Plastic injection molding in Improving the Spiral Screw

This case involved a spiral screw for a vegetable juicer, which our client requested us to redesign to reduce costs by changing from an all-stainless steel design to a combination of injection molding and stainless steel. The new design reduced costs by 50%. 

Initially, we didn't perceive this requirement as particularly challenging. The main hurdle was that we couldn't verify the product's performance through a prototype before injection molding, because the core structure was stainless steel, while the exterior plastic was produced through overmold injection.

After obtaining clear consent from our client, we decided to take a bold approach by skipping prototype validation and going straight to mold production. The development of the mold went smoothly, and the dimensions of the components produced met the design standards. However, unexpected issues arose during the actual juicer tests when using these components. According to the design, the spiral screw was to be positioned horizontally and fixed at one end only, but this setup caused severe shaking during operation, resulting in unstable juicer performance.

Our technical team quickly initiated a discussion on this issue. After a series of analyses and tests, we identified the root cause as the concentricity of the product. The center of gravity of the spiral screw was not precisely on the central axis, and with only one end fixed, significant eccentricity occurred during high-speed rotation, leading to shaking. This discovery was promptly addressed with high priority.

To solve this problem, we made meticulous adjustments to the mold and the internal stainless steel parts of the spiral screw. By optimizing the design and manufacturing precision, we corrected the concentricity of the spiral screw, ensuring its stability during operation. These adjustments, after rigorous testing, proved to effectively reduce operational shaking, controlling the end shake angle to within 2 degrees, successfully meeting the client's strict standards.

Although this project seemed to involve only a simple part, it actually encompassed complex engineering challenges and multiple trial-and-error processes. Each failure brought new insights and experiences, ultimately helping us successfully complete this improvement task, not only meeting the client's needs but also enhancing our team's capabilities in product design and manufacturing.