This makes sense. So really the MCX5 or any other 3+2 will only help in initially positioning the unit and then mill as a 3 axis. Thank you for both of your replies and help!
Most of the dental milling regardless of the hardware will be 3 axis cutting, for each unit the CAM will position the disk to an optimal tool reach position then perform an individual cutting cycle in 3 axis movement. To be more precise, except for finishing cycles, the actual cutting will mostly happen in 2+1 axis...constant Z spirals, increase depth by plunge rate, then repeat... Pretty much everything can be cut in 3+2...
Contrary to what Bob said, 3+2 is not a 4 axis mill. 3+2 is a 5 axis mill operated in indexed mode, the rotary axii are fixed and the cutting is performed in XYZ movement. Unless you're cutting complex geometries like implant bars, this is the standard in dental production.
Another operating mode is the simultaneous movement about all 5 axii. Advantages of the 5 axis cutting are: better surface finish since the tool can be kept tangential to the part, also can engage the whole cutting length vs. the tool tip, complex geometries (undercuts) can be cut in one cycle, increased reach, so shorter tools can be used to maximize rigidity (less deflection, better finish)... Sounds good, however it doesn't really work for the garden variety dental mills...the rotary axii lag behind the linear axii feedrate vise...therefore the cutting rate will be reduced to the speed of the slowest rotary axis...milling a crown all cycles in 5 axis cutting would take quite longer than 3+2 (or 3+1) per se... Another aspect is the lack of position feedback, most dental mills are driven by stepper motors are prone to loose steps (or worse: stall) when stressed or overdriven...hence the accumulated error is greater cutting in 5 axis vs 3+2...
Also a beefy CAM is needed to fully take advantage of the 5 axis milling, the watered down dental CAM versions just not up to that task IMO...mind ya an industrial 5axis CAM starts at $20k+...
Bottom line, is cool to show off with it, or to cut implant bars...have yet to see a production facility pumping out crows cut in 5 axis mode...
Back to the 4 axis mill, will have one rotary axis (or two rotary and two linear in case of the older Sirona units)... the cutting will be in 3+1 mode (flipping the disc is the "+1"),still lots can be achieved this way (all C&B),even screw retained bridges if the screw hole angulations can be lined up in one plane...and given the CAM is capable to index about the rotary axis...( and there are the "lollipop" tools, but that's another story)...Hope this helps...
