Die cutting packaging foam...

[peter.blais]

Hello, I'm a 3rd year M.E. student with a side business doing parts for watercooled volkswagens. Anyways, I have a few high end products and I'm looking to really convey that in the packaging, by packing them in die cut foam inserts.

Traditionally this wouldn't be economically feasible do to the cost of the tooling and the low quantities i'm doing, but I happen to be lucky enough to have a little bridgeport series 1 cnc, so my next thought was hell it wouldn't be that hard to make a punch / die to cut these out myself, using a cheap automotive press frame and I had planned to ditch the bottle jack in favor of a much faster pneumatic ram.

Anyways, the problem I run into is I have no idea what kind of force it will take in practice to shear the cheap low density charcoal packaging foam I planned on using.

I figured I may be able to save a lot of messing around by checking to see if there was anyone on here with any experiance stamping / cutting such soft material- and how tightly you fit up your punch / die (I was thinking a few thou would be fine for this? ), as well as what materials you used for each.

I'm on a budget (who isn't?) but I would like to get at least 1000 pieces through this contraption without repairing or replacing the punch or die. I was thinking aluminum would be more then strong enough, and sortof hoping to use a plastic female, but really I know nothing on punching this stuff.

This is basically what I'm shooting for:



Any help?

[Chuck Reamer]

An easier and cheaper way would be to get a gasket or seal shop to make you a cutting die. They use a piece of plywood that has strips of sharpened steel stuck into a router grove in the shape of your cuts. They are pretty damn cheap usually under $100, and work like hot damn. We have used them to cut sheets of rubber and its the only way to go for stuff like this.

An aluminum die with a plastic punch would probably leave a pretty sloppy, unprofessional looking cut.

[peter.blais]

hmmm, yes thats a pretty good idea. I actually saw something ~ similar on "how its made" the other day- they were using a press and a die similar to what you mention to cut foam for hockey goalie pads.

I'll call around and see if there is a gasket /seal shop that can do it, if not I can always fool with making that myself- I do have the stuff to do it, I'm just sure they would get it done much much faster. I am fortunate enough to be in salt lake city which is a pretty industrial town so there is usually somebody with what you need.

Just out of curiousity, the steel "blades" if you will- what kind of thickness is usually used there? If worst comes to worst I'm thinking I could brew that up myself, I've never milled wood before but I'm sure it can be done, just slow compared to a router i'm sure. Wouldn't kill me though for a one time / only once in a while job.

[pointcloud]

Get some old broken bandsaw blades grind them sharp, well if you only have to make one or two... You can cut (jig saw) some 3/4" plywood and screw it to the outside...

Also EPS foam is CHEAP, and you can have it fit whatever for pennies... I use it all the time, they do all the cutting for me... The most expecive I use is like $0.25..

[d.dixson]

I did this once myself. Used a stainless steel razor edged blade I found at the local saw sharpening shop. Sheared it up into the proper lengths. Found out that using gloves to handle them was important

hth

sorry, should have been a little more clear... these were bandsaw blades used by the meat packing industry. No teeth, just a razor edge.

[Chuck Reamer]

Originally Posted by peter.blais Just out of curiosity, the steel "blades" if you will- what kind of thickness is usually used there? If worst comes to worst I'm thinking I could brew that up myself, I've never milled wood before but I'm sure it can be done, just slow compared to a router I'm sure. Wouldn't kill me though for a one time / only once in a while job.

The blades are about .035 - .050 thick, I think the ones they use come with a sharp edge. You could use band saw or hacksaw blades like pointcloud suggested. Milling wood is a cake walk, you could easily make them yourself. You just need a torch to heat up the bends and a little bit of your own time.

I usually see them being used on a "clicker press", but you can use a small press or even do it by hand.

[pointcloud]

Just use a cheap air cyclinder (spe??ing)... ebay.. regulator, 110v valve and a light switch.

[One of Many]

Any steel rule die fabricator in your area can help you out. Once you see how they are made, you should be able to produce your own if you can locate the materials. Benders and notchers for the steel rule materials will be the bigger expense. Using dense silicon foam rubber inside and around the outside works great for die strippers. We do tons of this stuff on clicker and punch presses yearly.

This will take a fairly large air cylinder. Maybe 4-6"? Don't forget to install speed controls on the valve or flow controls on the cylinder. Dual palm buttons are a must and technically should incorporate an ant-tie down circuit!

DC

[peter.blais]

I was going to stick my load cell inline with the press / die and measure the force the bottle jack is putting out to get it done, then calculate the air cylinder needed from that.

I'll see what I can find in terms of steel rule / blades / whatever. I have some old bandsaw blades I'm just afraid I wouldn't get them ground exactly even- may end up with little tabs you have to tear where there is a low spot on the blade from some sketchy grinding work.

[Dar]

i made some of these dies and punched out model airplane kits for a customer.some of the material i cut was 1/8 ply. i used my hyd. press and a piece of nylon to cut against. it worked real well.
good luck Dar

[pointcloud]

A very small cyclinder will work with this foam you are useing.. No need for a 6" diameter... A 6" at 150psi has over 4200 psi on the piston face?

A 1" will have almost 120 psi, what is WAY more than you will need to cut this foam...

Your bottle jack will cut it with it's own weight..

All of the above is assuming sharpness of the balde is at it's best..

[peter.blais]

Pounds of force, not psi And yea your numbers are spot on- thats the kind of force I would expect if I was going to try to shear it with a punch / die arraingement, although even then, this is pretty soft stuff.

4230 lbs I think would flatten one of these dies.

Thats what I was hoping to hear, makes my life cheaper and easier. I just need to call around on tuesday for a diemaker locally. There are lots of internet guys too but local would be nice.

Sounds like I'm on the right track now, I probably just need to modify this press a bit so that I have a larger flat work surface to make my life easy- need to punch about 250 of these, plus another 500 thin rectangles for the top / bottom of the box.