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wierdscience
12-06-2005, 09:03 PM
Okay short(hopefully)story.

I re-surface plastic pelletizing dies at work.Originally the dies had a 1045 steel body and c-4 carbide tiles on the facings.I have been for years re-surfacing these in a water cooled tub grinder(small blanchard)using a 100% concentration 120 grit diamond wheel and water based coolant.

Cycle times were on average 5-10 minutes per die and wheel life was 60-75 dies before scrap.

Okay,now in addition to the old style dies they also are using a newer style that is faced with a Ti alloy which is hardened to 65-67 Rc.This alloy is tougher than nails.The only way I can surface it is to dress the diamond wheel 3-4 times per die.Needless to say wheel life has gone to hell at just 20-25 dies per wheel.Also cycle time has increased to 15-20 minutes.

I was wondering if a CBN wheel would do me better and if I could use it on both the carbide and the Ti alloy.I would not be able to switch back and forth between wheels as too much wheel face is lost in the truing operation after each change over.

The aproximate surface area being removed on each die is a ring 5" id x 6" od and about 1/32-1/16" deep hence the high dress rate.

Any clues?

JCD
12-06-2005, 10:04 PM
If you are dressing a diamond grinding wheel, you’ve got big trouble. You might try cleaning with a wheel or stick designed for the application.
I’m not an expert, but Norton, 3M and other abrasive manufactures can help. Contact your area reprehensive for help. If they don’t respond then contact the manufacturer directly.
Good luck.

andy_b
12-07-2005, 11:25 AM
do the new Ti dies last 4-5 times as long before needing to be resurfaced? if so, it sounds to me like you are actually making out better with the Ti dies.

it occurs to me, you aren't listening to the Grateful Dead while doing this, are you?

andy b.

chipeater
12-07-2005, 11:53 AM
IIRC, Evan's Better Half is a purveyor of abrasive products, including grinding wheels.

Perhaps she could be of help?

Steve

[This message has been edited by chipeater (edited 12-07-2005).]

Evan
12-07-2005, 11:58 AM
Darin,

It may sound strange but my wife suggests trying an aluminum oxide wheel on the titanium.

wierdscience
12-07-2005, 07:24 PM
<font face="Verdana, Arial" size="2">Originally posted by andy_b:
do the new Ti dies last 4-5 times as long before needing to be resurfaced? if so, it sounds to me like you are actually making out better with the Ti dies.

it occurs to me, you aren't listening to the Grateful Dead while doing this, are you?

andy b.</font>

Yes they last longer between grinding,but this is bad for me since I get less work.Understand that I am charging them for grinding the dies and reduced wheel life($235 each)and longer cycle times means more cost for me.

And no I never was a Greatful Dead fan although The Who is nice sometimes http://bbs.homeshopmachinist.net//biggrin.gif

wierdscience
12-07-2005, 07:27 PM
<font face="Verdana, Arial" size="2">Originally posted by Evan:
Darin,

It may sound strange but my wife suggests trying an aluminum oxide wheel on the titanium.</font>

I have already,the dies make an excellent dresser for them http://bbs.homeshopmachinist.net//biggrin.gif It's impressive too,I think I could get two dies from one wheel http://bbs.homeshopmachinist.net//biggrin.gif

I don't know what to do,this stuff is really tough.

fishfrnzy
12-07-2005, 07:47 PM
I don't know if this is practical for your application because alloy and coatings may vary, but......

I had a customer once that did alot of profile griding on tungsten carbide and he did all the major work with EDM then grinding while annealed and heat treated then gound down the last few thou after hardening.

Rustybolt
12-07-2005, 09:32 PM
Wierd. I just googled this up.

Date: 03/31/04
Author: Gena gurinovich@abrazive.spb.ru
Subject: Grinding Titanium with vitrified CBN
We have made several tests on grinding nickel and titanium alloys by vitrified CBN wheels with induced porosity. The result is: wheel does not get loaded and no metal burns. If intetersted, I could send test results by e-mail.

When I used to grind hardened dowel pins(60-62) in the centerless. I wound up using a soft Alum oxide wheel at a slower feedrate.(about1/4 of normal) The wheel wear was about double but acceptable.
When honing really hard material I used CBN in a metal matrix with a slow spindle speed and the stones lasted a lot longer. my.02