Molybdenum charge carriers are generally used in conventional metal hot zones for vacuum furnaces. In most cases, these consist of a number of heavy rails that are supported on the furnace floor by massive caps and bolts. For the ENERZONE range, Plansee uses particularly lightweight bearing rails made from molybdenum alloys which are bent into a U-shape.
The new charge carriers are less susceptible to distortion and are much easier to replace than their heavyweight counterparts.
Plansee has also replaced pure molybdenum with the molybdenum alloys ML and TZM, which have high recrystallization temperature and creep resistance. They are also rigid and nondeformable. Stainless steel elements have also been replaced with molybdenum, because a single layer of molybdenum has the same shielding effect as five layers of steel, according to the company.
In conventional shielding solutions, the spacers between the panels are arranged longitudinally.To prevent the deforming of the material, this design requires the use of particularly thick shielding panels.They ensure that the hot zone is nondeformable and guarantee that the cylindrical geometry is maintained. Plansee's engineers have now developed circumferential spacers. Combined with an external stainless steel support frame, these spacers guarantee adequate stability even when thinner panels are used.
The ENERZONE is equipped with special corner shielding elements to ensure that no heat escapes at the critical gaps between the side and ceiling or side and floor. Additional shielding discs also make sure that no energy is lost at the electrical ducts.
PLANSEE can also supply its ENERZONE hot zones in a new hybrid design, whereby conventional shielding panels are supplemented by an insulating aluminium oxide paper. The operation of the unit is not affected by the aluminium paper, and heating and cooling speeds, cycle times and purity constraints are all unimpaired. However, energy consumption is cut by 10-15%.
Compared to a standard variant, an energy-efficient lightweight construction reportedly offers:
- 15-20% weight reduction
- 20 % reduction in heating times in empty furnace
- 15 kW less heat loss
- 25-30 kWh reduction in energy consumption when heating and cooling the furnace
- 15 % reduction in cooling times.
