Vanagon EuroVan
Previous messageNext messagePrevious in topicNext in topicPrevious by same authorNext by same authorPrevious page (October 2020, week 3)Back to main VANAGON pageJoin or leave VANAGON (or change settings)ReplyPost a new messageSearchProportional fontNon-proportional font
Date:   Fri, 16 Oct 2020 07:29:19 -0700
Reply-To:   Alistair Bell <albell@SHAW.CA>
Sender:   Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:   Alistair Bell <albell@SHAW.CA>
Subject:   OT Friday , hard turning on the lathe with ceramic inserts
Content-Type:   text/plain; charset=utf-8

My family and friends just look at me blankly when I come home and tell tales of work. So I’ll bore you guys too. And it’s not meant to be some boasting or war story type thing. I’m just pretty excited at being able to experience something new and I think there are listmembers with some machining skills who might be interested and maybe, maybe, give me some pointers.

Been very busy at work with an ongoing project of many little aviation parts. But another job came in recently that was kinda cool. It’s to turn down 100 or so Igus linear guides. 20mm diameter, one end to have shoulder 14 mm diameter , 14 mm long. The other end drilled and tapped m10x1.5. The rods are case hardened to 55-60 Rockwell. The hardening about 1.6 mm deep.

My best carbide inserts would cut , but not nicely. So we got some sandvik ceramic inserts. Triangular, no rake, no chip breaker. I’ve never used this kind of insert before. There is, as you might guess, a range of ceramic insert types. These seem to be the most basic.

The info on them points to running them hard and fast . Chips coming off red hot, sparks etc. Oh and either with flood coolant or dry. Intermittent cooling supposedly shocks and cracks insert.

The lathe is a Haas TL-1 (cnc)

I immediately broke one insert on a hand fed test cut. I mean, it broke so easily...

Finally got the speeds and feeds right. About 400 surface feet per minute, 40 thou depth of cut, and 0.001 inch per rev. And I used constant mist coolant. I found the surface finish on the softer inside of the rods was better with the mist blasting. Note about measuring units. Lathe is set up in imperial, part was dimensioned metric.

The cool thing was, once I got the offset dialled in, I could repeatedly get 10 micron over target diameter. It was extremely consistent. Id bring to final dimension with a quick touch of 400 grit paper. The paper gave a nice polish. I had a 50 micron tolerance on the diameter.

So after about 15 parts done, and feeling cocky and happy, and the insert showing no sign of wear, the insert shattered on number 16.

So the plan is to index insert after 10 rods. Have potentially 6 cutting edges on each insert. Inserts were only 13 bucks each. Oh and if these inserts didn’t work, our tool salesman guy was recommending CBN ( cubic boron nitride) inserts. They cost 10 X more.

Drilling and tapping the other end was anticlimactic. Yes, drill and tap were expensive, but nothing exotic. And the drilling and tapping were done by lathe, rigid tapping.

Well that’s that. I wish I could say more about the aviation parts. They are kinda cool shapes and made mostly from 7075 aluminum. That stuff is now my new love. It cuts so nicely and is noticeably harder than 6061. Of course it is, but you can really feel it when working with it . It’s a bit of an stretch to say it’s like steel, but in some ways not far off.

Cheers

Alistair


Back to: Top of message | Previous page | Main VANAGON page

Please note - During the past 17 years of operation, several gigabytes of Vanagon mail messages have been archived. Searching the entire collection will take up to five minutes to complete. Please be patient!


Return to the archives @ gerry.vanagon.com


The vanagon mailing list archives are copyright (c) 1994-2011, and may not be reproduced without the express written permission of the list administrators. Posting messages to this mailing list grants a license to the mailing list administrators to reproduce the message in a compilation, either printed or electronic. All compilations will be not-for-profit, with any excess proceeds going to the Vanagon mailing list.

Any profits from list compilations go exclusively towards the management and operation of the Vanagon mailing list and vanagon mailing list web site.