Warm Extrusion Technology And External Processing
Warm extrusion forming technology is a new technology of metal forming with fewer chips. It is different from cold and hot extrusion in that blank is heated before extrusion, but its heating temperature range above room temperature and below the complete recrystallization temperature. It is basically in the temperature range of incomplete cold deformation and incomplete thermal deformation of the metal. In the metal-plastic forming process and production, the warm extrusion forming technology will solve the problem of plastic forming of various metals and meet the filling problem of complex forging shapes.
CXIN Forging has 630 tons of warm extrusion production line. The line can process under 5 kg of aluminum alloy and carbon steel products. The production line can also be combined with cold forging to do precision forging of pistons, cylinders, wrenches, bearing rings, watch shells, universal joint heads, rear axles, micro motor housings, turbine engine ring sleeve parts, and automobile tire nuts, etc.
Advantages Of Warm Extrusion Process
Compared with the cold and hot extrusion process, the warm extrusion process has the following advantages:
(1) During warm extrusion plastic forming, the deformation resistance of the blank is smaller than that of cold extrusion. The metal-plastic forming is easier than cold extrusion, and thus smaller press tonnage is required.
(2) The dimensional accuracy and surface roughness of warm extruded parts are better than the quality of hot extruded forgings. The mechanical properties are equivalent to cold extruded parts.
(3) There will be no need to perform the softening annealing process before or between the warm extrusion processes. This not only reduces the number of processes but also creates favorable conditions for continuous automated production.
(4) Warm extrusion plastic forming can adopt an extrusion process with increased deformation, making it possible to form non-axisymmetric special-shaped parts. This greatly expands the scope of application of this forming technology.
Disadvantages Of Warm Extrusion Process
(1) For specific product materials, the deformation temperature of warm extrusion plastic forming is difficult to control. The temperature can be too high to the point of exceeding the recrystallization temperature. This will affect the mechanical properties of the product. The temperature can also be too low, and this will affect the forming. Low temperature will also increase the required extrusion force.
For this reason, when designing the warm extrusion process, it is necessary to carry out the temperature test in advance. This is to ensure that the reasonable warm extrusion temperature can be accurately selected.
(2) Due to the large difference in the warm extrusion temperature of various materials, the applicable warm extrusion lubricant has not been completely solved so far. This has affected the vigorous promotion of the warm extrusion plastic forming technology.
(3) In the production and processing of warm extrusion, no mold material suitable for warm extrusion has been developed. This is due to the range of materials and their wider range of warm extrusion forming temperatures. This is another limitation affecting the adoption plasticity of warm extrusion and further development of the technology.
Temperature Selection of Warm Extrusion Process
(1) The warm extrusion temperature of ferrous metals
①10, 15, 20, 35, 40, 45, 50 steel and carbon steel and low-alloy structural steel, such as 40Cr, 45Cr, 30CrMnSi, 12CrNi3, etc., 650℃～800℃ during warm extrusion on a mechanical press and 500 ℃ ~ 800 ℃ when it is warm extrusion on a hydraulic press. When 15# steel is positively extruded on a high-speed hammer with a striking speed of 20m/s, the warm extrusion temperature is about 400℃.
②The warm extrusion temperature of 35CrA, 42CrMoA and other quenched and tempered alloy structural steels is 600℃～800℃.
(2) Warm extrusion temperature of non-ferrous metals and their alloys
① The warm extrusion temperature of aluminum and aluminum alloy is ≤250℃.
② The warm extrusion temperature of copper and copper alloy is ≤350℃.
③ The warm extrusion temperature of lead brass HPb59-1 is 300℃～400℃ or about 680℃.
④ The warm extrusion temperature of magnesium and magnesium alloy is 175℃～390℃.
Application Range Of Warm Extrusion Process
Warm extrusion has the advantages of cold and hot extrusion, which overcomes the shortcomings of both cold and hot extrusion processes. Therefore, it is widely used to produce fasteners, gears, valve bodies, pistons, cylinders, wrenches, bearing rings, and watch cases. It is also being used for the production of universal joint heads, rear axles, micro-motor housings, turbine engine ring parts, automobile tire nuts and many other forged parts.
These parts were originally produced by hot extrusion, cold extrusion and cold forging or machining. The actual production proves that good technical and economic benefits have been achieved after adopting the warm extrusion process. In some cases, warm extrusion is combined with any of these processes to produce the listed parts.
Cold/Warm Forging Composite Forming
For high strength steel and ultra-high strength steel parts with high strength and low plasticity, as well as large parts with complex shape and high precision requirements, the combined forming process of warm forging billet and cold forging precision forming is a more suitable processing method. Compared with conventional cold forging or warm forging process, it has the following characteristics:
(1) Less energy consumption.
(2) High material utilization rate.
(3) High production efficiency.
The forming process of warm forging billet is heated in a lower temperature range, and the mechanical properties of the billet after forming are better than the annealing state. After spherospheric annealing and surface lubrication, the billet can be accurately formed by cold forging, and the precision forgings can be obtained. Due to less process, short production process, so high production efficiency.