Mold Design & Fabrication for Complex Medical Devices

With 25 years of experience in mold development and project management, I have encountered the full spectrum of challenges in production mold designs and builds. Once a mold is constructed, making significant improvements can be expensive and, in some cases, may only be possible through complete replacement. Therefore, a thorough evaluation of product design requirements and manufacturing needs is essential for ensuring long-term product quality and mold life. Open, upfront conversations with the customer about these factors provide substantial benefits from the beginning of the mold design process all the way through to product and mold end of life.

UPFRONT CUSTOMER COLLABORATION

Design for Manufacturability (DFM) should begin with the request for quote (RFQ). Ultimately, our customer expects defined aesthetics, fit, and function from their product. The conversation must start with these expectations. Fully understanding the product’s application and requirements offers insights into potential opportunities for improving product quality, reducing manufacturing costs, and enhancing mold robustness, maintenance, and longevity. It is impossible to separate product requirements from mold and manufacturing considerations, and the best solution often requires a balanced compromise.

When reviewing a new RFQ and conducting a DFM analysis, our team performs a FMEA (Failure Mode and Effects Analysis) as we examine the prints, models, product requirements, and application. This helps identify potential risks such as thin or thick walls, sinks, warping, dimensional stability, air traps, weld lines, aesthetics, and delicate features. Simultaneously, we assess mold and manufacturing aspects such as gating, cooling, ejection, undercuts, draft, venting, fragile steel, part management, and packaging. After identifying any concerns, we collaborate with our customer to discuss mitigation strategies. Although this thorough, upfront review may take a little extra time, customers value knowing that we are a partner invested in ensuring the mold and production solutions are robust. Validating a mold which later struggles in production risks both product supply and quality, benefiting no one. Once awarded a project, we revisit these risks to confirm that previous concerns were mitigated and that no new issues have emerged.

For more complex projects, we may supplement the DFM review with additional tools, such as 3D printed samples from our Markforged X7 3D printer, which help us visualize part features, sizes, and potential risks. Mold filling simulations help verify potential concerns like weak weld lines, non-fills, air traps, and warping, and can also uncover challenges such as high pressures or inadequate thermal control, which may be difficult to identify otherwise. In cases where part geometries are highly complex, preliminary CAD splits can improve visualization of thin steel conditions, cooling challenges, and steel shutoff questions. Unresolved DFM items are reviewed with our customer before we proceed with formal mold design.

KEY MOLD DESIGN CONSIDERATIONS

Once the product design is finalized, full mold design begins. Building on DFM considerations, our cross-functional engineering team collaborates with the mold designer to ensure the design meets all technical specifications.

We focus on optimizing cooling to enhance part quality, including aesthetics and dimensional stability, as well as reduce cycle time and maximize mold life. This can involve standard drilled lines, conformal cooling, special alloys, or thermal pins.
Including proper sub inserts within the molding area is another key component to a successful project, providing sufficient access to molding areas for polishing, proper part release during demolding and venting. Venting is crucial for improving mold performance and part quality, reducing outgassing, preventing steel erosion, and extending maintenance cycles. Inserts also enable faster repairs, increasing mold uptime.
With hundreds of components in a mold, selecting the right materials is vital. Each component’s specific needs—such as surface finish, wear resistance, toughness, and thermal properties—must be carefully considered.
Alignment is also given special attention to prevent premature wear and ensure mold longevity. Misalignment can impact both mold life and product quality. To mitigate this, we incorporate multiple levels of alignment, including leader pins, straight parting line or zero-clearance locks, and cavity/insert interlocks. Additionally, we include thermal channels in the mold plates to maintain thermal balance and prevent misalignment caused by thermal variance.
As we move away from the part molding area of the mold, there are still many aspects to consider, such as adequate support and strength to withstand the molding pressures and clamp forces, proper sensors and cable management, protection of moving features, and alignment of the mold in the machine for post-molding part management.
Additionally, we carefully consider mold assembly/disassembly, maintenance, and repair for efficient mold management outside of the molding machine.
Throughout the process, customers are invited to participate in design reviews to ensure the mold meets their needs and expectations.

LASTING QUALITY AND EXTENDED MOLD LIFE

Our cross-functional engineering and skilled toolmakers team manages risk and maintenance strategies to safeguard customer assets and investments. We use advanced systems and sensors to monitor molds during production, ensuring optimal performance. Features like in-mold sensors, vision systems, and robotic sensing, in conjunction with integrated quality monitoring on our injection molding machines, help maintain production standards and protect the mold.

A robust preventative maintenance (PM) program is just as important as the design and development of the mold itself. Our strict PM program begins with a soft launch to optimize cycle counts between maintenance events, maximizing mold uptime and longevity. Molding cycles are tracked via direct communication between molding machines and our ERP system. PM strategies are tailored to each mold’s specific needs, and both in-press and out-of-press maintenance strategies may be utilized. Lubricants are carefully prescribed for each application depending on temperatures and other factors, and spare components are inventoried to avoid production delays.

These strategies provide optimized mold care, supporting long-term, high-quality product and extended mold life. Many of our molds have exceeded multi-million cycles, with some surpassing 10 million cycles, while continuing to produce high-quality products that meet the same strict specifications as the day the mold was qualified. It takes a well-executed DFM analysis, robust mold design and build, stringent maintenance program, and long-term production planning to reach this level of success.

CONFIDENCE IN YOUR MOLD BUILD PARTNER

In the medical device industry, where sustained quality is paramount, choosing a partner who delivers a mold of the highest quality is imperative to build the foundation for success. A high-quality mold is a wise investment that will provide long-term quality and peace of mind if you choose a mold-builder and molding partner who manages part quality and mold longevity through robust manufacturing and maintenance strategies.

At Plastikos and Plastikos Medical, we build most of our SPI class 101 molds through our sister company, Micro Mold. This uniquely advantageous relationship sets us apart among the precision molding industry. For larger molds or when additional capacity is needed, we may partner with outside mold builders. Through our extensive experience and relationship with Micro Mold, we know exactly what to seek in a competent outside partner in design and manufacturing philosophy, machining equipment, quality control systems, and reputation in the industry.

About the Author:

Jesse Barber is the Corporate Tooling Project Manager and joined Plastikos in 2020. He holds a B.S. in Plastics Engineering Technology from The Pennsylvania State University and a graduate certificate in Project Management from Southern New Hampshire University. Jesse’s primary role at Plastikos is overseeing the development and launch of all new and transfer mold projects, as well as associated production and maintenance support throughout the lifecycle of the mold. Outside of work, Jesse enjoys spending time with his family, church, and outdoor activities, including mountain biking, skiing, hunting, fishing and hiking.