Volumetric Positioning - Machine capability studies for CNC machine tools

M

mlthompson

Anybody have any suggested resources or experiences to share regarding performing machine capability studies for CNC machine tools. I've read a little regarding volumetric positioning, but am looking for hands-on experience knowing the benefits and shortcomings.

Thanks Much!
 

Coury Ferguson

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Re: Volumetric Positioning

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B

Boscoeee

Anybody have any suggested resources or experiences to share regarding performing machine capability studies for CNC machine tools. I've read a little regarding volumetric positioning, but am looking for hands-on experience knowing the benefits and shortcomings.

Thanks Much!

In my experience have performed capability studies to confirm the CNC tool could hold the stated tolerance of the machine. No in saying that it requires some discipline in you approach.
The following is a list of things to consider.

Perform ball bar testing on Verticals and Horizontals to confirm that you do not have any significant axis error.

Consider shooting in your machine tool with lasers Spindle to Table (not something we do unless there has been a crash)

Verify measuring gages are up to the task by performing a gage R&R.

Identify a production run of 20 - 40 parts or test pieces.

Verify that cutter, tools and fixtures are adequate for production.

Review program, is it programmed to nominal and not to high or low side of dimension? This can skewed your study.

Select skilled Operator or Machinists.

Run the study, restrict operator edit on only cutter compensation, collect data.

Perform analysis!

It is very important to understand the fixtures, tools, program, and operator can compensate for the machine tool capability. So in looking for machine tool capability, set the study up so that you are looking at the machine tool and not the set up! Essentially you can compensate with fixtures, tools, program, and operator to ensure an outcome that does not truly reflect the machine capability.

Hope that you have fun with this project!
 
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