Cast Iron Reaming Survey

I'd like a recommendation from all you gents & gals about reaming some cast iron holes. Parameters as follows:

Material: gray cast iron
Machine: #40 taper VMC
Holder: ER32 Collet, presume machine will probe to locate hole
Coolant: None, air blast only
Hole: Through hole, about 1.75" long. 11/16" diameter
Volumes: high. This is a long term job. Will be about 150 - 250 of each size weekly.
Tolerance: +/- 0.0004" on dia.


Hole will need to be sized 0.0005", 0.005", or 0.015" bigger.

Lack of coolant seems to be a big issue. I've always heard cast iron should be machined dry, but I really want to do it dry for a housekeeping perspective. Parts get wet, the cast iron chips & dust will stick to the wet part. Dripping coolant out in the floor causes a slick spot, etc.

I've started out with the generic 6 flute carbide tipped running about 400 RPM feeding at about 10 IPM. I'm slowly fading these out and replacing with full length carbide flutes. The steel flutes on top of the carbide of the current reamers seem to be what's wearing the most.

Obviously faster would be fantastic, but the real issue is hole size. I'd like to have a nice predictable tool life so I can be preventative about tool replacement.

So please. Let's hear your experiences. I'd like a recommendation on brand/type and also a feed/speed suggestion.

I would get a hold of salesmen for komet or the like with the replaceable head style reamers, seems most every popular brand has one now and with your tool life already known and parameters given I would bet you could get a gauranteed test run out of it. Running dry and without a "prebore" may be the only holdback but I think my tool rep would give it a go. Google Iscar's Bayot-ream for example, if youve got a tight spindle and decent setup I think it would be solid.

What is your realistic budget for tooling? This is a good volume of parts, and you need some serious tools.

I would be looking at a PCD or CBN tipped form tool. We have used Mapal and Guhring. You can get carbide shanks or HSS, in the sizes you are talking about, the price difference will not be much. You don't really need that much accuracy or surface finish, you just want longevity.

I would figure $1500 to $2000 for one of these tools. You will want to buy more than one. Figure on a hydraulic holder as well, you want as little runout as possible.

PCD and CBN cannot be resharpened by traditional means. The tips are cut with a wire EDM, and will need to be re-cut on EDM to sharpen, if possible.