Extrusion die making dates back to the late 18th Century when lead was softened by heat and hand pressed through a pipe onto a die with a plunger. The process quickly evolved with mechanical aides that made use of water pressure allowing for greater amounts of force. While the process has continued to advance, the basic steps have remained constant.
The strength of the finished product is often a factor of how much heat was needed to properly soften the alloy. Copper is relatively easy to work with since it can be forced through a die at temperatures of about a thousand degrees Fahrenheit. Nickel alloys will require temperatures twice as great, but the end product will be much stronger and more durable.
Extrusion die making remains an economical form of manufacturing components so long as the force required to push material against or through the die is not excessive. While the processes used have long surpassed pressure by hand, the mechanical means used require energy expenditures, and these always carry a cost. At a certain point, the manufacturing cost will be too great to justify the process, and alternative methods of production will be substituted. When sheer force is used without heat, the process is known as cold extrusion. The process works well with a number of metals including, copper, zinc, and steel. This method is attractive because it provides close tolerances and leaves surfaces extremely smooth. Shocks absorbers and gears are often made this way.
Presses are often used for extrusion die making. They are most often hydraulically driven with an emphasis on keeping the pressure constant throughout. This is done to avoid the sort of defects that can commonly occur in fabrication including cracking, splintering and surface lines.
Plastics and ceramics are also suitable candidates for extrusion die making. Both materials are used to make pipes by this method. Much of our food now even uses this process including pasta, breakfast cereals, cookies and candies.