Introduction : injection molding for medical is the go-to process for making medical supplies. It works by melting medical-grade plastics and then reshaping and molding them into the shape needed for medical devices.

This additive manufacturing process makes strong and durable medical injection parts with high-quality surface finish and high dimensional accuracy.

Also, since many medical devices are disposable, this technology is good for mass production while reducing the production cost of injection molding. Here we will talk about the basic ideas, main features, process flow, application scenarios, advantages and challenges of medical device mold injection molding in detail.

What are the Materials Used for Medical Plastic Injection Molding Process?

The medical injection molding process uses a wide range of material options to manufacture medical and pharmaceutical parts. There are various plastic injection molding materials used to make the process efficient. Some of them are .

Polypropylene (PP)

It is one of the most widely used plastics in the industry because it is durable. Polypropylene has strong chemical bonds and is a better material for making medical devices like beakers and test tubes.

Polyethylene (PE)

This stuff is the main thing in the plastic industry. It’s what they make a lot of industrial and commercial machine parts out of, and they make them in different stiffnesses. There are a lot of different kinds of it, and some of them are more durable than others. Some of the kinds are called LDPE, HDPE, and UHMW. UHMW is what they make most hip, leg, and other joint replacements out of.

Polystyrene (PS)

This is a strong plastic with almost no stretchiness. It is not bendy and has a high level of smash resistance and workability. It is mainly used for easily changed surfaces, has good size stability, and is very pretty.

Polyetheretherketone (PEEK)

It’s a thermoplastic that’s known for its high performance and excellent mechanical properties. It has high resistance to wear, radiation, tracking, and thermal degradation.

Polyoxymethylene (POM)

Polyoxymethylene, also known as polyoxymethylene ether, is a material that has excellent mechanical properties. It is often used to make parts that need to be very resistant to wear, like gears and bearings. It is also resistant to many chemicals and is pretty stable when it is around fuels, solvents, and many greases. It is easy to work with and is a common material for injection molding.

Polyphenylene Ether Sulfide Polyether Sulfone (PPSU)

Polyphenylene ether sulfide polyether sulfone (PPSU) can handle high temperatures of about 200 °C, has good stability to solvents and acidic and alkaline substances, and PPSU is radiation-resistant, so it is also used in radioactive environments. PPSU is transparent and can be used to make transparent medical packaging, steam sterilization equipment, etc.

What is the Process Flow of Medical Plastic Injection Molding?

Mold Design and Manufacturing

Mold design: First, based on the design drawings of the medical device or component to be made, design the structure and shape of the mold, including the mold cavity, gate, cooling system, etc. The quality of mold design will directly affect the quality and production efficiency of the final product.

The mold structure should meet the shape and size requirements of the product, and also consider factors such as the fluidity and shrinkage of the material.

Mold manufacturing: Injection molds are manufactured according to the mold design drawings. Generally, high-strength steel or aluminum alloy is used to make the mold to ensure the durability and stability of the mold.

Material Selection and Preparation

Material selection: Choose the right medical plastic materials based on what the product needs. Medical plastics usually need to be strong, work well with the body, and not get messed up by chemicals. Some examples are polypropylene (PP), polycarbonate (PC), and polyethylene (PE).

Different medical devices require different types of medical plastics, so the material selection needs to make sense based on what the product is.

Material preparation: Dry and pre-treat the plastic materials to make sure the materials are pure and stable. Pre-treat the selected medical plastic raw materials, including drying, mixing, color matching, and other steps to make sure the material preparation is good quality and stable.

Injection Molding

Heat and melt: Heat the plastic material until it melts and inject it into the mold using a screw or plunger.

Inject molding: The melted plastic goes into the mold through the gate, fills the mold, and makes the shape of the parts.

Cooling and solidification: The plastic in the mold cools and solidifies to form the final parts.

Parts Removal and Post-Processing

Remove the parts: Open the mold and take out the injection molded parts that have cooled and solidified.

Post-processing: Perform post-processing on the parts, such as trimming, polishing, and cleaning, to ensure the surface quality and function of the parts.

Quality Inspection and Packaging

Quality inspection: Inspect the parts for size, surface, performance, etc. to make sure they meet medical device standards.

The quality of medical devices is directly related to the life and health of patients, so we must strictly implement quality inspection. Common inspection methods include appearance inspection, dimensional measurement, tensile testing, biocompatibility testing, etc.

Packaging and storage: We package and store our qualified parts to make sure they stay safe and clean when we ship them to you and when you use them.

What are the Advantages of Medical Plastic Injection Molding?

Medical injection molding is a standout among similar production processes in the industry. With its smooth and seamless operation, the process has many advantages, including but not limited to.

High Precision and Accuracy

The medical industry needs to be super precise with its equipment because it’s dealing with blood and all the stuff inside your body. If you’re off by a few millimeters or inches, you can hurt people. That’s why injection molding is great for making plastic parts with super tight tolerances and maximum precision. Plus, it’s an automated process, so you don’t have to worry about human error or anything like that.

Little or No Material Waste

Just like any other manufacturing technology, injection molding for medical produces waste. When you manufacture parts, you’re going to have some excess waste. The nice thing about this process is that you can regrind and melt these excess parts and use them to make other parts. So, the waste generated after you manufacture medical prototypes is almost nothing.

Cost-Effectiveness

The way the medical plastic injection process is set up helps reduce unnecessary injection molding costs — large-scale production deliveries and high-volume manufacturing help maximize the process. Therefore, the injection molding process can reduce the cost per part whenever a large number of medical injection parts are produced.

Durability

Everybody knows that plastics used for injection molding are strong and durable. They have a lot of strength and can resist bad environments and use. So, the products made from this process can take heat, blunt forces, and vibrations without cracking or breaking. Also, when you sterilize them in an autoclave, they don’t fall apart from the high temperatures.

Ability to Withstand Sterilization Conditions

A lot of medical devices need to be sterile — free of any bugs and germs that can hurt people. That is, the sterilization process involves exposing these medical devices to tough conditions, like; high heat, radiation, or chemicals. So, the plastic stuff used to make sterilized instruments can keep their shape even after being in these tough places.

What are the Applications of Medical Plastic Injection Molding?

There are many ways to use injection molding in the medical device industry. People in the medical field like this process because the injection molded components can easily meet the quality and safety standards. Also, medical device plastic injection molding can help in these areas.The following are specific areas of medical applications .

Syringes

Injection molding manufacturing is widely used for producing various parts of disposable syringes, such as syringe barrels, plungers, and needle hubs, to ensure the accuracy and cleanliness of the products.

Medical Device Housings

Medical device injection molding is used to produce the housing and protective covers of medical devices, such as monitors, diagnostic equipment, etc., to ensure the strength and durability of the housing.

Surgical Instruments

Medical components for the production of handles and operating parts of surgical instruments, such as surgical forceps, scissors, etc., to make sure surgical instruments are accurate and reliable.

Laboratory Supplies

Used to make plastic supplies in labs, like culture dishes, test tubes, pipettes, etc., to make sure lab supplies are clean and accurate.

Conclusion

The new molding for medical devices is a game changer that’s shaking up the industry. Medical injection molding is one of the plastic injection molding process . It’s not just about making medical injection parts that meet industry standards, it’s about making them easy to use.

In this article, I’ll explain the basics and give you some important details . Zetar Mold is a famous injection molding manufacturer in China. If you have any injection molding services, you can always contact zetar mold .