Selection Criteria for the Type of Automation
Criteria | Pneumatic | Hydraulic | Hydropneumatic |
Cost | Lowest | High | Low |
Clamping force | Light - 2 to 3 kN max. Higher forces if no space constraints | Medium and heavy - above 5 kN | Medium and heavy -From 5 kN to 100 kN |
Clamping clyinder size | Bulky for even medium clamping force (Op.Pr. 5 bar) | Compact (For SPM Op.Pr. 30 to 70 bar) | Most Compact for heavy forces (Op.Pr. 150 to 200 bar) |
Clamping stroke | Wide range - from short to very long | Wide range - from short to very long | Short stroke - 50 mm max |
Clamping speed | Very fast | Fast | Fast |
Impact while clamping | Present | Not present | Not present |
Reliability | Low - as can be overpowered due to the compressibility of air | Most safe - due to the check valve and incompressibilty of oil | Safe - as factor of safety for force selection can be more |
Sequencing | Possible | Possible | Difficult |
Piping & circuit | Complicated | Complicated | Simple |
Oil heating problem | Not applicable | Present | Not present |
Return stroke, speed and power |
Fast due to double acting cylinder, but with low power | Fast, with power and positive due to double acting cylinder | Slugish due to spring return clyinder |
No. of clamping points | No limit | No limit | Limited, 3 to 5 per intensifier |
Other Applications | Material handling, Valve actuation, Door movement | Feed cylinders, Cutting, Hole punching, Deep drawing, Earth moving equipment |
Pressing, Assembly, Rivetting, Crimping, Cutting |
* Hydropneumatic automation referred above is with hydropneumatic intensifier. Hydropneumatic pump is not considered.