Gear Puller Heat Treatment Specify?

[xarka]

Hello...I need to specify the heat treatment, hardness, peening, etc of a basic three prong gear puller with 6 inch 'arms'....I have searched this site and the web and have not found much info. The design will go thru destructive testing, but I am trying to establish an engr. baseline. Several industrial strength pullers appear to have the surface peened. I do not have any good vendors in the area to discuss the project...any thoughts would be much appreciated.

 

[TVP]

I am not familiar with the requirements for a "gear puller", but I can recommend that you visit the website of Metal Improvement for more information on shot peening:

http://www.metalimprovement.com/

 

[alexit]

I have used cheap casting from China types and much better forging from USA types. I would say keeping high strenght with high toughness is better than very strong or very hard. Sometimes the threads are seperate part so they can be very hard and jaws are so soft they can be marred by hammer.

Please provide material type and I'm sure someone can help with heat treating ideas.

 

[xarka]

Thanks for the info...

The part is specialized therefore low quantity. The material type is 4140...the part will not be cast or forged. I am familiar with a heat treatment of a puller, involving high temperature then lye salt to temper or harden, but not sure if sufficient....investigating cyrogenics also. Design life 5000 pulls. Need the long jaws to prevent twisting. In summary, need a baseline heat treatment for specification....so far, 4140, Rc45, else???

 

[MetalsInc]

Without knowing really anything about what the part looks like (size, shape) or what it does...

You should be able to get Rc45 easily with a quench in oil and a temper - the time and temp will depend on your part geometry. It shouldn't require much of a temper though. This should be a very straight forward solution.

 

[swall]

LDahl--In order to recommend a heat treatment, it will be necessary for you to give us the cross sectional size of the puller arms. Also,how will you be fabricating the arms? Forget shot peening. There would be no benefit, as the puller will see intermittent loading over the course of its useful life. Shot peening is used to enhance the fatigue properties of a component (i.e. 100K or more loading cycles).

 

[redpicker]

I would be very cautious about using 4140 at 45 HRc. This material will have very low toughness at this hardness level and brittle failure may result.

I would not want to use 4140 above 38 HRc in an application where it will be exposed to high service stresses. Keeping it below 36 would be even better.

If you need the high hardness for the strength, you are going to need a material with high toughness, too. Maybe a 4330V or perhaps a maraging steel.