Buying a VMC： Considering Toolchanger, Coolant Delivery and Chip Removal

Some programmers shy away from using custom macros because they feel these macros make it more difficult to restart a program from the middle of a complex machining operation. This concern can often be overcome with a little planning. Indeed, custom macros sometimes make it easier to restart the program and run from the middle of a cutting tool’s machining operation.

The technique in this article was inspired by Chad Kluth of Mid Valley Industries in Kaukuana, Wisconsin. I was helping him resolve a different issue in a Carbide Turning Inserts bolt-circle hole-machining custom macro. I include it here since it is relevant to our discussion.

Kluth’s application involved machining very large and tough 4140 steel components used in the mining industry. He needed to drill as many as 100 holes, each 2 inches in diameter, around a bolt-circle pattern into a round face/flange to a 6-inch depth. As you can imagine, tool wear and tool breakage are big issues. Even a drill with new inserts may not make it all the way through the cycle without wearing out — and the drill could be 90 holes into the cycle when it does wear out. To make matters worse, a hard inclusion in the raw material could cause the drill to break at any time.

Kluth uses a universal bolt-circle custom macro capable of performing several kinds of hole-machining operations, including drilling, standard tapping, rigid tapping, reaming and counterboring. The original issue had to do with rigid tapping. Being a “universal” custom macro, the M29 command needed to ignore rigid tapping if the machine was performing any other operation. To solve this issue, we used “vacant” local variables.

As for skipping holes, an argument in the calling command specifies the number of holes to skip. For example, if the drill wears out during the 90th hole, the user needs to set this argument to 89. We used the K-word (L-word with older FANUC CNCs) in the canned cycle command to specify whether the machine should skip a hole. If K is set to zero (K0), the hole is skipped. If K is set to one (K1), the hole is machined.

Here is a sample program CCGT Insert containing an example calling command:

These are the mandatory arguments that must be in the calling command:

These are the arguments that are only required in special cases:

Here is the custom macro:

Here is a guide to the bolded items in the custom macro:

The Carbide Inserts Website: https://www.aliexpress.com/item/1005005874893569.html