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Forum index » Science and Technology » Engineering » Mechanics
Maximum Yield stress for Standard Hardened Steel dowel pins
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Jeff Finlayson
science forum Guru Wannabe


Joined: 02 May 2005
Posts: 142

PostPosted: Wed Mar 01, 2006 11:52 pm    Post subject: Re: Maximum Yield stress for Standard Hardened Steel dowel pins Reply with quote

John2005 wrote:

Quote:
I am using a standard hardened steel "pull out" dowel pin from
www.mcmaster.com as a bearing shaft. I need to know the maximum load
the dowel / shaft can support without taking a permanent set and/or
becoming permanently deformed or bent. I need the shaft to always
spring back to its original position after the load is removed.

I emailed Mcmaster, but they were not able to give the maximum Yield
strength of the dowels.

The minimum yield strength should be used for design.

Quote:
Does hardening increase the maximum Yield stress? If so, is there a way
to calculate or estimate how hardening affects the yield stress ?

Yes, depends on the alloy and amount of hardening/cold work/etc.
The more hardening/cold working/etc the stronger the material, but
the ductility is generally less for a given alloy.

Quote:
Here is what Mcmaster said about the dowels and pin material...

"Hardened Steel- Made from hardened steel such as C1541, or 4037 and
4140 alloy steel. Core Rockwell hardness is C47-C58 (surface hardness
is RC 60). .. Single shear strength is 130,000 psi. ..
All meet ASME B18.8.2. Length tolerance is .010"."

I would appreciate any advice or suggestions on how I can get a close
estimate on this, and what would be a reasonable safety factor to
apply. Nobody could get hurt if the device fails, but I just need it to
be reliable. I have to consider several factors when choosing a shaft
size, and everything fits in a tight space.

For a 4130 alloy steel with shear strength of 130,000 psi minimum,
the ultimate strength is 200,000 psi and yield strength is 165,000 psi
at room temperature.

See pages 2-20 and 2-25 here:
http://www2.tech.purdue.edu/at/courses/at308/Technical_Links/MMPDS/Chapter2.pdf

Use at least a safety factor of 2.0 on yield for normal operations.
Use a higher one if max loading is uncertainty. For hoisting a higher
safety factor of 3.0 or more should be used.

Quote:
There are tradeoffs and space constraints when going to a bigger shaft,
so I need to know how to estimate this in order to make the best
compromise. It's desirable to use the smallest shaft diameter possible,
that will support the load with a reasonable safety factor.

You need to have an estimate of the maximum load the pin might see to
determine that.
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John2005
science forum beginner


Joined: 24 Aug 2005
Posts: 34

PostPosted: Wed Mar 01, 2006 10:39 pm    Post subject: Maximum Yield stress for Standard Hardened Steel dowel pins Reply with quote

Hello everyone,

I would like to ask if anyone could please help me with the following
situation.

I am using a standard hardened steel "pull out" dowel pin from
www.mcmaster.com as a bearing shaft. I need to know the maximum load
the dowel / shaft can support without taking a permanent set and/or
becoming permanently deformed or bent. I need the shaft to always
spring back to its original position after the load is removed.

I emailed Mcmaster, but they were not able to give the maximum Yield
strength of the dowels.

Does hardening increase the maximum Yield stress? If so, is there a way
to calculate or estimate how hardening affects the yield stress ?

Here is what Mcmaster said about the dowels and pin material...

"Hardened Steel- Made from hardened steel such as C1541, or 4037 and
4140 alloy steel. Core Rockwell hardness is C47-C58 (surface hardness
is RC 60). Shear strength is the amount of force that the side of a pin
can withstand before breaking. Single shear strength is the amount of
force applied against a fastener in one place causing the fastener to
break into two pieces. Single shear strength is 130,000 psi. An
internally threaded tapped hole in one end of these pins lets you pull
them out with a removal screw or a threaded puller such as 92330A (see
page 3083 ) and reuse them. All meet ASME B18.8.2. Length tolerance is
.010"."

I would appreciate any advice or suggestions on how I can get a close
estimate on this, and what would be a reasonable safety factor to
apply. Nobody could get hurt if the device fails, but I just need it to
be reliable. I have to consider several factors when choosing a shaft
size, and everything fits in a tight space.

There are tradeoffs and space constraints when going to a bigger shaft,
so I need to know how to estimate this in order to make the best
compromise. It's desirable to use the smallest shaft diameter possible,
that will support the load with a reasonable safety factor.

Thanks for your help.
John
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