Medical Industry: Producing quality medical parts in short lead time

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In a project that had a short time frame and a tight budget, Polyfluor Plastics appointed Flexan, a US contract manufacturer, to produce high precision silicone components for in-vitro fertilisation at its facility in China.

For a medical device for in-vitro fertilisation, a European OEM required a special injection moulding component made of silicone, which alongside high quality should also have very precise dimensions, and special surface characteristics.

As the component also had to be manufactured within a short timeframe and on a low budget, with a volume of 400,000 units, polymer supplier Polyfluor Plastics decided to appoint the Chinese branch of US contract manufacturer Flexan.

The Suzhou-based branch, closely affiliated with the Chicago head office and managed according to the strictest Western quality standards, was able to rely on the parent company’s more than 70 years of expertise, says Flexan. However, at the same time, it offers clients the cost advantages of the Chinese site.

In addition, Polyfluor says it was able to drastically reduce the time to market with this decision. While there are frequently waiting times of up to six months at American and European production sites industry wide, the project with Flexan Suzhou progressed significantly faster: the plant produced the injection moulding tools within five weeks and provided the first samples just five days later.

“We were appointed by an OEM, to manufacture components for a product for in-vitro fertilisation,” explained Eric Wetzels, Managing Director of Polyfluor Plastics. This also included a special silicone injection moulded part, which is not very complex in itself, but the manufacture in a clean room according to the strict specifications of the customer posed a challenge.

“On the one hand, there were very small tolerances for the dimensions, but on the other hand it is required that its surface feels pleasant and smooth. This requires extensive knowledge, as for example the original material must be injected into the tools and cooled correctly.”

Polyfluor’s customer initially needed this component in a volume of 400,000 units, but subsequently an increase to up to 3 million would be possible.

“We asked several manufacturers: with the requirements for the components and the specified time and cost restraints. The quote from Flexan for production in Suzhou offered the best conditions, for example in terms of tool costs and delivery time,” continues Wetzels.

Production in China

The advantage of the Chinese branch with regards to time to market can be attributed to an industry-wide development. Western production sites are currently so stretched, that there are long waiting times for tools and products.

“With other manufacturers, it would have taken 4-6 months until the injection moulding tool had been built,” confirms Wetzels.

In contrast, he says Flexan was able to agree a time of two months.

“In Europe and the US, for example in our factory in Chicago, express tool manufacture is of course still possible – but with additional costs,” explains Werner Karau, European Commercial Leader at Flexan, who is responsible for the project with Polyfluor. “Here, the client has to think carefully, particularly if the same quality can be provided in China.”

Injection moulds finished after five weeks

However, the particularly short delivery time in Suzhou can also be attributed to the fact that the factory has many different injection moulding tools, and therefore has fixed capacity commitments with a large number of qualified tool manufacturers.

“These reserves generally allow us quick tool manufacture,” says Karau. At the same time, the Chinese branch can also rely on the knowledge of high precision medical silicone components, which has been accumulated since 1946. Due to these various factors, the injection moulding tools were able to be completed within five weeks, and the first samples were sent to Polyfluor around five days later.

“The component for Polyfluor will be manufactured by us in a hybrid LSR process,” explains Karau. The liquid silicone rubber, which is used as the raw material, is a twocomponent paste mixture, with short curing times, which is good for use in the temperature range of -55 to +210°C.

The two components are poured directly from the original containers into the injection moulding machine. After curing, the moulded parts are removed from the cores, a defined random sample is sent for inspection in the measurement laboratory, and after preparation of the tools, they will be refilled.

If the random samples of the measurement inspection are fine, the production quantity is checked in the visual inspection. All inspections will be documented, and if everything corresponds to the specifications, the parts are packaged in the clean room and stored.

The challenge with the silicone components for Polyfluor was that on the one hand there were strict tolerances in the dimensions, and on the other hand, the achievement of certain haptic and visual characteristics had to be considered.

“Even if all the dimensions are within the tolerance limits, a part may feel different to what the customer wishes. This can be determined after the first prototypes,” says Karau. “If the moulded part feels too firm, we can change the tool; for example, by getting closer to the lower tolerance limit, to have less material in the affected places.”

Ultimately, the surface is influenced by the tool, but also by temperatures, cooling and other parameters. A slightly finer surface was required with initial sampling, to achieve this haptic, the process parameters were adjusted, and the tool was fine polished.

Adherence to Western quality standards

“Due to our collaboration with Flexan Suzhou, we received our components very quickly, in the correct quality, in a high volume and at a competitive price,” says Wetzels.

“As a wholly owned subsidiary of Flexan, the plant combines the cost and capacity advantages of the Chinese site with US-American company standards. Western structures prevail in the management, all procedures are identical throughout the whole group, as far as possible,” confirms Karau.

Production and development management and quality management for example are internationally integrated. As with all other Flexan factories, Suzhou also adheres to the quality standards in accordance with ISO9001/13485 and undergoes the audits that inspect this conformity.

“The only difference between the American sites and China is that Suzhou is more set up to manufacture many different tools and parts in high quantities, while the US factories specialise in the manufacture of even more complex parts, and services for the end product such as assembly and secondary operations,” adds Karau.

Polyfluor says the project with Flexan Suzhou is another positive experience with the production of medical components in China. However, Wetzels knows from experience, that with manufacturers in the country who are not foreign-owned and/or subject to strict Western standards, you have to tread more carefully.

“We had a case where a Chinese partner assured us of a certain procedure. It was carried out that way a few times, but by the third or fourth delivery, the processes had been changed in secret, and produced cheaper, to their own advantage. That would not have happened with a German supplier for example.”

Wetzels doesn’t want to generalise, as even in the West you can never completely rule out black sheep, but he admits: “We check Chinese suppliers slightly differently to Western ones. Before sending each delivery, they are checked by an auditor, even more closely than is usual for the sector anyway.”

After the successful manufacture of the silicon components, Polyfluor is planning another collaboration with Flexan and the factory in China.


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