Aluminum production often faces several surface defects such as false joints, scratches, mechanical lines, black lines, bumps, and severe weld seams. These issues can lead to color differences or black bands, resulting in product rejection and irreversible damage. One of the main reasons for poor welding quality is low welding force, which is typically caused by insufficient extrusion force. Factors contributing to low extrusion force include mold design, process parameters, extrusion temperature, and extrusion speed. High extrusion temperatures help metal diffusion and bonding but also intensify the formation of welding defects. Additionally, high temperatures promote grain growth, leading to a coarser weld microstructure. When extrusion speed is too fast, it increases metal deformation work, raises temperature further, and reduces pressing force, thus lowering welding strength. In some cases, using graphite products as a slip-out station can cause black bands on the profile surface due to oxidation.
Failure of aluminum alloy extrusion hot dies is commonly attributed to cracking, wear, erosion corrosion, overheating, and thermal fatigue. The condition of lubrication within the mold significantly affects its lifespan. During the extrusion of aluminum and its alloys, lubricants are essential to reduce friction between the metal and the barrel wall, the piercing pin, and the mold surface. This helps minimize adhesion and tooling wear, ensuring smoother operation and better product quality.
Historically, improper use of lubricants led to surface contamination and even lubricant seepage into the center of the product, causing more noticeable "squeeze" effects. As a result, many manufacturers have adopted "lubrication-free extrusion" for bars and profiles. For tubes and hollow profiles, only the die surface and the piercing pin are lubricated. Recently, with advancements in tooling design and lubricant technology, the industry has made significant progress in lubricated extrusion. The development of high-temperature lubricants like JONYE has allowed for improved performance, especially in high-temperature extrusion processes.
When applying JONYE high-temperature lubricant during high-temperature extrusion, it helps prevent rust on the work surface at room temperature. Prolonged preheating ensures no decarburization or oxidation occurs on the protective work belt, preserving the original hardness of the working surface. It avoids soft spots and soft zones, enhances lubrication between the die and the profile, and reduces friction. This minimizes die blocking, crushing, and welding defects, resulting in smoother production, fewer ripples, and a better surface finish. It also prevents adhesion, sticking, and aluminum buildup, reducing mold repair frequency and extending mold life.
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