Design for Assembly Analysis with Adhesives

[UWMechE]

Hello,

I am trying to perform a DFA analysis (using the method for manual assembly from Boothroyd and Dewhurst). I have a point in the Assembly Build Instructions where a threadlocker is added to the threads of a screw. How do I take this into account? I guess I can just treat it as another component and give it a handling code and insertion code like all the others even though these actions actually occur in between the handling of the screw and the insertion of the screw.

Is anyone familiar with DFA analysis and the proper way to treat adhesives?

This is for internal learning/objectives as opposed to an actual redesign of a product. Otherwise I'd probably try to avoid using adhesive on the manufacturing floor and go with nylon patch screws or something. Then I avoid trying to add it to the analysis and avoid all the problems associated with the threadlocker itself!

Thanks!
UWMechE

 

[hydtools]

Put the application of threadlocker as the second step of installing the screw. Pick up screw, apply threadlocker, insert screw, tighten screw.
The threadlocker would be like a tool at the assembly station.

Ted

 

[MintJulep]

I would treat the screw with thread locker applied as a sub-assembly.

Pick up screw. Apply thread locker. Insert screw with thread locker. Tighten screw with thread locker.

 

[drawoh]

UWMechE,

On the shop floor, I would pour threadlocker into a cup, and instruct the worker to dip the screw into it before installing.

I have the Boothroyd Dewhurst book (Product Design for Manufacture and Assembly 2nd[ ]Edition), but I have not read up carefully on the systematic DFA analysis. Your bottle of threadlocker would be a consumable. Pouring threadlocker into your cup would be a setup, and applying the threadlocker would be an assembly procedure lasting a couple of seconds. Does this make any sense?

On the worksheet on Figure[ ]3.37, each line item is an assembly procedure, not a part. There is a note about applying tape. Would this be equivalent to your threadlocker?

I would not get too hung up about threadlocker being an adhesive. A lot of adhesive application has to be done carefully, to ensure a quality joint. The application time and the inspection time would be significant.

JHG

 

[UWMechE]

Thanks for all the suggestions!

I was getting caught up on every part needing a handling code and insertion code. I looked into some more examples that show certain things that are "standard" or "special" operations and do not receive a handling code.

Drawoh, I must have a different edition than you, but I did find the reference to tape application. It seems logical to consider the threadlocker a similar operation.

Regards,
UWMechE