Press Fit Aluminum Assemblies - Help to Avoid Marring

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blazed

Plastic

Joined

Apr 26, 2018

• Apr 26, 2018

• #1

I need to assemble a large number of aluminum assemblies in an arbor press by press fitting an aluminum piece into another piece of aluminum. I'm concerned about marring both the finished top and bottom surfaces during the press fit operation. What's the best way to avoid damaging the finished soft aluminum surfaces?

Thanks in advance for any tips, suggestions, etc. Being finished pieces, I don't want to damage them.

 

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Limy Sami

Diamond

Joined

Jan 7, 2007

Location

Norfolk, UK

• Apr 26, 2018

• #2

Welcome aboard

I'd be more concerned about the two parts galling and freezing together, - something Alu is renowned for.

As doe damage, masking tape on the Alu and softish, immaculately clean pressing pads.

 

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DDoug

Diamond

Joined

Oct 18, 2005

Location

NW Pa

• Apr 26, 2018

• #3

Heat one part, cool the other part.

 

cyanidekid

Titanium

Joined

Jun 4, 2016

Location

Brooklyn NYC

• Apr 26, 2018

• #4

Depending on the tonnage and surface area, Delrin plastic on the pressing surfaces might work.

Perhaps all three responses here combined.

1)Use a non-staining wax type lubricant such as Boelube to aid assembly,
2) create a temperature differential IF NEEDED (could be as down and dirty as a crockpot for one part, and an ice filled cooler for the other, dry ice if needed),
3) Delrin punch and anvil

Do test your pullout strength when it’s temp has equalized if you go with a lube though.

Let us know how how it goes. Could be some nice teamwork here?!

 

TeachMePlease

Diamond

Joined

Feb 11, 2014

Location

FL

• Apr 26, 2018

• #5

Make a fixture out of something softer than aluminum....

 

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AARONT

Stainless

Joined

Feb 19, 2013

Location

Madison, WI

• Apr 26, 2018

• #6

Make sure your pressing surfaces are clean with a good finish so it doesn't transfer into the aluminum. Put a piece of painters tape on the pressing surfaces and have at it. If you do this you will be fine.

 

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slowmotion

Cast Iron

Joined

Mar 31, 2013

Location

Danville Virginia

• Apr 26, 2018

• #7

Depending on the part size, your hand/eye co-ordination and your ability to handle stress, liquid nitrogen might work for you. I use it a lot on interference parts, you just don't want to stick one, that's the stressful part.

 

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azmachining

Cast Iron

Joined

Dec 26, 2014

Location

Central Valley, AZ

• Apr 26, 2018

• #8

As said heat one cool the other, masking tape on ram, and a piece of cardboard on table. That will work fine, but as said above I would be more worried about galling. Your design? From the sounds of it this assembly will be took a part once in a while? Maybe in the future use stainless to aluminum vs aluminum to aluminum?

 

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blazed

Plastic

Joined

Apr 26, 2018

• Apr 26, 2018

• #9

Thanks to everyone for your responses/suggestions.

This assembly requires a crush fit, meaning I can't freeze one part and heat the other to attain the desired crush when pressed. The assembly will never be taken apart, and the length of press fit is rather small - meaning even if my alignment is somewhat off, it will not bind.

 

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DDoug

Diamond

Joined

Oct 18, 2005

Location

NW Pa

• Apr 26, 2018

• #10

blazed said:

Thanks to everyone for your responses/suggestions.

This assembly requires a crush fit, meaning I can't freeze one part and heat the other to attain the desired crush when pressed. The assembly will never be taken apart, and the length of press fit is rather small - meaning even if my alignment is somewhat off, it will not bind.

Click to expand...

Huh ?

Please post some more details like some pictures & drawings.

 

Conrad Hoffman

Diamond

Joined

May 10, 2009

Location

Canandaigua, NY, USA

• Apr 26, 2018

• #11

It sounds like you just need the softer surfaces described above to protect the exposed aluminum. I don't get the "crush" fit. If the press operation goes smoothly, meaning no galling (unlikely), the end result will be the same if you get there by force or by expanding/contracting the parts with heating/cooling. If this is bare aluminum being pressed, we'd politely say, "we need to schedule a design review on that." I'd be looking at lubricants that do a good job on aluminum to prevent galling. Can't remember what works, lanolin or zinc oxide perhaps?

 

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Larry Dickman

Titanium

Joined

Jan 30, 2014

Location

Temecula, Ca

• Apr 26, 2018

• #12

a little KY jelly and a lead hammer