Common waste phenomena and reasons in aluminum extrusion production due to improper extrusion speed:
(1) Crack
Reason for occurrence: The extrusion outflow speed is too fast and the deformation speed is too fast. The deformation tensile stress exceeds the tensile strength, causing damage to the continuity of the tissue and resulting in cracks, which often occur at the tail and edge of the product.
(2) Needle like appearance on the surface
Cause: High extrusion temperature and too fast speed.
(3) Ma Mian
Reason for occurrence: The extrusion speed is too fast, the metal deformation heat is large, and the metal is easy to bond with the mold core working belt, causing the product to have a rough surface.
(4) Waves
Cause: Improper speed control, uneven flow velocity along the entire extrusion die section, and waves generated on the excessively fast side.
(5) Changes in profile dimensions
Reason for occurrence: For hollow profiles with large inner cavities or profiles with large width to thickness ratios, the outflow velocity at the front end of the product is too fast, resulting in expansion of the hollow profile; If the outflow speed at the front end of the product is slow, the hollow core material will shrink.
(6) Shrinkage of profiles
Reason for occurrence: The extrusion speed is fast, and the metal tends to flow unevenly along the extrusion direction, which increases the tendency. At the end of the extrusion, dirt on the surface of the ingot enters the interior of the product, forming a shrinkage tail.
Squeezing speed is one of the important factors affecting the quality and economic benefits of profile products. Based on the above analysis, improvements can be made in the following aspects in actual production:
(1) Improve the quality of aluminum alloy ingots by adopting appropriate extrusion process parameters and high-quality molds to enhance product quality and efficiency.
(2) In production, operators should control and adjust the extrusion speed appropriately based on the shape, size, degree of deformation, mold structure, and process parameters of the product, in order to improve product quality.
(3) Actively researching new extrusion processes to improve product quality and production efficiency.