From HD W punching tool steel supplied in hot rolled annealed bars in factory lengths of 4-5 meters.
- Cut bar to required length
- Bend the mould according to the template
- Straighten and adjust the cutting edge (the mould at the back must be wider by approx. 1 mm than the mould of the cutting edge)
- Weld the knife body as tightly as possible
- Grind the back edge
- Grind the cutting edge to obtain the required height
- Fit in the template (grind internal bevel, angle approx. 20°-30°)
- Grind the external bevel until the cutting edge is almost sharp (bluntness approx. 0,2 mm). The grinding angle depends on the material to be cut and should range from 20°-35°.
- Harden the knife. According to the available facilities the hardening treatment consists of
- Heating in the chamber furnance, temperature approximately 820°C, duration approximately 10-20 min.
Cooling in oil, renewed tempering in the chamber furnance at a temperature of approximately 300°C for approximately _-1 hour obtainable hardness approximately 48-50 HRC
- Partial cooling of the knife, approximately two thirds of the knife body is dipped into the oil bath (cutting edge first) and moved back and forth. As soon as any tempering colour has disappeared from the back edge, the knife is removed from the oil bath and turned round using abrasive paper to clean the cutting edge. When the cutting edge changes its colour to yellow-brown the whole knife is immersed in oil to complete cooling.
- Flame hardening
- Flame hardening with simultaneous water cooling
- However, these knives must still be tempered, either in a chamber furnance (temperature approx. 250°-300°C) or by an equivalent method. Therefore, the treated knives are not high quality knives.
- If necessary the mould has to be adjusted according to the template after the hardening process
- Finish grinding of the external and internal bevel to obtain a sharp cutting edge (careful grinding is advisable in order to maintain the straightness of the knife)
- Protect knife against corrosion (by greasing, painting, galvanizing etc
- Now the knife is ready for sale
Our special profile 53 X 8,5 X 5,5 X 2,5 mm in ready for delivery condition:
for auto-discharging sole cutting knives in hot rolled annealed bars in factory lengths