Case hardness

[PRADEEPGYM]

Hi
Anybody can help me?
How to decide what shall be the required case hardness value based on an application?
Example: A loaded roller rolling over a cam which is designed for n number operations. Then what shall be the hardness required for the cam & roller surfaces?

Pradeep

 

[dhengr]

PRADEEPGYM:
You would probably do well to talk with several outfits/companies which would be able to do the case hardening for you, and who have good experience at that process. Pick their brains to help you make your design decisions. This whole process has to do with the steels being used, their alloy and chemical makeup, their hardenability, their dimensions, the type of loading, number of cycles, etc. The case thickness and hardness is based on the contacting loaded parts, types of contact, the load magnitudes, etc. Someone has to have considerable experience with the case hardening issues, with historical data for various conditions, like abrasion and other wear, contact bearing stresses and strains, which guides them in their thinking about the best solution for a given problem.

 

[Tmoose]

The INA catalog used to have a section on the design of shafts to work with their needle bearings.
The "contact" and actual Hertzian stress had to be considered.
Low loads might provide decent life with HRC 30 shafting.

Heavier loads would require HRC 58 plus and a csse depth over 1 mm, and HIGH quality steel, and superb surface finishes, and extremely clean lubrication of unexpectedly high viscosity, and subtly crowned rollers.

 

[mfgenggear]

pradeepgym

there are many factors, such as # of cycles, rpm, hertz hardness required, under load, torque required.
the numbers are calculated to prevent chipping, scuffing, bearing loads, and bending failures.
s/n curves vs the load vs the cycles. The actual case and hardness is depending on those factors.

once a steel and case hardness required then a specification is required, example would be AMS2759/7