The autumn air is crisp and refreshing, and the workshop of the constant-speed drive shaft factory is brimming with vibrant energy. Led by Shen Jun, the team leader of the heat-treated shaft production line, everyone has hung a banner high above: "Warmly Celebrating the Major Breakthrough in Rapid Mold Changes on the UKL Shaft Production Line." The bold characters proclaim that the production line’s optimization project for rapid mold changes has achieved significant, phased results.

The UKL production line was newly built in 2014 by the Constant Velocity Drive Shaft Factory to support the B brand, thereby achieving its goal of entering the high-end OEM market. The shaft production line involves six key processes: cold extrusion, groove turning, medium-frequency quenching, straightening, stress-relief tempering, and non-destructive testing with demagnetization. Last April, led by Niapco Company in collaboration with the Constant Velocity Drive Shaft Factory, a comprehensive SMED (Single-Minute Exchange of Die) project was launched to revamp the entire production line. All employees worked together wholeheartedly, adhering to the principle of continuous improvement and adopting a proactive attitude toward optimization and detailed enhancements. Following the die-change renovation, the production line not only adopted higher-precision spline machining techniques and incorporated error-proofing devices but also achieved “one-piece flow” production through automated interconnections, significantly boosting production efficiency.

Today, as you step into the UKL shaft production line, you’ll notice that all tooling and molds are neatly arranged and uniformly positioned. Rows of folders stand out vividly, each bearing yellow labels that clearly indicate the standardized operating procedures and process drawings for every stage. After numerous rounds of training, each production step now runs smoothly, and employees carry out their tasks with precision and order—this is the result of everyone’s hard work and dedication. The journey so far has certainly not been easy.

United in purpose, our efforts will never be in vain.

By analyzing a massive amount of video data, we identify the root causes of problems and pinpoint areas for optimization.

The very first step in the initiation of the SMED project was to gather comprehensive information on the current mold-change process and identify any existing problems. The production line involves a total of six operational steps, with numerous handling procedures and a wide array of complex factors at play. How to collect and statistically analyze production details from a data-driven, more scientific perspective posed a significant challenge. After careful deliberation, under the leadership of production line team leader Shen Jun, every single operation step was recorded using video footage. This approach not only faithfully reproduced the actual operational procedures but also accurately documented the time spent on each step. Once an enormous volume of video data had been compiled, the production-line mold-change project established a preliminary “data repository.” With this robust foundation of data and video materials, identifying problems became much easier and more evidence-based.

The constant-speed drive shaft factory and Niapco Company hold meetings twice a week, focusing on addressing and optimizing the mold-change process. During the initial month and a half, everyone’s sole focus was sitting in the conference room, staring at a large screen and meticulously “playing back”—frame by frame—the actual footage of production-line operations, repeatedly watching, pausing, and rewinding. The goal was to pinpoint the root causes of existing problems and discuss whether there was room for optimization. By combining video analysis with detailed data review, the project team has identified various production factors related to mold changes, including operation steps, durations, frequencies, and the number of personnel required for each model. On the whiteboard in the conference room, different mold-change steps and durations are labeled using red and yellow tags, with additional information such as travel distances, travel times, and waiting periods clearly indicated. This visual approach makes it easy for everyone to make adjustments, refine procedures, and perform statistical analyses.

Fully promote and precisely improve.

Analyze every step and pay attention to every detail, making operations more effortless and intuitive.

Using the 5WHY analysis method, the project team systematically identified and organized the tasks to be performed when the machine is started up and those to be carried out after it is shut down. They separated internal operations from external operations and, based on this analysis, proposed three improvement measures: conducting regular maintenance and repairs on cold-extrusion dies off-line; placing die-changing tools and bolts in a dedicated die-changing cart for Brand B; and creating time charts for both off-line and on-line operations to clarify the workflow.

After analyzing each step of the process, we discovered that even a small improvement in detail can help eliminate a great deal of unnecessary waste. For example, take something as basic as tightening a screw: if workers do it manually, it might take three to five minutes. But by upgrading the tool to an electric one, they can tighten the screw in just a few dozen seconds. The time saved on each screw, when multiplied across all stages of the process and applied to large production runs, can lead to tremendous efficiency gains.

Driven by this relentless dedication to leaving no detail overlooked, the project team discovered that certain preparatory tasks before mold changes could actually be carried out while the machine was running—yet they had been performed only during machine downtime. The essence of the mold-change upgrade lies precisely in minimizing machine downtime and maximizing production efficiency. To this end, everyone has been diligently searching for the optimal way to shift internal operations to external ones. Our investigation revealed that the current equipment used for the car clip spring groove—a system relying on hydraulic fluid movement and distance adjustment—cannot accurately measure the actual travel distance, making adjustments extremely cumbersome. Therefore, the heat treatment production line proposed a machine modification plan that adopts servo-based distance adjustment to address this issue. Moreover, since the medium-frequency quenching equipment lacks a filtration system, flow rates often become erratic, especially after shutdowns and mold changes when cleaning is required. This cleaning process used to consume about 40 minutes per shift, twice a day. To tackle this problem, the production line added a new filtration system, reducing the cleaning frequency to roughly once every three days, thereby significantly saving time.

Before the mold-change and rectification, many processes were performed by a single operator. After conducting trials, we added an assistant, enabling two operators to perform parallel tasks simultaneously and combine their efforts into one operation—achieving two outcomes in a single step, thus making the workflow simpler and smoother. In addition to the reallocation of personnel and the consolidation of processes, we’ve also been continuously optimizing and improving our management and technical procedures. All tooling and molds on the shaft production line have been systematically arranged and positioned in fixed locations; moreover, the straightening equipment has been upgraded and replaced, significantly enhancing debugging efficiency. Over the past year and more, we’ve held weekly meetings to address and follow up on the issues from the previous week, tackling problems bit by bit and making improvements down to the smallest details. Gradually, one by one, these issues have been resolved. Workers report that the optimized and upgraded operational procedures are now much easier to master and far more convenient to use.

Take the initiative and get things done in a practical way.

The project team demonstrated a sense of ownership and worked together to ensure the successful completion of mold-changing, renovation, and upgrade efforts.

The success of the mold-changing project is inseparable from everyone’s spirit of craftsmanship—striving for perfection, remaining relentlessly focused, being meticulous in every detail, and pursuing excellence. Zhang Xiaodong, a commissioning technician, is a prime example of this spirit in action. As the person in charge of production maintenance, he spends his days shuttling back and forth through the workshop, solving problems and easing difficulties for the production team. In the eyes of his colleagues, he’s a highly trusted maintenance expert. During his work, he noticed that the cylinders had a relatively short service life, requiring repairs three times a year at a cost of 9,800 yuan per cylinder. Drawing on his extensive experience in maintenance and commissioning, he replaced these cylinders with pneumatic cylinders costing less than 300 yuan each. The new cylinders operate smoothly and reliably, enabling the company to save 58,000 yuan annually.

Recently, workers have reported that oil drips continuously during the cold-extrusion process, contaminating the workpieces during transport and making them difficult to clean. This also leads to excessive oil consumption and higher costs. After repeatedly examining the issue and pondering possible solutions, Zhang Xiaodong visited other production lines for investigation and discovered that adding an air source could effectively remove oil stains from the spline surfaces. He promptly submitted a proposal, and after the equipment was installed and调试ed, the problem was successfully resolved.

Countless employees like Zhang Xiaodong, who roll up their sleeves and take the lead in getting things done, have worked together to successfully complete the mold-change renovation and upgrade of the UKL production line. Seeing these encouraging results, Shen Jun, team leader of the heat-treated shaft production line, said: “During this mold-change renovation, everyone was highly cooperative, with everyone’s hearts and efforts united as one. Now, frontline workers can carry out their tasks more efficiently and conveniently, which fills us with great satisfaction. The advanced management methods and automated processes have effectively boosted our production capacity. Moving forward, we’ll continue making improvements and working hard to generate even greater benefits for the company.”