Engineering help

[admin]

I am using an air cylinder of 100mm bore operating at 6 bar. The force from the catalogue states it will generate 4524 Newtons yet I cannot fully press in a 4mm steel dowel pin (4.004/4.012) into an Aluminum part of hole of dia 3.983/3.993 mm by 11mm deep. Anyone have any idea what went wrong? I need some Engineering help.

[admin]

If your calculations are correct you may have a problem with the actuator leaking. The air may be bypassing the piston seals which will reduce the thrust. Is there any excessive air exhausting through the exhaust ports of the valve?

[admin]

The force of 4524 Newtons doesn’t leave much room for friction losses. Unless it is a ‘frictionless’ cylinder, I always allow 11-20% loss due to internal seal friction. Did this force come from the manufacturer or from a generic piston size/pressure table? If you dig a little you can probably get a % loss number from the manufacturer’s catalog. Is there any potential side loading during the pressing action? This could be causing additional side load adding to friction. Are there external guides (bearings/sleeves/shafts) contributing to friction? How straight is the pin when it starts-is it possible to start ‘crooked’? Is the rod area on the pressure side subtracting from the force? If none of the above than I’d look further at the pressure generated at worst case press and the friction factor between dry steel and aluminum-I assume that is where you started.

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