trying to drill steel casting 54c

[nonstop]

I need to drill 10 1.008 dia holes 2.4 deep in steel casting thats 52 54c. Now using a flat bottom indexable with through the spindle coolant at 750 rpms and a feed of 1.7 ipm. i get 2 holes per edge. Any suggestions on tooling or speeds and feeds would be appreciated. thanks

[Leigh @ Kodiak]

Seems like you could bump up the feed.

[jeff]

What type of steel is it?

Where is the insert wearing the most? on the bottom cutting edge or the outside edge?

Can you use a solid carbide drill and then interpolate a flat bottom with an endmill?

[nonstop]

What type of steel is it?

Where is the insert wearing the most? on the bottom cutting edge or the outside edge?

Can you use a solid carbide drill and then interpolate a flat bottom with an endmill?

 

its a 4140 4150 the bottom of the insert wears out. we tried increasing the feed but no luck.

do you know of a good company that will make a custom drill with a good insert? This is a very tough job,

this job has 10 slots which we use iscars helido high feed 1.5 dia mill at 680 rpm and 68 ipm at .04 doc

and it grinds the inserts down like nothing. these #s are the best results so far. The material has a case hardening of 52 to 54 rockwell .125 deep and 46 to 48 below that. I think because its cast theres xxxx in the casting that causes the problems.

[Tim Johnson]

Take a 5/8" hard milling end mill and helix bore the casing approx. s1100 @ 20ipm .002 doc. Then go back to your standard tooling.

[trumper777]

I run a similar type part. At that Hardness. I agree with Tim, Helix bore out through the first .200. My feeds and speeds on the drilling cycle itself are 250SFM (947RPM) with .0075 feed. So its roughly 7IPM. (This will obviously vary on the machine your running it on.) I run my parts on a Nakamura-Tome WT-300.

 

I tend to lean towards Kennametal or Sandvik for my drilling. A little more $$$ up front, but tend to last longer.