Application of Box type Resistance Muffle Furnace in Powder Metallurgy Industry

In the powder metallurgy industry, the box type resistance muffle furnace is a key equipment for core processes such as metal powder drying, oxide reduction, metal ceramic combination, formed part sintering, and heat treatment. Its application covers the entire process from raw material pretreatment to finished product performance optimization, as follows:

1. Core application scenarios
Drying and pretreatment of metal powder
Remove moisture and volatile impurities from the powder by low-temperature heating (such as 100-300 ℃) to prevent pores or cracks caused by moisture evaporation in subsequent processes. For example, iron-based powder metallurgy products need to be dried in a muffle furnace before pressing to ensure the flowability of the powder and the uniformity of the compact density.
Reduction of high melting point metal oxides
Reduce metal oxides (such as iron oxide and nickel oxide) to metal powders under hydrogen or inert atmosphere. For example, in the production of tungsten powder, tungsten trioxide (WO ∝) is reduced to metallic tungsten powder in a hydrogen reduction furnace at 700-900 ℃, with a purity of over 99.9%, meeting the requirements for the preparation of hard alloys.
Synthesis of Metal Ceramic Compounds
Synthesize metal ceramic materials (such as TiC, TiN) through high-temperature solid-state reaction. For example, the synthesis of titanium carbide (TiC) requires mixing titanium powder with carbon powder and holding it in a muffle furnace at 1600-1800 ℃ for several hours to form a ceramic phase with high hardness and wear resistance, which is used for tool coating or wear-resistant parts.
Sintering of powder metallurgy formed parts
Densify the pressed green body at high temperature to form the final part. For example:
Iron based parts: sintered at 1120-1150 ℃, with a density of 7.2-7.4 g/cm ³ and a tensile strength of ≥ 400 MPa;
Stainless steel parts: After sintering at 1250-1300 ℃, their corrosion resistance is significantly improved, making them suitable for medical devices or food machinery;
Copper based parts: sintered at 850-900 ℃, with excellent conductivity, used for electronic connectors or electric brushes.
Heat treatment of sintered parts
Adjust the performance of parts through processes such as quenching and tempering. For example, high-speed steel (such as M2) needs to be quenched at 1250 ℃ and tempered three times at 560 ℃ after sintering, with a hardness of HRC 63-65 and a red hardness (hardness at 600 ℃) ≥ HRC 58, meeting the requirements of cutting tools.

2. Technical advantages
Accurate temperature control
Equipped with PID intelligent temperature control system, temperature fluctuation ≤ ± 5 ℃, supports multi-stage program temperature control (such as 30 stages), and can accurately simulate complex sintering curves. For example, the sintering of titanium alloys requires rapid cooling after insulation in the beta phase region (above 882 ℃), and the muffle furnace can achieve precise control of the heating rate of 5-10 ℃/min.
Flexible atmosphere protection
Some models are equipped with air inlet and exhaust ports, which can be filled with hydrogen, nitrogen or vacuum environment to prevent metal oxidation. For example, tantalum powder sintering needs to be carried out under vacuum or argon protection, and a muffle furnace can ensure an oxygen content of ≤ 10 ppm to avoid material embrittlement.
Uniform heating and energy saving
Adopting ceramic fiber or alumina furnace, with low heat capacity and good thermal conductivity, combined with modular heating elements (such as silicon carbon rods and silicon molybdenum rods), to ensure temperature uniformity of ≤± 10 ℃ inside the furnace. For example, when sintering large parts (such as gears with a diameter of 500mm), the performance difference between each part is ≤ 5%, while saving 30% -40% electricity.
Strong structural adaptability
The furnace design is flexible and can be customized with square or circular, side or top opening structures to meet the sintering needs of parts of different sizes. For example, powder metallurgy friction plates require sintering in a bell jar furnace with external force due to their large diameter and thin thickness, while muffle furnaces can achieve similar functions through customized furnaces.

3. Industry Cases
Case 1: Production of Hard Alloy Cutting Tools
Equipment: Box furnace (1200 ℃).
Process: After pressing WC Co hard alloy powder, it is vacuum sintered at 1400-1450 ℃ to form a dense structure.
Effect: Hardness reaches HRA 92-93, bending strength ≥ 3000 MPa, meeting the performance requirements of CNC cutting tools.
Case 2: Sintering of Metal Injection Molding (MIM) Parts
Equipment: High temperature furnace (1650 ℃).
Process: After injection molding stainless steel feed, degreasing treatment (450 ℃) and sintering at 1300 ℃.
Effect: The part density reaches 7.8 g/cm ³, the porosity is ≤ 1%, and it is used for mobile phone card holders or medical devices.
Case 3: Post processing of 3D printed metal parts
Equipment: Tube furnace (1200 ℃).
Process: After laser melting and forming 316L stainless steel powder, degreasing at 900 ℃ and sintering at 1250 ℃.
Effect: The sintered body has a density of 7.8 g/cm ³ and a tensile strength of ≥ 600 MPa, suitable for lightweight structural components in aerospace.