Contract manufacturing
Partnering with micro moulders
Accumold is a leading company in providing micro moulding for medical device OEMs. With years of expertise and troubleshooting, it is vital that micro moulders have the business culture, personnel, equipment and infrastructure in place to provide the service necessary to ensure a successful project outcome.
icro moulders for medical device OEMs deal with low, medium and high volume runs in a variety of different materials, all requiring different levels of validation. The companies must also have the expertise in handling, storing and processing often extremely expensive and sensitive materials that in many instances will be used in critical implantable applications.
M
The transition from injection moulding machines that can effectively produce small parts and machines that can produce ‘micro’ parts and features, is important, and micro moulders must be able to utilise state-of-the- art equipment designed for exacting micro applications. Micro injection moulding machines – which may be manufacturing parts with weights less than 0.005g – are typically handling much smaller volumes than traditional injection moulding machines. This means that there are significant effects on residence times and material degradation that all have to be expertly understood and controlled, as do feed and gating systems that also need to be designed with ‘micro’ in mind. Experience is the key, as micro moulding is not just macro moulding scaled down. It is in the area of tooling for micro moulded medical parts that time and money can be wasted if the micro moulder does not have the expertise required.
Tooling for micro moulding projects does not require an extrapolation of the rules governing tooling in traditional injection moulding. Features in micro moulded parts often exceed the allowable tolerances in traditional injection moulding, and similar issues are confronted in the areas of venting and tooling mismatch. Micro moulders must be in a position to employ an array of moulding technologies, including the latest computer numerical control (CNC) machining technologies.
bio-resorbables, liquid crystal polymers, and PEEK, it is necessary to use and understand the nature of tooling materials such as stainless steel rather than traditional tool steels which may not be able to withstand the high temperatures necessary and can corrode. Process parameters in micro moulding are different in many ways from traditional injection moulding, but key is an understanding of the balance between melt temperature, injection
“As many medical applications use high-temperature, high-performance materials such as bio-resorbables, liquid crystal polymers, and PEEK, it is necessary to use and understand the nature of tooling materials.”
Polish to finish
Other tooling issues specific to micro moulding are requirements for an understanding of polishing for micro- mould cavities, and the heating and cooling implications when dealing with extremely thin steel inserts that can be negatively affected by temperatures involved in many medical moulding applications. As many medical applications use high-temperature, high-performance materials such as
pressure, and injection velocity, as well as their effect on dimensional accuracy. In addition, attention must be focussed on micro moulds that in many instances require mould alignment to less than 5µm, and with gate diameters that are typically anything from 60 to 200µm. All these considerations then must keep the processing window of the selected material in check so as to not compromise the integrity of the resin. Due to the often-critical nature of micro medical parts and products, it is necessary to manufacture under cleanroom conditions. With extremely exacting quality and traceability systems, complete control of the entire manufacturing process is required, and adherence to the parameters set out in ISO 13485 (harmonised with ISO 9001) are hugely important, setting out the requirements for a comprehensive quality management system for the design and manufacture of medical devices. ●
Plastic parts are manufactured through an industrial injection moulding process. 48
www.accu-mold.com Medical Device Developments /
www.nsmedicaldevices.com
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