CNC test pieces for milling and turning - I need to run a process capability study

B

Brian Hunt

I need to run a process capability study on CNC milling and turning machines. The company has never done this and we don't have test pieces - e.g set milling to make holes at various x, y, z parameters and then measure these to establish variation and capability.

Rather than design something from scratch, is anyone able to let me have a copy of test piece designs?

Thanks for any help

Brian
 

Hershal

Metrologist-Auditor
Trusted Information Resource
If you have design capability, you should be able to design your own test pieces.

Some things to keep in mind are the rated accuracy and capability of the machines, the number of tools each machine (if you have more than one) has, the number of pallets (if it accepts multiple pallets) it can handle.

You want to test the limits, and have the measurements done using calibrated equipment.....a high-end CMM or vision system if available.

Hope this helps.

Hershal
 
B

Brian Hunt

proposed cnc test piece

Thanks for your comments Hershal. What I have in mind is the diagram below. This will be used on several old cnc milling machines which have all been recently maintained. My plan is to run the CNC program to produce this test piece 10 times on each machine and then measure the x and y dimensions from the bottom left hand corner of the test piece. I'm not sure of the overall dimensions yet - ideally towards full deflection on all axis and at some points between this and zero.

Am I on the right road here? Any comments would be appreciated.
 

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