Insert Molding: Enhancing Functionality in Medical Devices

One of the cutting-edge techniques driving advancements in medical device manufacturing is insert molding. In this technical post, PDC explores the concept of insert molding, its applications in medical device manufacturing, and how it enhances functionality and design flexibility. 

Understanding Insert Molding 

Insert molding is a specialized injection molding process where a preformed component (the insert) is placed into the mold cavity before the polymer is injected. The molten polymer then surrounds the insert, forming a single integrated part. This technique allows for the encapsulation of inserts with precision and repeatability, creating robust and durable components with complex geometries. 

Applications in Medical Device Manufacturing 

Insert molding offers many advantages in medical device production. It enables the integration of multiple materials and components into a single part, reducing assembly time and costs while enhancing product reliability. Common applications of insert molding in medical devices include: 

  1. Catheters: Insert molding is utilized to encapsulate metal or plastic components within catheter shafts, enhancing flexibility, strength, and functionality. 
  2. Surgical Instruments: Inserts such as metal blades or tips can be encapsulated within instrument handles, providing ergonomic grips and improved surgical precision. 
  3. Implantable Devices: Insert molding enables the encapsulation of electronic components, sensors, or drug delivery systems within implantable devices, ensuring biocompatibility and long-term reliability. 
  4. Fluid Handling Components: Inserts such as tubes, connectors, and valves can be encapsulated within fluid handling components, ensuring leak-proof seals and fluid control. 

Enhancing Functionality and Design Flexibility 

Insert molding offers significant benefits in terms of functionality and design flexibility for medical devices: 

  1. Material Compatibility: Insert molding allows for the use of a wide range of materials, including metals, ceramics, and thermoplastics, enabling the integration of dissimilar materials with varying properties to meet specific performance requirements. 
  2. Miniaturization: By encapsulating small, intricate components within the molded part, insert molding enables the miniaturization of medical devices, allowing for less invasive procedures and improved patient comfort. 
  3. Complex Geometries: Insert molding enables the creation of complex geometries and features that would be difficult or impossible to achieve with traditional assembly methods, allowing for innovative designs and improved device performance. 
  4. Reduced Assembly Time and Costs: By consolidating multiple components into a single molded part, insert molding reduces the need for assembly operations, lowering production costs and minimizing the risk of assembly errors. 

Conclusion 

Explore how insert molding boosts your medical device’s functionality, flexibility, and reliability. Insert molding and Over molding are considered interchangeable terms in the plastics industry and for the following statements should not be included in the same conversation as True 2-shot molding (2K).   

Mastery in Precision Molding – Insights from Our Expertise:

Both operations involve either a manual or robotic placement of  a substrate into a mold, which could be a previously molded plastic component, a single catheter tube, multiple catheter tubes with metal collars for structural integrity or to ease laser welding in assembly, a marker band, a metal hypotube, a metal cannula, a 100 micron thick film for titer plate backing,  a MIM micro surgical component or an electronic sensor.  The typical failure modes seen in the industry is not having the expertise during the DFM phase to understand the tolerance variation of the substrate.  Therefore, if the substrate is purchased from an external vendor, albeit the purchased component may be within the print tolerances, the steel tolerances that PDC operates to of +/-.0001” may create a situation of excess flash or tool damage if part is at the high end of the tolerance.  What this means is that during the DFM, every input into the project must be assessed and if required, different sets of core pins or shut offs may have to be fabricated and utilized based upon the tolerances of that particular lot of purchased substrates.  Another planning activity is you are over molding with a high temperature and you have a substrate that be .015” in diameter.  How do you handle this if you are dealing with a 380°F tool, what safeguards do you have in place to ensure proper positioning within a .0001” , is it stamped component or a steel rod that may stress relieve when it comes in contact with the hot mold, whereby the part may cross the parting line and damage it upon mold close?  PDC’s stringent PFMEA and DFM process considers all known variables and even goes as far as what could happen during the molding process.  Even if it is something that is “far-fetched”, it needs to be discussed and noted as a failure mode.  PDC operates with automated and manual substrate placement which utilizes precision fixtures/load bars and cameras; therefore, we understand what is going on between the platens every cycle.   

With a passion for miniaturization and implementation of advanced micro molding techniques,  PDC’s attention to detail for insert molding/over molding creates a highly repeatable and scalable process, which allows our clients to rely on us for continuity of supply, ultra-high quality with components that traditionally have tolerances of +/- .001” and below.