Looks like a CCMT insert from the photo , If it where me i would double the spindle speed and depth of cut.

On my S7 with CCMT inserts the best finish is with at least a 20thou depth of cut and a fairly fast feed to get a decent chip.

Reduce your tool overhang too, if you can.

Edited By David Standing 1 on 15/04/2019 21:18:08

Try the other end of the insert or a new insert and see if it improves , make sure the tool is on centre .

Could also try a drop of coolant or neat cutting oil

Nothing to add really – as others suggest you are being too cautious for TCT.

Even 10 thou is quite shallow, you should ideally aim for 2/3 tip radius minimum.

Neil

Start by finding out what the official makers data-sheet figures for speed, feed and depth of cut are. Carbide insert tooling does generally need to be worked hard to get a good finish but that doesn't always mean very high speed. Some of the ones intended for use on manual machines have surprisingly low surface speed requirements.

For example I have some rhombic inserts made by Sandvick grade H10F, type CNMG 0432-23 whose book surface speed range is 85 – 100 ft/min. Go much faster and the edge disappears. Feed is 5 to 9 thou per rev and depth of cut range 14 to 145 thou, 100 thou is suggested as a typical depth of cut to start with. Basically you play with the depth of cut to get nice short tightly curled blue chips leaving a good finish.

I have others specified for 500 to 1000 ft / min which is more what folk expect and one finishing type that works best at approaching 1,500 ft/m albeit with a recommended feed of around 6 thou per rev at 14 thou depth of cut. Somebody read the ft/min as m/min when purchasing. Ooops! So they need to go three times as fast as I expected. Difference between mildly scary and seriously frightening. Chip blizzards are bad enough in brass. Blue hot steel is much worse. Awesome finish tho'.

Clive

Edited By Clive Foster on 16/04/2019 00:34:34

Have a look at my post at the bottom of this page to see how DOC and feed affect the finish, the harder the tool is worked the better the finish you get.

Greenwoods speeds do seem rather tame, quick look at Korloy for a CCMT at 3" in general steel is 750rpm.

Also if you can only take a cut of 10thou before you get slip and jams then I'd say something is amiss with the machine.

Has anyone zoomed in on the insert tip ? Looks chipped to me and if it is no amount of feed rate change will make it work . I typed in greenwood type 1 insert into google and couldn’t see anything of use , in have had issues recently with cheap inserts that won’t cut anything and i put it down to dodgy inserts .

If you need to do things on a tight budget stick with HSS otherwise be prepared to fork out for known quality carbide inserts – the cheap junk isn’t worth it , been there done that got burnt !

Ok thanks Jason , I’m not familiar with that brand .

To me looking at the finish and zooming in on the photos the finish looks to be tearing and the tip looks like the radius is gone – when things go awry i look at this first ,Its a simple thing to change and check .

Ian.

+1 for the sharp polished inserts sold for aluminium. As said they work a treat on steel. Was doing some 50mm diameter mild steel this morning and the finish was superb, but you need to be careful since the edges can be damaged quite easily if mistreated. And yes keep the speed up.

Doug