Tormach PCNC 1100 - Hole Milling 17-4 PH, The Test

Описание: This is a follow-on video to the earlier testing of 17-4 PH stainless steel (Condition A) on the Tormach PCNC 1100. One of the operations involves putting a hole in the part that has a tightly controlled tolerance (not tight enough to require reaming, though). Profiling operations aren't terribly challenging, but a helical hole entry in an unfamiliar metal sounds unsettling.

The hole needs to be finished to .55x", so bulk material removal by drilling a 1/2" hole is an easy way to avoid a full width of cut helical ramp entry. Operations shown in the video are as follows:

Spot drilling:
1/4" 2F carbide spot drill (didn't make it past the 2nd peck)
610 RPM, 4.27 IPM

Hole drilling
1/2" HSS, TiN-coated twist drill
Fail #1: 300 RPM, 2.10 IPM
Fail #2: 300 RPM, 1.05 IPM
Cut: 600 RPM, 2.10 IPM

Hole milling, helical entry, "roughing"
.375" 4F carbide, TiAlN end mill
Speed: 2790 RPM
WOC: .016"
Hole #1: 3° helical angle, 37.5 IPM
Hole #2: 4° helical angle, 37.5 IPM
Hole #3: 5° helical angle, 37.5 IPM
Hole #4: 3° helical angle, 45 IPM
Hole #5: 4° helical angle, 45 IPM
Hole #6: 5° helical angle, 45 IPM

Hole milling, profile finishing
WOC: .0105" (holes 1 through 3)
WOC: .0108" (holes 4 through 6)
DOC: .3125"
Feed: 30 IPM

Some work is still required on the tool paths. The best hole was Ø.004" (#4 and #5) undersized and the worst (#1 and #2) was Ø.008" undersized.

On a side note, given the two crunched up drills from the work, it's getting to be close to time to put together a CNC Fail Compilation.