There are many factors to considering when comparing different press technologies such as reliability, repeatability and more.
When it comes to comparing different press technologies (pneumatic, hydraulic, servo), one of the common arguments manufacturing engineers like to make is: “it’s a cylinder that goes up and down. Other than force range, as long as it goes up and down, how different can they be?”
However, force range is only one limiting factor among many others. In reality, there are several crucial factors that are often overlooked. Neglecting these factors can seriously affect the quality of the assembled products and the true cost of the system over time.
Among these factors, beyond mere up-front price, are accuracy, repeatability, responsiveness, programmability, data and energy usage.
| SERVO | HYDRAULIC | PNEUMATIC | |
|---|---|---|---|
| Force Range | Capable of range from0.2kN up to 1,000kN | Capable typically of range from 50kN to over 1MN | Capable of lower force range typically up to = 50kN |
| Accuracy | Accurate to within mere ounces throughout full range of press | Only capable of pressing to hard stop or max of range | Only capable of pressing to hard stop or max of range |
| Repeatability | Repeatable positionally to within microns and to within fractions of a newton | Only capable of pressing to hard stop or max of range | Only capable of pressing to hard stop or max of range |
| Responsiveness | Capable of incorporating real-time in-process feedback and adjusting “on-the-fly” | Only capable of pressing to hard stop or max of range | Only capable of pressing to hard stop or max of range |
| Programmability | Fully programmable for accurate force & position throughout entire range, as well as for multiple part models on same line | Only capable of pressing to hard stop or max of range | Only capable of pressing to hard stop or max of range |
| Data | Complete captured and gauged (by integrated sensors) for every part produced which can be stored for product and process verification as well as process improvement | No Data | No Data |
| Energy Efficiency | Only consumes (significant) power during active cycle | Constantly consumes significant energy maintaining hydraulic pressure and wastes significant energy in the form of heat. Also prone to leaks and affected by ambient conditions | Constantly consumes energy maintaining pneumatic pressure and is very prone to leaks |
| Cleanliness & Safety | Safest, cleanest and quietest option. No messy oil to spill and leak. Capable of sensing unsafe conditions BEFORE unfortunate incidents occur. | Notoriously dirty and known for Creating Unsafe Conditions from Leaking/Spilled Hydraulic Fluid. Typically loud. | Known to aerosolize various materials (i.e., lubricating Oil). Typically loud. |
So sure, there are manufacturing technologies that “go up and down” to press parts, but THEY ARE NOT ALL THE SAME.
All Electric Servo-Press Systems, such as those provided by Promess Inc., offer clear advantages, as well as lower cost of ownership over the life of the system.