Tuesday, March 6, 2012

Repeatability Problems

Dear A Tech...
"I recently bought a three year old, gently used CNC mill and discovered it's not repeatable and I'm having problems maintaining min. tolerances. Can a technician call me about fixing this? I'm getting conflicting reports from three service guys!" Thanks, Desperate.

Dear Desperate,
Position errors are very common and are typically caused by worn-out ballscrews being used as positioning devices, physical deviations in the machine being transferred to the finished part, or by encoder feed back errors.
Our technicians are routinely called out on these "mystery" types of problems. Experience has trained us to first analyze the type of error being reported in order to reduce the possibility of chasing erroneous causes. You stated in your email that your machine is not repeatable. Non repeatability can be caused by your encoder missing counts, ballscrew growth, or a control component failure. Since today’s controls use stable solid state electronics with no moving parts, failures are rare. So, let’s focus on the first two causes: encoder miscounts and ballscrew growth.

Click Here to download my full response.

Craig D’Ambrosio
General Manager
A Tech Authority, Inc.
(909) 614-4518

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