Plastic shaft bearing with a deflection tolerance for the internal and external diameter of 0.005mm

A customer had used a machining process in the early stage of development, and later used a wet polishing process. However, they were struggling to meet the specifications, even during this development stage. Nichiei received inquiries from them and recommended using an injection molding process. The part was made from acetal (POM), a crystalline resin that has a high post-molded shrinkage rate, something that was unacceptable to the customer. To solve this problem, we worked with the customer to produce a machine that could measure molding tolerance precisely, and observed the variation over time 1 month, 3 month, 6 month and 1 year after molding. After confirming that there was no change in dimension, mass production was started. Based upon the volumes required, Nichiei built a 4-cavity tool with a tolerance of 2u-3u, supporting the mass production of 300,000 bearing shafts per month.

Thick-walled bearing shaft: Coaxiality tolerance of 0.01mm

A customer had used a machining process to meet the specifications in the early stage of development. The process was time-consuming, costly and yields were low due to quality issues. Nichiei was contacted by the customer and recommended injection molding. A major concern for this part was the fact that it was thick-walled, which often leads to a surface indentation, or “sink mark”, due to material shrinkage during cooling. In fact, molding this part with a coaxial tolerance of 0.01mm was extremely challenging, but Nichiei was able to solve all the problems, producing a blemish-free part which is now in full commercial production.

Plastic bearing shaft: Circularity of 0.002mm; External diameter tolerance range of 0.008mm

A customer was struggling to achieve tight tolerances in a molded part requiring circularity of 0.002mm and an external diameter tolerance of 0.008mm. Nichiei offered a proprietary molding methodology that is now meeting both the performance and specification requirements, resulting in a very satisfied customer.

Insert gear of JGMA Grade 0

A customer realized they needed a plastic gear to reduce the noise in their Office Automation equipment. Since plastic alone would not meet the high temperature requirements of the part, it was suggested that they include a metal component within the plastic gear. However, a metal/plastic insert molded gear typically does not maintain the tight co-axial tolerance required for a JGMA Grade 0 gear. The customer came to Nichiei who then developed a new (patented) molding technology to produce an insert molded gear that maintains the necessary accuracy and dimensional stability, while meeting the fitness-for-use requirements of the part.