If one were to cite the manufacturing processes most crucial to the medical device industry, it’s fair to say injection moulding would rank high up the list. Ideal for producing large volumes of parts, and therefore meeting the needs of a sector that works on impressive scales, this technique has been around for decades but became increasingly sophisticated following the advent of computer-aided design (CAD). Today, if you want to drive down costs and ramp up quantities, injection moulding may well be your go-to solution.

"It offers a wide range of opportunities for medical device companies to produce more ergonomically correct components, and allows them to use a large variety of antimicrobial materials," says Gus Breiland, customer service engineering manager at Proto Labs. "The injection-moulding materials and manufacturing processes are much better now than they’ve ever been before."

The technique has become particularly popular in recent years, given the drive towards miniaturisation. Injection moulding is well suited to manufacturing parts with precision, meaning the final product can be as thin, light and sleek as required. Today’s techniques allow engineers to fill a geometry that would have been impossible in years gone by.

Similarly, as ever more products become single-use only, environmental factors are more important – you need to be able to dispose of that device in a clean and sustainable way. With injection moulding, you can ensure the product can be incinerated and won’t end up as landfill.

The techniques in question do, however, require a high degree of specialisation, generally beyond the remit of your typical small-to-medium medical device company. For this reason, many companies choose to outsource their injection-moulding activities to one or more contract manufacturers.

Step by step

"Most companies use a four-stage process, which is phase one of demonstration, phase two of design validation, phase three of product launch and phase four of post launch and production launch," explains Breiland. "Any company would love to minimise the number of manufacturers they use within that process – they can control consistency and don’t have to explain their intentions five times to five different manufacturers. So the key aspects for OEMs is trying to find companies that can support them through all phases of development."

Unfortunately, sourcing a contract manufacturer that covers all bases can be tricky. Once stage two has been accomplished, and a company has passed through its design verification, it is necessary to comply with a greater range of rules surrounding clean room, packaging and handling. Not all injection-moulding manufacturers have the necessary facilities in-house.

"If you’re fortunate enough to find a contract manufacturer that can accept the entire project and source all those items, that’s a true find."

At Proto Labs, for instance, the company’s involvement is confined to the early stages. Given that it focuses on prototypes and low-volume production – specifically, producing injection-moulded parts at speed from a company’s 3D CAD model – it is not equipped to deal with the latter part of the process. That is where a separate injection-moulding company, tailored toward high-volume orders, would come in.

Luckily, this does not have to entail extra hassle for the client. As Breiland puts it: "What we try to do is minimise the amount of time it takes to get to that prototype, so the customer can focus on finding the next stage and can get to market faster by reducing their overall cycle time."

In other instances, the initial contract manufacturer may in fact orchestrate the next part of the process, finding a subcontractor that can take on a different part of the assembly. For instance, the OEM might find a design house that can take ownership of the whole project, sourcing the various components of the assembly from suitable contractors as required.

"If you’re fortunate enough to find a contract manufacturer that can accept the entire project and source all those items, that’s a true find," says Breiland. "Some manufacturers are there to serve a purpose, and they specialise in one aspect of that assembly. But there are always different levels of contract manufacturers, and typically there’s a third party that will find all the manufacturers and eventually hand over an actual product for the OEM to test and continue with."

Keep in touch

So how can an OEM ascertain what will best suit their needs, making sure their chosen contract manufacturer is a good fit with their organisation? The intuitive – yet often neglected – answer is communication.

For any company that is outsourcing parts of its process to a contract manufacturer, it is important to instigate a dialogue right from the outset. They should not assume that their latest contractor will do things the same way as their previous contractor; every organisation is different and has its own specific, even idiosyncratic, working practices.

"Sometimes, in the need for speed, there’s the assumption that the drawing will say everything and that the contract manufacturer will come back to you when they have questions, but that’s the wrong approach," warns Breiland. "You want to be on the phone to them, asking the questions that make you comfortable with them. It’s very much like if you’re buying a car – you’re not just going to send a cheque and expect someone to deliver something to you. You want to develop that relationship."

This may entail confronting the contract manufacturer directly if there are any concerns or suspicions.

"That’s how we learn what they need, and how we learn to work better with our customers," Breiland explains "The other thing is trusting your gut feeling – if you don’t like what you’re hearing, and the contract manufacturer isn’t conforming to the things you need for the project, that’s a good sign that you need to find someone else – and that’s OK. Pushing the manufacturer past their capabilities isn’t always going to result in that manufacturer gaining experience and giving them the product you want. Sometimes you need to move on."

In situations where the OEM and contractor are mismatched, it can be tempting to stick with what has been started so as to avoid unnecessary delays. For the most part, however, it is better to accept the slight setback in the process and find a partner that better suits your injection-moulding needs. As is always the case in outsourcing, cultural affinity is crucial; both parties need to feel that they’re aligned in working towards a common goal.

After all, there are many experts working in the field of injection moulding, and experts are not immune from working at cross purposes. It is crucial that the OEM understands its contractor’s manufacturing processes and capabilities, and allows its designers and engineers to provide recommendations as to where those capabilities would be better served.

Give and take

Naturally, this works both ways. The contract manufacturer should also feel free to give suggestions and take some ownership over its part of the development process. It may struggle to provide an adequate service if no concession is made to its own preferred modes of working.

In fact, the OEM needs to pay attention to its own design first and foremost. When creating any plastic part, it is vital to use a uniform thickness and draft. Ideally speaking, draft would be kept to a minimum, but there should be consistency in its geometry either way. This will help standardise the temperature of the part, and ensure the moulder does not struggle with injecting resin through the cavity.

"In real estate it’s ‘location, location, location’ and in manufacturing it’s ‘communication, communication, communication’. That’s the biggest driver of success."

"The more efficiently you make a stamping die or injection mould work, the more you follow the basic rules of uniform wall and draft, the better the moulder is going to be able to support your geometry," Breiland explains. "Challenging the process is good – that’s how the industry grows and that’s how a geometry becomes groundbreaking. But if you completely ignore some of the fundamental rules, then whether that be plastic injection moulding, whether it be casting or whether it be liquid silicone rubber, the manufacturing process won’t work well."

He believes that there is a balance to be struck between complete prescriptivism and an overly lax approach to design.

"Always be collaborative, and always try to leave some room in your design for modifications, to make manufacturing easier," he advises. "But communication is key. In real estate it’s ‘location, location, location’ and in manufacturing it’s ‘communication, communication, communication’. That’s the biggest driver of success, and the biggest hindrance to success is making assumptions and not communicating with your manufacturing group."

With injection moulding now firmly entrenched as an indispensable part of the manufacturing process, these words are set to remain pertinent for some time to come. Especially where you will be relying on not one but several contract manufacturers, it is absolutely crucial that all parties are on the same page and that you can trust them to handle your injection-moulding needs with aplomb.