Impact Extrusion

PROCESS MATERIAL. IMPACT EXTRUSION COLD FORMING COLD EXTRUSION SHEET METALWORK MACHINING POWDER METAL SINTERING... 

There is a material to process compatibility risk for impact extrusion, cold forging, cold extmsion, sheet metalworking, machining and powder metal sintering processes because their respective process capability maps relate to the ideal material case. 

IMPACT EXTRUSION PROCESS CAPABILITY MAP (RADIAL TOLERANCES ONLY)... 

BODY COLD FORMING STEEL IMPACT EXTRUSION... 

In different forms (bar, casting such as sand, centrifugal, die, pernianenl mould, etc., extrusion, forging, impact extrusion, pressing, sintered, powder pressing)... 

Seams can be soldered, welded, cemented, treated with solutions, compound lined, dry, etc. Seams can be one piece drawn, stamped, or pressed. They may be drawn and wall ironed (DWI) or drawn and redrawn (DRD). Seams may be treated by impact extrusion (rigid and flexible, e.g., collapsible aluminum tubes are annealed). 

General descriptions of the cold working process are given in Refs 3, 4, 5, 6 7. Its modification known as impact extrusion has been used mostly for shaping nonferrous metals (Ref 11), but can be used also for iron or steel... 

Figure 12.5 Rheological data (IS011403-2) for a super high-impact extrusion resin that has a volumetric flow rate (IS01133, 200°C/5.0kg) of 4...

Metal containers produced by impact extrusion must be decorated as the last stage rather than the first stage. The process normally used is rotary dry offset letterpress. Drawn containers may be decorated either before fabrication (by offset lithography) or after fabrication (by dry offset letterpress). The choice depends on the depth of draw and the amount of distortion which can be tolerated. Deep drawn components are invariably decorated after forming. 

The impact extrusion process is used to produce open-ended collapsible tubes from softer metals such as tin and lead. When aluminium is used, it work-hardens during the forming process and the resultant tubes must be annealed to regain flexibility. Alternatively aluminium tubes may be left in their work-hardened state as rigid containers. Impact extrusion is a particularly useful process to produce containers with a high length to diameter ratio, e.g. up to 7 1. A slug of the metal to be formed is held in a female die and is struck by a punch which has the same form as that of the inside of the ultimate container. Upon impact the metal flows up the outside of the punch. A stripper plate then removes the extruded container on its return stroke. 

The use of Monobloc cans produced by this method is usually restricted to smaller sizes for cost reasons, but in countries where aluminium is cheaper relatively large aerosols are produced. Impact extrusion is also used to produce open-ended cylinders onto which bases are seamed, e.g. general purpose liquid containers and two-piece aerosol cans. In this case a ring slug is used rather than a disc, and the lower end is formed in the shape of the shoulder during the extrusion process, e.g. as for collapsible tubes. 

An alternative method, which provides a greater degree of protection than a simple snap-on cap is to apply a screw finish to the container so that it will accept a prethreaded plastic or metal cap. The actual neck finishes applied to metal containers, and hence the caps used, are not identical to those applied to glass. Aluminium caps are usually preferred for compatibility and appearance reasons in that they can be made to match the container itself. Like the container they can be plain or lacquered internally and externally and decorated or embossed/debossed with a logotype. Due to their relatively shallow depth, caps are produced by drawing rather than impact extrusion. 

Figure 10.2 Collapsible metal tubes produced by impact extrusion...

A broad area of application of plasticizing action of the medium is the use of surface active substances in the treatment of metals by pressure (dragging, rolling, impact extrusion). Plastification of surface layers of the treated metal due to the surface active components incorporated into greases and lubricants significantly reduces loads that one needs to apply in order to carry out these processes. It also improves the quality of the surface and decreases the level of internal stresses in the near-surface layers of a metal... 

Only up to 10% of heat can be removed with the cathode airflow since the water balance must be maintained. To remove the waste heat from the system additional heat sinks are needed. It was established that heat can be transferred very efficiently at the stack sides. Commercially available heat sinks were mounted at the sides using electrically isolating thermal interface materials. To add as little extra weight and volume as possible to the system, high performance pin fin coolers were used. The heat sinks are made of pure aluminum with a thermal conductivity of above 220 W m" by means of impact extrusion. 

Figure 2.3 Tensile stress vs. strain for SABIC Innovative Plastics Cycolac EX39— highest impact extrusion ABS resin for sheet and blow molding applications.

ShMt (Coin d) Molding and oxtnision compounds High-impact extrusion Inieclion Allyl diglyool carbonate oast sheet... 

Coated Acrylic/PC Alloy PMMA MMA- Styrene Copolymer Impact- Modified Heat- resistant Acrylic Multi- polymer Extrusion High-Impact Extrusion iDjection Ally Diglycol Carbonate Cast Sheet... 

ABS 243 - extrusion blending resin ABS 495 - medium impact extrusion grade... 

Impact extrusion similar to cold extrusion, but cold billet is plastically deformed by a single blow of the tool. Can be forward or backward extrusion (Hooker process). 

Maximum section ranging 0.25-22 mm, depending on material for impact extrusion. No limit for cold forming. 

Process capability charts showing the achievable dimensional tolerances for impact extrusion and cold forming are provided (see 3.4CC). 

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