The Role of Injection Moulding in Ultra-Thin Wearable Devices

Paul Runyan, VP Sales & Marketing at US-based plastics fabrications company Accumold, discusses how injection molding works and the impact of wearable devices such as continuous glucose monitors.

Products created from Accomold's injection moulding techniques

The Role of Micro Moulding in Wearable Device Innovation

The advent of wearable devices like continuous glucose monitors (CGMs), insulin pumps, and smartwatches has revolutionised personal health management, offering real-time monitoring and improved convenience for users. Central to the development and miniaturisation of these sophisticated devices is the process of micro moulding, a form of injection moulding. This highly specialised manufacturing technique allows for the creation of ultra-small, super-thin, complex components with precise dimensions, essential for the compact and functional designs of modern wearables. By enabling the production of tiny parts with intricate details, micro moulding plays a crucial role in enhancing the functionality, reliability, and comfort of these devices, making them more user-friendly and effective.

Also read: Navigating the complexities of micro moulding for medical devices

Driving Innovation in Wearable Technology 

As the wearables market continues to expand rapidly, driven by the growing demand for personalised healthcare and lifestyle technology, micro moulding is at the forefront of this dynamic innovation. The process not only supports the miniaturisation of devices but also fosters the integration of advanced materials and multi-functional components, pushing the boundaries of what wearable technology can achieve. By allowing manufacturers to explore new design possibilities and overcome the limitations of traditional manufacturing methods, micro moulding is instrumental in driving the next generation of wearable devices, ensuring they are smaller, smarter, and more efficient than ever before.

What are the Advantages of Using Micro Injection Moulding?

From the perspective of a micro moulding specialist being approached by customers from across various wearables sectors and indeed industry in general, the most common question we get asked at Accumold is “how thin can you mould parts.”

The ability to micro mould extremely thin parts offers several significant advantages for wearable devices, which are increasingly defined by their need for compactness, comfort, and functionality. One of the primary benefits is the reduction in overall device size and weight. Thin micro-moulded components allow for slimmer designs, making wearables like smartwatches, continuous glucose monitors (CGMs), and insulin pumps less bulky and more comfortable to wear for extended periods. This is especially important in devices meant to be worn continuously, as user comfort is directly linked to adherence and overall effectiveness of the device.

What is the Latest Technology for Micro Moulding? 

Another key advantage is the enhancement of flexibility and adaptability in device design. Extremely thin components can be integrated into flexible circuits or other bendable structures, which is essential for wearables that need to conform to the contours of the human body. This flexibility not only improves user comfort but also increases the durability of the device, as thin, flexible components are less prone to damage from bending or other physical stresses.

Micro moulding thin parts also enables the incorporation of more advanced features into wearable devices. For example, it allows for the integration of complex microfluidic channels, sensors, or electronic circuits within a very limited space, which is crucial for the development of multifunctional devices. These components can perform multiple roles within the same footprint, allowing for a higher degree of functionality without increasing the size of the device.

Thin micro-moulded parts contribute to the aesthetic appeal of wearables as well. Sleek, lightweight designs are not only more comfortable but also more desirable to consumers, who often favour discreet and stylish devices. By enabling the creation of thin, unobtrusive components, micro moulding plays a pivotal role in meeting consumer expectations for both form and function, ultimately driving the success and adoption of wearable technology in the market.

Overcoming Challenges in the Micro Moulding Process

The demand for increasingly thinner micro-moulded components places significant pressures on the micro moulding process, challenging the capabilities of traditional manufacturing techniques and pushing the boundaries of precision engineering. As wearable devices and other miniaturised technologies continue to evolve, the need for ultra-thin components grows, demanding that micro moulding processes achieve new levels of accuracy, material handling, and process control. Expert micro moulders, such as Accumold, have developed specialised techniques and technologies to overcome these challenges and meet the rigorous demands of modern manufacturing.

Precision, Tolerance Control, and Material Selection in Injection Moulding Process

One of the primary pressures on the micro moulding process is the need for extremely tight tolerances. As components become thinner, even the slightest deviation in dimensions can lead to functional failures or assembly issues. Maintaining high precision in the production of ultra-thin parts requires advanced moulding techniques and cutting-edge machinery. Expert micro moulders like Accumold address this challenge by employing state-of-the-art (and in Accumold’s case proprietary) equipment capable of producing components with micro-scale precision. This includes specialised injection moulding machines that can handle very small volumes of material with exacting control, ensuring that every part meets the required specifications without compromise.

Material Selection and Handling for Ultra-Thin Applications

Another significant pressure is the handling of materials that are suitable for ultra-thin applications. The selection of materials for micro moulding must consider factors such as flow characteristics, thermal stability, and mechanical properties, which become increasingly critical as components are made thinner. Thinner components require materials that can fill the mold cavity completely and consistently (without simply increasing injection pressure), without defects such as warping, short shots, or incomplete fills. Very often the key is to design tools in a way that is sensitive to material flow issues, and to facilitate material flow without introducing too much stress.

Advanced Mould Design and Fabrication Techniques

The design and fabrication of moulds for ultra-thin components present another set of challenges. As components become thinner, the moulds themselves must be engineered with incredible precision, with features that are often measured in microns. This level of detail requires highly specialised mould-making techniques, including the use of high-precision CNC machining, electrical discharge machining (EDM), and other advanced fabrication methods.

In the micro moulding of low-profile parts, split lines and venting strategies must be meticulously adapted to ensure the integrity and precision of the final components. Split lines, where the two halves of the mold meet, must be positioned and engineered with extreme accuracy to minimise flash which can affect the part's performance and aesthetics. For low-profile parts, the split lines should be strategically placed in areas where any residual flash can be easily removed or will not interfere with the functionality of the part. Venting is equally critical. Effective venting strategies are necessary to allow air and gases to escape during the injection process, preventing defects such as voids or short shots. In the context of low-profile components, vents must be designed to be as small and precise as possible to avoid creating marks or weakening the part's structure. By carefully designing split lines and optimising venting, expert micro moulders like Accumold can achieve the high level of detail and quality required for successful low-profile micro moulding.

Optimising Process and Ensuring Quality Control

Accumold’s expertise is such that in some instance it can modifying surface textures on the mould to strategically facilitate venting in very thin areas of a component, creating micro-channels or textured surfaces that allow trapped air and gases to escape during the injection moulding process. These micro-textures, often implemented as fine grooves or roughened surfaces, are designed to be small enough not to interfere with the surface finish or structural integrity of the thin component but sufficient to provide a pathway for air to evacuate from the mould cavity. This approach helps to prevent defects such as voids, burns, or incomplete fills, particularly in thin sections where traditional venting may be challenging. By optimising the texture of the mould surface, Accumold is able to ensure that these critical thin areas are fully formed, maintaining the high precision and quality required in micro-moluded parts.

Producing ultra-thin components also places significant pressure on process optimisation and quality control. The micro moulding process must be carefully controlled to ensure consistent production of parts, as any variation in temperature, pressure, or material behaviour can result in defects. Accumold addresses this challenge through rigorous process optimisation, utilising real-time monitoring and control systems to maintain stable production conditions.

The company also employs advanced quality control techniques, such as in-line inspection and metrology, to ensure that every part meets the necessary specifications. This includes the use of high-resolution optical and tactile measurement systems that can detect even the smallest deviations from the desired dimensions.

Innovation and Continuous Improvement in Micro Moulding

Finally, the demand for thinner components drives a continuous need for innovation in the micro moulding process. Companies like Accumold are constantly pushing the boundaries of what is possible, exploring new materials, technologies, and methodologies to meet the ever-evolving needs of the market. This commitment to innovation is crucial in overcoming the pressures associated with ultra-thin injection moulding, as it allows the company to stay ahead of industry trends and deliver solutions that meet the highest standards of performance and reliability.

Conclusion: Meeting the Demands of Modern Manufacturing

The pressures placed on the micro moulding process by the demand for ever thinner components are substantial, requiring advancements in precision, material handling, injection mold design, and process control. Expert micro moulders like Accumold rise to these challenges through a combination of cutting-edge technology, profound expertise, and a commitment to continuous improvement, ensuring they can meet the demands of modern manufacturing and continue to drive innovation in the field of micro moulding and wearable devices.