Precision Mold Making And Mass Production For Medical Hearing Aids

Client Requirements

Structural integrity, especially when making small parts, dimensional accuracy, sink marks, and short shots were some of the major concerns of hearing aid manufacturing that the client wanted First Mold to help them solve. Since they were operating on a tight budget, they needed a partner that would help them avoid common molding faults that would burn their limited resources.

The right solution had to thoroughly consider every aspect of hearing aid part production to ensure the costs remain low for competitive pricing of the final product. The ultimate goal was for First Mold to deliver a steel injection mold with a dimensional accuracy of 0.05mm and modified ejection mechanics that perfectly match the client’s design blueprint.

Challenges

Through R&D, the client has come up with innovative ideas for hearing aids parts manufacturing, which include thinner parts, a smaller form factor, and improved ergonomic design, intended to make it easier for people with hearing loss to use their products for a longer period without feeling discomfort.

The client’s design blueprint included an over-the-ear hearing aid plastic case that has a smaller form factor compared to the widely available models on the market. Smoothly producing small hearing aid parts using plastic is always a challenge. Also, the thin walls demanded by the client to reduce the overall weight of the product could lead to parting lines during molding.

Another challenge that First Mold had to navigate was the smooth, glossy surface appearance indicated in the design blueprint. For the in-ear part of the hearing aid, First Mold’s advanced software allowed the client to scan the mold impression of the patient’s ear and convert the scans into models for 3D printing.

They were keen about working with a hearing aids part manufacturing company specialized in injection molding to bring their innovative design to life. After a tour of the Zhongshan City mold facility, the client was confident that First Mold was the right partner for the job.

The client’s preference for injection molding was based on long-term cost-saving potential and the ease of finding employees with the right technical skills to operate them. The client specifically wanted molded hearing aid parts for three main reasons, namely:

• To save space within the shell, thereby giving them room to fine-tune the acoustics of their proprietary hearing aids,
• To reduce the number of components, which saves costs in the long run,
• To make the final assembly faster, where fewer employees can assemble more products, which helps to cut the size of their payroll.

Solution

Based on the design blueprint presented by the client, First Mold suggested a single cavity mold, for the best dimensional accuracy, to help the client achieve the small form factor, ergonomic design and gloss surface finish. An ISO13485-compliant quality management system was implemented to maintain product quality and user safety throughout the hearing aid parts production process.

Tooling

Through rigorous feasibility studies, First Mold determined that the client can cut hearing aids parts manufacturing costs over time and speed up production, using steel injection molds. The client initially suggested a family mold, but First Mold advised against that on the basis that it would significantly compromise precision, which would not be suitable for the high-end hearing aid production that the client was hoping to achieve. The steel mold was ready to be delivered to the client in 6 weeks.

Advanced Testing

Before onward delivery to the client, the single cavity mold was put through rigorous testing. First Mold’s quality assurance team produced several small runs of the designed product using the choice material to ensure the products met the dimensional accuracy, aesthetic recommendations, and mechanical properties (snap-fit design for faster assembly) of the client’s design blueprint.

What the client gained by working with First Mold

By partnering with First Mold for their hearing aids parts manufacturing, the client received a mold intentionally crafted to avoid the common faults associated with molding, especially when dealing with small plastic parts with thin walls, including short shots, flash, warping, and sink marks. With the mold crafted by First Mold, the client can produce over-the-ear hearing aids with a custom design and glossy finish that will give their product a premium feel. The client also received professional advice on mold making that helped them to rethink their initial plan of opting for family mold, which would have created dimensional accuracy challenges that would have impacted their product’s appeal.

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