17-4 PH H900 .040" hole through .720"

micrometer_50 · Aug 11, 2009

17-4 PH H900 .040" hole through .720"

I'd like any suggestions to improve my results

I'm using a Hamilton Varimatic (desktop hand operated drill press)
with a speed range of 800 to 9350
I'm running it at 6100rpm
Carbide drill 118 deg point
CoolTool Oil

I'm getting only 6 to 8 pieces per drill.

I am holding the part in a custom fixture,
with a drill bushing to guide the drill.

Thanks for any help you might offer.

Limy Sami · Aug 11, 2009

Thats 18 X D sheesh,....... 6-8 pieces a drill ;- wear or breakage?

micrometer_50 · Aug 11, 2009

Mostly wear. Usually a chipped cutting edge.

Tank · Aug 11, 2009

You could try cutting down the RPM to see if that will extend tool life. It might not be worth it due to loss in cycle time though.

That 17-4 at H900 is 40-47 HRC. Cobalt sometimes will out preform carbide in this range. Might be worth a try if you haven't tried these ideas.

micrometer_50 · Aug 11, 2009

I'l try slowing it down.
At this RPM, the cobalt didn't even finish one part.
Maybe it will do better at a slower spin.
Thanks

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17-4 PH H900 .040" hole through .720"

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