Achieving Uniform Hardness on Saw Blades

Objective

Utilizing induction heating to draw back steel saw blades to a Rockwell hardness of between 50 and 52. The hardness should be within 1/2 to 1 point between the teeth and the back of the blade. Processing must be performed at a rate of 60 inches per minute

End Product

Steel saw blade

Equipment

Ambrell 7.5kW output solid-state induction power supply with a step down transformer and a remote heat station containing three (3) busses and eight (8) capacitors with a total

capacitance of 0.66
F. A water-cooled coil was designed and developed specifically for this application utilizing single and double turns

Materials

Steel band saw blade measuring 2.125" wide, 0.042" thick

Temperature

700 ºF

Frequency

80 kHz

Testing

The Ambrell equipment was used to achieve the following goals:

• The necessary heat pattern was accomplished through the use of a uniquely designed channel coil and a step down transformer to reduce the voltage

• A feed rate of 60 inches per minute was also met through the use of the unique channel coil and specifically designed fixture.

Benefits

Resulting mean hardness of 50.3 Rc was measured for fifteen saw teeth on a Wilson Superficial Hardness Tester, fulfilling the ultimate goal established by the customer.

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