Molybdenum Threaded Rods & Screws for Vacuum Furnace Hot Zones

Molybdenum Threaded Rods and Molybdenum Screws are precision-machined components manufactured from high-purity molybdenum rods. They are specifically designed for use in vacuum furnace heating chambers (hot zones), where conventional steel fasteners fail due to extreme temperatures, vacuum conditions, and repeated thermal cycling.

By machining molybdenum rods into fully threaded rods, studs, bolts, and screws, these components provide reliable mechanical fastening and structural support for molybdenum heat shields, heating elements, support frames, and insulation assemblies inside high-temperature vacuum furnaces.

Why Molybdenum for Threaded Components in Vacuum Furnaces

1. High-Temperature Mechanical Stability

Molybdenum maintains high strength and stiffness at temperatures above 1200–1800°C, far exceeding the limits of stainless steel or nickel-based alloys.

In the heating chamber:

• Threaded rods do not soften, creep, or elongate under load

• Fastening force remains stable during long high-temperature cycles

Result: secure fixation of heat shields and hot-zone structures over extended furnace operation.

2. Low Vapor Pressure for Clean Vacuum Environments

Molybdenum has an extremely low vapor pressure at vacuum furnace operating temperatures.

In the heating chamber:

• No metal evaporation or outgassing

• No contamination of heating elements or processed materials

Result: stable vacuum levels and clean furnace atmospheres, critical for sintering, brazing, and diffusion processes.

3. Excellent Resistance to Thermal Cycling

Vacuum furnaces operate with frequent heating and cooling cycles, which can loosen or fracture conventional fasteners.

Molybdenum threaded rods:

• Have low and predictable thermal expansion

• Maintain thread integrity after repeated thermal cycles

Result: reduced risk of loosening, distortion, or thread seizure inside the hot zone.

4. Material Compatibility Inside the Hot Zone

Using molybdenum threaded components together with molybdenum plates and shields avoids differential thermal expansion.

In practice:

• Mo screws + Mo heat shields + Mo frames expand uniformly

• No stress concentration at fastening points

Result: longer service life of the entire hot-zone assembly.

Typical Applications in Vacuum Furnace Heating Chambers

Molybdenum threaded rods and screws are commonly used for:

• Fixing molybdenum heat shields and radiation screens

• Supporting heating elements and hot-zone frames

• As vertical or horizontal tie rods in furnace hot zones

• Assembly of insulation structures and reflector systems

• Structural fastening in sintering, brazing, and diffusion furnaces

Product Forms

• Molybdenum fully threaded rods (studs)

• Molybdenum screws and bolts

• Custom thread designs according to drawings

Thread types: Metric / Inch / Custom profiles

Technical Specifications

Material Grades:

• Pure Molybdenum (Mo ≥ 99.95%)

• High-Purity Molybdenum (Mo ≥ 99.97%)

• La-doped Molybdenum (for improved recrystallization resistance)

Diameter Range: M3 – M30 (custom sizes available)
Length: up to 2000 mm
Thread Condition: Rolled or machined threads
Surface Finish: As-machined / Ground

Manufacturing Process

1. Selection of high-purity molybdenum rods

2. Hot forging or rolling

3. Stress-relief heat treatment

4. Precision thread machining or rolling

5. Dimensional inspection and thread verification

All threaded components are inspected for straightness, thread accuracy, and surface integrity before delivery.

Advantages Compared to Conventional Fasteners

Quality Standards

• ASTM B387 / ASTM B386

• ISO 9001 Quality Management System

• Material certificates and inspection reports available

Packaging & Delivery

• Cleaned and protected packaging for vacuum use

• Wooden cases suitable for international shipping

• Flexible lead times for standard and custom designs