Wieland Zenotec select PMMA milling

[saso]

I milled a Mesostructure in Trinia on a PMMA strat worked just fine.

With special cutters? Strategy for implant bridges...

 

[Sevan P]

I think it was normal carbide for first test, Special cutter run 2x faster in rpm didn't want to destroy anything lol!

 

[CoolHandLuke]

you really don't need much special for Trinia or Trilor, just good chip evactuation.

theres a limit to how fast you want to be spinning the tool too, because while small chips are best for high speed machining, theres a point at which that stops being useful and instead becomes problematic.

you can spin the tool so fast that it just melts the material you are cutting, and that can be detrimental in 3 ways. 1. the thing you want to make you end up with melty spots if you finish milling it. 2. the melted material tends to adhere to tools with coatings, making you have no more sharp edge but a crusted blunt edge. 3 you might be spinning so fast that your machine can't produce torque at that rpm, rendering your tool into a bomb.

for glass polymers like trinia and trilor, no big deal. for peek, pekk, pmma, and polycarbonate, big big deal. 1 flute cutters work best for these materials because it allows you as much capacity as possible for chip removal. this means you can run it faster. but faster within reason, remember you now have a tool with one edge, which is not well balanced. keep within the torque curve.

 

[saso]

A really good explanation, it makes sense...
So, will test to mill PEEK with carbide and later maybe with special cutters, hope nothing goes wrong

 

[brayks]

you really don't need much special for Trinia or Trilor, just good chip evactuation.

theres a limit to how fast you want to be spinning the tool too, because while small chips are best for high speed machining, theres a point at which that stops being useful and instead becomes problematic.

you can spin the tool so fast that it just melts the material you are cutting, and that can be detrimental in 3 ways. 1. the thing you want to make you end up with melty spots if you finish milling it. 2. the melted material tends to adhere to tools with coatings, making you have no more sharp edge but a crusted blunt edge. 3 you might be spinning so fast that your machine can't produce torque at that rpm, rendering your tool into a bomb.

for glass polymers like trinia and trilor, no big deal. for peek, pekk, pmma, and polycarbonate, big big deal. 1 flute cutters work best for these materials because it allows you as much capacity as possible for chip removal. this means you can run it faster. but faster within reason, remember you now have a tool with one edge, which is not well balanced. keep within the torque curve.

CHL speaks the truth. another thing to consider is that as your spindle speed increases your programmed feed rate needs to increase to maintain the proper surface feed (SFM) as recommended for the tool and material. This will help as the "burning" of material will be less of an issue. However, even if your spindle can produce the torque required, if your machine and fixturing is not rigid enough, the resultant increased vibration will drastically decrease your tool life, significantly decrease restoration finish quality, and almost certainly cause chipping of the margins.

Spindle torque at operating RPM and machine/fixture rigidity are among the most important machine characteristics when evaluating performance of any milling machine and often the most misunderstood and overlooked.

In machining any material, the heat generated by the cutting process must be "absorbed" in the chip (not the work-piece or cutting tool) with the resultant chip being cleared and not allowed to remain in the cutting area to be accumulated, re-cut and transferred to the tool. Therefore proper cutting parameters (rpm, feed rate, depth & width of cut) must be maintained. In high-speed machining, these parameters, including radial chip thinning must be taken into account.

 

[saso]

So, these special cutters rule the world speed and precision, amazing result. Thanks everybody for help.