Well, the parts are centerless ground before they get to machining. It would be nice if it could be that way. Tried some coolant fed twist drills today. One from Sumitoma and the other from Tirex. They didn't do too bad but we still ended up with the exit sides big. Had my QA do a density check...
We have tried different grinds from a b;unt angle to a sharp one. Getting the run out to settle down is hard enough as it is, but we have to maintain an 8 second run time. We have to push the drills pretty hard, in fact had a drill loose its head at the weld. Go figure. We have had a Star cutter...
We have three stations doing the drilling each doing a third of the part. The first third is being done with a .303 gundrill, the second is a .302, the last is again a .303 from the other side. The first and last drills are guided by bushings that cradle the face of the part, the second is using...
Well, since the last time I left a reply things have changed. We are going to drop the gun drills all together and go to a TX style drill or even a margine drill, like Kenametal's. And it seemed before that our reamer size to hole size may have been a bit of a factor. There was only about .006...
Here's another question for you folks. With what we have to work with, what would be a good feed and speed for a two flute gun drill, "Drill Masters", in inches per rev. and a suficient RPM? Again the material being a compacted powder metal that cuts like grey cast iron, drill size at...
We do use a carbide bushing to guide the gun drills. The bushing cradles the front of the part. I have been getting a consistant .0004 to .001 on the entrance with a solid carbide gun drill. I am drilling from both ends, meeting in the middle. then reaming. The center of the part ends up with...
The dia. of the part is .562, the hole size is .303, the distance is 4.004 long. The drills are rather long, 9inch. Tried one flute and two both having the same results. The entrance is usually .001 to .004 and the exit is .003 to .008. This even happens when there is a precast hole in the part...
I'm haveing problems drilling concentric to the O.D. The work is being done in a Hydromat Indexing machine in which the tooling is rotated and moved into the material. I have tried gundrills and reaming and fluted drill to size, with or with out a previous hole, and we always end up with a...
