Speeds and Feeds for Tipped Tools (not HSS)

Speeds and Feeds for Tipped Tools (not HSS)

These data are based on material from the Greenwood Tools web site, www.greenwood-tools.co.uk

Speeds
The table suggests cutter speeds for the most commonly machined materials when using carbide grade H13A tipped tools. Be prepared to adjust a speed in the light of safety and other considerations. The calculations are based on:

Speed (rpm) = Cutter surface speed for the material (mm/min) / Cutter circumference (mm)

Select the milling cutter diameter. Move across to the workpiece material. Read off the speed as appropriate for a roughing or a finishing cut.

(Note: F1 mill, 2000 rpm max; WoodWorker 8000 rpm max.)

Feeds
Calculate a feed rate on the basis that the feed per insert is between 0.05 and 0.10 mm. The value chosen in this range should be based on:
§ the required surface finish.
§ the power of the spindle motor.
§ the rigidity of the machine, workpiece and general set-up.

The equation to use is:-

Feed Rate (mm/min) = Speed (rpm) x Number of Inserts in Cutter x Feed per Insert (mm)

Where a large amount of stock is to be removed, the cutting edge will generally last longer if shallower cuts are taken at higher feeds rather than deeper cuts at lighter feeds.

Power requirements
Some people worry about power requirements when facing milling on light, low-powered machines. Their worries are usually unfounded. For example: for a 63mm dia CoroMill® 245 cutter with H13A grade inserts cuts mild steel at 350 rpm with a feed rate of 127mm/minute and a cut 38mm wide x 1.5mm deep - the motor power required to drive the cutter is only 280 watts (F1 mill and WoodWorker spindle motor, 440 watts).

(In general terms, it can be said that 746 watts is required remove 1 cu in of steel or 1.5 cu in of cast iron in 1 minute. By multiplying the feed/minute (in inches) by the width of cut (in inches) by the depth of cut (in inches), an approximate spindle motor power is given. For example:
feed 4ins/minute, width of cut 1/2ins, depth of cut 1/8 ins requires 4 x 1/2 x 1/8 = 1/4 horsepower.)

Doubling the feed or doubling the depth of cut doubles the power required.

Tipped cutters are so 'kind' to the machine that someone described it as 'just like mowing grass!'

Greenwood Tools stock a useful range of milling cutters and lathe tool holders and tips, often at attractive prices and ideal for the Emco F1 mill and Emco 5CNC/5PC lathes: see their web site, above.

Cutters for Metals
Cutters for Wood, MDF and Plastics
Materials for Machining
Measuring Offsets
Setting the Origin for Machining
Speeds and Feeds for High Speed Steel (HSS) Tools
Tool Organisation