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|Material:||Carbon Steel||Process:||Cold Extrusion Process|
|Machining:||CNC Machining||Surface:||Anti-rust Oil|
|Packing:||Plywood Crate||Heat Treatment:||None|
cold forging parts,
cold forged components
Cold Extrusion Process Products Manufacturer Precision Machining Part For Auto Cars
Product Description and Process
Cold Extrusion Process Products Manufacturer OEM Cold Extrusion Part For Auto Cars
Production process: cold extrusion process
Machining process: CNC machine, machining center, lathe, mill machine, drill machine, etc.
Surface treatment process: anodic oxidation, Dacromet coating, paint coating, powder coating, etc.
Product Material and Uses
Normally produce with aluminum L1, L2, L3, L4, L5, Aluminum alloy LF21, LY11, LY12, LD10, Brass H62, H68, carbon steel Q195, Q215, Q235, Q255, 10, 15, 20, 25, 30, 35, 40, 45, low alloy steel 15Cr, 20Cr, 20MnB, 16Mn, 30CrMnTiA, 12CrNiTi, 35CrMnSi, stainless steel 1Cr13, 2Cr13, 1Cr18Ni9Ti, etc.
The extrusion products are widely used for auto-car parts, truck parts, train parts, vehicle components, aviation industry components, gear parts, spline parts, universal joint crossing shaft, other machinery components, etc.
Cold Extrusion Process
The process of cold extrusion is carried out at room temperature or at marginally elevated temperature, with the assistance of Extruder and Extrusion Machines. These equipment / machines are specially developed on the basis of innovative Extrusion Technology. Cold extrusion can also be defined as the process of shaping of a cold metal by striking a slug. This striking is done with a punch (in closed cavity), which forces the metal in upward direction around the punch. This process is also called Cold Forging, Cold Pressing, Extrusion Pressing, and Impact Extrusion.
Cold extrusion is done at room temperature or near room temperature. The advantages of this over hot extrusion are the lack of oxidation, higher strength due to cold working, closer tolerances, better surface finish, and fast extrusion speeds if the material is subject to hot shortness.
Materials that are commonly cold extruded include: lead, tin, aluminum, copper, zirconium, titanium, molybdenum, beryllium, vanadium, niobium, and steel.
Examples of products produced by this process are: collapsible tubes, fire extinguisher cases, shock absorber cylinders and gear blanks.
Forward Extrusion: In this process, the material flows in the direction of the punch displacement. Also, the rod / tube diameter is reduced by forcing it in a die, through an orifice. A variation of this process is known as Hooker Extrusion. In this process, a billet (tubular) is forced by way of a forward extrusion die. This force is applied with a punch and a mandrel that act as a pusher and reduces the outer diameter along with elongating the tubular portion, respectively.
Backward Extrusion: In this process, the material flows in the other direction of the punch displacement. The billet, which is enclosed in die, is forced to flow in the backward direction from the annular region that resides amidst the die and punch.
Lateral Extrusion: In this process, the material flows in the perpendicular direction of the punch displacement. The material, which is enclosed by the punch and die, is forced to flow through orifices that are radially placed.
Advantages & Disadvantages of Cold Extrusion
Cold extrusion is highly advantageous as it is used to withstand all the stresses that are created by the extrusion process. There are various advantages of cold extrusion over the hot extrusion, some of the important ones are listed below:
Apart from the above-mentioned advantages, there are some disadvantages as well that are associated with cold extrusion. These are lubrication cost, higher loads, limited shape complexity, and limited deformation.
Applications of Cold Extrusion
Steel for Cold Extrusion
Carbon steels up to 0.3% C can be easily cold extruded. Higher-carbon steels up to 0.5% C can also be extruded, but the extrusion ratios are limited and spheroidize annealing may be required. Backward extrusion generally requires spheroidize annealing for both low- and highcarbon steels. Alloy steels are harder than their carbon steel counterparts and hence require higher pressures for extrusion. They also work harden more rapidly, thus limiting their extrudability and intermediate annealing is often required to restore extrudability. Alloying elements differ in their effects on strength and hardenability. If possible, it is desirable to choose alloying elements so as to minimize strengthening while achieving the required hardenability: for example, boron increases hardenability with minimal strengthening. Steels in the AISI 4000, 4100, 5000, 5100, 8600, and 8700 series can be cold extruded without difficulty up to 0.35% C. The AISI 4300, 4600, and 4800 steels are more difficult to extrude and less desirable for cold extrusion. Free-cutting resulfurized steels also have lower forgeability than their carbon steel counterparts, as they are more susceptible to rupture during cold forging due to their higher occurrence of sulfide inclusions. Sulfur is typically limited to 0.02%. Low-carbon resulfurized steels can be extruded if care is taken to keep metal in compression throughout the process. Internal purity of steel is critical in cold extrusion especially at high extrusion ratios. Central segregations increase the tendency for internal fracture along the axis of the extrusion (chevrons). Killed steels are specified for cold forging to ensure homogeneous structure. Aluminum-killed steel is preferred over silicon-killed steel for difficult extrusions due to the reduction in strain hardening and reduction in strain aging achieved. Silicon is kept in the low range of 0.2%. Silicon-killed steels, however, have better surface quality, which might be critical in any postextrusion operations. Seams, laps, and scratches on steel surface can be tolerated up to 1% of the bar diameter if cold extrusions are machined at the surface. However, if net-shaped features are being cold extruded, then the seams and laps have to be removed prior to forging by peeling or turning the steel bars. Although cold extrusion is a compressive process, it is typically preceded or followed by processes of cold heading and heat treatments, which require defect-free surfaces. The steel manufacturer often certifies steels meeting the cold extrusion requirements as “cold extrusion quality” or “cold working quality.” To ensure surface quality of steel hot-scarfing during semifinshed state (blooms) and eddy-current testing in the finished state (bars) is sometimes required. Steel bars are available as normal hot rolled, precision hot rolled and cold finished. Normal hot-rolled bar is made to standard AISI tolerances and is the least costly form of steel for making slugs. It is also likely to have deeper surface seams and greater depth of decarburized layers. In addition, the variation in the outside diameter of hot-rolled bars will cause considerable variation in weight or volume of the slug, despite close control in cutting to length. Whether or not the surface seams and decarburization can be tolerated depends largely on the severity of extrusion and the quality requirements of the extruded part. In many applications, acceptable extrusions can be produced with slugs cut from hot-rolled bars. Precision hot-rolled bars have 50% better tolerances on size than normal hot-rolled bars and smaller decarburization layer. These bars are made by performing a special precision-sizing operation during hot rolling. Cold-finished bars are made by taking the hotrolled bar through a costly series of cold-drawing steps to give them tighter dimensional tolerances (25% of normal hot-rolled bar tolerances). Therefore, the size variation in cold-finished bars is considerably less than that in hot-finished bars. However, some seams and decarburization will also be present in cold-finished bar stock unless removed by grinding, turning, or other means. Some users gain the advantage of cold-drawn bars by passing hot-rolled bars or rods through a cold-drawing attachment directly ahead of the slug-cutting operation. Turning, peeling, or grinding of cold-finished bars will eliminate the difficulties caused by decarburization and seams. For some extrusions, especially those subjected to surface treatments that cannot tolerate a decarburized layer, previously machined bars or machined slugs must be used. Another practice is to turn and burnish normal hot-rolled bars to remove surface defects. These practices are mandatory for precision net spline/gear forming or products requiring induction hardening, which cannot withstand a decarburized surface.
Contact Person: Mr. James Wang
Tel: +86 13213152686