# Cutting Data

SELECTING SPEEDS and FEEDS (Turning and Parting Off)
The following table shows suggested r.p.m. for the most commonly machined materials. Look for the nearest diameter to the one you wish to cut, and move across to the workpiece material. Then simply read off the r.p.m.
* We assume your machine will not run at speeds faster than 2500rpm. Where the theoretical speed is greater than that, we have indicated with an asterisk.
a) The required surface finish.
The following table shows suggested r.p.m. for the most commonly machined materials with carbide grade H13A. Look for the diameter of your milling cutter, and move across to the workpiece material. Then read off the r.p.m. as appropriate for a roughing or a finishing cut. You should then select the nearest speed available on your machine, taking safety and other practical considerations into account. You can happily run slower if necessary, especially if it is unsafe to rotate the chuck at the indicated speeds.
* We assume your machine will not run at speeds faster than 3000 rpm. Where the theoretical speed is greater than that, we have indicated with an asterisk.
The feed per insert should be based on:
Some people get worried about power requirements when we talk about facemilling on light, low-powered machines. Very often, their worries are unfounded. The following example should give an idea as to the practicalities:- Using a 63mm dia CoroMill® 245 cutter to cut mild steel with H13A grade inserts:- At 350 rpm, with a table feed of 5 ins/minute, and assuming a cut of 1½ ins wide x 1/16 ins deep. The motor power required to drive the cutter would only be 0.38 Horsepower (=0.28kW)! Doubling the feed would double the power required, as would doubling the depth of cut. These cutters are so 'kind' to the machine, one of our customers commented that using it was 'just like mowing the grass!' In general terms, it can be said that 1 horsepower can remove 1 cubic inch of steel in 1 minute. (or 1.5 cu in of cast iron)
Therefore, by multiplying the feed/minute (in inches) by the width of cut (in inches) by the depth of cut (in inches), an approximation can be made as to the required spindle motor power. For example, a feed of 4 ins/minute, with a width of cut of 1/2 ins, and a depth of cut of 1/8 ins would use approximately |