Did You Know?

Did you know what is interesting about medical device manufacturing? It is this razor-thin balance between state-of-the-art technology and regulatory compliance. And in the case of injection molding of medical equipment—well, there you go, the real fun commences.

You are in the medical device business, so you have likely pined over the issue of FDA requirements, pondered over clean room classifications, or perhaps even lost sleep over validation protocols. Believe me, you are not a single case. So let me take you through all you want to know about injection molding of medical devices, and I assure you that it will be real, no corporate language, no complexity that is not necessary.

The Reason Why Medical Device Injection Molding Is Not a Typical Manufacturing Process

The thing is that medical device injection molding is not all about melting plastic and blasting it into a mold. When you are making parts that may end up in someone’s body or when dealing with important fluids, the cost is astronomically higher than something like, say, a phone case or a toy.

It is a very detail-oriented process. We are talking about tolerances in thousandths of an inch, materials which must retain their properties after sterilization, and documentation which would make a novelist envious. But honestly? It is this that makes it so enticing.

Medical injection molding is the combination of engineering and life-saving potential. Each small part, whether a syringe barrel, a surgical instrument handle, or a drug delivery device must work perfectly. Safety of the patients is a matter in which there is no such thing as good enough.

The Role of FDA (And Why They Are Actually Your Friend)

I want to clarify one thing first: the FDA is not out to make your life hard. It may seem like that when you are up to your knees in documentation, but their requirements are there because of very excellent reasons.

Medical devices are divided into three classes by the FDA, and the classification defines how far you will have to dig in order to achieve compliance:

• Your low-risk things would be Class I devices, i.e., tongue depressors or bandages. The needs in this case are not all that complex, but the term relatively is doing a lot of work in that statement.
• Class II devices are such things as powered wheelchairs or pregnancy test kits. We are now entering more serious areas of special controls and in many cases a 510(k) premarket notification.
• The most demanding requirements are imposed on Class III devices such as pacemakers, heart valves, and other life-supporting devices. When you are processing parts to make these, you had better strap yourself in because you are in for a thorough ride through FDA rules.

But what is important here is this: whether you are classified as a drug or medical device, or both, you are supposed to adhere to Current Good Manufacturing Practices (cGMP) as per FDA. And when it comes to injection molding, it is showing that you have the ability to control all processes of your process.

Clean Rooms: The Intersection of Science and Sterility

It is… it is an experience to enter a clean room. The air is different, fresher somehow. Everything gleams. And those bunny suits? They are not ornamental.

The classification of clean rooms is done in terms of the number of particles per cubic meter of air. The lesser the number, the cleaner the room. In the case of injection molding of medical devices, you will normally work with:

• ISO Class 7 (Class 10,000): This is your basic starting point with many medical device applications. No more than 352,000 particles (0.5 µm or greater) are contained in the air per cubic meter. Sounds too much? It is in fact extremely clean compared to what is in normal room air.
• ISO Class 8 (Class 100,000): Less stringent requirements, appropriate to devices that do not make direct contact with body fluids or tissues. Here you will get approximately 3.5 million particles per cubic meter.

There are some highly demanding applications that demand ISO Class 6 or even Class 5. At these stages, we are dealing with air that is so clean that a single individual walking through can raise contamination issues.

The Real Question: How to Keep Clean Room Integrity

Designing a clean room is another thing. How to maintain it clean when you are running high-volume injection molding? That is where it becomes dicey.

Consider this: injection molding incorporates heating up materials to hundreds of degrees, hydraulic systems pumping up and down, mold opening and closing thousands of times. All this action desires to produce particles and pollution. It is as though you are attempting to maintain your kitchen immaculate as you prepare a Thanksgiving dinner for twenty people.

The remedy is a multilayered control. HEPA filtration systems are overworking, and they maintain positive pressure, which prevents the entry of contaminants. Operators are strictly followed as far as gowning is concerned—I mean strictly. Leave the morning coffee at home: you are not allowed to carry it anywhere close to the production floor.

Specific attention should be paid to equipment as well. The run-of-the-mill injection molding machines will not do. You require machines built to be used in a clean room; their hydraulics must be sealed, they use special lubricants, and the surfaces are not prone to shedding particles. Other plants also employ the use of electric machines to get rid of hydraulic oil completely.

Material Selection: More Involved Than It Seems

Selecting the proper material to be used in the injection molding of medical devices is similar to selecting the right ingredient for a recipe—except there is a lot more at stake, and the FDA is hovering over your shoulder.

Any thermoplastic is not going to work. Medical-grade resins must be biocompatible (hello, ISO 10993), survive sterilization, and frequently must be transparent or have a certain mechanical property.

Typical players are:

• Medical-grade polycarbonate: Sturdy, clear, and is a radiation sterilization champ.
• Polyethylene: Chemical resistant and flexible, ideal in containers and tubes.
• PEEK: PEEK when you need something that scoffs at extremes.
• Liquid silicone rubber (LSR): When it comes to those plush, supple parts that have to get along with human flesh.

However, the twist is that you must have total traceability of these materials. Each pellet must have a paper trail. The suppliers are required to issue compliance certificates, and you can bet the FDA would like to see them at audit.

Process Validation: Demonstrating Your Process is Working One Hundred Percent of the Time

I told you documentation would make a novelist jealous? That is where process validation really pays off.

The FDA demands that you demonstrate, not merely assert, that your injection molding procedure is repeatable so as to yield devices that are in specification. This is comprised of three steps which will be very familiar:

• Installation Qualification (IQ): Demonstrating that your equipment is installed properly and to specification. All the gauges, all the sensors, all the safety systems must be checked.
• Operational Qualification (OQ): Showing that the equipment will perform correctly within the planned range. You will test the machine in different conditions and report it all.
• Performance Qualification (PQ): The Mega. Producing real product to demonstrate that the process will always make good parts. We are talking statistical analysis, capability studies, and volumes of data to fill a small library.

And then when you think you have finished? The process of verification continues so that nothing drifts with time. This is because processes are a funny thing that change when you are not looking.

Some of the Most Common Traps (and How to Avoid Them)

I have witnessed some amazing failures in this industry after several years. No, not to frighten you; it is better to learn from other people’s mistakes than make your own.

The first one is underestimating documentary requirements. The casual alteration of cooling time? Document it. Lots of switched materials? Document it. Sneezed about the machine? Okay, not that, but you see what I mean.

Even the most experienced molders get caught up in contamination control. The negligence of one operator in the correct gowning procedures can poison the whole batch. That is why training, the ongoing, comprehensive training is so important.

Poor maintenance of molds is also a killer. Medical molds are exposed to harsh environments and stressful cycles. Leave it up to neglect maintenance and you will see quality drift quicker than you can say corrective action.

The Human Element: Team Training to Win

Technology and processes can take you so far. Medical device injection molding is made or broken by your people.

Training is more than educating a person to use a machine. Your team should know why each procedure has been established, the effects of their actions on patient safety, and the consequence of failure. It is a lot of work; however, it produces a culture where quality is not just a department, but it is the responsibility of all.

Training refreshers are not only a good thing but a must. There is the natural tendency of complacency. That time-saving thirty-second shortcut? It may appear to be harmless, yet it may lead to a deviation that may cause weeks of delay in shipments.

Future Trends: What is Coming Next

The medical device injection molding environment continues to change. Micro-molding takes things to the edge, whereby components are made so tiny they cannot be seen. The various materials used in multi-shot molding have been formulated in a way that was not imaginable a decade earlier. And automation? It is transforming the way clean rooms operate and eliminating the risk of human interference and contamination.

The topic of sustainability is also getting larger. What is the trade-off between single-use safety and environmental responsibility? It is an issue the industry is addressing head-on with inventive materials and recycling programs becoming popular.

Your Way To The Future

It is not easy medical device injection molding. Had it been, everybody would do it. This is combined with technical accuracy, regulatory conformity, and consistency in quality standards resulting in entry barriers that lock out less serious participants.

But to the ones who want to take the challenge? The payoffs are huge. It is not just a plastic shaping process; you are making parts that enhance and salvage lives. Each achievement of a production cycle is a sign of millions of patients, who will be grateful for your quality commitment.

Begin by having a good idea of what type of device you have and what regulations govern it. Develop your quality system from the ground up, not as an add-on. Make good investments in equipment, materials, and most importantly, in people. Write down everything, check it, and do not stop making it better.

Transforming an idea into a compliant medical device component is a complicated, challenging, and sometimes even frustrating process. But when you have that first approved bit, that you know is all right and will do good to the patients somewhere? That is what is worth all the effort.

Just keep in mind that the FDA and clean room requirements are not the enemy; they are the guardrails that make everybody drive on the right side of the road, so to speak, and that is patient safety. Learn to embrace them, learn to master them, and you will succeed in one of the most rewarding areas in manufacturing.

Are you ready? Welcome to the world of injection molding of medical devices, and do not believe me—it is not dull.