Rotary milling feed rates on Heidenhain LE430

[Aeroparts]

We're trying to do rotary milling on a Hermle C600U with Heidenhain LE430 control but cannot figure out what the machine is wanting for rotary feed rates.

The mill is a 5 axis machine but it could just as well be a 4 axis for our needs. We only use the 5th (A) axis for positioning and then do combinations of X, Y, and C moves to machine our parts. The machine is configured in Inch mode and our programs are all in Inch mode as well. We program everything in Gibbs and output in Heidenhain Conversational.

For the entire time we've owned the machine we've had issues with long cycle times and occasionally broken tools when rotary milling but since we are entirely a development shop never really gave it any thought . Recently we had to run a larger batch of parts that were taking over 4 hours each to machine on the Hermle. In an effort to meet delivery we decided to run the parts on another machine simultaneously and using the same Gibbs program posted for the other machine our cycle time dropped to under two hours. This caused the light bulb to come on and we started looking into what was going on with our Hermle.

Since this discovery we've been pulling our hair out trying to determine what this control is wanting for a feed rate. The book indicates that in normal mode (M116 not active) feed rates for rotary moves are in degrees per minute. This seems to be the case when only the C axis is being moved, but as soon as a XYC move is made it isn't the case. We've done a multitude of tests to try and determine what the machine needs for feed rates but every time we think we've figured it out our next test kills our theory.

Does anyone out there have a Heidenhain 430 that is being used for rotary milling with XYC axis moves and how do you determine the feed rates? If we could identify a formula or method for establishing the correct feed rate it would be easy enough to have our post updated but neither Hermle or Heidenhain seem to have an answer. Hopefully someone out there has the simple answer that seems to be escaping us!

Thanks in advance for your help.

[marvreil]

Hi. I have over 25,000 hours on Heidenhain controls, TNC 426, 430, 530, and i530. All of my programming is done at the control, and I am very familiar with the parametric side of the control. I also teach my system for using the parametric system, and have had extremely good luck with the students if they are willing to listen/try. Contact me at marvreil@yahoo.ca