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.
This project was an innovative mask that we conceived and designed entirely in-house. The mask separates nasal and oral breathing and is effective at combating the harm of air pollution. The design supports a high degree of personalization and is compact and simple to put on. Each mask contains fully 10 filters, allowing not just for more effective filtering, but also ensuring that the mask has a longer lifespan. The design is patented and makes a significant difference to the health of all those that use it.
During the planning stage, we decided the mask had to meet the following criteria:
It should be made from high quality polypropylene (food grade).
It should be resistant to both high and low temperatures, and be soft and flexible.
It should be comfortable to wear and easily portable.
The surface material should have a natural feel.
It should be tough and durable.
The surface should be porous and breathable.
For each project, we always carry out a design assessment. After analyzing the structure and technical requirements, our team discovered that the design was going to place high demands on the materials, and that it was important to make sure the mask could stand up to a variety of temperatures. This would later add challenges when it came to assembly. With such high requirements we had to take extra care at each stage of the design process and ensure the materials were the perfect fit. In the end we went for a combination of silicone and soft polypropylene, which would ensure the mask was comfortable to wear whilst still meeting requirements and robustness and thermal durability.
Challenges and Solutions
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.
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.
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.
We are one of the first Protofab branches in the world. We have recently launched our first showroom in Norway, and currently are also opening a branch in Poland. We can be reached from all over Northern Europe, a short distance from Sandefjord Airport (Near Oslo).