by Michael Riehn
Hydraulic presses are normally offered with multiple ram speeds, such as; Fast Approach, Pressing and Fast Retract. Typically, these speeds are expressed in Inches Per Minute.
The Fast Approach Speed is designed to lower the ram quickly during the portion of the stroke that does not require any force. The pressing speed is commonly referred to as the working portion of the stroke where force is required and is usually slower.
After the working or pressing portion of the stroke is completed, the ram retracts at a Fast Retract Speed which affords little force. This Retract Force is commonly referred to as the “Stripping Force”.
Many customers with mechanical press experience refer to press speed in cycles per minute. Hydraulic presses can be designed to provide a certain amount cycles per minute once the cycle profile has been determined. The cycle profile consist of an accurate description of the physical aspects of the cycle. These aspects are:
1. Distance of ram travel under no load (Fast Approach)
2. Distance of actual working stroke (Pressing)
3. Distance of Fast Retract (usually the combination of the previous two distances)
4. Any Dwell Time at the bottom of the stroke or while under pressure
Once these parameters have been established, the appropriate ram speeds can be developed in conjunction with the right power system to provide the necessary cycles per minute.
Variable ram speeds are also available through the use of flow controls and variable volume pump systems. These and many other cycle profile characteristics can be provided - ask your Beckwood Press Systems Engineer for more details.