The Single Cell Die Oven
The single cell die oven using radiant energy, is now accepted globally as the premium contemporary technology for safely, accurately, and rapidly heating extrusion dies. A good single cell oven must bring the die to a uniform target temperature in a relatively brief period of time, without exceeding the annealing temperature of the Hi13 die steel, or negatively affecting the nitride layer, while using as little energy as possible, and having a small footprint,
Challenges
If a die is left at temperature for a lengthy period, the bearing will oxidize. This will result in poor surface finish on the section.
If the correct heating cycle which included a “heat-head” for the die is not used, the oven will act as a soaking oven, extending time to temperature and/or delivering cold dies to the press.
If more than one die is put in a single cell oven, all temperature control is lost. The single cell oven then becomes simply a small chest oven.
If a die sits for a prolonged period before being run, all accuracy is lost. Unless controlled, a heated die in shop floor ambient temperature will lose 50C every 10 minutes. In addition breakthrough pressure will be considerably increased.
CASTOOL Tooling Systems
Castool pioneered the use of single cell die ovens after they first appeared in Japan in the early 80’s, and just now has well over 1000 ovens in use globally. Current models reflect the experience gained over the years as the technology of die heating has gradually evolved.
One key to the most effective use of single cell ovens is the optimizing of the heating program used for each die. It is based on the size and mass of the die, thermo-conductivity of the die steel, energy added by the resistance heaters, and heat lost to the environment. From the mass of knowledge now available to Castool from its large user base, the logarithm used on its controller for each die is now in fact a calculation rather than an estimate. This method is the most reliable means today to accurately and safely heat a die.
Castool is well-known for the ongoing service and technical advice it provides its customers. This is usually expedited by its large network of local representatives.
Typically, a new die oven customer will provide Castool with a die that will then have several thermocouples installed. Its heating cycle will then be fully documented prior to delivery, or at the customer’s plant after delivery. Existing single cell die ovens can also be documented for temperature and energy use
Posted by: Paul Robbins
