Mold creation: CNC milling, CNC spark machining, EDM wire cutting
Manufacturing technique: Injection molding
Mold material: Heat treated S136, hardness 48-52
Tool material: NAK80
Challenges and Solutions
1. The positioning of the holes presented a number of problems when it came to production. We went back to the design team and suggested that the radius of the holes be increased slightly and they be spaced out a little more. This would also cause a reduction in the total number of holes. These minor changes wouldn't affect the functionality of the mask, but would make it significant easier to produce, eliminate the chance of defects, and improve the mask's thermal performance.
2. We discovered that the original design was going to result in a lot of trapped air, which could lead to defects and imperfections. The injection molding team suggested further spacing out the larger holes as a way of combating this.
3. The original design included an internal cover that we felt would add unnecessary complexity to production. In the interest of keeping the process as simple as possible, it was recommended that surrounding area be made level, making the injection process more straightforward and keeping costs down.
After solving the minor issues above, we then moved forward with production of the mold. For the mold insert we chose heat treated S136 with a hardness of 48 to 52. For the mold frame we chose 50C. This then underwent milling, drilling, filing, heat treatment, grinding, CNC laser cutting, EDM wire cutting, spark machining, and polishing. Then it was time for assembly, and finally injection.
This project highlighted the close cooperation between design team and the production team, as they were able to overcome a number of small issues and produce a successful product that met all requirements. The mask has sold very well in China and elsewhere in Asia, and demand continues to grow. We enjoy challenges and this project was one of the most satisfying we have worked on. If you have a similarly challenging project requiring professional and innovative solutions, we'd love to hear from you.