Medical Injection Molding: Precision and Quality in Healthcare Manufacturing

Table of Contents

Medicine meets creativity and productivity in medical injection molding. 1

The medical field is undoubtedly the industry with the highest need for creativity, efficiency, and precision. Manufacturing healthcare components with the best quality requires a different level of creativity. 

Medical injection molding infuses a revolutionary technique with the employment of precision engineering and the malleability of plastics to engineering safe, reliable, and high-quality medical devices. 

A major challenge in the medical industry is the enormous demand for innovative products that are biocompatible and sterilization compatible to meet every patient’s need. But with medical injection molding, these needs are adequately met. Join us as we take a broader perspective of this manufacturing method to attain the precision and quality of healthcare products.

1. Importance of Medical Injection Molding

1.1 Overview of Medical Device Manufacturing

The industry that holds manufacturers accountable to its firm conditions of industry standards is the medical sector due to a high expectation of manufactured components. The manufacturing of medical devices requires meticulousness and strict compliance with industry-set guidelines. 

Furthermore, injection molding is required to manufacture intricate dimensions and designs for medical components such as catheters, drug delivery systems, and syringes. Also bear in mind that most medical devices are custom-made designs. This makes injection molding a more suitable method compared to others like high-quality CNC machining

In addition, manufactured medical equipment is often done in large volume to satisfy various requirements. With the medical injection molding technique, these instruments can be produced at a reduced cost without compromising on quality and complete compliance with the FDA’s conditions. 

The scalability it provides permits medical injection molding to meet the increasing demand for healthcare devices in the medical sector. Meanwhile, a host of regulations and guidelines are in place to ensure quality. The Quality System Regulation (QSR) and the ISO quality standards are a few of such standard requirements of manufacturers of medical components.

1.2 Benefits of Injection Molding in Healthcare

The benefits of injection molding in healthcare are countless. However, a quick mention of some of these benefits is crucial. Its cost-effectiveness, repeatability, design flexibility, and scalability are a handful we’ll be exploring at the moment. Without wasting any more time, shall we?

Cost-efficiency: The ability of injection molding to manufacture large volumes of medical components with high quality and optimal performance is an advantage that makes injection molding in healthcare an indispensable method. And not on top of that, it minimizes waste and maximizes efficiency by incurring limited labor costs. 

Design flexibility: The design for medical instruments can be complex, but it’s a feat injection molding is capable of handling. The flexibility injection molding offers allows for the molding of intricate and near-impossible designs. Medical tools and equipment are of varying designs and dimensions that are not unattainable for injection molding.

Scalability: This is essential to the medical field as the need for medical tools and instruments continuously gets increasing requests. Nevertheless, injection molding meets that need effortlessly as the cycle time involved in making different parts is fast and efficient. 

Repeatability: The ability to manufacture consistent medical parts repeatedly makes injection molding absolutely the best for the healthcare industry. The cycle times are repeated without encountering too many blemishes. 

2. Material Selection for Medical Injection Molding

2.1 Biocompatible Materials

Material selection in injection molding has consistently proven to be an important aspect that can either adversely affect production or be beneficial. However, selection is based on the qualities the material manifests and the performance requirements of its application. For medical purposes biocompatibility must be topnotch and a material’s ability to perform optimally should be second to none. That’s why tests are executed in determining the best material to be selected using industry-prescribed attributes for specific applications. 

Nevertheless, medical injection molding materials include polypropylene (PP), polyethylene (PE), polycarbonate (PC), and polyurethane (PU). These medical-grade thermoplastics are selected based on the mechanical qualities they exhibit, and their suitability for medical purposes. These mechanical properties are likened to their flexibility, strength, and chemical resistance. Moreso, silicon elastomers also play crucial roles in medical injection molding. 

2.2 Sterilization Compatibility

Amongst all industries, the one that does not permit microorganisms and contaminants in its equipment and tools is the medical sector. In eliminating any possible contaminants and ensuring the safety of these materials, sterilization compatibility measures have been set to nullify them. And they are not limited to but include

  • Steam autoclaving: In steam autoclaving, materials meant for medical injection molding are immersed in extreme temperature and pressure as they are expected to have high resistance to heat and withstand the autoclave process. Once this is completed, the materials under this test should retain their qualities without deformation or degradation. The steam autoclaving process favors thermoplastics like polycarbonate (PC) and polypropylene (PP). Thermoplastics like PVC on the other hand cannot withstand such heat.
  • Ethylene Oxide (EtO) sterilization: This form of sterilization unlike steam autoclaving is a low-heat sterilization method. Yet it suits high-temperature sensitive materials. Ethylene oxide sterilization entails the penetration of the ethylene oxide gas into the material to ensure the decontamination of the material.
  • Gamma irradiation: This is the exposure of materials to high radiation which dispels unwanted properties in the material. Though, some materials experience degradation due to severe radiation exposure. Materials such as polypropylene are in such a category of materials that can not endure the heavy radiation they are exposed to. 

2.3 Chemical Resistance and Durability

A material’s ability to offer chemical resistance among other features it possesses gives it an extra advantage over some of the other materials. Materials are often exposed to several chemicals during medical use or operation. 

Chemicals such as bodily fluids, disinfectants, and solvents included are chemical substances that can deteriorate the qualities of a material that isn’t suited for this harshness. For instance, polyethylene, polycarbonate, and polypropylene are some materials with excellent chemical resisting attributes. 

Likewise, durability also contributes to the long-term use of the medical tool. Usually, materials are subjected to all kinds of stress patterns to determine how reliable they will be during their lifespan. Additionally, fiber and fillers in some cases are infused to boost material strength and performance considering wear and tear in the material lifespan. 

Medical examination room

3. Design and Manufacturing Considerations

3.1 Design for Manufacturability (DFM)

Designing and manufacturing considerations are as important as any other medical injection consideration given that they contribute to the overall outcome of the part being manufactured. 

With design considerations, factors such as draft angles, parting lines, and wall thickness are often key considerations. Draft angles are what ensure that the medical component being manufactured is easily ejected from the mold without defects and without compromising the reliability of the component. 

Also, adequate wall thickness ensures that the part is intact and compact. Optimizing wall thickness translates automatically to production efficiency and effectiveness. Meanwhile parting lines are responsible for ensuring a seamless separation of the molds while maintaining component soundness.

On top of that design for manufacturability is likewise hinged on certain requirements including proper gate placement, a steady flow path, and sufficient venting. The full optimization of all these additional parameters guarantees a perfectly molded medical piece using injection molding. 

3.2 Tooling and Process Validation

Tooling in medical injection molding is an important part of design and manufacturing. Unique tools such as mold are required to accurately fulfill the manufacturing standards of medical devices. The mold’s capacity to manufacture top-quality medical instruments is often a high priority consideration. 

As a result, high-quality mold manufacturing with apt attention to detail ensures reliable molds employable in manufacturing medical tools and equipment. In medical injection tooling, molds with uniquely built materials such as aluminum or steel must ensure tight tolerant standards to assist with the intricate designs of medical devices. 

As per the process validation, this is to ensure that the injection molding process parameters are duly met to increase manufacturing competence. This entails alignment of the component’s construction with the mold design and the requirements for the desired parts. In doing this, the temperature, pressure, and cycle time are considered accordingly. 

3.3 Quality Control and Testing

In the high-quality mold manufacturing industry, procedures that ensure compliance with industry regulations and requirements in each process are vital. Also, precise tests to ascertain quality and performance of the final products are established. 

These monitoring procedures and steps are commonly referred to as quality control and such evaluations are also present in medical injection molding. Hence, quality control standards are essential to avoid complications and controversies before and after the manufacturing process. 

For medical components, quality control measures include dimensional inspection which inspects and ensures the component design alongside the specified tolerances required for such part manufacturing. Tools deployed for such inspections range from coordinate measuring machines (CMMs), to vision systems and optical scanners. 

Various tests are implemented in the quality control process. One such is a visual test which inspects the presence of defects or hidden flaws. Furthermore, the material test is done to check for material properties such as flexibility, strength, durability, and optimal performance. 

Then comes the biocompatibility test, which is the most crucial test of all as it inspects the component’s alignment with the human body. If the biocompatibility test isn’t successful, then the part isn’t worthy of use in the field. 

All necessary quality control test standards are to be validated by the medical sector quality and standard management institutions represented by QSR and ISO 13485 standards. 


4. Applications of Medical Injection Molding

4.1 Medical Device Components

While new inventions like 3D printing technology offer innovative manufacturing methods, medical injection molding is a more versatile tool in the production of medical components. Medical device components assist in administering medical services reliably and efficiently. Some of the medical devices manufactured by medical injection molding include.

  • Syringes: This medical device is a well-known device even for children. Syringes are manufactured employing the medical injection molding method. It is a critical medical instrument deployed for the proper administration of medications to patients. Just ask a child what a syringe is, and you’ll be surprised. It entails creating syringe barrels, caps, and plungers which require precision and uniform dimensions, and tight tolerances. 
  • Connectors: These are multifaceted medical devices that permit and enable the easy passage of fluids, connect other medical tools, and certify a leak-free connection. Connectors can possess intricate dimensions but with injection molding, it becomes an easy-peasy lemon-squeezy. 
  • Catheters: These are another kind of medical device that aids the comfort of patients while in a procedure. These devices have hugely been a success due to the employment of injection molding in forming their parts such as the hubs, tips, and tubes. 

Insulin pens, inhalers, and infusion sets are the other medical devices deployed in providing healthcare to individuals who require it, all due to the precision of injection molding. 

4.2 Surgical and Dental Instruments

The dental and surgical departments of the medical field aren’t left out as part of the beneficiaries of instruments formed by injection molding. Surgical and dental tools rely on sterilization compatibility, precision, and user-friendly designs in carrying out patient treatment in the safest form possible. 

  • Surgical tools: With surgical tools, instruments such as scalpel handles, forceps, and retractors are all devices created from injection molding. With the use of injection molding the functionalities of these surgical instruments are phenomenal. Medical practitioners can get a good grip and ensure the accurate delivery of medical services to patients, with their safety as number one. 
  • Dental instruments: a huge stakeholder in the injection molding method of manufacturing medical components is the dental department. Mirror frames, handles, and other tool handles are made by injection molding. What dental patients seek is comfort and with the right tools the dentist can perform his duties efficiently. With the ability to withstand sterilization measures, these tools can retain their mechanical qualities.

Bone plates, screws, and discs can also be categorized as part of surgical tools which also require dimensional accuracy, strength, and biocompatibility for the effective performance of these tools. 

4.3 Healthcare Equipment and Packaging

The healthcare equipment and packaging applications of plastic injection molding offer barrier properties and chemical resistance properties that ensure long-lasting, safe, and functional qualities of packaging and healthcare equipment. 

Healthcare injection molded components include respiratory tools, ultrasound equipment, and blood pressure monitors. The functionality and longevity of these tools are enabled by the integration of user-interface units, housings, and other geometrically complex features. 

Diagnostics equipment manufactured by injection molding are medical imaging tools, test kits, and laboratory instruments. These important components are reliant on the efficacy of the injection molding process. And the efficacy of this method provides sterilization capacities, accuracy, and reliability in dispensing precise results to potential customers.

Packaging instruments in the medical and healthcare industry are recipients of injection molding. They are custom-made and pocket-friendly, hence their applicability in the industry. Trays, containers, and packs of different shapes and sizes are produced by injection molding methods. And they provide safety, organization, and tamper-proof features. 


In a nutshell, this means that injection molding has been a major part of the medical world, and its reliability in the manufacturing process makes it indispensable. From benefits such as scalability, repeatability, flexibility, and budget-friendliness; to material selection which includes biocompatibility, sterilization compatibility, and chemical resistance and longevity. In addition, design and manufacturing considerations must be factored, with tooling and process validation and quality control and testing at its core. Conclusively, its application is versatile in manufacturing healthcare and packaging, dental and surgical, and major types of medical device components. 


Gary Liao

Gary Liao

Gary Liao is the Engineering Manager of TDL Company and has more than 20 years of mold design experience.

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