Roll forming machines (or metal forming machines) are made from strips of metal (most commonly rolled steel) into specific configurations. In most applications, the required cross-sectional profile of the part is specifically designed for the machine to bend the metal as needed. In addition to roll forming, these machines perform many metalworking tasks, including material cutting and roll stamping.
Most roll forming machines work continuously. The material is sent to the machine, in the process, the material continuously enters each operation station, and finally, the final product is completed.
Roll forming machines use multiple workstations to bend metal at room temperature, with fixed rollers both guiding the metal and making the necessary bends. When the metal strip passes through the roll forming machine, each group of rolls bends the metal slightly more than the previous roll position.
This progressive method of bent metal ensures the correct cross-sectional configuration while maintaining the cross-sectional area of the workpiece. Roll forming machines typically run at speeds of 30 to 600 feet per minute and are ideal for manufacturing large or very long parts.
Roll forming machines are also well-suited for manufacturing precision parts that require little, if any, finishing. In most cases, depending on the material being molded, the final product has excellent finishes and very fine details.
Roll Forming Basics and the Roll Forming Process
The production line of a basic roll forming machine can be divided into four main parts. The first part is the inlet part where the material is loaded. The material is usually inserted in a sheet or fed from a continuous web. The next part is the station roll, which is the position where the roll forming is actually performed, the position of the station and the shape of the metal in the whole process. Fixed rollers not only shape the metal but also the main driving force of the machine.
The next part of a basic roll forming machine is a cutting press that cuts the metal to a predetermined length. Due to the speed of the machine and the fact that it runs continuously, flying blades cutting technology is not uncommon. The last part is the exit station, where the finished part is ejected from the machine onto a roller conveyor or table and moved manually.
Roll Forming Machine Developments
Today's roll forming machines have a computer-aided tool design. By integrating the CAD / CAM system into the roll forming equation, the machine can reach its full potential. Computer-controlled programming provides an internal "brain" to the roll forming machine to capture product defects, minimizing damage and waste.
In many modern roll forming machines, a programmable logic controller ensures accuracy. This is important if the part requires multiple holes or needs to be cut to a specific length. Programmable logic controllers increase tolerance levels and reduce accuracy.
Some roll forming machines also have laser or TIG welding capabilities. Including this option on real machine results in a loss of energy efficiency, but eliminates the entire step in the manufacturing process.
Roll Forming Machine Tolerances
Dimensional variation of a part created through roll forming is based on the type of material used, the roll forming equipment, and the actual application. Tolerances can be influenced by varying metal thickness or width, material spring back during production, the quality and wear of the tooling, actual machine condition, and the experience level of the operator.
The Benefits of Roll Forming Machines
Aside from the benefits discussed in the previous section, roll forming machines offer the user some specific advantages. Roll forming machines are energy efficient because they do not expend energy to heat material—the metal shapes at room temperature.
Roll forming is also an adjustable process, suitable for projects of different durations. In addition, roll forming can produce precise, uniform parts.
Set up for roll forming success
The operator sets up the roll forming line, runs the test part, and finds that the results are outside the tolerance range. So he adjusted the line and ran another test part, measured it, and adjusted the line again. Then again. Then again.
Roll forming is a complicated process, but setting up a production line does not need to be so cumbersome. Why does it take so long to set up? Operators and supervisors may blame old equipment or unrealistic tolerance requirements.
Or materials may be a major issue. Strips can have radians or curvatures. Arcing can occur in the material during rolling or slitting and upstream of the shop floor. Rolling mill coils with edge waves are cut into narrower coils, showing random camber angles in the outer frame, affectionately called "snake-shaped". You can also use cross, dish, center buckle or oil can. Good leveling can help minimize these material issues.
In other words, when seeking to improve the consistency of any roll forming operation, important things and purchasing practices should be part of the conversation. But you cannot ignore the best roll forming practices.
Many challenges can be attributed to insufficient documentation of best practices, insufficient maintenance of machines and tools, and lack of training. In fact, setting up a roll forming machine definitely shouldn’t be a black art.
