by Rebekah Fuller, IQS Editor
The full range of today’s hydraulic presses is some of the most powerful and versatile manufacturing equipment. Achieving the highest compressive force of all the power presses, these machines are crucial for the forming and molding of a wide spectrum of materials: metals, plastics and composites, rubber, wood, and laminates. From deep drawing essential parts, such as tanks and fenders for the production of motorcycles, to creating 2,640 plastic credit cards per hour, the manufacturing realm would be lost without hydraulic presses. The scrap metal processing industry also relies on sheer hydraulic press force to smash discarded cars and such into compact, manageable squares of reusable material for pop cans, paper clips, etc.
It’s really fun to see all the things hydraulic presses can crush. Just search the popular social networking sites (I like StumbleUpon) to find great before-and-after photos and video depicting the unmatched force of these machines. My favorite examples include a homemade wooden press that squashed a disposable propane gas tank to a 3-inch height using 300 pounds of pressure. The creator of this makeshift press explained that he used an empty propane tank because he likes to live on the edge and the soup can just didn’t satisfy him. It is not recommended to try that stunt at home, but the real reason he created the contraption was to press a stuck spindle out of a milling machine countershaft that he was cleaning.
From this small scale example to the enormous car crusher hydraulic presses (there’s a great video of a beautiful Porsche being smashed between massive platens – plates that exert or receive pressure – and discharged as a compact square of scrap), the concept remains the same: the non-compressible liquid (usually oil or water) within a hydraulic cylinder fills the chamber above the piston with liquid (i.e. hydraulic) pressure and causes the piston to exert a thrusting force that moves the platen.
The type of press described above is the flat press. There is also the roller press that is constructed with a series of large, cylindrical rollers powered by hydraulics. When material like sheet metal is fed between the rollers, it can be bent and curled, and strips of metal inserted at an angle can be made into piping. However, there seem to be more examples of flat presses in the manufacturing world. Below is an example of the basic flat press design; it’s a 10 to 50 ton pressure capacity laboratory press from Grimco Presses Inc.
Higher capacity hydraulic presses can generate hundreds of tons of pressure, and full hydraulic press lines complete with press-to-press transfer robots or feeders and ancillary equipment, such as scrap conveyors, scrap chutes and discharge conveyors, can produce thousands of tons of total pressure for efficient high-volume production.
Multiple Hydraulic Press System from Grimco Presses Inc.
The C-frame press gets its name from the shape of its frame and is used for many industrial processes, including forming, bending, straightening, blanking, punching, drawing and riveting.
C-Frame Press Image from Wabash MPI
Laminating presses have more specialized uses. In general they create laminates, two or more layers of materials united using heat and pressure. The materials can be the same or different, and often something is sealed between two layers of plastic. Applications include applying film to various materials and creating credit cards, identity cards and printed circuit boards.
Laminating Press Image from Grimco Presses Inc.
Stamping presses are quite specific in application. Their two main purposes are shaping or cutting materials by deformation with a die for the metalworking or automotive industries.
Transfer presses, also referred to as encapsulation molding presses, are used for precise, controlled material transfer involving rubber, thermosets, epoxies and silicones. Transfer press products include encapsulated electronics and insert molded catheters, needles and other medical devices, plugs, connectors, rotors and sensors. Molding and laminating presses offer the fastest production, highest quality and least scrap when they are made as vacuum presses with a vacuum chamber surrounding the work piece. This means air, gas vapors and fumes are removed, thus eliminating defects and creating the most desirable resin flow and temperature and pressure control.
Transfer Press Image from Wabash MPI.
Other hydraulic press applications not mentioned yet include seam bonding, splice molding, trimming, coining, crimping, hydroforming, reaction injection molding or RIM, elastoforming and forging.