Powder Metallurgy Gear

What is Powder Metallurgy?

Powder metallurgy is a process technology that involves producing metals or using metal powders (or a mixture of metal and non-metal powders) as raw materials, which are then shaped and sintered to create metal materials, composite materials, and various types of products. In a broad sense, the powder metallurgy industry includes products such as iron-based cutting tools, hard alloys, magnetic materials, and powder metallurgy products. In a narrower sense, powder metallurgy refers specifically to powder metallurgy products, including powder metallurgy parts (which make up the vast majority), oil-impregnated bearings, and metal injection molded products.

Process Flow

1. Powder Production Powder production is the process of turning raw materials into powder. Common methods include oxide reduction and mechanical processes.
2. Mixing Mixing involves combining various required powders in specific proportions and homogenizing them to produce the green powder. This process can be dry, semi-dry, or wet, depending on the specific requirements.
3. Forming Forming is the process of pressing the homogenized mixture into a mold to create a compact with a specific shape, size, and density. Forming methods are generally divided into pressure forming and pressureless forming, with die pressing being the most commonly used method in pressure forming.
4. Sintering Sintering is a critical step in the powder metallurgy process. The compact is sintered to achieve the final desired physical and mechanical properties. Sintering can be classified into single-component and multi-component sintering. Besides conventional sintering, there are also special sintering processes such as loose sintering, infiltration, and hot pressing.
5. Post-Processing Post-processing after sintering can be done in various ways depending on the product requirements. These methods include finishing, oil impregnation, machining, heat treatment, and electroplating. In recent years, new processes such as rolling and forging have also been applied to the post-sintering processing of powder metallurgy materials, achieving favorable results.

Process Characteristics

1. The density of the products is controllable, allowing for the creation of porous materials and high-density materials.
2. The grain size is fine, with uniform microstructure and no component segregation.
3. Near-net shaping is achieved, with material utilization rates exceeding 95%.
4. Minimal or no machining is required, with machining operations reduced to only 40-50%.
5. The composition of the materials is controllable, which is beneficial for the preparation of composite materials.
6. It enables the preparation of refractory metals, ceramic materials, and nuclear materials.

Advantages and Disadvantages

Powder metallurgy gears are commonly used in various automobile engines. While they are very economical and practical in large-scale production, there are still areas that need improvement. Let’s take a look at the advantages and disadvantages of powder metallurgy gears.

Advantages:

1. Generally, powder metallurgy gears require fewer manufacturing processes.
2. When manufacturing gears using the powder metallurgy method, material utilization can reach over 95%.
3. Powder metallurgy gears have excellent repeatability. Since these gears are formed by pressing in molds, under normal usage conditions, a single mold can produce tens of thousands to hundreds of thousands of gear blanks.
4. The powder metallurgy process allows for the integration of several parts into a single piece.
5. The material density of powder metallurgy gears is controllable.
6. In powder metallurgy production, to facilitate the removal of the gear blanks from the molds after forming, the working surfaces of the molds have a very high surface finish.

Disadvantages

1. Powder metallurgy requires mass production; generally, a batch of over 5,000 pieces is more suitable for this process.
2. The size of the gears is limited by the pressing capacity of the machine. Presses typically exert between a few tons to several hundred tons of pressure, and gears with a diameter of up to 110mm can be produced using powder metallurgy.
3. Powder metallurgy gears are limited by their structure. Due to the constraints of pressing and mold design, it is generally unsuitable for producing worm gears, herringbone gears, and helical gears with a helix angle greater than 35°. It is generally recommended to design helical gears with an angle within 15 degrees.
4. The thickness of powder metallurgy gears is limited. The mold cavity depth and the press stroke must be 2 to 2.5 times the gear thickness. To ensure uniform density along the gear height, thickness is a critical factor in powder metallurgy gears.

Thank you for reading. Looking forward to serving you with our exceptional gear solutions. #BeyondGears #GearManufacturing #MadeInChina

Read More: