Powder Metallurgy Gear
The main advantage of powder metallurgy is that it is made of powder materials sintered, so the oil bath since the lubricity is very good, tooth shape and all sizes can be formed, generally not another processing;The disadvantage is that relative to the traditional processing gear, the strength is insufficient, can not transfer large torque, tooth precision is generally in 6 ~ 9 level, dimensional accuracy is generally the highest IT7 ~ 6 level.
Powder metallurgy is a new manufacturing technology, with its advantages, especially suitable for mass production. But it's not for every situation.Powder metallurgical processing requires the manufacture of the corresponding die, using powdery metal through sintering and the corresponding process to make the parts.The strength varies according to the material used.
1. the vast majority of refractory metals and their compounds, false alloys, porous materials can only be manufactured by powder metallurgy method.
2. because the powder metallurgy method can be pressed into the final size of the compaction, without or little need for subsequent mechanical processing, it can greatly save metal, reduce product costs.The loss of metal in the manufacture of products by the powder metallurgy method is only 1-5%, while the loss of metal in the production of products by the ordinary casting method may be as high as 80%.
3. because the powder metallurgy process in the material production process does not melt the material, it is not afraid of mixing with the impurities brought by the crucible and deoxidizer, and sintering is generally carried out in vacuum and reducing atmosphere, not afraid of oxidation, and will not give any pollution to the material, it is possible to make high purity materials.
4. powder metallurgy method can ensure the correctness and uniformity of the material composition ratio.
5. powder metallurgy is suitable for the production of the same shape and a large number of products, especially gear and other high processing costs of products, with powder metallurgy manufacturing can greatly reduce the production cos.
The density of common atomized powder (including carbon steel and copper-carbon alloy steel) is above 6.9, and the quenching hardness can be controlled around HRC30.
In general, the density of the pre-alloyed powder (AB powder) exceeds 6.95, and the quenching hardness can be controlled around HRC35.
High prealloyed powders with density greater than 6.95 and quenching hardness controlled at HRC40.
Powder metallurgy products made of the above materials have stable density and material, and the hardness after heat treatment meets the corresponding requirements, so their tensile strength and compressive strength will reach a better peak.
However, because the density of PM products is not as high as that of No. 45 steel, the highest density of PM pressing parts is usually 7.2 g/cm, while the density of No. 45 steel is 7.9 g/cm.Forced carburizing of powder metallurgy or high frequency heat treatment exceeding HRC45 will make the powder metallurgy products brittle due to high quenching, resulting in the strength of the powder metallurgy products.
1. High material utilization rate, up to more than 95%
2. No or only a little cutting is required
3. Good dimensional consistency of parts, good stability and high precision.
4. Strength comparison: professional powder metallurgy manufacturers have optimized the powder metallurgy mold design, and the tensile strength and compressive strength of the gear produced are close to that of the hobbing gear.For example, the driven gear of the automobile gearbox with high transmission intensity is also powder metallurgy gear.Visible, powder metallurgy gear is practical and extensive.
5. Powder pressing molding using mold molding, can produce other cutting hobbing technology can not produce complex shapes.
6. Because it is suitable for mass production, the production efficiency is high and the cost is lower than cutting.
7. Suitable for mass production, so the price is absolutely competitive.