How to call out staking on a print
How to call out staking on a print
(OP)
A ground pin is slip fit through a housing into another housing. These housing are to rotate about each other, and neither is fixed (only when in a locked state are they fixed). The pin allows them to move when the mechanism in unlocked.
Question is that on the print there is a callout for staking. "Stake two places on diameter 180deg apart"
After reviewing the dFMEA this is not sufficient for the possible failure mode.
In the past I have called out stakes two ways, or a combination of both.
1.Dimensionally, with a minimum depth of the deformed stake. Also someone recommended calling out a "deforemed materail minimum ID. This method would allow QE to check with a gage pin.
2.With Minimum pull/push out force. I think this method to be preferred, but also know that it is a destructive test.
I was wondering how other called out mechanical staking and if any recommmendations on how the staking should be called out. (I also know that putting manufacturing processes on prints is not recommended, but this has to be the fastening method as it was proven and PPAPed this way)
Thanks in advance!!
Question is that on the print there is a callout for staking. "Stake two places on diameter 180deg apart"
After reviewing the dFMEA this is not sufficient for the possible failure mode.
In the past I have called out stakes two ways, or a combination of both.
1.Dimensionally, with a minimum depth of the deformed stake. Also someone recommended calling out a "deforemed materail minimum ID. This method would allow QE to check with a gage pin.
2.With Minimum pull/push out force. I think this method to be preferred, but also know that it is a destructive test.
I was wondering how other called out mechanical staking and if any recommmendations on how the staking should be called out. (I also know that putting manufacturing processes on prints is not recommended, but this has to be the fastening method as it was proven and PPAPed this way)
Thanks in advance!!





RE: How to call out staking on a print
RE: How to call out staking on a print
RE: How to call out staking on a print
You need to define what you want. I.e., design and dimension the tool to be used, and/or fully dimension the deformed condition to be achieved.
Mike Halloran
Pembroke Pines, FL, USA
RE: How to call out staking on a print
We occasionally do that for safety critical welds in tension, for example.
Cheers
Greg Locock
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: How to call out staking on a print
Your minimum pull/push test is probably only destructive if the component fails. If it passes the pin is still in place and serviceable, right? This may be a good way to go, although testing adds time to manufacture.
What exactly do you mean by staking? I think we used a different term back in the UK.
Are you deforming the actual pin or the ends of the holes to stop it coming out (we used the term peening for this)
When I had a similar situation we actually put a dimple (think it was center drilled) in the ends of the pin which then facilitated deforming it more easily. I think we used a press type tool, probably modified from a rivet press.
Sadly I can't remember the wording we use. The deformed ends of the pin stuckout, almost like a small rivet head, they weren't flush.
Trying to equate a level of deformation to match the equivalent/required push/pull force may be timeconsuming. Especially if your 'staking' method doesn't give consistent results.
KENAT, probably the least qualified checker you'll ever meet...
RE: How to call out staking on a print
The term Staking in the US usually means deforming the body of the part surrounding the part to be held. Most often it is done with a center punch or a staking punch, a small chisel like punch about 1/8" wide. I think this is the custom tool Mike talked about.
B.E.
RE: How to call out staking on a print
This way you don't have to have a separate operation in your process for the staking. Look at this website for an idea of what you could use.
www.driv-lok.com
RE: How to call out staking on a print
After that clarification I like MDAPSEY idea or equivalent.
Can it be made some kind of interference fit in one part while free to rotate in the other?
KENAT, probably the least qualified checker you'll ever meet...
RE: How to call out staking on a print
RE: How to call out staking on a print
I knew generally it's possible, I think I've done it. I meant in the OP application is this a workable solution.
I've investigated the groove pin idea before but it didn't work out, as I recal we couldn't get them made in the quantity we wanted for a good price (they would have had to be a special) and we would have had to do qualification testing for the application.
Is there a design guide somewhere for this type of thing though?
KENAT, probably the least qualified checker you'll ever meet...
RE: How to call out staking on a print
Thanks for the comments and suggestions. I need to restate a portion of my original post. The Ground pin "IS" press fit into one housing, but the stake is a countermeasure because their is also a lateral load applied which theoretically, and once in a real world application worked its way out. I think if I draw a sketch you will get the idea better.
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or try the link:
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RE: How to call out staking on a print
RE: How to call out staking on a print
I think the grooved pin is probably a good idea, but not as common of a part as a ground machine dowel pin. THe pin is right out of ASME standards and thus costs less than special application items. Automotive industry has no room for cost increase as margins are at a premium already. Anyways I appreciate all the comments and feedback but was wondering if anyone had worked with staking. Like bearing crosses in a u-joint yoke. These are sometimes captured by staking the yoke.
I have to make a change within the current process capability. Changing the pin is not an option. Changing the amount of press fit by increasing/decreasing the hole sizes is an option. Also how and how much I stake is an option.