6 inch bore pneumatic cylinders

[Nmbmxer]

How much pressure are you running? Any way redesign to use airbags instead of a cylinder? Could be 25% of the cost.

This 8” bag has 10” of stroke and is $120:

https://www.amazon.com/Slam-Specialties-SS-8-Single-Port/dp/B00B0YCDB4

 

[George-H]

How much pressure are you running? Any way redesign to use airbags instead of a cylinder? Could be 25% of the cost.

This 8” bag has 10” of stroke and is $120:

https://www.amazon.com/Slam-Specialties-SS-8-Single-Port/dp/B00B0YCDB4

The cylinders I use are rated for 250PSI, but I only have 2 customers that run the machines at that pressure. Running the cylinders at 250PSI has some challenges so most people opt out of that pressure range and stick to 40-150PSI from standard shop compressors.

There is a company, I think out of business now, called PNEUCO. They made a pneumatic press brake using an airbag/bladder. I looked into it when I was designing my first couple prototypes but never took a shot at designing a machine using air bags. I have never used one... Without a piston I would guess the force would be non linear, and they would have no possibility of being double acting?? They sure are cheap though... Might be worth a shot at designing a machine that can overcome the challenges of using an air bag.

Have you ever seen or used one in a pressing application?

 

[Orange Vise]

largest cost at the moment for building my own cylinders is the cost to have a local shop make me the pistons and thread the cylinder rod on a CNC lathe, am I crazy to interpolate the pistons on my HAAS haha!!??

Nope, not at all.

The rod can be threadmilled, and the O-ring groove in the piston can be interpolated with a keyseat cutter.

The OD of the piston doesn't even make contact with the tube ID, if I understand correctly.

 

[Nmbmxer]

The cylinders I use are rated for 250PSI, but I only have 2 customers that run the machines at that pressure. Running the cylinders at 250PSI has some challenges so most people opt out of that pressure range and stick to 40-150PSI from standard shop compressors.

There is a company, I think out of business now, called PNEUCO. They made a pneumatic press brake using an airbag/bladder. I looked into it when I was designing my first couple prototypes but never took a shot at designing a machine using air bags. I have never used one... Without a piston I would guess the force would be non linear, and they would have no possibility of being double acting?? They sure are cheap though... Might be worth a shot at designing a machine that can overcome the challenges of using an air bag.

Have you ever seen or used one in a pressing application?

I don’t know exactly what your machine looks like. A bag would be single acting, what do you use the return for? A ram return function or stripping would require a lot less force and could use a much smaller commodity cylinder vs a 6” bore one. The force would be linear, they design them so they extend upward vs ballooning outward.

 

[Bill D]

I would look at making cylinders with tie rods. Buy the dom honed tube. make endplates and voila. Or make the endplates a part of the machine itself.
Bill D

 

[DDoug]

I don’t know exactly what your machine looks like. A bag would be single acting, what do you use the return for? A ram return function or stripping would require a lot less force and could use a much smaller commodity cylinder vs a 6” bore one. The force would be linear, they design them so they extend upward vs ballooning outward.

Apparently the OP will NOT post a pix or two of said machine.....
So everything is simply wild guessing.....

 

[Garwood]

Air bags are great if you can use them. For double acting just add another bag.

And yes. You can mill the pistons and gland. I know a guy that designs and builds square and oval air and hydraulic cylinders. He doesn't make those pistons on a lathe.

 

[john.k]

Truck brake components used drawn closed end cylinders with pistons and leather seals operating inside.