Vacum Chuck Small Parts

[Russh67]

Hello Every One:

 

We are trying to design a vacuum chuck to hold small parts so it can be pocket milled and contoured to cut off. We want to machine several at once. We tried several things and cannot get the part to hold strong enough to mill. It holds down but slides around. We were using sticky, 2 sided tape, but the quantities required make sticky method too time consuming.

 

Our latest attempt was to use a small o-ring type material, buna-n maybe to seal around the perimeter of the part and used a 3/4 HP vacuum pump. I did search the forums and found some great tips regarding gasket material. The part is so small that we figured we should just use the thin o-ring we had lying around here stick it in a groove and be done with it....didn't work.

 

Thank you very much in advance.

 

Here is a layout.

Doc2.doc

[Guest]

Don't forget to criss cross channels to create a larger surface area for creating a vacuum instead of just around the perimiter

[rhettmandel]

I would suggest using a bigger piece of material and nest the 4 parts using break off tabs, that way you don't have to be to intricate with the vacuum channels. Also I use the gasket material from vaculok. Their gasket material has given me the best success. The smallest size they make is 1/16 wide by 9/32 tall. Here's My link

 

http://www.vaculok.com/Gasket_Material.html

[Russh67]

Thanks guys for relying to me....

 

I would suggest using a bigger piece of material and nest the 4 parts using break off tabs, that way you don't have to be to intricate with the vacuum channels. Also I use the gasket material from vaculok. Their gasket material has given me the best success. The smallest size they make is 1/16 wide by 9/32 tall. Here's My link

 

 

 

One thing we didn't do was provide vacum for the cut off part... should I connecting the parts with the cut off tabs maybe? make the whole thing a little more stable?

[MattW]

Vacuum hold down force is a function of the area you are sealing off to provide the force, as well as the vacuum level your pump can pull. Without knowing what you are using, I am going to guess you can pull 28"Hg fairly easily, which works out to around 14 psi. If the red box in your pic as the area you are sealing off, you are probably getting less than 50 pounds of hold down force.

 

The amount of force resisting the part moving around is going to be a function of the friction between your workpiece and your fixture.

 

Another thing to point out is it does not take much of a leak to spoil your vacuum. If your vacuum level goes up much when you pinch off the supply, you need a better seal/ tighter system.

 

Also, don't cut through into the area you have sealed off. It may seem obvious, but... there is a reason I mention this.

 

Looking at your parts, I would suggest a much bigger piece to start with. 10" x 10" would be very resistant to movement.

[Russh67]

Thank you Matt very much....

[Newbeeee™]

+1 on Matt and also make your vac fixtures from aluminium. Ally (fixture to ally parts) has a coefficient of 1.3 by memory (which means 1x lb of vacuum (downward) force needs 1.3 lb to move it.

[Russh67]

Nwebeeee:

 

Thank you for replying to me.

 

He (the other designer here) tried Acrylic and it was a total a disaster, lol, We are making aluminum now.

[Russh67]

Thanks Guys....

 

The parts were connected using the beak off tabs and a larger stock was used to increase the surface area. He also held the stock down as well as the parts.

 

He used the peel off sheet gasket material from one of the links.

 

Thank you again guys for help..I ended up well..