Qingdao Hengxin Transmission Co., Ltd., located in Qingdao, Shandong Province, specializes in the research, development, production, and sales of industrial chains. Its R&D work covers material selection, precision forming, heat treatment, surface protection, and testing.

For materials, the company selects carbon structural steel and alloy structural steel based on load and environment. Incoming materials are inspected for composition and hardness. For heavy-duty chains, the R&D team studies clean steel and micro-alloying to improve fatigue resistance and reduce inclusions.

In design and manufacturing, chain plates are formed by precision stamping or laser cutting, while pins, bushings, and rollers are machined with CNC equipment. Engineers optimize pitch, plate profile, and assembly clearance to reduce stress concentration and improve load distribution.

Heat treatment is a core research area. Controlled atmosphere furnaces perform carburizing, quenching, and tempering. By adjusting carbon potential and temperature, the team achieves high surface hardness and a tough core, improving wear resistance and impact performance. Surface treatments include blackening, zinc plating, and zinc-aluminum composite coatings for different corrosion environments.

Testing covers breaking force, elongation, wear life, and dimensional accuracy. The inspection center has tensile testing machines, hardness testers, metallographic microscopes, and salt spray chambers. Custom chains can undergo fatigue or extreme load tests to verify reliability under demanding conditions.

The company’s chains are used in conveying machinery, lifting equipment, packaging lines, mining, port handling, food processing, and agricultural machinery. It also provides non-standard development for high temperature, corrosion resistance, heavy load, and extended pitch applications. Future work will focus on automated production, precision testing, and process optimization to improve chain consistency and reliability.