Less is more: Accumold talks ultra-thin walled micro moulding

Aaron Johnson, vice president of marketing and customer strategy, Accumold discusses trends towards ultra-thin walled micro moulding, as well as electronics and their roles within medical devices.

In the run up to MD&M West 2019 in Anaheim, California, it was announced that a key topic of interest would be trends within electronics, with a particular focus on the miniaturisation of devices that customers have now come to expect as the norm. Accumold found itself talking ultra-thin walled micro moulding, as well as electronics in medical devices during MD&M West.

Ultra-thin walled micro moulding is becoming increasingly challenging as a result of trends within electronics such as wearables, and due to the pressing demand to improve patient care. Johnson provides a unique insight as to how this affects the manufacturers of small and micro injection moulded components.

What are the challenges associated with ultra-thin walled micro moulding?

There are many challenges associated with ultra-thin walled micro-moulding. The strong drive to reduce form factors means that design engineers are often looking towards wall thickness as an opportunity to gain space. As a result, this is putting a lot of pressure on component manufacturers and is pushing ultra-thin walled micro moulding to the extreme. One of the main challenges is the profound relationship between the geometry and the material selection, particularly with high aspect ratio wall sections. In these circumstances it can be hard to follow specific guidelines.

An ultra-thin wall section e.g. about 75 microns thick over a high aspect ratio of more than 25:1, is achievable but is very material dependent. When you're looking for material properties to match the geometry you're after it can be very challenging. For example, polyetheretherketone is a commonly desired biocompatible resin but is not friendly to high aspect ratio ultra-thin moulding. Liquid crystal polymers (LCPs) on the other hand can perform very high aspect ratios but may not have the physical characteristics you’re after. It becomes more than just a simple guideline for aspect ratio and usually comes down to the experience of the micro moulder.

What are some essential applications of ultra-thin walled micro moulding?

Wearable devices, micro surgical tools, diagnostics, transcatheter or endoscopic components are a few of the common medical devices looking to push the limits when it comes to ultra-thin walled micro moulding. Applications that are looking to do more in the same space, or more in less, are commonly looking to push the limits with their form factors. The more they can reduce the form the more space they can have for other components, or the more they can reduce the overall footprint.

What is the best material choice for ultra-thin walled micro moulding?

LCP is probably one of the best performing materials when it comes to high aspect ratio ultra-thin walled micro moulding. Other materials including polyethylene, polypropylene, or polyoxymethylene are also very capable with these dimensions as well. In some situations, polymethyl methacrylate, polybutylene terephthalate or nylon could also be good choices. Each of these materials present their own advantages and limitations. The design plays a key factor in the success of a material for this purpose.

Which elements should manufacturers test when using ultra-thin walled micro moulding?

The structural and mechanical properties will need to be tested if they are important for the functionality of the part. Environmental testing is also very common, especially in high heat applications where material stability is important. Plastic parts that don't have a lot of mass can sometimes behave unexpectedly, therefore a test is always recommended.

What are the latest trends for medical devices?

It is thought that medical devices will never stop looking to reduce their size. There is a high demand to produce more minimally invasive devices, and to find newer opportunities within patient care that can reach further into the body with less effort. The medical device market continues to push the limits of mechanical design with the hope of improving patient care.

What are we seeing in new applications?

Wearable applications are the latest trend within medical devices. It is thought that putting more care in to the hands of the patients often provides better data and more immediate feedback resulting in better care. Advancements in electronics, drug delivery, diagnostics, etc., have all brought innovative products to market. Manufacturing processes like micro moulding have helped enable these technologies to provide the most value to the patients with the least amount of impact possible.

What is important to consider when choosing a manufacturing partner like Accumold?

Experience is the number one factor when choosing a manufacturing partner for micro moulding. Partners are required to build the tools, process the materials and produce high quality output, and this can be daunting.

Secondarily, whenever interviewing a new potential partner their capability is not the only important factor. It is also very important to make sure that they are able to sustainably meet the scalability required, as a disruption in the supply chain can be extremely frustrating. It is very important to ensure your new partner is well equipped beyond the prototyping phase.

Why is it important to choose a manufacturing partner that understands trends in electronics?

As with any product or service keeping up with the needs of the customers is non-negotiable. It is important to understand that form factor reduction and pushing the limits with micro injection moulding could be key future solutions. Having a manufacturing partner that understands the trends in electronics enables the organisation to focus on the mechanical trends and the material science driving tomorrow's products.