Power Through Pressmaster Hydraulic Press


When the pressing application requires a force of 10 tons or more, manufacturers can count on hydraulic, hydropneumatics and pneumohydraulic presses. Some assembly technologies evolve too fast or too slow, while others change at a pace that’s just right. Hydraulic presses belong in the latter category, according to some suppliers, and that’s a good thing. The biggest area of growth for pressmasterhydraulic press technology lies in the controls system. Automotive, aerospace and medical manufacturers want and need advancements in operator control, press-data acquisition, process monitoring, quality control and maintenance scheduling. These benefits nicely complement the hydraulic press’s ability to generate high force over a small area and equally throughout the stroke. All of these capabilities are important to companies with hydraulic pressing applications, especially those that require 10 tons or more of force.

Pure Power
Pressmasterhydraulic press have been used on assembly lines for a long time. Since Joseph Bramah patented the first hydraulic press in 1795, it has assembled products for industries as diverse as appliances, rail systems, marine transport, automotive, aerospace, agriculture, energy storage and consumer electronics. A hydraulic press features an electrically driven hydraulic power unit and a hydraulic cylinder that moves the press ram. Maximum force is determined by the cylinder’s bore size and the operating pressure. Press force is consistent throughout the entire stroke range, and, the stroke is smooth because hydraulic oil is not compressible. Ram speed is limited by the flow and oil volume restrictions of the hydraulic power package and circuit.

Hydropneumatics
A variation on the pneumatic press, the hydropneumatics, or air-over-oil, press uses both pneumatic and hydraulic power to drive the ram. The press consists of a hydraulic cylinder, an air-over-oil intensifier and an oil reservoir. Upon activation, a hydropneumatics press is initially driven only by compressed air. At this stage, known as fast approach, the ram descends rapidly with low force. When resistance is encountered, the intensifier is automatically energized by a directional control valve, hydraulic power takes over and the full force of the press is applied. At the end of the cycle, the ram retracts rapidly.

For high-force applications requiring short power strokes, a hydropneumatics press may be more cost-effective than a pneumatic press. However, the opposite is true for high-force applications requiring power strokes of 2 inches or more. Typically, the power stroke of a hydropneumatics press is about one-fifth of the total stroke. Some split-design systems can achieve power strokes of more than 4 inches.

Pneumohydraulic
Pneumohydraulic and hydropneumatics presses are quite different technologies. Pneumohydraulic cylinders convert air power into oil power, and feature special seals that keep air and oil completely separate. In contrast, air-over-oil pressmaster hydraulic press use air and then hydraulic power. Because the air is directly pressing on the oil, the air can leak into the oil, resulting in a spongy effect when the air bubbles are compressed during pressing.



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