RIM, known as Reaction Injection Molding, is now broadly applied in medical device development. This article will discuss the following topics:

1. The medical device development process.

2. The reasons why RIM is applied in medical device development.

The medical device development process

Compared with other industries, medical device development is facing many industry-specific problems. Medical device companies not only need to solve common design problems but also take great responsibility for patient safety and are subject to multiple and extremely strict regulatory guidelines.

Then how is a new medical device developed? Usually, it will take at least 9 steps.

1. Confirm the development plan

The medical device company needs to make sure what kind of products they want to develop, during which they need to list the laws and regulations of their target markets and do risk analysis in advance. After that, the team needs to come up with a product design and development plan, covering the staff involved and their responsibilities, timeline, milestones, and specific plans, as well as the resources needed.

2. Design and development plan review

Review the plans based on clear standards to figure out their deficiency, errors, and contradictions to improve.

3. Design and development of the medical device

During the design phase, product design files must be finished, such as assembly diagrams, part diagrams, schematic diagrams, block diagrams, production drawings, and motion diagrams. 

4. Design and development review

Review the designs to figure out their deficiency, errors, and contradictions to improve, to ensure the standardization of the whole process and the effectiveness and safety of the final product before it is on the market.

5. Verify the medical device designs

After all the design and development work is done, it is time to start a series of verification testing. It involves product testing (for example in-process testing, finished product testing, performance testing), packaging testing/verification, testing and verification of materials, aging testing, testing of stability and reliability, key process feasibility testing, verification of reliability and stability, sterilization verification, compatibility test with other instruments, drug compatibility test, and leach test.

In the period of product testing of medical device development, rapid prototyping is involved. If the amount needed is not big, for instance, 1 set or 2 sets, CNC machining is the most economical prototyping method. If the amount is larger, for smaller-sized plastic medical devices, vacuum casting is the optimal manufacturing way. For large-sized and thin-walled ones, reaction injection molding is a better option.

6. Confirm the design and development

Medical design and development confirmation need to be done through clinical evaluation. It includes non-clinical studies and clinical trials. 

7. Design and development conversion

After confirmation, preparation work, which involves making medical device prototypes and trial production, should be done before mass production.

8. Design and development modification

Modification may happen during and after design and development.

9. Registration

When the design and development are finally confirmed, the medical device company must register the product to be proved for selling.

As a rapid prototyping and low-volume production service provider, X Rapid Technologies is deeply involved in Phase 7. In most cases, we make medical device prototypes through CNC machining, vacuum casting, and 3D printing. Afterward, mass production will be done by reaction injection molding.

The reasons why RIM is applied in medical device development

People often choose plastic injection molding as the machining method of mass production. Although the cost at the earlier stage of injection molding is high, its economic advantages, such as the extremely high production molding efficiency, long service life of the mold, and high output production, to a certain extent, offset the high mold cost.

However, for large-sized medical devices, in most cases, each hospital only needs to purchase one at most. The production quantity often does not meet the MOQ of plastic injection molding. Or, even when plastic injection molding is applied, the quantity produced is not enough to offset the excessively high cost of the mold. At this point, RIM is an excellent choice.

RIM (Reaction Injection Molding) is a process for making unreinforced thermoset parts rapidly in an environment of low pressure and room temperature. It uses a simple resin injection system with two pressurized chambers. Because the raw material is liquid, it can fill the mold cavity quickly under low pressure. So it reduces the clamping force and the cost of the mold, thus especially suitable for the production of large-sized parts. All the advantages of RIM are as follows:

1. Shorten the product development cycle and reduce product development cost

Because of the low-pressure injection nature of the RIM process, the mold is usually made of epoxy or aluminum. The mold cost is much lower than that of plastic injection molding, and it takes less time to process. So it is super suitable for short-run and prototype production. In this case, RIM widely shortens the product development cycle and saves product development costs, thus enabling the developer to enter the market quickly and seize the initiative.

2. Suitable for the production of large-sized, small-batch, and high-quality products

Because of the low viscosity and good liquidity of raw materials, RIM can form complex parts under very low pressure. It has the incomparable advantage to produce enclosures with larger areas. The wall thickness can vary from 6mm to 28mm in the cross-section of the same molded part, which is incomparable to other processes. Therefore, the products with large wall thickness variations can be molded in one piece to improve the reliability of product quality. The sizes of the product are stable.

3. Its process of encapsulating the inserts is very simple

You just need to put the inserts into the mold. The encapsulation will be done during the molding process. It is widely used for encapsulating steel or aluminum structural frames, window glass, electronic sensors, etc. 

4. In-mold finishing

The painting can be applied to the mold before injection. And it can be integrated with the polyurethane material during the molding process to complete the finishing of the part in the mold. You have to paint after injection, thus reducing the costs.

5. The products are of high quality

Products made by RIM have high strength, low weight, dimensional stability, good corrosion resistance, good weather resistance, and good impact resistance. They are also heat-resistant and heat-insulate.

Apart from short-run production, RIM can also produce medical device prototypes. No matter whether your project is during development, in the pre-production phase, or ready to be manufactured, X Rapid Technologies is always here ready to help you to make medical device prototypes and products. We are also delighted to offer design suggestions from the perspective of a manufacturer.

FAQs of medical device prototypes

1. What materials are available for medical device prototypes?


If there is no special requirement for material, ABS is the first choice. It is easy to be machined and post-treated.

For transparent parts, you can choose transparent PMMA, PC, or transparent ABS.

For wear-resistant parts, you can choose POM or PA (nylon).

For parts of high tenacity, you can choose PA (nylon) or PP.

For heat-resistant parts, you can choose epoxy resin, bakelite, black PC, or PA (nylon).


Aluminum 6061-T6 is the cheapest and most common option.

Other metals include copper, brass, zinc, stainless steel, steel alloys, magnesium, etc.

Soft rubber:

In rapid prototyping, soft rubber parts can be made via vacuum casting. The raw material is PU.

2. Can you do the assembly work?

Yes, as long as you provide the 2D drawings for assembly. To make sure there is no interference with other parts, even if we don't need to do the assembly, it will be better if you let us know if the parts we make have assembly relationships with other parts. We will also check all the files before manufacturing to figure out if there are interferences between parts and provide design modification suggestions.

3. What is the average shipping fee for shipping medical device prototypes to countries outside of China?

The sizes of medical device prototypes are usually large, so it is not easy to estimate the shipping fees. In cases where you need to know the freight during the quotation period, we will try to simulate how the parts can be packed and offer an estimated package size and shipping fee.