[quote=“Julien, post:28, topic:15778”]
what I hear is that friction and deformation are causing heat (nobody disagrees here right?), heat needs to go somewhere, some of it in the chip and some of it in the workpiece, but anyway the surface layer is just a lot of future chips, so in the end what matters is how fast one can get hot material out of the way, be it with lots of very thin chips or fewer thicker ones. @WillAdams told it better than I just did though [/quote]
IMO the best way to cut acrylic is to minimize heat generation by minimizing chiploads (unless something like Aluminum HSMing occurs.) Since the melting temperature of acrylic is much lower than Aluminum, any HSMing would occur at a much lower endmill temperature.
It appears that early on in this discussion BW wisely gave up on his “deformation” argument. All of the heat is caused by friction. It tries to melt the cut edges but virtually none of it is conducted (goes) into the plastic. Any residual heat will be conducted into the endmill. Here’s plastic experts’ recommendations for cutting/routing acrylic. “The spindle speed required to produce a satisfactory edge is 10,000 to 20,000 rpm. A smooth, constant feed rate of 10 to 25 feet per minute is required to prevent localized heat buildup, which will cause smearing or gumming of the cut edge.”