By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Forum House Ad Zone

Cutting Tool Steel

All Topics | Latest Posts

Search for:  in Thread Title in  
<< First < Prev 1 2
Andrew Johnston30/11/2011 22:56:22
avatar
7061 forum posts
719 photos
Chris; thanks for the information.
 
However, I think you are wrong about industry having no need for it. I use Garr carbide milling cutters, as it is what my local tool supplier stocks. Their catalogue has several pages in the back dedicated to feeds and speeds for use in hardened steel up to 70 HRc, which I suspect is about as hard as HSS gets. As I understand it the driving force is the machining of pre-hardened mould dies, to avoid heat treatment distortion that may occur if the mould is hardened after machining.
 
Regards,
 
Andrew
chris stephens01/12/2011 00:06:54
1049 forum posts
1 photos
Hi Andrew,
What I meant was that industry does not need to machine HSS in its hardened state. If there were a need it would be easier to do batches in the "soft" state and then harden.
I quite see that there is a need for machining hard metals, apart from my playing.
chriStephens
Chris Trice01/12/2011 01:50:06
avatar
1376 forum posts
10 photos
So as a rule, what sort of speeds are we talking compared with say machining a carbon steel?

Edited By Chris Trice on 01/12/2011 01:50:36

Andrew Johnston01/12/2011 08:44:28
avatar
7061 forum posts
719 photos
Chris S: I don't disagree with you.
 
Chris T: According to my Garr catalogue they recommend the following for 60-65 HRc. Normal machining is at 75fpm, so for a 1/2" cutter 575rpm and 0.0012" chip load. For high speed machining at the same hardness they recommend 450fpm, 3450rpm and 0.0009" chip load for a 1/2" cutter. Airblast is recommended, but dry machining is acceptable. Seems pretty fast to me, but I assume the idea is to run the chip shear zone hotter than red heat, so softening the metal.
 
Regards,
 
Andrew
Andrew Johnston29/12/2011 13:38:37
avatar
7061 forum posts
719 photos
I finally got around to trying this. I used an uncoated carbide Garr 10mm 3 flute endcutting endmill. The cutter isn't new by any means. The material used was a piece of new 5/16" square HSS from a model engineering supplier; so god only knows what it actually is! I did two trials at differing speeds and feeds. In both cases I cut dry and cut the full width of the material with a depth of cut of 0.5mm.
 
1. First, I tried 600rpm and a feedrate of 50mm/min. This equates to a surface speed of 62ft/min and a chip load of 0.0011". The cut worked, but the mill (Bridgeport) clearly wasn't thrilled, as there was a hint of vibration. The finish looks ok, if a bit uneven. The Ra measures as 0.86µm.
 
2. Second, I tried 2500rpm and feedrate of 150mm/min. This equates to a surface speed of 258ft/min and a chip load of 0.0008". The mill was happy with the cut, no detectable vibration, and as a bonus there was a rather pretty circle of orange light around the cut with tangential shafts of orange coming off, just like a Catherine wheel. The finish looks good, and the Ra measures as 0.26µm.
 
My hardness tester is in a state of dis-assembly, so I haven't been able to make before and after hardness measurements.
 
Best Regards,
 
Andrew
Ian S C30/12/2011 11:17:19
avatar
7468 forum posts
230 photos
I was looking for some information on some cast iron, and got into a site for carbide cutting tools, thes included some called Omega-6 M70, specially designed for HSS and other tool steels.
The same site offered a sharpening service for end/ slot mills, carbide burrs, drills, down to 3 mm. Only thing is, I forgot to note the name of the site, not that I'll be needing the service. Ian S C
<< First < Prev 1 2

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Sign up to our Newsletter

Sign up to our newsletter and get a free digital issue.

You can unsubscribe at anytime. View our privacy policy at www.mortons.co.uk/privacy

Latest Forum Posts
Support Our Partners
cowells
Sarik
MERIDIENNE EXHIBITIONS LTD
Shopping Partners
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest

 

Donate

donate