Extrusion presses are used to form non-ferrous metals such as brass, copper-nickel and aluminum-bronze, as well as stainless steel, into rods, wires or tubes. The metal blank is first heated to its forming temperature and is then pressed through the die using a ram. This gives the metal its external shape.
Extrusion dies are exposed to high mechanical pressures. A high level of frictional heat is also generated between the die and the workpiece. Clearly a job for us. By adding small quantities of hafnium carbide, we get our molybdenum ready for a long service life in your extrusion press.
Molybdenum-hafnium carbide (MHC) is highly temperature-resistant, has a high level of thermal conductivity, a low coefficient of thermal expansion and a high recrystallization temperature. MHC retains its shape even when used at temperatures of up to 1 550 °C. At temperatures up to 800 °C, MHC is suitable for use in die inserts. At higher temperatures, we recommend using MHC for full dies. The benefits to you for a long service life:
- Optimum nondeformability and dimensional stability
- Low tendency to crack in the case of edged profiles
- High thermal stability
- High thermal conductivity
- Low thermal expansion
- Good hot ductility
- Very high recrystallization temperature
We supply our MHC components in disc form with or without drilled start hole.
The best way to machine MHC.
Whatever you want to do with our material - just ask us.
- Hard metal ISO HW-K15
- Point angle: 120 degrees
- Clearance angle: 10 degrees
- Cutting speed: 80 m/min (with cutting emulsion)
- Feed: 0.01 - 0.05 mm
- Hard metal ISO HW-K15
- Cutting angle: 25 degree
- Clearance angle: 7 degrees
- Cutting speed: 100 - 150 m/min (with cutting emulsion)
- Feed: 0.05 - 0.20 mm
- Cutting depth: up to 3 mm
- Silicon carbide cutting wheel
- peed: 28 m/s
Tips on using your new die.
- WCu electrodes
- Wire eroding possible
Temperature: Before the first extrusion operation, heat the die to at least 350 °C. The temperature of the die should not fall below 250 °C during the intervals between press operations. After use, cool the die to ambient temperature and note that MHC dies should not be cooled with water.
Shrinkage of die inserts: Despite the low coefficient of thermal expansion, the shrinkage of MHC inserts is very manageable at 5.6 • 10-6 m/mK. The application of caulking at various points prevents the insert from being pulled out of its holder. During the first extrusion operation, the die may retract by 0.1 to 0.15 mm in the area of the sliding surface which imparts the shape to the workpiece. But there's no cause for alarm: This effect disappears again after the appropriate correction has been made during the subsequent press operations. After correction, the die remains nondeformable and dimensionally stable.
Hairline cracks: Sometimes hairline cracks may occur at the inlet radii. These do not impair the functioning of the part. Only if the pressed material adheres to these hairline cracks is it necessary to retouch the die. To do this, we recommend manual polishing using a fine linen cloth and diamond paste.