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Plastic Mold Steels


Technical Center:

In this section we will feature answers to commonly asked questions. Check back often, as this page is regularly updated.

- Material Removal Rates 
- To Calculate Surface Feed
- To Calculate Chip Load
- To Calculate Feed Rate

International Mold Steel specializes in pre-hardened mold and tool steels that are considered to be the finest available in the market place today. Because of their unique and homogenous make-up, deviation in hardness or hard spots is a thing of the past. When machining these materials it will become immediately apparent that much faster metal removal rates can be achieved.

Material Removal Rates 
Consider this: material removal rate during this time span in approximately 300 pounds of steel. It showed that we could remove a lot of steel with moderate surface feet but a heavy chip load. Once again, the clean make-up of the material made this possible.

To Calculate Surface Feed
Surface speed is usually given in feet per minute. It is the distance (in feet) that the outermost cutting edge of a rotating tool (circumference) covers in the span of 1-minute.

To understand how this translates into spindle speed, or revolutions per minute (rpm) that the cutting tool is revolving, review this example:


Surface feet 400 feet per minute Diameter of cutting tool is 4 inches. Revolutions per minute (rpm) if cutting tool is ____


C = Surface feet per minute (feet) D = Diameter of cutting tool (inches) R = Revolutions per minute of cutting tool (rpm)

R = (C x 12) = (400 x 12) = 4800 = 382 rpm 
       (D x Pi) (4 in. x 3.14) 12.56

If you need to know surface feet per minute and the cutter diameter and spindle speed is known, you will have this equation:

C = Pi x D x R = 3.14 x 4 x 382 = 400 sf. 
             12                  12

To Calculate Chip Load

Chip load is the amount of materials (in .001 inches) that each cutting flute or cutting insert of a rotating tool removes.

Chip load is calculated by dividing the distance of the table travel or feed per minute in inches by the spindle speed of the machine. This will give you the distance the cutter traveled in one revolution. This number is then divided by the number of cutting flutes or inserts.


Spindle speed is 450 rpm. Table travel or feed rate is 60 inches per minute. Number of flutes or cutting inserts is 6.


R = Spindle speed (rpm) 
I = Number of cutting flutes or inserts 
S = Distance of feed rate or table travel in inches. 
C = Chip load

  ( S
)  (


)   .
C = = .13333  = .0222
    I   6  

To Calculate Feed Rate

S = C x I x R =

S = .0222 x 6 x 450

To find rpm of spindle or R with chip load and feed rate known: 

R =    S    =        60        =    450 rpm 
       I x C       6 x .0222



Recommended Reading

Unique Characteristics


Typical Chemistry

Mechanical Properties

Physical Properties

General Design Guidelines

Processing Guidelines

Welding Guidelines

Technical Center


  International Mold Steel, Inc. 
1155 Victory Place
Hebron, KY 41048 USA 
Tel: 859.342.6000
Fax: 859.342.6006
Sales E-mail: [email protected]
Literature E-mail: [email protected]