Greenerd : Selecting a Hydraulic Press (2024)

Selecting press tonnage in the typical press room is often little more than guesswork. If, for example, a job is successful on a 100-ton mechanical press, it tends to stay there for the life of that job. The job may never have been tried at 75 tons or at 50 tons.

With a hydraulic press, however, you can adjust tonnage quickly and easily, tuning the press to precisely the right tonnage for each specific job.

The answer, again, is yes in most cases. There are some specific limitations. Drop hammers and some mechanical presses seem to do a better job on soft jewelry pieces and impact jobs. The coining action seems sharper if the impact is there.

In deep drawing, however, the full power stroke of a hydraulic press produces significantly better results.

Otherwise there are very few examples where the application of 100 tons of hydraulic force produces any significant difference in the character of the part given the same tooling.

Shear in the dies will reduce blanking tonnage for hydraulic presses in the same way it does for mechanical presses.

The more critical the work and the more demanding the tolerances, the greater the reserve tonnage capacity should be.

• Distance reversal limit switches
• Pressure reversal hydraulic switches
• Automatic (continuous) cycling
• Dwell timers
• Sliding bolsters and rotary index tables
• Die cushions
• Ejection cylinders or knockouts
• Electronic light curtains and other devices
• Touch screen controls
• Servo system feedback for precise, consistent, repeatable stroke control

Here are just a few construction points that will provide a basis for comparison of one machine with another:

1. Frame. Look at frame construction-rigidity, bolster thickness, dimensional capacity, and other factors.
2. Cylinder. What diameter is it? How is it constructed? Who makes it? How serviceable is it?
3. Maximum system pressure. At what psi does the press develop full tonnage? The most common range for industrial presses is 1000 to 3000 psi.
4. Horsepower. The duration, length, and speed of the pressing stroke determines the horsepower required. Compare horsepower ratings.
5. Speed. See page 5 to determine the speed of a hydraulic press.