Optimal feed rates for CNC machining

What are the best feed rates for CNC work? October 31, 2000

We are running a CNC simulation program for wood, for educational purposes. I need some information on the optimal RPM feed rate, for a more realistic simulation.

Can anyone tell me where I may be able to obtain information on the optimal speed for various wood machining processes?

Forum Responses
For flat-panel processing in 1/2-inch veneer-core plywood or 3/4-inch melamine (particleboard core), generally 9 to 12 meters per minute will yield acceptable results. You would typically use a 1/2-inch compression bit for such routing, spinning 14,000 to 18,000 RPM. These guidelines will generally work for pretty much any kind of "spiral" bit, be it an upshear, downshear, or compression.

Solid wood can be somewhat tricky depending on how you are going to cut it. Poplar, for instance, can usually be power cut and you can run at a decent speed, in the 5- to 9-meter range. Hickory on the other hand will split, splinter, or generally come apart if you don't climb cut it. I like to slow the speed a little when climb cutting anyway, but with hickory, I would probably cut it somewhere in the 2- to 5-meter range, depending on what exactly I'm doing.

Some general rules of thumb: If you are routing large pieces you can generally use high feed rates. If you are doing long, straight lines you can use higher feed rates. Obviously the flip side of this is that smaller pieces will require slower feed rates, as will intricate routing.

A lot of times when I am doing long straights followed by corners I will ramp the speed down before I get to the corner and then ramp up after the corner. I'm not sure how many P2P guys do this, but the router guys know what I'm talking about.

Another consideration is the size of the piece you're routing. This not only could have a bearing on your feed rate, but your tooling as well. Whenever possible I will use an upshear bit, to get the dust extracted as best I can.

All this info is based on my experience using a Busellato Optima P2P. There are other machines out there that do other things. Some of the new routers claim to be effective at 1,500 inches per minute, but I have yet to see this put to practical use.

Check a CNC tool manufacturer's catalogue. They often list a chart with material/feed rate info.

There really are no references that provide the information you are seeking, at least not that we are aware of. We have put together some basic information about feed rates, spindle speeds, chiploads, etc. for several different materials, based on our experiences. The examples presented in the other responses as well as the suggestion about tool catalogs are good starting points also.

Optimal feed speeds for CNC machining of solid woods depend on a variety of factors. Wood thickness, type of material, part layout, horsepower, RPM, finish cut or ruffing cut.

Our .375-inch diameter ruffing tool can machine at 2,400 IPM at 24,000 RPM, machining .875-inch plywood. This is not practical in most operations and requires a newer piece of CNC equipment and software.

A three-flute ruffing tool will provide you with the fastest feed speeds when machining solid wood. This a great tool used for sizing material prior to adding a profile and also for the upholstery industry.

A two-flute ruffing/finisher will provide you with feed speeds 20 to 30 percent less than a ruffer, and has less tool life. A two-flute finishing tool will provide the same feed speeds, but again, less tool life.

Let's say you are machining a 3/4-inch-thick hardwood and can achieve feed speeds of 600 IPM (15m) based on your part layout. You would use 15,000 RPM to increase your tool life. At 800 IPM (20m) on the same material, use 18,000 RPM.