View Full Version : Inserts for Cast Iron

07-13-2009, 11:27 PM
What properties are involved in inserts designated for machining Cast Iron. How would they do across the board with steel, Al, brass etc.

07-13-2009, 11:57 PM
Many of the negative rake inserts will machine cast nicely regardless of grade assuming nice clean cast like Durabar.Even if the mfg doesn't rate the insert as being particularly suited for cast.Most inserts are rated in industrial terms for industrial use and meant to last hundreds of hours in production.

Since few HSMs ever turnout 50gallon drums of cast shavings in a week it's not much of an issue.Brass and aluminum aren't a problem either.For aluminum,the only time I use inserts is when machining an alloy with a high silicon content,or anodizing.

Basically if I have a CNMG 422 insert in a KC850 grade carbide in the toolholder,I'm not going to sweat a change over a few hours running in cast or bronze.

If it's filty cast with sand and blow holes.....well that's when you bust out the C-2 brazed points....or chunk it in the scrap pile:)

07-14-2009, 12:01 AM
I worked at a foundry we used C2 negative rake it was the olny thing that would take the pounding interupted cuts and sand finnish.

C6 carbide would last just a few seconds, its way too brittle.

07-14-2009, 09:22 AM
The reason for my question wsa two fold:
1. I have some Sandvik TNMG 332-QM H13A K20 5N456 743
2. I was looking for TNGP 331 inserts. Carbide Depot has them in Kinnemetal KC730

I was asking how you thought these would perform on other materials.

Glenn Wegman
07-14-2009, 09:43 AM
Here's what Kennametal says

'Composition: A PVD TiN coating over a very wear-resistant unalloyed substrate. Application: For general purpose machining of high-temperature alloys, aerospace materials. refractory metals and 200 or 300 series stainless steels. The thin, uniformly dense , smooth coating increases wear resistance and reduces problems with built-up edge. It also provides an unusually good combination of properties for machining difficult-to-machine materials and aluminum. The substrate offers superior thermal deformation resistance, depth of cut notch resistance, and edge strength. Run at higher speeds than uncoated grades. Most ground periphery inserts have a sharp edge.'

07-15-2009, 11:00 PM
Cast iron generates a tremendous amount of heat and abrasion.
A flat top insert or an insert with a shallow chip breaker and a wide land with a thick CVD coating is preferable. The Sandvik insert you mentioned has a sharp, positive geometry for free cutting, short chipping materials and the H13 grade is a hard uncoated grade suitable for stainless or hi-temp alloys. KC730 is definitely not for cast.
It has a thin PVD TiN coating meant for lubricity, not wear resistance.

Give me a shout at curtis@latheinserts.com
I have a bunch of samples and partial packs I can send you for free. I can't sell broken packs to the production shops.