A Heading machine is a piece of equipment that transforms metal wire into complex shapes, including fasteners, without the use of heat. This machine uses a series of high-speed replications of hammers and dies to shape the metal at normal temperatures through plastic deformation, which saves materials and costs compared to other methods of forming metal. The machine can produce a wide range of parts, including core aluminum and iron rivets as well as screw heads and internal threaded bolts. The machine is also used to produce specialty pieces, such as those found in bridges, automotive manufacturing, and electronics.
The earliest stages of the process for producing headed fasteners start with a coil of wire being sheared to length. After the shearing stage, the wire is pulled through a draw box to change its diameter to match the specific fastener size needed. It may also go through a straightener before entering the header, which can help it maintain a consistent diameter throughout the length of the part.
After the coiled wire is pulled into the cold header, it will reach a point called a wire stop. At this point, a cut-off knife will move across the wire and cut it down to a specific length. This slug is then put into the heading machine and formed into a particular shape.
Once the slug is in the heading machine, it will be struck by punches that will be placed inside of the die. Each punch will place a blow into the material and create a certain shape for the finished fastener. The number of punches is dependent on the type of headed fastener required. For example, a simple screw will only need one punch, while a large bolt will require several punches to achieve the desired head size.
Each strike of the punch creates a new section of the slug that is shaped into the final fastener, but the entire progression must be completed in order to achieve the correct head size for the part. For instance, if the end result is to be a hexagonal headed screw, all of the punches must be positioned to form that shape.
There are two main types of forming processes for creating headed parts: cold forming and upsetting. Cold forming is the more common of these two, and it utilizes a series of tools to change the shape of the coiled wire into a finished intricately shaped product. The tooling method can be utilized to decrease or increase feedstock diameters, and it can even remove small amounts of material through piercing or trimming.
The other method, upsetting, utilizes a simpler forming process and involves moving the coiled wire through continuous die and tool openings to displace and shape the working metal into a new product. This type of forming can be utilized to increase feedstock sizes, as well as decrease or increase the finished fastener’s overall height and diameter. The resulting finished product will have a lower tolerance than the product made using cold forming.