This comprehensive handbook is organized into introductory material and six sections. Click the links to navigate between sections.
What Is a Hydraulic Press Used For?
Where Are Hydraulic Presses Used?
What Are the Different Hydraulic Press Frame Styles?
What Value-Added Features Are Common in Hydraulic Presses?
What Are the Components of a Hydraulic Press?
What Factors Determine the Cost of a Hydraulic Press?
What Is a Hydraulic Press?
A hydraulic press is a machine that employs fluid pressure created by a pump to push a cylinder at a set force to compress, assemble, draw, punch, trim, stretch, stamp, and form materials for a variety of industries. Available in an unlimited combination of sizes and frames, hydraulic presses operate at varying speeds and pressures depending on the application.
How Does a Hydraulic Press Work?
A hydraulic press works by pressurizing fluid to create force. Fluid is pumped by a motor into the cylinder through the cap end port and rod end port, depending on whether the press is extending or retracting. By pressurizing the cap end of the cylinder, the cylinder is forced to extend. By pressurizing the rod end of the cylinder, it is forced to retract.
The foundation of a modern fluid power system is based on Pascal’s Law, which states that pressure is equal to the force divided by the area. By increasing the pressure and/or the forming area (larger cylinders and/or bed size), more force can be achieved. This creates unlimited potential for creative engineering and customization in a hydraulic press.
What Are the Benefits of a Hydraulic Press?
The primary benefits of a hydraulic press are: full tonnage throughout the stroke, customization, flexibility, and longer tool life.
The variable stroke in a hydraulic press is programmable, with the ability to achieve full tonnage anywhere throughout the stroke. This is a hydraulic press’s greatest advantage.
The principles of hydraulic force inherently allow for customization, flexibility, and creative engineering. Due to the programmability of the system, hydraulic presses can meet both simple and complex forming requirements. Hydraulics allow presses to be designed for down-acting, up-acting, side-acting, and multi-action operations. Power systems can be placed above, below, or adjacent to the press. Large-bed presses can be designed for low-tonnage applications, and small-bed presses can be designed for high-tonnage applications. The possibilities are endless.
Hydraulic press tooling is developed to fit the application, not the press. Hydraulic presses use hydraulic relief valves embedded into the hydraulic circuits to protect against overloading, which places undue stress on the tooling.
Applications: What Is a Hydraulic Press Used For?
If tangible goods are being manufactured, chances are a hydraulic press is involved—whether in a specialized role like forming or assembling panels or parts, or the entire process, like minting coins. In short, hydraulic presses are used in any forming or fabrication process that requires a precise, set pressure.
Here is a comprehensive list of hydraulic press applications. Click on the links to view the specific application.
- Bulge Forming
- Compression Molding
- Extruding (or Extrusion)
- Flying Cut-Off
- General Forming
- Hot Forming/SPF
- Injection Molding/Reaction Injection Molding (RIM)
- Pad Forming
- Powder Compacting
- Steel Rule Die Cutting
- Stretch Forming
Assembly presses are just what they sound like: presses used to assemble parts and goods. They can be standalone for simple, one-step assembly processes, or used in series, as in an “assembly line” for complex applications. Assembly operations performed on a hydraulic press include track pin assembly, inserting bushings or bearings, joining, fastening, riveting, crimping, clamping, press fitting, punching/blanking, motor and transformer stator core stacking, spring testing, staking and swaging.
Presses for bending and straightening are often characterized by their horizontal, side-acting C-frame configuration. This peculiar design is driven by the press’s purpose: bending (or straightening) elongated stocks that are easier to load and unload horizontally, such as I-beams for the railroad industry, alloys for aerospace parts and chassis for off-road vehicles. Side-acting bending/straightening presses almost always have gib-guided rams to ensure maximum parallelism despite off-center loading.
Bulge forming presses are actually sophisticated, high-tonnage clamps that apply force to the tooling to counteract the pressure being injected into the forming chamber. During the bulge forming process, operators insert a blank into a mold mounted inside the press and introduce pressure, typically via water or air, into the chamber. The pressurized media forms the material to the shape and contour of the tool.
Fluid (hydro) bulge forming is typically used to form cylindrical shapes such as tubes or canisters, whereas pneumatic (air or gas) bulge forming is most often used to form spherical shapes such as discs or tank heads.
Hydraulic clamping presses automate and streamline one of the most time-consuming steps in sheet metal fabrication: setting up clamping operations. Rather than manually loading punches and securing bolts and set screws, operators simply load the tools into a hydraulic clamping press system, and the entire setup is clamped and seated by the press.
Coining, also referred to as minting, is a process performed on a hydraulic stamping press in which a significant amount of force is applied to a closed die containing a workpiece, forcing the metal to conform to the shape of the die. The coining process produces a very fine and detailed surface finish while also work-hardening the surface of the part, making it an ideal solution for manufacturing coins, medallions, complex electronic parts, and jewelry.
Compression molding presses, also knowns as thermoforming presses, use heat and pressure to form substrates like plastics, resins, epoxies, composites, and other materials into three-dimensional shapes. Pressure is applied as needed throughout the heating, dwelling, and cooling stages to create the desired shape and to ensure that proper curing and hardness thresholds are reached.
Flexible programming is key to successful compression molding. The ability to tell the press when to apply pressure, how long to dwell, and how much heat to provide at any point throughout the forming cycle will determine the efficacy of the finished part.
Compression molding is especially well-suited for production of large, detailed fiberglass, plastic (Torlon, Vespel, etc.), silicon or polymer (PEEK) parts. In the automotive industry, for example, compression molding presses are used to form many large flat or curved car parts, such as hood liners, fenders, scoops and spoilers.
Crimping presses are typically small, low-tonnage machines that perform a secondary operation on an existing part. These machines can be hydraulic or servo-electric for added precision and accuracy. Larger hydraulic crimping presses are commonly used in industrial settings for hose, tube and pipe-end forming, cable- and wire-harness assemblies, and other crimping operations.
A hydraulic deep drawing press uses a multi-action configuration to ensure consistent material flow and reduce wrinkles and tears throughout the forming process. The most common deep drawing applications use a punch tool mounted on the press bed and a cushion below. The blank material is placed on the draw ring supported by the bed cushion. During a cycle, the upper tool contacts the blank, and the cushion retracts downward, forming the material over the stationary punch.
Embossing is a sub-application of stamping, characterized by the pressing of a raised (or recessed), often ornamental, design onto a larger surface such as a sheet or panel. Mechanical presses are adequate for embossing simple designs or textures on smaller, thinner stocks, but more precise embossing applications require the full, consistent tonnage throughout the stroke that hydraulic presses provide. Technologies like pre-fill valves and short-stroking can be used to increase speed during the cycle on a hydraulic embossing press.
Extruding (or Extrusion)
Usually horizontal and side-acting, extrusion presses form shapes by forcing metals or plastics through a die or series of dies. The resulting extrusions can be thick or thin, solid or hollow, and can even be tapered or stepped depending on the tooling. Metals can be extruded cool or heated to “billets” above the recrystallization temperature of the metal. Cool extrusion adds strength and hardness to the metal stock. Plastics are almost always extruded in a molten form. The most commonly extruded thermoplastics include nylon, polycarbonate, polyethylene, and polyvinyl chloride.
A key technology in mining, sewage treatment, chemicals and food/beverage production, hydraulic filter presses are most often used in the dewatering stage of the drying process to separate solids from liquids in pre-thickened sludges and slurries. A hydraulic cylinder compresses an array (or stack) of filtering plates, removing the impurities and suspended solids from the injected slurry.
Often tightly integrated with other metal forming operations such as stamping, roll forming or extrusion, flying cut-off presses cut already-formed sections (such as round or shaped steel tubing) to specified lengths.
Forging is one of the world’s earliest metalworking applications, traditionally performed using a hammer and anvil. Modern hydraulic forging presses can be configured to accommodate open and closed die forging, impression die forging, hot forging, and cold forging. Due to the versatility of a hydraulic press, forging operations that require superior part strength, custom shapes and sizes, or unique performance specifications can be formed with ease. This includes automotive crank shafts and transmission parts, aircraft stabilizers, hand tools, hardware, and cutlery. Additional features like heated platens and cooling channels within the press bed add to the press’s operational flexibility.
Hydraulic presses used in general forming must be versatile due to the frequent tool changes and fluctuating demands of job shops and contract manufacturers. Often, these presses are required to perform multiple applications within the same facility or a range of operations within the same general application. Because they need to be adaptable to an array of tasks, presses used for general forming tend to be high-tonnage (500+ tons) 4-post machines with large working areas and unrestricted access to all sides of the working area.
Hot forming and superplastic forming (SPF) presses use extreme heat—up to 2,000°F—to form titanium, high-strength aluminum and other alloys. The heat increases the plasticity and elongation characteristics of the material, allowing it to be formed at much lower tonnages compared to cold forming—without risk of cracking, spring-back, or residual stress.
SPF uses extreme temperatures in conjunction with argon gas to form large, high-strength alloys into complex shapes in a single step. During the cycle, the heated material is clamped between a die and a plate. Argon gas is injected into the forming chamber, pushing the blank into the die. The resulting parts have a fine surface finish and are near-net-shape, eliminating the need for secondary finishing.
In the most basic sense, hydroforming presses use fluid (oil or water) to form metal and composites into finished parts. There are two primary types of hydroforming: sheet hydroforming and tube hydroforming.
Sheet hydroforming machines are hydraulic presses that use a rubber, neoprene, or urethane diaphragm in place of the upper platen. When the diaphragm is pressurized with fluid, it acts as a universal die half, extending over an unmated tool and blank that rest unsecured in the forming chamber. The result is a near-net-shape part with a smooth, unmarred surface that requires no secondary finishing.
Tube hydroforming presses act as a clamp for a mated die set by holding the blank material in place. As water is injected into the tube stock, it pushes against the dies, making the desired shape.
Injection Molding/Reaction Injection Molding (RIM)
During the injection molding process, resin powders or pellets are dispensed into a hydraulic press via a hopper, heated to their liquification point, and injected into the die via a pressurized screw or plunger. In the mold, the liquid resin is distributed into the various cavities via a main channel or sprue. Once the material cools and solidifies, the finished products and sprue are ejected. Hydraulic injection molding presses are often engineered in a horizontal configuration to allow for optimal material flow into the die cavities.
Reaction Injection Molding (RIM) is commonly used to manufacture polyurethane by combining two liquid polymers. Once pumped or injected into the heated mold, the liquids generate an exothermic reaction to create the desired polyurethane. The finished part could be rigid or flexible depending on the polymers. Presses used for RIM act as large clamps that hold the tooling closed while the substrate inside cools and hardens. RIM presses are often low tonnage (under 100 tons) and can have rotating and/or tilting bases to facilitate even coating of the liquids inside the die cavity.
See also: Compression Molding
Rubber pad forming presses, also known as Guerin box presses or elastoforming presses, use an enclosed rubber or urethane pad box as a universal die half to form parts over a single, un-mated tool. During a cycle, the tool is placed unsecured onto the press’s bed bolster, and downward pressure is applied. The fully-contained pad box prevents the rubber from extruding outside of the work area during the forming process.
Hydraulic rubber pad presses typically offer a higher forming pressure and larger forming area at a lower cost than hydroforming presses, but the resulting parts often require secondary finishing to achieve the desired tolerances.
See also: Hydroforming
Powder compacting is a compression molding process used in ceramics, pharmaceuticals, construction, brick-making and other industries to form complex shapes from metallic, ceramic, composite, PTFE, and other powder compounds. Hydraulic presses used for powder compacting are commonly multi-action, allowing operators to set fill heights via the lower or middle cavity while also providing uniform compaction density. With a triple action design, for example, the main ram applies downward force to the powder, a middle “cavity” ram sets the fill depth, and a lower “knockout” cylinder ejects the finished parts.
Presses used for punching and blanking essentially perform the exact same function: making holes in a sheet of metal, plastic, carbon fiber, or composites. The primary difference between the two applications is the finished workpiece. If the desired end-product is the sheet with the hole in it, it is punching. If the end-product is the smaller piece extracted from the sheet, it is blanking. In either case, speed, accuracy, and repeatability are the main requirements manufacturers seek in punching and blanking presses.
Breakthrough shock is a common by-product of punching and blanking. To counteract this, many hydraulic punching and blanking presses are equipped with technologies like Active Leveling Control and hydraulic shock dampeners to ensure parallelism throughout the cycle.
Die spotting presses are used in the creation, maintenance, and repair of molds and dies to verify the contact points between their upper and lower surfaces prior to production. A spotting press dedicated to this inspection step requires much lower tonnage than a production press but high precision and stopping accuracy to achieve acceptable results and prevent damage. Gib-guided presses offer the greatest precision but 2- or 4-column models can suffice when tolerances are less stringent.
Try-out is the step after die spotting in the creation of molds and dies, in which the milled tooling is tested under production conditions. Tryout presses must therefore have both the precision and controllability of spotting presses as well as the tonnage of the production press that will manufacture the final part.
Because both spotting and try-out involve frequent manipulation and inspection of tooling, these presses are typically equipped with a 180° slide tilt option called a “booking ram” to facilitate easy die access and accommodate frequent die changes.
Staking is an assembly process in which parts are joined by creating a friction or interference fit between them—as opposed to riveting, screwing, bolting or bonding. A staking press assembles the parts by slip-fitting a boss in one component into a hole in the other, then expanding the boss as needed to achieve the desired joint strength. In hot staking (or thermoplastic staking), the press simultaneously heats the boss in a plastic part while applying the necessary forming pressure to complete the join.
A stamping press, or metalworking press, uses a mated die set to form, shape, mark, or cut metal. Stamping is one of the most universal terms in the metalworking industry because it spans a wide range of industries, applications, and materials. This array requires incredibly diverse machinery, from large mechanical or hydraulic presses to small tabletop or benchtop presses.
Steel Rule Die Cutting
Similar to trimming, steel rule die cutting uses the force of the hydraulic press, paired with hardened and sharpened steel rule cutting dies, to straight-cut materials to their finished sizes—from carpet and rubber to plastic, foam, leather and even metal. Cutting dies are loaded into grooves in a base (or “die board”) that is attached to, or pre-configured with, the press. If needed, rubber strips or blocks are positioned on either side of the cutting dies to prevent sticking and ensure proper ejection.
See also: Trimming
In stretch forming (or wrap forming), metal sheets or extrusions are clamped into a press via “jaws” and stretched around contoured dies to create desired shapes. Stretch forming produces components of varying complexity—from simple curved parts like aircraft skins, to parts with intricate geometries and non-uniform cross sections. Most leading-edge parts, joined structural sections, and contoured trim are created using this method. Constant tension minimizes imperfections and wrinkles, and the stretching of the metal increases its yield strength. There are two basic types of stretch forming:
Sheet Stretch Forming: Sheet stretch forming machines use a large sheet metal blank, placed atop the die or stretch form block. The blank is held in place by gripping jaws which hold the edges of the sheet metal. During the cycle, the stretch form block (die) moves upward and pushes against the sheet until it forms into a contoured shape. Features like oscillating carriages enable the machine to form a variety of complex bends and angles in one cycle. Sheet stretch forming machines are most commonly used to form large metal panels for the aerospace and transportation industries.
Extrusion Stretch Forming: Extrusion stretch forming machines use long pieces of metal (blanks), clamped between circular gripping jaws which are attached to movable arms. The contoured die is mounted to a die table attached to the machine. During the cycle, the arms engage (either independently or simultaneously) to wrap the blank around the contoured die. The resulting extrusions are used primarily in the aerospace industry for wing stringers, chords, and other structural parts.
Hydraulic trimming presses and cutting presses are used to debur, deflash, or otherwise remove excess material from workpieces after other forming or casting operations. They can also be used to cut large stocks into their finished shapes—sometimes in tandem with other forming operations like flanging. In practice, trimming presses are usually configured with shuttles, belt and conveyor systems, and ejection cylinders to automate loading, unloading, and scrap removal.
See also: Steel Rule Die Cutting
Industries: Where Are Hydraulic Presses Used?
- Consumer Products
- Energy: Oil/Gas & Nuclear
- Job Shop
- Medical & Healthcare
- Military & Defense
- Plastics & Rubber
- Research & Development
- Safety Products
- Waste Management
No other industry depends more on the versatility and precision of a hydraulic press than aerospace. Whether it’s hot forming/SPF, composite and compression molding, rubber pad forming, sheet hydroforming, draw forming, ring expanding or stretch forming, the aerospace industry uses hydraulic presses to form countless plastic and metal alloy parts on commercial, private and military aircraft. From fuselages and exterior wing stringers to interior wall sections and everything in between, hydraulic presses are instrumental in manufacturing today’s modern air fleet.
Aerospace production and MRO functions consistently require low-volume, high-mix production equipment to accommodate an array of high-precision part families. That’s why fluid cell and deep draw sheet hydroforming are often the only viable solutions to accurately form aluminum, aluminum alloy, stainless steel and other materials (even titanium) into finished parts with the specified strength, lightness and other properties, free of surface marring.
The agriculture industry relies on hydraulic presses to manufacture the tools farmers need to produce, harvest, store, and package the food we eat. From tillage discs and blades to parts for tractors and heavy machinery, hydraulic presses of all shapes and sizes are required to meet the diverse needs of this industry. It is even common to see small hydraulic shop presses used on farms to make on-site repairs, replace bearings, press gears, compact materials, and perform other routine tasks.
Home and commercial appliance manufacturing entails several distinct hydraulic press applications that together form the backbone of appliance production. Medium-tonnage, 4-post or gib-guided general forming presses with large working areas are usually the work horses behind the forming and drawing of sheet metal into refrigerator, laundry, oven/range or other appliance housing panels. Punching and blanking presses create the necessary holes and slots into the panels, and assembly presses—small and large—load the bearings, insert the motor shafts, assemble the switches and thermostats, and more. Hydraulic presses are a common choice for appliance manufacturers because they are often able to combine several of these functions into a single machine, saving valuable time, money, and floor space.
Brake pads, hood liners, tires, windshield wipers, exhaust systems, batteries, and formed panels are just a few of the countless automotive components made by hydraulic press machines. Automotive industry hydraulic press applications include stamping of high-volume engine and transmission parts, assembly of ball joints, door locks, wire harnesses and insertion of bushings and bearings into steering columns and transmission components, tube hydroforming of exhaust pipes, molding and fusion of brake pads, compression molding of rubber tire treads, and of course, general sheet forming of exterior body panels.
Use of hydraulic press technology in the automotive industry has expanded into new areas in recent years, driven by the need to mass-produce parts and components for electric and hybrid-electric vehicles. Hydraulic presses are used to produce battery housings, enclosures and the batteries themselves, as well as lighter-weight substitutes or equivalents of familiar parts and panels to reduce vehicle mass.
Low-tonnage hydraulic presses at room temperatures have all but replaced time-consuming traditional kiln firing in the manufacture of high-volume, mass-produced ceramic products like floor and wall tiles, bricks and porcelain slabs. Even comparatively complex ceramic shapes, however, can be die-pressed or hydroformed to as-sintered tolerances requiring no subsequent green machining. In the semiconductor industry, hydraulic presses are integral to the forming and finishing of ceramic substrates and wafer processing equipment, as well as other technical ceramics used for electrical, mechanical, chemical and vacuum applications.
Wiring and cabling is the backbone of the world’s telecom and utility infrastructure. These industries depend on dedicated crimping presses of all shapes, sizes and configurations, rigged with special interchangeable dies, or applicators, calibrated for specific cable-contact combinations. Electrical and telecom cover plates from interior wall outlets and switch covers to rugged outdoor panels and manhole covers are created with forging or stamping presses. Assembly presses make the housings and large switches in electrical switching stations and substations.
Hydraulic presses help pave our roads and construct the buildings we live and work in, from large pre-cast concrete panels, lighting post tops, heat exchangers for heating and cooling systems, and lightweight insulation panels. With applications like mixing, spreading, molding, and forming, hydraulic presses are used in many construction and infrastructure projects. Hydraulic presses also play a vital role in testing the attributes (such as tensile strength) of construction materials like concrete and steel. Such testing would be impossible without hydraulic press systems equipped with precision controls and feedback systems.
Hydraulic presses are vital to the manufacture of an assortment of non-food consumer goods found on retail shelves. Powder compacting is the standard method for packaging makeup in “compacts” and forming ceramic dishes. In athletic shoe manufacturing, trimming presses die-cut the fabric “uppers,” which are then bonded to the rubber sole portions, made separately via compression or injection molding. Many other familiar products are also compression molded: toys, kitchen utensils, toothbrush and disposable razor handles, doormats, plastic bowls, cups, plates, and many more. Cellulose sponges and similar cleaning products are produced in sheets, then cut to size in a steel-rule die cutting press.
See also: Food & Beverage
Trade Schools, labs in Engineering, Materials Science and Physics departments at most universities, and even national laboratories rely on hydraulic presses for instruction in various fields of study. Most presses in educational settings are 2-post or c-frame machines in the low-to-mid tonnage range, but programmability, flexibility, and data collection for analysis are the features most often cited by educators as key to effective instruction.
See also: Research & Development
The metal and plastic parts and casings that comprise virtually all manufactured toys, telephones, computers, thermostats, remote controls, and other everyday gadgets are formed, stamped, and assembled using hydraulic press technology. Hydraulic presses are also integral to manufacturing many types of printed circuit boards found in modern electronics, forming the ceramic substrates, wafer processing equipment and other vital components the semiconductor industry relies on.
Energy: Oil/Gas & Nuclear
The oil, gas and nuclear energy sectors employ high-tonnage hydraulic presses for a variety of applications including clamping of pipeline and bulge hydroforming large tank heads for fuel transport. Hydraulic ring expanders are especially common in the energy sector to hot- warm- or cold-fabricate large, strong ring-shaped parts for turbines, windmill flanges, and many other applications. Ring blanking is a specialized hydraulic hot-forging press operation to make the pre-formed rings for subsequent precision tooling. In the green energy sector, a recent innovation employs ceramic firebricks to convert excess electricity during low demand to stored heat. These bricks are formed using the same hydraulic dry-pressing and hot-pressing compaction processes that have long been used to make other refractory bricks.
Food & Beverage
One of the first applications of any type of press was to extract oil from seeds, nuts, fruits and vegetables. Today, nearly all plant-based oils are extracted via cold-pressing, but beyond that, hydraulic presses of all shapes and sizes carry out countless tasks—from chopping, dicing, juicing and filtering to shaping, forming, sealing and packaging—across the food and beverage supply chain.
Sanitation and FSMA compliance considerations spotlight the importance of advanced control systems that collect performance data as the press operates. But even at the specification and design stage, those same considerations impose unique restraints, like stainless steel contact surfaces and non-toxic/non-reactive polymer hose and seal materials. To mitigate fluid contamination risk, press systems can be designed with up-acting rams and all hydraulics below the work area, or pre-engineered for use with “Generally Regarded as Safe” (GRAS) biobased hydraulic fluid substitutes. Servo-electric presses that operate without hydraulics can eliminate the risk of fluid contamination completely.
Job shops and contract fabricators use hydraulic presses of all types and sizes to quickly, accurately, and cost-effectively deliver contracted runs to their customers and perform myriad other tasks. These manufacturers need versatile, flexible machinery that can be adapted to a wide range of forming, stamping, cutting or assembly applications. High-tonnage 4-post hydraulic presses with large beds and multi-sided access to work areas are suited to the widest array of press applications. Contractors who require the highest precision and force control (for aerospace, defense, and automotive production) often invest in gib-guided hydraulic presses.
Manufacturers of commercial, residential, architectural, and industrial lighting rely on hydraulic presses to produce fixtures and shades in an array of shapes, sizes, materials and finishes. Forming solutions in lighting can be simple and straightforward or complex and multi-faceted. In many instances in the lighting industry, the choice of a press involves factors beyond simply obtaining a desired shape, such as preserving (or helping achieve) a finish or patina. Sheet hydroforming presses are especially common in lighting manufacturing because tooling is comparatively inexpensive, and they avoid the surface marring and scuffing associated with matched die systems.
Hydraulic presses are an integral part of modern shipbuilding. Shipyard presses are typically large machines for cold-forming the multiple curved plates of a ship’s hull and inner sheathing. For geometries that cannot be achieved by the point pressure of a down- or side-acting hydraulic press, repeated stressing of the plate in a “roll press” that consists of three rollers can achieve the required results. Hydraulic presses also bend (or straighten) the metal beams that form a ship’s keel, gunwales, ribs, and other skeletal members. For non-structural and engine parts, most of the same hydraulic press applications found in the automotive industry also apply to ship building.
Medical & Healthcare
Hydraulic presses are used in the medical industry to manufacture medical devices and components because they are versatile and offer tight control over forming operations. From assembling cathodes in pacemakers and forming titanium artificial joints to hydroforming knee and ankle orthotics, bending endoscopy tubes, and compressing seats for wheelchairs, presses that offer strict part traceability are paramount. In the pharmaceutical industry, multi-action powder compacting presses for tablet production are essential.
In biotech, the French pressure cell press is widely-used for isolating proteins and other cellular components in labs and industrial enzyme production. Precise pressure control is an absolute requirement in these presses to achieve the optimal conditions for cell disruption.
Medical and pharmaceutical manufacturers also rely on advanced hydraulic press control systems that collect and analyze IoT data in real-time to comply with regulatory and governmental requirements. For ultimate cleanliness, some cleanroom and laboratory environments prefer servo-electric presses to eliminate the potential for part contamination.
Presses used for metalforming, metalworking, and metal stamping employ mated die sets to deform all types of metal including aluminum, stainless steel, titanium, and other high-strength alloys. These machines vary in size, tonnage, and actuation type depending on the metal being formed and can feature ancillary equipment such as coil feed systems, progressive dies, and/or pre-heat furnaces and ovens.
See also: Stamping
Military & Defense
Military ground vehicles, planes, and ships are made using many of the same hydraulic press applications and processes as those employed in the civilian automotive, aerospace, and marine sectors, but rigorous military specifications often require creative manufacturing solutions. Compression molding of composite helicopter blades and interior UHMW panels in nuclear submarines as well as molding and assembly of steel and rubber track-blocks for a tank’s treads are just two of the myriad of military transportation examples. Defense and law enforcement contractors also use hydraulic presses for compression molding of helmets and protective armor plates, powder compacting of energetic materials for ammunition and fuse assemblies, stamping and assembly of rifle, handgun, magazine, clip and artillery parts, and shell-loading.
Modern hydraulic press technology is key to the manufacture of machinery, tools and infrastructure that make mining easier, safer and more efficient—from shearing steel bar stock to making hot forged parts in a temperature-controlled forging press. At the operational level, hydraulic filter presses are widely used to dewater slurries that contain mined ore.
See also: Filtering
Plastics & Rubber
Hydraulic compression molding presses can form a range of materials including plastics, composites, epoxies, and rubbers that make goods like tires, mulch, edging, and playground flooring. Compression, injection and thermal transfer molding are crucial applications for this industry in order to form the lightweight, high-strength bonds necessary to make these products viable.
See also: Compression Molding
The railroad industry relies on hydraulic presses to precision-bend and straighten sections of I-beam rail for installation on railroads. These bending and straightening machines (also known as bulldozer presses) are horizontally-acting hydraulic presses, usually with gib guidance. The same machines are also used in the railroad industry to shape angle iron and other details in the manufacture of subway and railroad cars. Forging presses are central to the hot forming of wheels for railway cars and locomotives.
Research & Development
Academic, government and corporate research facilities employ hydraulic presses to develop new products and test existing ones for quality control and assurance. One notable widespread R&D application of hydraulic presses is testing the compressive, tensile and flexural strength properties of hardened concrete.
See also: Education
Hydraulic presses form many key industrial and consumer safety products, from compression molding of helmets, goggles and other common PPE items to forging and bulge forming pressure vessels for fire-extinguishers, propane tanks, vacuum chambers, boilers, heat exchangers, and reaction vessels. Drawing presses are central to the manufacture of rupture discs to prevent damage or failure due to over-pressurization or vacuum.
The space industry relies on hydraulic presses to form precision parts for launch vehicles, rockets, manned spacecraft, and satellites. These presses commonly feature very large bed sizes and high tonnages (1000+ tons) to accommodate the varying part sizes. Sheet hydroforming is used by the space industry due to the forming flexibility and high precision. In fluid cell sheet hydroforming, a pressurized rubber diaphragm acts as a universal die half, applying uniform pressure over the part’s surface to produce near-net-shapes.
As in the auto industry, metalforming is a fundamental aspect of non-automotive, commercial transportation manufacturing. Hydraulic presses form the stainless steel or aluminum alloy sheet exteriors of rail and subway cars, compression mold plastic contoured seats for city buses, straighten and assemble tractor-trailer chassis, form steel roadside guard-rails and more.
Hydraulic presses are used in the waste management sector to compact, bale, press, and destroy, scrap metal, waste paper, electronics, and other materials under extreme tonnages. Everything from cars to circuit boards can be recycled using a hydraulic press. Large, hydraulic frame and plate filter presses are used in sewage treatment to dewater sludge.
Types: What Are the Different Kinds of Hydraulic Presses?
Two-post hydraulic presses, also known as two-column hydraulic presses, are characterized by the two steel posts on the left and right of the forming area that offer guidance to the ram. These machines are composed of a crown weldment, ram weldment, and bed weldment joined together by the posts on either side. Hydraulic systems can be crown-mounted in certain instances but are often skid-mounted due to the limited space above the crown. Access to the forming area is limited to the front and back, but two-post presses are an economical choice for applications requiring less than 500 tons of force and a forming area smaller than 36 inches. Jobs requiring a larger bed size or higher tonnage typically need the additional ram guidance and rigidity of 4-post or gib-guided presses.
Four-post presses, also known as four-column presses, are composed of a crown weldment, ram weldment, and bed weldment joined together by steel posts on all four corners. These machines offer ultimate access to all sides of the working area and are one of the most flexible and most common press designs, with tonnage capacities up to 10,000+ tons. Hydraulic systems can be crown-mounted or skid-mounted with ease to accommodate any footprint requirements, and forming areas vary widely from very small to very large depending on the application requirements.
Benchtop presses are small manual, hydraulic, pneumatic, or electric presses that can be mounted to a benchtop or rolling cart. They are typically low-tonnage machines (under 50 tons) with standard frame configurations. C-frame and H-frame are the most common frame styles for benchtop presses, but they can also be 2-post or 4-post for added precision.
C-frame presses, also commonly referred to as gap frame presses, offer three-sided access to the working area thanks to their unique “C” shaped frame which wraps around the bolster plate. Hydraulic systems on c-frame presses are often crown-mounted to fit within limited floor spaces but can also be be skid-mounted. In bending and straightening applications, C-frame presses can be configured horizontally to accommodate very long parts like railroad I-beams. Inherent to a typical C-frame design is a tendency for the machine to “yawn” or deflect as tonnages and bed sizes increase. Although this “yawning” effect can be mitigated by using gib-guided ram bolsters or special bushings, C-Frames are best-suited for processes needing smaller bed sizes and lower tonnages, such as assembly.
A gib-guided press, sometimes called a straight-sided press or slab-sided press, uses adjustable gibs to guide the reciprocating motion of the ram for maximum squareness and parallelism throughout the stroke, even when the load is off-center. These presses typically have a steel frame that is either welded (unitized) or modular. Most multi-action presses use this frame style because of its high precision and versatility.
Side-acting hydraulic presses can be 2-post, 4-post, or c-frame configurations depending on the needs of the application. Certain applications like straightening, bending, and injection molding benefit from (or require) a horizontally-configured press with a side-acting ram to ensure optimal forming results. Sheet stretch forming, extrusion, and frame-and-plate filter presses are also almost always horizontally configured and side-acting. Depending on the application, even some trimming, stamping and assembly challenges are better addressed with horizontal, side-acting presses.
Multi-post hydraulic presses are most commonly used when an application requires multiple zones of force control due to varying part sizes. For example, during the formation of larger parts, all the zones can be synchronized to allow consistent force across the surface of the part. When smaller parts are being processed, however, individual zones that are unused can be “turned off” to ensure the press maintains parallelism during off-center loading. These zones can be calibrated separately or synchronized to allow consistent force across the full surface area. The number of posts used on a multi-post press is determined by the number of zones of force control required.
Features: What Extra Features Are Common in Hydraulic Presses?
- Active Leveling Control
- Dynamic Bed Cushion
- Energy Efficient Press Technologies
- Heated Platens
- Press Safety Systems
- Quick Die Change Systems
- Tilting/Rotating Base
Active Leveling Control
Active Leveling Control (ALC) is an optional hydraulic press feature developed by Beckwood and offered on 2-post and 4-post hydraulic presses. ALC uses a closed-loop system to compensate for off-center loading and breakthrough shock: the two most significant factors affecting die wear and longevity. ALC systems employ a high-speed motion controller, linear transducers, and proportional control valves to synchronize press actuators and maintain bed-to-ram parallelism throughout the stroke. Read more here.
Hydraulic presses with automation are ideal for repetitive, programmable, low mix/high volume manufacturing tasks. Equipment such as conveyors, robots, shuttles, RFID scanners, and pick-and-place systems markedly increase throughput and quality while decreasing downtime. In recent years, costs for hydraulic press automation features have dramatically decreased, making these systems much more accessible to both large and small manufacturers. For more information about press automation, download Beckwood Press’s Guide to Press Automation.
Dynamic Bed Cushion
Commonly required for deep draw metalforming applications, a bed cushion is used to apply resistance force to ensure that the material is drawn smoothly, without wrinkling or tearing. A dynamic bed cushion allows the resistance force to be controlled and changed at different points throughout the stroke based on the position of the cushion. This multi-zone control is the key to reducing scrap rates and improving part quality in many draw forming applications.
Energy Efficient Press Technologies
With the soaring cost of energy and prioritization of environmental sustainability, modern hydraulic press technology has evolved to reduce energy consumption and material inefficiencies, decrease noise pollution, and lower emissions.
Servo-electric presses are the ultimate green press solution because they run entirely on electricity (no hydraulics) and therefore also the risk of contamination from oil leaks and spills. However, major strides in energy efficiency and environmental sustainability have been made for hydraulic presses as well. These include:
Variable Frequency Drives (VFDs): Motor controllers that dramatically reduce energy consumption by supplying voltage to the press only as-needed, according to the real-time load. VFDs also greatly reduce noise levels.
Pneumatic dwell system: A small pneumatically-powered hydraulic pump integrated into the hydraulic circuit that allows the primary electric motor and pump to literally shut down during processes with long dwell cycles. This results in huge energy cost savings over the life of the press.
Soft start technology: A mechanical device that limits the initial in-rush of electric current and gradually ramps up the press’s motor speed, conserving power and prolonging the life of the motor.
Hydraulic presses equipped with heated platens are used for applications in which heating the material being formed either makes it more malleable (as in metalforming), or changes the properties of the materials being formed to create the finished part (as in composites or injection molding). Heated platens on a hydraulic press are steel pressing plates, to which the tooling is attached, that can be heated using water, oil, or electricity. In most cases, these machines offer multiple zones of heat control to ensure optimal forming temperature across the entire surface of the platen. To protect the press structure from undue heat stress, thermal breaks (insulation) are commonly used in conjunction.
Press Safety Systems
As with all heavy machinery, the safety of hydraulic press operators, maintenance workers and general personnel is the number one priority. Safety standards for hydraulic press systems are codified in the ANSI B11.2 Hydraulic Press Safety Standard, the Canadian CSA Z142 Code for Power Press Operation, the CE European Union standard, UL Standard 508A and others. To ensure safe operation, modern hydraulic presses typically come equipped with safety couplers for cylinder-to-ram attachment, redundant solenoids to control hazardous ram motion, two-hand touch controls for press actuation as well as an array of light curtain and hard-guarding options. As safety standards have toughened around the world, many advanced safety features are now in demand. These include:
Ram Safety Catcher System (RSCS): A Ram Safety Catcher System restricts the movement of the hydraulic press’s ram throughout the stroke and secures the static load of the ram and tooling in the event of a sudden loss of hydraulic pressure, a break in the lifting mechanism, or even a power outage during operation.
Light Curtains: Light curtains are one of the most commonly used hydraulic press safety features. These devices use a strip light transmitter and receiver to guard the openings of the hydraulic press and keep the point-of-operation free for loading and unloading while ensuring continued operator safety. The transmitter sends a beam of light to the receiver, and when the curtain of light is broken, the press will stop actuating immediately.
Physical Guarding: Standard hydraulic press safety guards are composed of a metal-mesh material to maintain a degree of visibility within the working area, but Plexiglas (polycarbonate) guards provide a solid physical barrier without sacrificing visibility. These interlocked barriers can be offered as fixed guards, doors with hinges, or vertically sliding gates that open via a powered mechanism or counterbalance system.
Area Scanners: Area scanning is an optional hydraulic press safety feature for establishing a configurable safety perimeter—or warning zone—around the machine. With a single zone scanner, any breach of the programmed zone results in a machine shut down. With multiple stage zones, concentric regions with progressive warnings are programmed: blinking light, audible alarm, machine shut down, etc. Hydraulic press area scanners typically employ invisible infrared lasers and calculate distances using the time-of-flight principle, similar to how advanced cameras measure depth-of-field.
Quick Die Change Systems
The manual swapping-out of tooling dies on a hydraulic press is often cited as one of the most inefficient processes in manufacturing. Quick Die Change (QDC) is an umbrella term encompassing a set of add-on press integrations that, when properly selected and configured, can ease die changing bottlenecks, reduce risks and hazards, and markedly streamline processes.
At the center of a Quick Die Change system is an Automated Die Storage & Retrieval System (ASRS) that stages and shuttles the different dies as the press operates. Die consoles and bolster extensions facilitate the loading and unloading of the dies. Roller or ball-style hydraulic or pneumatic lifters shuttle the dies into and out of the press, and magnet and/or clamp fastening systems position, mount and retain the dies on the press. Bed shuttles add a further degree of flexibility in configuring a QDC. Read more here.
Hydraulic presses used for traditional injection molding and Reaction Injection Molding (RIM) benefit from the ability to rotate and tilt the mold during or after injection to aid the material flow within the cavity. Excess air inside the mold often prevents the raw material from filling the cavity to an optimum level which can affect the structural integrity of a formed part. With a tilting/rotating base, as material is injected into the press cavity, the press can be swiveled side-to-side or rotated up to 180-degrees front-to-back, thereby redistributing material into parts of the mold that were previously filled with air.
Terminology: What Are the Components of a Hydraulic Press?
Bed: The press bed is the flat, stationary, machined surface that supports the lower bolster or dies.
Bed Cushion: Commonly required for deep draw applications, a bed cushion is used to apply resistance force when pushed upon. This resistance force ensures the material is drawn smoothly, without wrinkling or tearing. Bed cushion force can be dynamically controlled throughout the stroke, allowing the resistance force to change based on the position of the bed cushion.
Bed Height: The bed height on a press machine is the distance from the bottom of the press structure to the working height or the top of the bed bolster. If a press requires a pit, the working bed height could be defined as the distance from the floor to the top of the bed bolster.
Bolster: The bolster is the removable plate that serves as the working surface of a press. The plate is typically bolted to the bed and ram weldments. Tooling is attached to the bolster, which can feature a variety of work-holding features such as T-slots, drilled and tapped holes, lift rails to accommodate quick die change systems, and more.
Bushing: Found on 2-post and 4-post hydraulic presses, the bushing is a fixed or removable cylindrical metal lining used to guide the ram and reduce friction. Graphite-impregnated bronze bushings that do not require external lubrication are the longest-lasting type of bushing.
Crown: The crown on a press is the upper structural weldment containing cylinders that drive the motion of the ram.
Cycle: A hydraulic press cycle is the complete movement of the ram, from the initial start position back to the same start position, that may include feeding and removal of the material or workpiece(s).
Cylinder: The cylinder is the main actuator of a press. This mechanical actuator converts pressure into linear movement, creating force.
Daylight: Also commonly known as the open height of a press, daylight is the distance between the bed bolster and the ram bolster when the ram is fully retracted.
Deflection: Deflection is the amount of deviation from a straight line that occurs when force is applied to the structure of a press. In c-frame press designs, this is often referred to as yawning, and expresses the amount a frame flexes under a load. See also: Types: C-Frame/Gap Frame
Dwell: Dwell is the amount of time required for a press to maintain pressure during a cycle. This is typically accomplished by using pressure lock valves or variable volume pumps that are remotely controlled during long periods of precise pressure holding. Hydraulic presses often use pneumatic dwell systems, powered by a pneumatic pump integrated into the hydraulic circuit, to reduce noise output and energy consumption.
Finite Element Analysis (FEA): Finite Element Analysis is computerized method for predicting how a press’s structure will react to real-world forces such as vibration, heat, fluid flow, etc. Performed during the press engineering phase, FEA works by breaking down a real object into finite elements and using mathematical equations to predict the behavior of each element.
Gibs: Gibs are adjustable metal bolts on gib-guided (or “straight-sided”) presses that guide the reciprocating motion of the ram to ensure squareness and parallelism. Gibs are usually provided with replaceable liners and are adjustable front-to-back as well as left-to-right to enable the setting of proper clearance and to compensate for wear. See also: Types: Gib-Guided/Straight-Sided
Heated Platens: Heated platens are steel plates to which the press’s tooling is attached that are heated using water (steam), oil, or electricity. These systems usually require thermal breaks (insulation) between the platens and the press structure. Heating controls can be separate or fully integrated into the press control system.
Human-Machine Interface (HMI): A Human Machine Interface (HMI) is a programmable touch screen computer that initiates the press cycle, monitors press health, and logs critical data and cycle parameters. On a hydraulic press, the HMI also acts as a check-engine light for the hydraulic system, notifying operators of oil particulate count, viscosity, temperature, and leaks.
Hydraulic Power Unit (HPU): The Hydraulic Power Unit (HPU) on a hydraulic press is a system comprising the tank, motor, hoses, pumps, and chillers that work in unison to create pressure. It is the mechanism that applies pressure to drive motors, cylinders, and other parts of a hydraulic system. HPUs are typically either skid-mounted or crown-mounted on the press, depending on the footprint requirements.
Motor: The motor on a hydraulic press is the electric machine that transforms hydraulic energy (fluid power) into rotary energy.
Platen: Platens are the steel plates, sometimes heated, that are attached to a moving or stationary press member. See also: Features: Heated Platens
PSI: PSI is an abbreviation for Pounds per Square Inch, a unit for measuring pressure in a hydraulic press.
Pump: A pump is the device that converts mechanical force and motion into hydraulic fluid power on a hydraulic press.
Ram (or Slide): The ram (or slide) is the middle weldment on a press that slides within the frame to create pressure on the tool or die. The ram can move vertically or horizontally depending on the press configuration. Some multi-action hydraulic presses even have multiple rams for complex forming processes.
Ram Knockout: A ram knockout is an ejection device required by many press operations that strips the formed part from the punch or die.
Ram Speed: Ram speed on a hydraulic press is the total time it takes for the ram to move from the open to the closed position, measured in IPM (inches per minute). Speed is also commonly measured at the three distinct stages of the stroke:
Fast Approach Speed lowers the ram quickly during the portion of the stroke that does not require any force.
Pressing Speed, commonly referred to as the “working portion” of the stroke, is when force is required and speed is slower.
Stripping/Retract Speed is after the Pressing portion of the stroke is completed, when the ram retracts at a Fast Retract speed which affords little force.
Return on Pressure: Return on pressure is a programmable hydraulic press cycle parameter that uses an adjustable pressure sensing device (transducer) to determine the desired maximum pressure to be achieved by the ram. Once this pressure is achieved, the ram completes the cycle by returning to the “Home” (or “Up Limit”) position.
Return on Position: Return on position is a programmable cycle parameter on a hydraulic press that uses a position sensing device (transducer) to determine the desired position to be achieved by the ram. Once this position is achieved, the ram completes the cycle by returning to the “Home” (or “Up Limit”) position.
Shut Height: Shut height is the distance between the bed bolster and the ram bolster when the ram is fully extended. This is commonly known as the “Closed Height.”
Stroke: Stroke is the total distance the ram can travel, from full extension to full retraction.
Stroke Control: Most hydraulic presses feature Adjustable Retract Limit Switches to restrict the retract distance of the ram (also known as the “Up Limit” Position). Using only the required stroke for part loading and unloading can shorten cycle times. Other programmable limits may include: Slow Down Limit for deceleration from Fast Speed to Slow Speed; Bottom Stop Position and/or Bottom Stop Pressure.
T-Slot: A t-slot is a notch machined into the platens of a press to hold the die in place. This work-holding feature also facilitates quick die changes.
Throat Clearance: On c-frame (gap-frame) presses, the throat clearance is the distance from the vertical centerline of the bed to the back of the press behind the bed. This measure is required to determine the diameter of parts and tools that can be positioned within the press. See also: Types: C-Frame/Gap Frame
Tie Rod: Tie rods on a 2-post or 4-post press are long rods with threads and nuts on both ends that hold the frame members together. These rods are stretched to place the frame members under compressive load.
Tonnage: Tonnage is the maximum amount of force a press machine can exert, typically called out in U.S. tons.
Transducer: A transducer is a device that measures the linear position or pressure of the ram or cylinder rod.
Weldment: Weldments are structural components formed by welding together steel plates. Most hydraulic presses have three main weldments: crown, bed, and ram.
Pricing: What Factors Determine the Cost of a Hydraulic Press?
The cost of a hydraulic press can range from as little as $10,000 to over $5 million, depending on the press type, capabilities, and age. For this reason, it is important to consider all the factors that influence cost.
H-frame shop presses and benchtop presses with a C-frame configuration are usually the lowest cost hydraulic press due to their small size and low tonnage capacities. Larger c-frame presses and 2-post presses are the next lowest in cost but are also limited by size and tonnage capacities. 4-post and gib-guided hydraulic presses are typically more expensive but offer the largest range of flexibility and highest precision tolerances. For this reason, it is important to consider all the factors that influence cost.
Standard hydraulic presses are pre-engineered for cost efficiency, but they are limited in size and force by the pre-determined specifications for the product line. They also may not include supplemental options like heated platens, automation equipment, or Active Leveling Control. This means you may have to compromise on a particular parameter in order to fit within the standard specifications or pay extra for certain features.
Unlike shop presses or standard machinery, custom hydraulic presses are engineered to order and usually come at a higher price tag. But, you’re guaranteed to own a machine that’s tailored to your exact application needs. Bed size, speed, tonnage, heating, cooling, automation, and more are fully customizable to meet any process goals. To mitigate costs wherever possible, custom press manufacturers frequently use value engineering principles and standard, off-the-shelf components.
Factors such as tonnage, speed, accuracy, ancillary operations and programmability all play integral roles in determining the final cost of a press and whether you need a standard or custom
Used presses typically have a lower upfront cost than new machinery, but as with standard presses, you’re limited to the pre-determined specifications. Additionally, hidden costs are common on used presses because you often don’t know the maintenance history or stresses previously imposed on the existing press structure and components. These machines almost never come with a warranty, and maintenance services and replacement parts can be difficult to source. Similar to a mechanic testing a used car, used press buyers should enlist factory trained technicians to perform a used press audit prior to purchase to uncover and curb hidden costs and limitations.
As noted above, new presses can vary in cost depending on size, tonnage, speed, and many other factors, but unlike used presses, they are built using the newest components and come with a manufacturer’s warranty. New presses are free of hidden costs and don’t require costly retrofits after installation. Many new press manufacturers also encourage customers to attend the final inspection and runoff to verify all key performance specs are met prior to shipment.
In summary, the cost of a press can vary greatly depending on the type, job requirements and whether it is new or pre-owned. Due to this, pinpointing the exact cost of a press is best established with a specialist who can provide accurate, customized pricing per your specifications.