Even in today’s world where plastics and polymers dominate, metalworking remains a vital part of many industries in the U.S. Metals and metal-worked pieces are critical components in many goods, from tiny computer chips and watch gears up to the molded pieces forming kitchen appliances, and even further to the carefully formed outer structures of cars, airplanes and other machines.
Press Machine Basics
Most metals in manufacturing are managed by press machines. This is a generic term for a collection of machines that use force, usually applied by pressure, to shape metals and metal blends into pieces needed to feed a specific type of industry or manufacturing.
Press machine is a term that represents the many different types of machines that can be used for different source metals and applications. They are also called machine presses, forming presses or mechanical presses.
In general, a press machine works by applying pressure to a metal in a set configuration to deform the metal from its original shape into the desired final shape. Metals can start as molten fluids, pressed sheet metal materials, or as raw material bars or chunks. The shapes they eventually obtain are designed by product engineers who need the components to build their end products. Various press shop production machines add the work energy necessary to take the metal from its original form to a final part.
Types of Press Machines
There are so many different types of press machines that it makes sense to qualify them based on their operative mechanism. In this case, there are three main modes of operation:
- Hydraulic presses use hydraulic fluid, a non-compressible liquid that acts as a lever to apply pressure to the metal. A compressive force acts on the liquid in one area, and without any other release, the fluid moves into another area, driving another piece of the machine with that transferred force. Hydraulic presses can create complex shapes and are used in forging, molding, punching and forming types of operations.
- Mechanical presses use a basic mechanical force, often applied by a ram, to deform the metal from one shape into another. For example, a type called a press brake is used to bend sheet metal to a particular shape, like the back of a computer or the front piece of an oven. A type called a punch press uses the applied mechanical energy to punch holes through a metal form. One of the most important applications is a stamping press, which uses carefully cut dies to deform metal into a specific shape using mechanical energy.
- Pneumatic presses use the power of gas compression to drive their mechanisms. In a pneumatic press, gas is compressed in one area, which forces it to expand into another area, producing a force with which a piece can be shaped into another conformation. These presses are used in applications such as shearing, punching, bending, forming and extruding operations.
Press Machine Details
Press machines can also be categorized by the way that they interact with the metal they are working with:
- A forging press is a press that applies a slowly increasing pressure onto a die that is shaping a particular piece. This slowly applied pressure allows the metal to keep certain key properties, can be applied to different shapes and configurations, and can be economical.
- An impact press uses a single sudden force to reshape metal according to a layout determined by a die. While impact pressing has limitations in terms of the complicated shapes or configurations, it is often used to make impressions or punch holes into metal parts quickly.
How Does a Press Work?
The key to a press machine is the plate or die used to reshape the metal from its original form into the desired piece or part. These carefully formed pieces are pressed against the surface of the metal to deform it into the desired shape. Sometimes they are one-sided; the metal is placed on a flat surface and the forming element descends to push and press it into the desired shape.
Sometimes these dies are two-sided. In most of these cases, sheet metal is stretched across the surface of the bottom die, and the top die comes down to shape the sheet metal into the three-dimensional space defined by the gaps between the top plate and the bottom. Carving these dies and plates is often initially done by hand, especially for intricate pieces and parts.
Read More: Uses for a Shop Press
Industries Using Press Machines
Press machines are critical components of many manufacturing industries. This type of machinery produces essential metal pieces that make up many of the end products in today’s markets. For example, a die forging press can be used to make high-strength materials out of metallic alloys for petrochemical industries that make tanks, piping and other machinery to manage chemical reactions. They are also used in transportation industries, aerospace applications and nuclear power applications.
On the other end of applications, press machines can be used to make small parts, such as screws, nuts, washers, nails and other small hardware accessories. The advantage to using a die impact press for these applications is the regularity. Assuming all inputs are correct, these presses produce identical pieces and parts every time. Punch presses are also used to punch pieces from flat sheet metal or from other pre-formed metal parts to create, for example, the pieces used to assemble a motor or a pump.
Training to Operate a Press Machine?
As with any heavy machinery, training is required to use a press machine. There are many hazards that an operator faces on the job. These machines use incredibly high pressures and forces to deform metal as needed. The pressures can cause extreme injury or even death to an operator.
With hydraulic or pneumatic presses, liquids or gases are contained under high heat or pressure. There is a risk of injury if parts of the press fail and spray fluids onto the operator. There may be other hazards depending on the materials, metals, and fluids used to create the parts. In most cases, industries are well-informed and provide general safety training to address all of these potential hazards.
Operational training is also required. Many modern press machines are controlled digitally, which gives the operator some distance from the process. However, manual input is often needed. In most cases, this involves the loading or unloading of the required dies that form a particular part or manual adjustments necessary to make sure they align correctly at the start of the process. Manual input can also involve the loading of the raw material metal or unloading of the finished product, although this process is often automated. In most modern plants, this equipment is automated, and operators only need to interfere for troubleshooting purposes.