Lubricants For Rubber Pad Forming Press

[Kaitte]

We are currently operating a rubber pad forming press in order to form sheet metal aluminum parts for aerospace applications. We are currently having a number of problems with this forming operation that I believe may be alleviated by using a forming lubricant. The issues that we are having are:

[ul]
[li]Difficulty forming certain geometries such as those that require deeper drawing.[/li]
[li]The sacrificial rubber pad sticking to both the work piece and the main forming pad.[/li]
[li]Excess wear on both the sacrificial rubber pads and the main forming pad.[/li]
[/ul]

Additionally, we are constrained by the fact that we are working on aluminum (2xxx,6xxx,7xxx series) for aerospace applications. The parts that are being formed will go through subsequent processing (heat treating, alodize/anodize, painting) and therefore it is very important that any lubricant we use does not contaminate, corrode, or otherwise damage our parts. Additionally, we also need to consider the ease of applying the lubricant and cleaning it off after the parts are formed.

Based on the research I've already done, I've already ruled out any kind of powder based lubricant such as talcum powder, anything containing silicon, and anything containing graphite. I am, however, having difficult narrowing down my selection any further than what I just outlined.

It seems like a dry film lubricant (MoS2 or PTFE based) could potentially be used on the sacrificial rubber pads as well as the main forming block although I am having difficulty finding anything that explicitly confirms this. This type of lubricant would be appealing because it could potentially be sprayed onto the rubber pads once per day at the end of the shift and allowed to air dry overnight. This seems like it would improve our situation without adding manufacturing steps to apply and then remove an oil based lubricant.

Another option would to use a drawing oil of some kind. This option appears like it would meet our needs for lubrication, although it would require additional manufacturing time to apply and then remove the oil after forming.

Vanishing oils may also be an option, but there appear to be environmental as well as health concerns with using them.

Does anyone have any experience with using lubricants for this type of application? I could use some help and guidance moving forward here.

 

[berkshire]

I have not had experience with using liquid lubricants for Hydroforming Aluminum parts , but have had success with using 6 or 8oz fiberglass cloth over the part to prevent the first pad from sticking to the part. This was using a Verson Wheeler press with about a 4" draw on the part.
B.E.

You are judged not by what you know, but by what you can do.

 

[berkshire]

Kaitte,
You might also look at 60 70 durometer polyurethane pads instead of rubber.
B.E.


You are judged not by what you know, but by what you can do.

 

[Kaitte]

I am looking at experimenting with different thickness and hardness's of the sacrificial pads, thanks for the suggestion Berkshire.

 

[btrueblood]

Not clear why talc and graphite are not possibilities - is the dust an exposure issue for workers? Or is cleaning the parts afterwards (to accept paint/plating/adhesives) the problem?

Water washable lubricants like glycerine, propylene glycol (and either of those with a bit of dish soap added) are really great for cleanup, just rinse in clear water. There was a forming process I was familiar with where they used soap flakes for lubrication; nowadays you can't buy true soap flakes no more...

 

[berkshire]

When stretch forming parts we used to use Duck butter by Oatey , the stuff was messy and had to be cleaned off afterwards with a pressure washer, and if you did not get it all off, it would leave black marks ( carbon residue) on heat treated parts.
I would not suggest using this in a hydroform press, but if it works for stretch forming and you do not mind doing the cleanup, it is out there.

B.E.

https://www.oatey.com/2377261/Product/N/Hercules-2-lb-Duck-Butter-

You are judged not by what you know, but by what you can do.