Extrusion is a process wherein long metal parts are created in a fixed cross-sectional profile to produce different shapes such as rectangular to solid round, to T shapes and L shapes that serve as special connectors. Materials used include metals such as aluminium, titanium, copper, steel, lead, tin and other materials such as ceramic, polymers and concrete. Extrusion supplies or parts are used in the automotive and construction industry as window frames, aircraft parts and even railings.
Extrusion process comes in 3 different types – warm, hot and cold.
Hot Extrusion is done at high temperatures of approximately 50 to 75% above the melting point of the metal one is working with. The high temperature is important as it prevents the material from hardening and makes it easier to cast the materials into the die. Hot extrusion for metals varies example: Steel – 2200-2400F, Aluminium – 650 – 900F and titanium – 1300 – 2100F. Lubrication is needed as the hot temperature and pressure can damage the die lifespan. Many companies would use lubricants such as oil, graphite and glass powder to lubricate the die. Hot extrusion is expensive because of the equipment and maintenance needed, however cost is compensated if work done is continuous.
Cold extrusion on the other hand is another type, which makes use of room temperature instead of high temperature in casting the materials. Cold extrusion is done for materials, which can withstand stress such as copper, aluminium, steel and titanium. The advantage of using this process is that there is no oxidation involved and the finished product has good mechanical properties and excellent surface finish. Products that make use of this process include aluminium cans, collapsible tubes and cylinders.
Warm extrusion is done normally above room temperature and below the recrystallization temperature. Temperature range is from 800 to 1800F.
Extrusion has many advantages compared to other manufacturing process as (1) it can create complex cross sections that are often needed especially when used as connectors; (2) it works with delicate materials as it only includes compression and sheer force able to deform raw materials into complex finished without the material breaking due to tension; (3) it also makes it possible to produce products continuously or in staggered process. (4) Last but not the least is the fact that since the process is almost accurate, the use of secondary machining is reduced.
Although extrusion is used in the manufacturing industry, wear and tear can happen when one least expects it including defects such as surface cracking, internal cracking of extrusion supplies and lines in the surface of the die. With that said, companies can look for an extrusion specialist who can help them upgrade, maintain and design their extrusion equipment to prevent these problems from cropping up.