The sintering furnace is one of the most important pieces of equipment for powder metallurgy. It is designed and manufactured according to specific process requirements. The most common type of powder metallurgy sintering furnace is the electric furnace.
In essence, the sintering of powder metallurgy products is also a heat treatment process, similar to traditional dense metal heat treatment. However, due to the special nature of powder raw materials, powder metallurgy sintering has the following characteristics:
- Stresses generated during the compaction of powder blanks must be eliminated.
- Liquid phases may appear during the sintering process.
- Compacted blanks have low strength and must not collide; material transfer during sintering should be smooth.
- Sintering temperatures are higher than general heat treatment, requiring more precise temperature control.
- Blanks contain a limited amount of volatile additives, which must be removed during the preheating stage.
- Powder blanks have a large free surface, so a protective atmosphere is generally required during sintering, and the process is highly sensitive to the type of sintering atmosphere.
- Metal powders generally have an oxide film on the surface, which affects contact between metals and hinders sintering; reduction of metal oxides is required during the process.
Using information about steel or cast products from clients, many parts can now be converted to powder metallurgy products, helping reduce procurement and production costs for customers.
A powder metallurgy sintering furnace uses metal powder (or a mixture of metal and non-metal powders) as raw material and produces metal or alloy components through forming and sintering. It is mainly used for compacted iron-based, copper-based, and other powder metallurgy products.
Precautions for Using Powder Metallurgy Sintering Furnaces
- When using hydrogen or ammonia decomposition gas, first purge the furnace with nitrogen. Only after ensuring all air is removed should you energize the furnace, to prevent sparking or explosions.
- For furnaces using molybdenum wire as heating elements, protective gas must be introduced before energizing to prevent oxidation and brittle fracture of the wire.
- Furnace doors and gas exhaust outlets should be flame-purged to prevent oxygen ingress or hydrogen escape, which could cause explosion or gas poisoning.
- For furnaces with iron-chromium-aluminum resistance wire, pause at ~1100°C for about 30 minutes before further heating to prevent surface overheating and damage.
- During heating and operation, regularly check airflow, water flow, and the proper function of electrical and temperature control instruments.
- Before shutting down the furnace, turn off power first. Only stop gas and water supply after the temperature drops below 200°C.
- Avoid frequent furnace start-stop cycles except for maintenance. Frequent cycles accelerate aging of heating elements, damage refractory materials, reduce atmosphere purity, and cause temperature fluctuations.