Diamond Bits Versus Carbide Bits

Diamond bits last longer in hard materials, but may not be as sharp for quality cutting. January 14, 2008

The company I work for is debating whether to switch over to using diamond router bits. The carbon router bits we are using now are dulling quickly, cutting MDF and hardwoods. We have been told the diamond router bits would stay sharp and last longer. PLC and diamond bits - are they the same? Are there difference grades of diamond bits? Also, we been told that on our profile bits, only one wing would have to be diamond, and the other would be carbon. Also, would the speed have to be reduced cutting wise when using diamond?

Forum Responses
(CNC Forum)
From contributor J:
For MDF or PBD laminated with HPL, we use PCD bits. However, the recommended feed speeds are much slower than for carbide. But I usually run ours closer to the carbide speeds, and I have broken one.

From contributor S:
The diamond bits are made for production cutting at high feed rates. If you're looking for quality cutting, diamond is not the answer, because there will be occasional chipping.

From contributor J:
The diamond bits that I've used have slower recommended feed rates than the carbide bits. But yes, they are not as sharp as carbide bits.

From contributor K:
Diamond bits will not achieve the speed that carbide can, that is a fact. They do last a lot longer in most cases, but on some materials they don't perform that well. In my experience the diamond profile cutters have done very well, but the compression, up and down style has not. The loss of speed and cost to replace or sharpen has not been cost effective. The time it takes to replace or sharpen diamond is too long unless you know what you need and when you need it well in advance.

From contributor G:
PCD tools are great for MDF doors. With diamond, the initial costs are greater, but after 1-2 services is where the pricing lowers. You have not mentioned the quantity of doors you produce, but if it's over 100 per week, PCD should be the choice. We [Courmatt] do provide a cost evaluation between TCT, Insert and PCD, which should assist you making a choice. Feed speeds would not change, but may actually be higher with PCD, depending on your profile. The only time we suggest using a a compression PCD is only if your parts are small or feed speeds are not over 200 IPM.