Milling inserts are always going to have to withstand impact as they come round into contact. I'd try starting with light cuts on alli, then brass, then mild steel progressively. If they do chip, they're not going to be very useful anyway.

I think the only way to find out is to try it!

Multi-insert face-mills have been available for many years and I don't recall any general complaints about them being more likely to chip inserts than any other type of tool-holder.

The nervousness about chipping carbide is partly folk memory and partly real. Carbide inserts usually consist of many small particles of a very hard material like Tungsten Carbide bonded together in a matrix. Not solid – more like the grit in a grinding wheel than HSS. The matrix is usually a metal. Early inserts were brittle, but they've been gradually improved over the last 80 years or so. Modern formulations are much less brittle. Unfortunately, one way of reducing the cost of inserts is to cheapen the matrix material and to cut down on the amount of carbide in the mix. This might be done by a reputable maker selling tips for work not requiring high shock resistance, or it might be done less honestly because low-cost matters more to the customer than high-performance. Another issue is manufacturing rejects – a batch of inserts might fail shock-testing and be sold-off as 'unbranded'.

My experience with cheap inserts has been generally acceptable – most are happy to take interrupted cuts. But about 20% of my inexpensive stock have failed prematurely – especially sharp ones and threading tips. The very worst were bought cheap at an exhibition: opening the box a few months later I discovered them to be obvious rejects, they work – but not reliably. Inserts bought from the usual suspects on the forum are OK rather than brilliant, but for my lightweight hobby needs top-quality inserts aren't economic.

We don't know if the inserts that came with your tool are good or rubbish! I've had new tools come with inferior inserts and new tools arrive fitted with good ones. Can't tell by looking but cutting steel will soon give the answer.

Another point is whether or not a 4-point tool is useful in your particular workshop. The advantage is they can remove metal at high-speed but that may not suit your equipment. A mill driving four cutting points needs a good deal more power and rigidity than one spinning a single-point tool, and a hobby mill might not have the ommph necessary to get the best out of a 4-point cutter. Again, I think you can only find out by trying it. Depending on the mill you might find it's great for Brass, Aluminium and Cast-iron but steel is too much.

Dave

Have a look at my posts in this thread to see what a difference some decent inserts made to one of these cheap facemills.