Solution for Thread Surface Micro-Crack Propagation Under Low-Temperature Storage

In daily metal cap production, most tiny thread micro-cracks cannot be detected by conventional finished product inspection. These subtle flaws sit dormant on threaded aluminum caps and anti-theft caps, showing no quality issues right after production.

From our long-term cooperation with overseas packaging buyers, we have summed up a common practical problem. For caps shipped to high-latitude regions or stored in 0–5°C cold warehouses for two weeks or longer, those hidden micro-cracks will slowly spread due to continuous low-temperature metal brittleness changes. In actual assembly tests, this problem normally triggers a 3%–8% thread breakage rate, a hidden loss that many manufacturers overlook in normal-temperature production checks.

After repeated machine debugging and process verification, we found that standard thread rolling settings only focus on normal-temperature molding efficiency. They ignore the slight shrinkage and toughness decline of aluminum materials in low-temperature environments, which is the root of micro-crack expansion.

Based on actual production scenarios, we fine-tuned the ductility forming parameters of our rolling equipment and upgraded the physical compression process of thread molding. This mild process adjustment optimizes the internal density of cap threads, improving the metal's low-temperature toughness adaptability.

In real field tests with our clients, the optimized process effectively restrains micro-crack growth during cold storage and transit. It can lower the low-temperature thread failure rate to under 1.5%, helping finished caps maintain stable quality for cross-border logistics and long-term low-temperature storage.