Plastic injection molding involves heating plastic polymers to their molten form, then injecting them into an aluminum or steel mold where they solidify into the desired shape. The technique is the go-to method for creating several plastic parts and components.
This additive manufacturing process is a mainstay in the medical industry because it gives rise to products that adhere to stringent FDA regulations and other medical regulatory bodies.
Manufacturers of medical injection molding parts use medical-grade plastics to ensure each fabrication suits its intended purpose.
This article discusses the rudiments of plastic injection molding for the medical industry, including its advantages, applications, and other injection molding techniques.
Without much ado, let’s get right into it.
Benefits of Plastic Injection Molding for Medical Parts
Plastic injection molding is superior to other manufacturing techniques, especially for creating medical parts. Below are some of its advantages to the medical sector.
A Wide Range of Material Choices
Injection molding allows machinists an extensive array of materials, regardless of the stringent specifications that the medical industry demands. The technique is suitable for different kinds of plastics, including engineering and medical-grade thermoplastics.
These materials include polypropylene, ABS, polyethylene, and PEEK, all sterilizable and biocompatible, further reinforcing their use in the medical industry.
Cost-Efficiency
The technique of injection molding medical parts is cost-effective. It supports high volume reproducibility of identical parts, which helps streamline the process and cut production costs.
The process helps reduce the cost of quality healthcare by fabricating medical devices, components, and other products at a reduced cost per part.
Durability
A critical feature of injection molded parts is their extreme durability. They are often crash and abrasion resistant. Likewise, they can withstand high temperatures and adverse use and environmental conditions.
Many medical products often undergo harsh treatments, especially heat sterilization – consequently, the need for parts that can withstand such treatments.
Exceptional Accuracy
Medical devices and products deal with delicate components, so high dimensional accuracy is needed. Should a product fail to reach precision standards, it may prove fatal.
That said, injection molding is an automated manufacturing process, ensuring products meet high tolerance and precision requirements.
Resistance to Contaminants
Sine medical products interact with blood and internal human structures. It is paramount that the production process evades contamination. Indeed, these components undergo further sterilization to confirm that they are germ-free.
A manufacturing process like injection molding that limits contamination reduces sterilization needs and ensures that products meet FDA requirements.
Applications of Plastic Injection Molding in the Medical Device Industry
Plastic injection molding guarantees products of high quality and meets safety and other FDA standards. Consequently, the vast application of this procedure in creating medical devices.
Below are typical applications of injection molded parts in the medical industry:
- Medical housings and enclosures, including laboratory and diagnostic equipment, monitors, insulin pumps, etc.
- Surgical implants
- Knee and joint replacements for orthopedics.
- Different surgical equipment, including handles of scalpels and forceps.
- Components of drug delivery systems.
- Simple lab supplies and essential medical equipment like blood bags, test tubes, catheters, syringes, masks, nebulizers, insulin pens, beakers, etc.
- Containers and various packaging for pharmaceuticals.
The Materials Used in Medical Injection Parts
As mentioned above, manufacturers use a group of materials ( medical-grade plastics) to create medical plastic injection molded parts. Note the plastic of choice is often restricted to thermoplastics because of their better heat pliability.
Below are typical materials used in medical injection parts.
Polyethylene (PE)
Polyethylene is a standard engineering thermoplastic suitable for various applications, including manufacturing medical parts and products.
The polymer aggregates thousands of ethylene monomers, providing the plastic with considerable strength, versatility, and chemical, environmental, and impact resistance.
In addition, it is highly pliable and easy to process, making it an economical material. Polyethylene is suitable for manufacturing tubings, pharmaceutical containers, connectors, IV sets, and more.
Polycarbonate (PC)
Polycarbonate is a tough, strengthened medical-grade plastic polymer. It has excellent mechanical and chemical properties, including flexibility, high temperature, impact, and abrasion resistance.
It also possesses excellent biocompatibility, making it highly suitable for manufacturing medical gadgets. This suitability makes it ideal for creating various medical injection molded parts, such as medical housings, blood filters, reservoirs, oxygenators, surgical instruments, etc.
Polyetheretherketone (PEEK)
PEEK is a standard engineering plastic polymer with suitable characteristics for various applications.
It has high performance and is resistant to harsh conditions and environments, including chemicals, thermal degradation, and radiation. This durability ensures it confers products of high dimensional accuracy.
Besides its top-notch properties, it possesses excellent biocompatibility. It is a common material for injection molded surgical implants and equipment parts.
Standard products fabricated with PEEK in the medical industry include dental implants, hip and knee replacements, forceps, etc.
Polypropylene (PP)
Like polyethylene, polypropylene is one of the most used engineering-grade plastics because of its suitable chemical and mechanical properties.
In fact, it is more rigid and possesses higher temperature resistance. In addition, it is lightweight and highly durable, reinforcing its use in the medical industry.
It manufactures medical packaging, pharmaceutical containers, connectors, tubings, hip and knee replacements, and laboratory apparatuses like Petri dishes and beakers, among others.
Silicone
Unlike other materials previously discussed, silicone is not a typical plastic. It is a synthetic, flexible elastomer comprising silicon, carbon, hydrogen, and oxygen atoms.
However, like other materials, it is compatible with biological molecules, making it suitable for manufacturing medical products.
In addition, it is resistant to high-temperature conditions and is suitable for injection molding. Also, it is an economical material, especially for bulk unit fabrications.
That said, it is a common material for creating breast implants, catheters, respiratory tubings and devices, watertight connections, pacemaker leads, etc.
Considerations For Selecting Materials for Medical Plastic Molding
Knowing that parts to be used in creating medical pieces and gadgets must meet strict requirements. There are specific criteria you must consider before selecting injection molding medical products. They include the following.
FDA Requirements
Any material to be used in medical products manufacturing must adhere to FDA guidelines of safety and biocompatibility. Before your product gets approved for human use, each step in the production process must be validated and verified to ensure it meets FDA standards.
The material will be checked for its potential for toxicity, leaching, compatibility with biological molecules, and overall safety.
Also, it must possess excellent physical, mechanical, and chemical resistance, considering some of these products may get exposed to harsh conditions. If any of the requirements fail, then it won’t be approved.
Therefore, you must check through FDA material guidelines to ensure the selected material suits your intended use. That said, when choosing plastics, it is best to use medical-grade plastics like the ones discussed above.
Withstand Sterilization Processes
Medical products and equipment must be sterile and devoid of microbes, pathogens, and contaminants. Therefore, the material selected for manufacturing such products must withstand extreme sterilization conditions.
It often involves exposing the product to high temperatures or chemical sterilants to ensure they are free of all contaminants, guaranteeing safety for use.
Again, it is better to select medical-grade plastics, as they often possess suitable properties capable of withstanding these extreme conditions without compromising their tolerance and precision specifications.
Operational Environment
Where the medical product or device will be used is another critical consideration when selecting materials. As mentioned earlier, many medical products get exposed to harsh conditions.
Therefore, the material chosen must possess excellent characteristics to prevent thermal or chemical degradation, warping, etc. Another thing to consider is biocompatibility, especially when creating implants and body parts replacements.
Durability and Strength
Plastics selected for medical injection molding parts must have good physical and mechanical properties. Indeed, plastics are brittle and fragile compared to metals.
However, medical-grade plastics possess considerable strength, toughness, and flexibility, making them highly durable. These features limit the chances of biohazards and allow the use of these products and gadgets for a long time.
General Use
The general purpose of fabrication should also determine the kind of material you select. For example, many medical products, like syringes, tubings, respirators, etc., are for one-time use.
Therefore, an economical, pliable, lightweight, and recyclable material is best. You do not want to overspend on such a process.
However, because of the intricacies of medical products, they must comply with the industry standard. In addition, you must consider ease of processing, chemical resistance, and biocompatibility.
Common Types of Injection Molding Techniques Used to Manufacture Medical Devices
Besides basic plastic injection molding, manufacturers and machinists adopt other techniques for manufacturing molded medical parts and products. Below, we will examine some of the common ones.
Thin Wall Molding
Thin wall molding is one of the most used techniques in injection molding. It involves creating thin – less than 1mm – and lightweight plastic parts at a high volume, saving production costs and shortening lead times.
This technique ensures that the parts produced are of exceptional precision and accuracy, making them valuable to the medical industry. Thin-walled components are cost-effective and avoid material wastage.
The technique allows manufacturers to integrate fine details, complex features, and intricate geometries into medical products, enhancing the parts’ functionality.
For example, it will enable the design of medical devices with precise drug dosing and drug delivery systems, microfluidic channels, etc.
However, it’s also suitable for more relatable and regular medical devices, including syringes, catheters, inhalers and respiratory devices, surgical implements, etc.
Gas-Assisted Injection Molding
Gas-assisted injection molding involves running a controlled quantity of pressurized gas (often Nitrogen) through channels in the mold cavity as you inject the liquefied plastic.
The pressurized gas presses the polymer against the mold, creating hollows, channels, and sections within the plastic as they solidify.
This technique’s main advantage is creating plastic parts with a smooth, delicate, and enhanced surface finish, eliminating sink marks and strengthening the plastic. It is typically used in creating hollow and complex features, such as frames of beds, wheelchairs, etc.
The technique is also suitable for housing medical devices, including enclosures for gadgets like insulin pumps and other wearable devices. However, the method is not suited for parts with sharp corners, considering it’ll inhibit the optimum flow of the pressurized gas.
Metal Injection Molding (MIM)
As the name suggests, this involves strictly using metal instead of plastic. It follows the same principle of injection molding, with the main difference being using powdered metal instead of plastic and resin polymers.
That said, it’s a suitable method for fabricating metallic components of medical products and devices. Indeed, plastics are highly beneficial, but so are metals.
For example, MIM guarantees products with greater strength and durability. Also, metal components play crucial roles when needing small-sized equipment with high density, enhanced design flexibility, and surface finishing.
The process is necessary for fabricating orthopedic and dental implants, surgical apparatus, prosthetics, endoscopic components, precision-based drug delivery systems, etc.
Liquid Silicone Injection Molding
Liquid silicone injection molding follows the typical plastic injection molding process. However, it involves creating parts and structures with molten silicone.
Liquid silicone rubber is a highly biocompatible material, making it a valuable material to the medical industry, especially for creating implants.
Like other injection molding techniques, it guarantees products with marked dimensional accuracy, resistance to harsh temperatures, and parts consistency.
It also supports other additive manufacturing methods, like overmolding, allowing the fabricating of more complex structures. Moreover, it is cost-effective and resistant to contaminants, further reinforcing its use in creating medical products.
Besides implants, the technique is suitable for creating catheters, tubings, seals and gaskets, baby care products, infusion pumps, respiratory masks, surgical equipment, etc.
Kemal: Your Expert for Medical Injection Molding Services
Do you need a partner to help you fabricate injection-molded medical products? Your search has ended; at Kemal, we offer premium injection molding services at competitive pricing.
We are an ISO 9001-certified company, so you are assured that whatever we manufacture adheres to FDA regulations.
Our facilities house some of the latest machines, with highly skilled professionals adept in the latest technologies, ensuring that your fabrication meets all your design specifications.
Besides medical injection molding, we offer services in additive manufacturing techniques like 3D printing and metal extrusion.
Also, we offer premium subtractive manufacturing services in CNC machining, sheet metal fabrication, etc. We advise the best way to build your project, especially for custom orders. Just upload your CAD files; we offer you a free DfM analysis.
Conclusion
Medical injection molding is used to manufacture plastic components in hospitals, pharmacies, and other healthcare facilities.
Having read this piece so far, you have a clearer understanding of plastic injection molding and how it benefits the medical industry.
As mentioned, the process can fabricate almost any plastic part, making it suitable for various industrial applications.
