Need some collective wisdom from the group. Here is all the information I can give.
The Part: Imagine a aluminum part with an open-center Figure 8 (figure 8 with the center connector erased) shape (similar). Wall thickness is 3.5 mm for the entire shape. Overall dia (top-bottom) is 102 mm, inside distance at the narrow point is 30 mm At 4 points along the sides projecting toward you from the page, are some ~15 mm long projections that vary in height from 5 mm to 25 mm (same wall thickness).
The machine: Gang-tooled CNC lathe. 105 mm between tool pockets. Part is held in a collet, with approximately 42 mm finished height protruding from the collet.
The tooling: Tool 1: Iscar PCD tipped parting tool. Tool 2: PCD tipped 35° finishing tool, 0.8 R (35° is required because the face of the part needs profiling - some somewhat large radii- anything larger backcuts during the profiling...i.e. the backside of the tool cuts out what it isn't supposed to) R is fixed by the part print. There is ~40mm between the inside of the parting tool, and the tip of the finishing tool, in the Z axis direction, can't go any more because the parting tool would hit the collet when the finishing tool was cutting. Due to the amount of X axis travel, the finish tool tip is about 90 mm radially from the tip of the parting tool in X.
The Task: Taking our modified figure 8 shape as above, and assuming it is in plane with your monitor, the projections toward you, we want to part off about8 mm into the monitor. Since the parting tool is 4 mm wide, this leaves a ring of about 4mm thickness, plus the projections. Then we must profile the face of the part left in the collet.
The Process Specs: Initial RPM for cut-off: 2500 Part to within 2.5 mm of the ring being parted, slow spindle to 200 RPM, decrease feed. After piece parts, ramp back up to finish cut RPM. (not really relevant)
The Problem: Every so often, you get a chipped finish tool, apparently from impact with the parted ring as it was parted. Watching the machine, it looks like it almost always falls pretty much straight down when it parts off, but apparently not *every time*. Does anyone have any suggestions as to how to protect the finish tool from the departed ring, and still be able to machine with the finish tool? This is an automated process, so stopping the machine between the two tools is not an option. I've tried facing with a normal tool, but the wall thickness is so thin it breaks chunks out below the finished machined surface and that is not acceptable. (seriously interupted cut here folks...) The process we have works great as far as machining goes, it's just dinging a very expensive tool way too often. Any thoughts would be appreciated.