chip breaker configurations available. The SPG and SPU have no chip breaker, just a flat top. For most chamfering applications, a simple SPU-422 insert in a gold coated grade will work satisfactorily. The “U” designation stands for Utility Grade and this is a pressed insert that is formed to the final size. SPU inserts are not as accurate dimension wise as a SPG insert but this is immaterial for chamfering using only one insert.
The gold coating increases wear resistance and will allow the insert to last longer. In order for the gold coating to stick to the sharp edge of the insert, the edge must be slightly “dulled” or rounded. We are talking only a few thousandths of an inch.
Gold coated utility inserts can be used for chamfering most all carbon steels either solid rounds, pipe, or threaded parts. In order to get the cleanest cut and good insert life, the feed rate must be sufficient to allow the cutting edge of the part to take a depth of cut that is thick enough so the chip is thicker than the radius on the end of the part. Chips in the range of .005 to .008 inches are most common.
A SPG type insert is a ground insert. This means the top and bottom of the insert have been ground to thickness after pressing of the insert. This insert is more accurate and the edges are sharp.
When chamfering stainless steel, an uncoated ground insert is best. Stainless will
work harden if the insert “rubs” on the material and wear the insert prematurely. All manufactures of the inserts make a grade that is suitable for stainless.
If the insert does not cut cleanly when chamfering stainless threaded parts the thread will be rolled over and the nut or gauge will not assemble onto the part. For this reason a “G” insert will cut cleaner.
It is suggested that you consult your supplier of inserts and see which grade of their brand they recommend for the type of material you are processing.
