g huns

Drilling/Reaming Moldstar 90

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We are really good at machining this crap, but drilling and reaming it on an NC is new to us. The drilling don't scare me. I can find a similar material in Walter's GPS and wing it from there, but reaming scares the hell out of me. I have reamed plenty of holes in materials like it in a Bridgeport and still have nightmares about it. It tends to be very grabby. 

 

We use a lot of Fullerton carbide reamers. I am leaning towards one with a right hand spiral flute, supposed to be good for abrasive materials. But they say a left hand flute is better for harder materials. This stuff is about 30Rc, so not really "hard", but not soft either. Have to ream 22, 5mm and 22 8mm holes. Any advice?

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I've had better luck maintaining hole size with straight flute coolant through reamers with the correct speed and feeds. Right hand spiral are more inclined to run oversize.

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I've had better luck maintaining hole size with straight flute coolant through reamers with the correct speed and feeds. Right hand spiral are more inclined to run oversize.

 

Whose reamer do you use? I can never find a coolant thru, carbide reamer that's long enough for what I need. Here's what I gotta do...

 

5mm%20reamed_zpsuxrrtybq.jpg

 

The reamer needs to reach at least 2" deep. I was talking to my Guhring guy, their 5mm only reaches 40mm, 1.574". But it is about 3" overall. I am thinking of buying a couple and relieving the 6mm shank a bit farther back to get the reach I need.

 

My 8mm hole problem is solved. The pins that fit in them are core pins, so they are to size with a plus tolerance. I drilled them with a Walter A6589DPP-8. Pins have a perfect slip fit. :thumbsup:

 

I know I can't pull that off with the 5mm. Those are holes for ejector pins, which are always undersize.

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I use Hannibal Carbide for TSC reamers. For non TSC I usually get pretty good selection from Morse for HSS reamers that have carbide flutes.

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Hannibal is my go-to reamer as well.
We ream huge amount of titanium and inco with excellent results. For thru holes I prefer to go with right hand spiral left hand cut (*Correction per Matthew's comment below- should say Left Hand Spiral, Right Hand Cut*) and coolant between flutes.
We also use Sandvik, Fullerton, Iscar, and Komet.

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I pulled a stupid. LOL

Let's see if I get it right this time...

Left hand spiral right hand cut.

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try a straight flute drill if your really that concerned. If your going the reamer route i'd suggest hannibal straight flute(chip pushed in front of cutting edge and not up the flute to possibly build heat and blow hole oversized imo) reamers, carbided tipped or hss. Qualify the start of the hole(to ensure perpendicularity) at least to a depth of the cutting tool diameter and about .01-.012 under finish size. Spin it slow and feed it rather heavily. I've also been known to stop spindle before retracting out of hole. It seems to help with blowout. As far as the material itself, that's no concern. I think it cuts without problem if tooling is sharp, as well as material kept cool and sufficiently lubricated at cutting edge. Breaking thru might be hard on tool if the drill rolled burr out bottom, ive found carbide to be prone to pushing over a hefty exit burr in copper, Dormer TiN coated parabolic split point drills work well. I've found these to take a heavy clip load, but standard SFM. No spot needed(if you do keep it light, just need to clear the drill web thickness) and its comfortable without any peck retracts if chip easily escapes via flutes. Enjoy :)

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