Lou Kren Lou Kren
Senior Editor

Rely on Hydraulic Presses to Do More

August 30, 2020


Decades ago, proprietary hydraulics offered by press manufacturers were expensive propositions that lacked dependable accuracy and limited the ability to provide maintenance and repair outside of that offered by the OEM. By the 1990s, explains Christopher Shelton, president of Pacific Press Holdings, which provides Pacific Press and Multipress hydraulic presses, that was changing, as off-the-shelf, less-expensive hydraulic components―easier to replace and maintain―became available. This development offered improved accuracy to boot.

Today, as the technology has continued to evolve, the accuracy and repeatable performance of hydraulic presses make them candidates for a variety of intricate metal forming applications, including in aerospace, which requires extremely tight tolerances. Such tolerances, according to Shelton, can be held thanks to today’s servohydraulic technology, which among many benefits provides an automatic-feedback loop. In the age of Industry 4.0, where information is king, hydraulic presses now offer real-time communication of vital data. This includes remote access to the machines on the shop floor, to help maximize a metal forming operation’s performance and productivity.

Flexible Formers

hydraulic-presses-four-post-double-actingFlexibility is another key feature of today’s hydraulic presses, to the point that some employ more than one process.

“We’re seeing an influx of machine buyers using a hydraulic press to form metal and, separately, resin,” Shelton explains. “Someone will buy a machine and want it configured to bend steel, and then, through the use of a heated die, to form resin.”

Besides dual use for metals and resins, other recent application upticks, report Shelton, include metal forming for medical parts and firearms components.

Flexibility is assisted by the dependability of hydraulic presses, and their ability to stay online with minimal maintenance-related downtime. How?  By using off-the-shelf hydraulic components and standard-sized cylinders, reports Shelton.

“This eases replacement and repairs, and metal formers need not stock unique components or wait excessively for delivery of replacement parts,” he says. “If a machine does go down, due to a bad valve, for example, it can be back up and running in a matter of moments. With quick-disconnect on the electrical, a technician simply removes four bolts to take out the valve, then retightens the bolts and plugs the electrical back in—just a few minutes and issue is resolved.”

Another factor that delivers flexibility: Tonnage capacities for hydraulic presses range from 1 to well above 1000 tons, according to Shelton, in a variety of styles, including C-frame and two- and four-post models. 

As for speed, hydraulic presses run more quickly than you might think.

“We just quoted a job for a customer that needed 12-in. ram travel on a 1000-ton press,” Shelton offers. “So, the ram lowers 12 in., dwells for perhaps 0.5 sec. to form the part, then returns 12 in.—all of that with a cycle time of 1.5 sec.”

Handle Variety of Part Sizes, Operations

hydraulic-presses-two-post-cellPart-size capabilities vary with tonnage requirements, as a press’ bed size directly correlates with tonnage capacity, or, to put it more accurately, on cylinder size.

“A small C-frame press may have a 6 by 6-in. bed, whereas, in the quote I described above, that 1000-ton press, with a 22-in.-ID cylinder, has a 48 by 36-in. bed,” says Shelton. “The cylinder needs the volume to produce the needed force. On the 1000-ton press, a prefilled valve dumps a massive amount of oil into the cylinder, and we include a 500-gal. oil tank on that press to house the oil.”

Metal formers producing small firearms components account for many recent buys of one-, two or three-ton presses, reports Shelton, with larger-tonnage machines mostly used for specialty applications. Oftentimes, specialty applications call for customized machines, with some press manufacturers offering custom models in addition to standard offerings.

“A standard press may be modified where we install an additional cylinder on the side because a metal former wants to provide a finished part right on the machine, to perform a knockout, for example,” says Shelton, describing customization options. “A metal former can send over drawings for a part and we’ll work up the needed press size and drive, then design the machine as well as any automation if they need to pick up or transport material within the press area.

“In the metal forming industry, it’s gone from a press maker saying, ‘we supplied the machine, you figure out the rest’ to a machine builder providing the entire solution,” Shelton concludes. “That’s because a metal former’s engineering staff consists of experts on the products they make, not necessarily experts on the machinery. Talk to any press provider and you’ll find that as a whole we are becoming solutions providers and not just machine builders.” MF

Industry-Related Terms: Bed, Die, Form, Forming, Hydraulic Press, Point, Ram, Resins, Run
View Glossary of Metalforming Terms

 

See also: Pacific Press Technologies, Multipress, Inc.

Technologies: Stamping Presses

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