How much pressure can you expect from a pneumatic press?

For discussions related to designing and making ski/snowboard-building equipment, such as presses, core profilers, edge benders, etc.

Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp

Post Reply
Nanook
Posts: 11
Joined: Mon Oct 19, 2009 7:13 pm
Location: The Mountains, Montana

How much pressure can you expect from a pneumatic press?

Post by Nanook »

I know I'm being ignorant, but I cant find the numbers on how much pressure a pneumatic press can put out. Im looking for a figure in lbs. My mold is made for a single hose, 9" wide by 78" long. Im hoping to get 45 psi. I dont know if this number is right, but I'm getting 63,180 lbs of pressure over the entire press. This number cant be right.
NA
NOO
K
User avatar
MontuckyMadman
Posts: 2395
Joined: Fri Jun 20, 2008 9:41 pm

Post by MontuckyMadman »

someone more knowledgeable than I will chime in but these calcs are all over this place.

I am kinda scared thinking about it but.

78 x 9 x 45 = 31,590 x 2? = 63, 180?
knightsofnii
Posts: 1148
Joined: Tue Jan 08, 2008 6:02 am
Location: NJ USA
Contact:

Post by knightsofnii »

that's why we build them with i-beams with bridge-bolts.

Haha thats the biggest calculation I've done since getting my ME degree, sad :(.
Doug
Nanook
Posts: 11
Joined: Mon Oct 19, 2009 7:13 pm
Location: The Mountains, Montana

Post by Nanook »

Ya I wasnt sure about multiplying it by 2, but there is a top and bottom mold, so it may be right. If anyone can give an acurate number I'd appreciate it.
NA
NOO
K
User avatar
nate
Posts: 88
Joined: Mon Sep 07, 2009 5:56 pm

Post by nate »

I am quite curious about this. I tend to think you don't need to multiply by two, but I have no proof either way. I'd love to hear something decisive.
hugocacola
Posts: 191
Joined: Thu Mar 22, 2007 8:00 am

Post by hugocacola »

multiply by 2 aply when you are using 2 firehoses...
doughboyshredder
Posts: 1354
Joined: Mon Sep 17, 2007 7:37 pm

Post by doughboyshredder »

contact patch is what you need to measure. Fully inflated your hose may not be in contact for the whole nine inch width. (This is why we use cat tracks). In essence though your calcs are seemingly correct. psi times actual contact area. At 70 PSI my press is taking about 120,000lbs of pressure.

In other words your press needs to be insanely strong to press at a high psi.
Broflovski
Posts: 5
Joined: Sun Oct 11, 2009 8:58 am

Post by Broflovski »

63, 180 is wrong

9" wide flat, we could approximate 7" contacting the mold when inflated (to be safe, I think it will be less). Assuming every inch of the 78" contacts the mold you'll have

78in x 7in x 45lbs/in^2 = 24,570

Long story short, if you didn't engineer your press to handle that load take out a life insurance policy ASAP.
doughboyshredder
Posts: 1354
Joined: Mon Sep 17, 2007 7:37 pm

Post by doughboyshredder »

tantrum wrote:63, 180 is wrong

9" wide flat, we could approximate 7" contacting the mold when inflated (to be safe, I think it will be less). Assuming every inch of the 78" contacts the mold you'll have

78in x 7in x 45lbs/in^2 = 24,570

Long story short, if you didn't engineer your press to handle that load take out a life insurance policy ASAP.
Actually, you are wrong.

The air bladder is making contact on the top and the bottom. The calculation should be 78 x 14 (7 on top 7 on bottom). You have 1092 square inches of contact. Multiply that times your intended pressure of 45lbs per square inch and you see that you need to make sure that your press can withstand about 50,000 lbs of pressure not including your safety factor.

Determining actual force at the laminate is a differet topic.
Nanook
Posts: 11
Joined: Mon Oct 19, 2009 7:13 pm
Location: The Mountains, Montana

Post by Nanook »

perfect. that is just what I was wondering. With that, I have some great ideas, and ill post once I get the press made. thanks
NA
NOO
K
Post Reply