What should be the ideal material for gears of intermediate wire drawing machine ? Should it be case hardened low carbon steel , fully hardened high carbon steel or toughened medium carbon steel?

In my opinion, gears should be fully hardened high carbon steel but remember to change them in sets so that a new gear is not harder and tougher than an old mating gear.

Regards,
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com

The most used materials for gears (Central Europe) are:

16 MnCr 5 BF (1.7131)
20 MnCr 5 BF (1.7147)

Also used materials are

42 CrMo 4 QT (1.7225)
50 CrMo 4 QT (1.7228)
34 CrNiMo 6 QT (1.6582)
30 CrNiMo 8 QT (1.6580)

As Mr. Stewart-Hay wrote it is recommended to change the gears in sets. It is also recommended to use the original spare parts from the machine manufacturer.

If you want to copy the gears it is not recommended to copy the gear dimensions. It is better to measure the center distance between the shafts. This distance is usually < +/- 0,05 mm. Then calculate the corresponding gear dimensions. In theory it is also recommended to use two different materials to prevent pitting. The material of the pinions are usually better and harder.

Best regards

Juan Carlos González Villar

Kabel.Consult.Ing
www.kabelconsulting.de

20 Mn Cr 5 is a low carbon steel which is case hardened and it can withstand good impact load. Am I right ?

20 MnCr 5 BF is a so called case-hardening steel according to DIN 17210. The suffix BF is important.

After the case harden and grinding procedure ->

Surface hardness 57 + 5HRC
Depth of case max. 3 mm
Hardness on depth of case 550 HV 1

If you have problems with pitting (small holes on tooth surface) or tooth fractures or tooth cracks;

The solution is not to make the gears harder, its better to change the module of the gear set than to change the gear material.

Best regards

Juan Carlos González Villar

Kabel.Consult.Ing
www.kabelconsulting.de