Molybdenum alloy insert MHC

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Product overview Extrusion presses form non‑ferrous metals (brass, copper‑nickel, aluminum‑bronze) and stainless steel into rods, wires or tubes by pressing a heated blank through a die. Extrusion dies are exposed to very high mechanical pressures and significant frictional heat. Adding small quantities of hafnium carbide to molybdenum (MHC) increases service life of die inserts.

Advantages

• Optimum dimensional stability
• Low tendency for crack formation on edged profiles
• High high‑temperature stability
• Good thermal hardness and hot ductility
• Low thermal expansion
• High thermal conductivity

MHC properties Molybdenum‑hafnium carbide (MHC) is highly temperature‑resistant, combines high thermal conductivity with a low coefficient of thermal expansion and retains shape up to approx. 1550°C. MHC inserts are suitable as die inserts up to about 800°C; for higher operating temperatures consider full dies. Inserts are supplied as discs, with or without a drilled starter hole.

Machining recommendations
Drilling

• Tool: Carbide ISO HW‑K15
• Point angle: 120°
• Clearance angle: 10°
• Cutting speed: 80 m/min (with cutting emulsion)
• Feed: 0.01–0.05 mm

Turning

• Tool: Carbide ISO HW‑K15
• Rake angle: 25°
• Clearance angle: 7°
• Cutting speed: 100–150 m/min (with cutting emulsion)
• Feed: 0.05–0.20 mm
• Cutting depth: up to 3 mm

Grinding

• Wheel: Silicon carbide grinding wheel
• Speed: 28 m/s

Spark erosion

• Electrodes: WCu electrodes
• Wire eroding possible

Use and handling tips

• Preheat the die to at least 350°C before the first extrusion.
• During intervals between press operations, keep the die temperature above 250°C.
• After use, cool the die to ambient temperature; do not cool MHC dies with water.
• Shrinkage: coefficient ≈ 5.6 · 10-6 m/m · K; initial retraction of 0.1–0.15 mm can occur in the sliding surface area during the first extrusion and should be corrected in subsequent operations.
• Fine surface cracks may occur at inlet radii without impairing function; if pressed material adheres in cracks, rework by manual polishing with a fine linen cloth and diamond paste.

Product specification MHC insert specification (product specification available for download).

Technical characteristics

• Material: Molybdenum‑hafnium carbide (MHC)
• Retains shape up to ~1550°C
• Recommended for inserts up to ~800°C (for higher temperatures consider full dies)
• Coefficient of thermal expansion: approx. 5.6 · 10-6 m/m · K
• Thermal conductivity: high
• Mechanical exposure: designed for very high mechanical pressures and high frictional heat in extrusion
• Supply form: discs, with or without drilled starter hole
• Recommended drilling: Carbide ISO HW‑K15; point angle 120°; clearance 10°; cutting speed 80 m/min (with emulsion); feed 0.01–0.05 mm
• Recommended turning: Carbide ISO HW‑K15; rake 25°; clearance 7°; cutting speed 100–150 m/min (with emulsion); feed 0.05–0.20 mm; cutting depth up to 3 mm
• Grinding: silicon carbide wheel; speed 28 m/s
• Spark erosion: use WCu electrodes; wire eroding possible
• Initial dimensional change: possible retraction 0.1–0.15 mm in sliding surface area on first extrusion
• Handling: preheat ≥350°C before first use; maintain >250°C between operations; do not quench with water