Lubrication of aluminum particles
(1) Lubrication is very important to the cold extrusion process. It not only affects the plastic deformation of aluminum pellets and the quality of the extruded parts but also directly affects the strength and life of the die. The aluminum particles are usually lubricated with zinc stearate powder.
(2) After drying, the aluminum particles are cold-extruded to room temperature, then poured into the drum, and an appropriate amount of zinc stearate powder is added for stirring, commonly known as "mixed powder". The mixing time should not be too long, and the white misty powder on the surface of the aluminum particles should be regarded as the standard.
(3) The mixing time is too short, the zinc powder on the surface of the aluminum particles is not uniform, and the thread-like defects are prone to appear during cold extrusion. If the powder time is too long, the zinc powder will be embedded in the aluminum particles, and the pitted surface is easy to appear during cold extrusion.
