Effect of sand on Carbide

[BenK]

I'm trying to get some cycle time out of an aluminum casting. Currently they are using a facemill with PCD inserts to rough and finish the faces. I know I could save a lot of cycle time by switching to a Seco Square 6 facemill to rough the part and keep the PCD to finish but the concern is tool life of the carbide inserts. I have already been talking to Seco about doing a PVD coating on their aluminum inset but I'm not having any luck. My question is how much does the residual sand from the casting process play into the tool life on a polished carbide insert? 

[Newbeeee™]

Ben - stupid question but is it definitely a sand casting? Most castings nowadays are lost-wax (investment) where there should be no sand and what your asking is then not a problem.

If it is sand, again usually they grit blast to clean the casting so should be no sand again.

I think the only way you will find out on something like this is to try it.

FWIW we ran Hertel tips that had diamond tip and they lasted forever, but this was on a finishing operation. I've never used PCD...

[Guyinthedesert]

We do a lot of 356 castings and they eat up face mill inserts. I would like to find a better alternative.

[BenK]

Newbeeee, Not a stupid question at all. I'm going off what the company is telling me, so I'm fairly certain its a sand casting. Unfortunately I'm only here until the end of the week so trying it isn't an option. I'm just trying to gather some information so I can make a few suggestions.

[Reko]

I've machined a lot of sand castings, and the bottom line is, it doesn't matter what insert you use... sand always wins. It is very abrasive.

 

One thing to remember is do not  take small cuts... if you do, the focus of the heat ( which is exactly what carbide to sand abrasion produces ) is entirely at the tip of the insert... then the tip wears... the inclusion at the deteriorating tip produces even more heat and then insert failure is imminent.

 

The only solution is to take deeper cuts ( slower speeds/feeds ) to get under the sand... the insert will notch higher up, but that's okay... and you'll see more "dust" but the inserts will last much longer.

 

Bottom line though, no carbide can win with sand, so choose an inexpensive grade and take deeper cuts to get underneath.