×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Aluminum Casting Porosity Sealing

Aluminum Casting Porosity Sealing

Aluminum Casting Porosity Sealing

(OP)
I have some small (4”x4”x2”) porous aluminum castings that I would like to seal for a low pressure application <10 PSI.

I do not have a way to vacuum impregnate these in house, nor do I want to send these parts out at the moment. I have found some 2 part, brush on sealants. (http://impco-inc.com/#how-it-works) ...But I would also like to avoid mixing and brushing.

Ideally, I am looking for a solution in which I can dip and (temperature?) cure.

Does anyone have any suggestions for me?

RE: Aluminum Casting Porosity Sealing

Dipping will require hundreds of times the volume (cost) of sealant compared to brushing and would only be done in a production environment.

When solvents evaporate you get shrinkage, which is not good for creating a seal. Also solvent vapors cause air in voids expand which creates bubbles and pin holes in coatings.

What kind of product will turn from liquid to solid when you want it to, and not in the container without solvent evaporation? A two part reactive material that must be mixed, or a hot-melt.

RE: Aluminum Casting Porosity Sealing

(OP)
Thank you. Very good information!

Let’s assume production environment; do you have any hot-melt suggestions?

RE: Aluminum Casting Porosity Sealing

Loctite 290.

From the data sheet:



I have used it successfully to seal weld porosity at 350 psi.

RE: Aluminum Casting Porosity Sealing

We've used:

FP114A from http://microleak.com/

We just brush it on the interiors of the gearbox castings.

RE: Aluminum Casting Porosity Sealing

(OP)

Thank you both.

I do not understand the reason behind Step 2 of the porosity sealing for Loctite; could someone clarify?
Allow to cool to 85C (then?) apply the product? Or apply the Loctite while the part is at 121C?
I wouldn’t understand the reason behind the former interpretation here; for both heating and cooling the part both before applying the Loctite, but that is how I am reading it. I could understand heating during or after Loctite application.

The Microleak product looks perfect… however it’s been a week of calls and email to the company with no responses.

So, I am still open to ideas.

RE: Aluminum Casting Porosity Sealing

I assume the purpose of heating and cooling is to help draw the product in to the substrate. The product is applied once it has cooled to 85C. If applied hot the 290 would cure before capillary action can draw it deep into the pores.

Honestly I've applied it at room temp and it works just fine.

RE: Aluminum Casting Porosity Sealing

The purpose of heating to 121C is to remove any liquid water that may be in the pores. 85C is a safe temperature to apply the adhesive, where it is not too reactive and has a low viscosity. Cooling from 85C will help draw the adhesive into the pore.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login



News


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close