Air cylinder to punch plastic box

[jeffrey001]

Hi,

Have a lot, probably thousand on small ABS box to machine on a CNC router.

One side have a 1/4 hole, OK, I drill it on the drill press

Top have various cut out that I make on the router.

On one side, there's a small square cut out around .625 X .450.

I would like to build a small arbor press to punch that hole but replace the handle with an air cylinder.

Walls are 0.073 thick.

Have a Haas cnc VMC so I will build the press.

Would like to know if this can work and how big the cylinder should be.

Would use a standard punch and die set.

Thanks, Jeff

[RomanLini]

Sorry this does not answer your punching question, but have you considered laser cutting?

You can farm the job out and the laser should cut it quite quickly and cleanly. Laser can also be quicker and cheaper for quantities as the boxes do not need to be clamped (faster job change) and there is little mess etc.

With walls 0.073 thick a laser should cut it very nice and leave pro-looking glass smooth edges.

[jeffrey001]

Hi, I don't really want to invest on a laser cutter right now.


I do it for a company near me so I don't want to sub-contract either.

Since those are molded ABS, walls are tapered so not easy to put them on a gig to made those cut out.

So by using a small punch press, this would be much faster and could use a foot activated air switch.

I'm looking for some air cylinder and think will give it a try.

Thanks, Jeff

[Dennis Rech]

Originally Posted by jeffrey001 Hi, Have a lot, probably thousand on small ABS box to machine on a CNC router. One side have a 1/4 hole, OK, I drill it on the drill press Top have various cut out that I make on the router. On one side, there's a small square cut out around .625 X .450. I would like to build a small arbor press to punch that hole but replace the handle with an air cylinder. Walls are 0.073 thick. Have a Haas cnc VMC so I will build the press. Would like to know if this can work and how big the cylinder should be. Would use a standard punch and die set. Thanks, Jeff

Multiply the hole perimeter x the plastic thickness x the shear strength of the ABS (about 6,000 to 8,000 psi - varies with temperature).
You will end up with a force of about 1000 pounds. So with 100 psi, you will need about 10 square inches of cylinder area.
This is in theory, and the shear strength of ABS came from the Internet.
Plan on having some extra air pressure and a nice sharp punch or the ABS will stretch and tear or show stress marks.

Instead of punching, I would make a simple slip-on jig to fit the side of the plastic box and cut the hole out with a hand or pin router.

Dennis