Adhesive used for fixturing.

[pdybeck]

I have an assembly where two parts are assembled via a Standard Locknut thread type. I need these two parts to maintain a concentricity to one another that the thread profile can't guarantee. The idea of using something like a loctite product in combination with an assembly fixture that maintains the concentricity we need has been discussed. The adhesive product would be applied to the threads and the fixture used to maintain the concentricity. The adhesive would be allowed to cure in the assembly fixture. Once cured, the assembly would be ready for use with the correct concentricity maintained. Can anyone suggest an adhesive that has the capabilities we need to accomplish this? Some considerations would be strength, cure time, ability to wick-in and fill areas (viscosity?) but not too viscous so that it runs into places we don't want, temperature range. etc... Please feel free to enlighten me on any possible products that could be used and/or anything else that we need to consider in a product that will be used in this fashion. Thanks in advance for your help.

Pete Yodis
Harold Beck and Sons

 

[rnd2]

A filled non-slumping epoxy would be a good start. Cure times can range from 5 minutes at room temp to many hours. There are many systems ranging from room temp cure to heat activated.
Nut removal would be extremely difficult once the resin has cured.

 

[pdybeck]

rnd2,

Thanks for the quick response. To clarify or add another item to the list, nut dissaembly is not needed - so it could be permanent but it doesn't have to. Could you recommend any specific products i.e. manufacturer and specific type of product - like "Loctite #270"? Who makes "filled non-slumping epxoy's" and under what product name? Thanks for the help.

 

[unclesyd]

You might want to call these people and discuss your problem with fixturing/holding.

http://www.belmontmetals.com/products/low-melting.cfm

There are several people in the business that have different materials for this problem
I am looking for one that uses a foam or wax and does a good job on some parts

A good source for epoxies is:

http://www.masterbond.com

 

[rnd2]

I defer to unclesyd for local US manufactures. If you are familiar with Ciba-Geigy and they are handy from a supply perspective they have a huge range and can definetly assist. If it is correct to assume the product you are treating will operate in "normal temperatures" say 0 to 130 deg F then look for a product with good adhesive and non-slumping properties. The adhesive properties seem to tail off with higher temperature rated epoxies, at least that is our experience. This can be overcome by machining matching locking grooves into the nut and thread. The epoxy forms and sets as a kind of rigid O ring in the grooves. But this involves extra work and may not be neccessary for your job. There are plenty of epoxies out there and pretty much all of them will get the job done. You need to select the one that works best for your application.

 

[MadMango]

You might want to also look as Sika, they have a broad range of adhesives and epoxy products. Might work for your application, might not, depending on the physical scale of your project.

International:

http://www.sika.com/

USA:

http://www.sikaindustry.com/

Ray Reynolds
"Computers in the future may weigh no more than 1.5 tons."
Popular Mechanics, forecasting the relentless march of science, 1949
Have you read faq731-376 to make the best use of Eng-Tips Forums?

 

[rnd2]

unclesyd, re looking for wax, are you looking for an epoxy with self releasing properties?

 

[unclesyd]

rnd2,
Just thinking outside the box. Also trying to keep pdybeck thinking. Have many times have you written off an idea, but later after a conscious or subconscious evaluation develop a different opinion of it or have it generate a spark for another idea in a new direction. I have done this several thousand times over my career.

As you know there is always another way to accomplish a particular task, but whether it's better or the best way is still the question.

We fabricated a tremendous number to very delicate parts and used all sorts of materials to fixture components.

Non-permanent fixturing materials we used:
LT Melting Metals
Waxes
Hot Met glues
Foams
Filled Epoxies, glass, carbon, and others
Ferro-Fluidics
Even ice

If one gets fixed on a particular process it's hard to ever change once it gets ingrained in people’s minds.

 

[rnd2]

Great stuff unclesyd.
I got the feeling Pete wants his part to maintain excellent concentric integrity in use for a long time after assembly.
Good luck with your project Pete.

 

[pdybeck]

unclesyd,

Funny you mention thinking outside the box. I just had that discussion with someone in manufacturing here. Thats actually how we arrived at the fixturing/adhesive idea to keep our concentricity we need. rnd2 is correct. Manufacturing is meeting with Loctite today with a list of thoughts that I wrote down for them. I will hear back sometime tomorrow. Thanks for all the input. Keep it coming if you can think of anything else.

Pete Yodis
Harold Beck and Sons

 

[unclesyd]

pdybeck,
Appreciate the response.

Get ALL the information you can from the representatives. This is also a great opportunity to establish a contact within the company, you will need one.

One point I've tried to make in previous posts is not to get into the NIH. (Not Invented Here) syndrome, instead use the AIA (Anything Invented Anywhere) approach.

If possible let us know how it turns out.

unclesyd

 

[pdybeck]

unclesyd,

(AIA), I like that philosophy. Hope you don't mind if I use that one. That's thinking outside the box. I will attempt to keep everyone informed of the results, it may just take a little while as I am sure people understand. Thanks for the help.

Pete