brayks
Well-Known Member
Sponsors
Full Member
- Messages
- 805
- Reaction score
- 277
...Other brands make a lot more noise. Too bad we can't modify the strategies to fix this. I think AG PMMA is a lot softer? or easier to mill. The strategies are just not made for other brands. Who knows
Your problem is most likely related to your "milling condition" and vibration/chatter. Your tool/bur is likely deflecting and not actually machining the stock it was intending to remove leaving too much stock for the following tool. Result is bad fits, poor finishes and broken or heavily worn tools.
The "milling condition" is a function of many parameters including: SFM (function of spindle speed & tool diameter),chip load, feed rate and machine and fixture rigidity.
Actually tool/bur manufacturers provide a chart that, for various materials being machined, shows the recommended SFM range, feed rate and spindle speed. Some even show the chip load which basically is the thickness of a chip removed by one cutting edge of the tool. Chip load is a function of cutting feed rate, spindle speed and number of tool cutting teeth (flutes).
Noise is a function of vibration induced chatter, which means the tool (bur) is bouncing around slamming in and out of the cut which will cause: bad fits (areas are not being completely machined),poor finishes, excessive tool wear and tool breakage.
The above is a simple overview of a more complex matter beyond what I can provide in this post but I believe it pretty much gets to the point.
It's unbelievable/unacceptable to me that a user cannot change a templates machining parameters associated with optimizing the machining condition (depth of cut, step-over values, spindle rpm, feed rates, etc). but you should at least be able to manually adjust the feed rate and spindle speed via feed rate override "buttons"
I would first use carbide or better yet carbide coated tools (we use TiSiN). Slow the feed rate down via the feed rate override button. You should hear a difference as the reduction in feed rate reduces the vibration. Also check your spindle speed as this will also have an effect. Depending on your tool diameter and coating a range of say 25,000 to 38,000 rpm should work well - that is a wide range and the optimum value can often be found withing a 100 rpm band.
Just a thought...