Rapid Injection Moulding: Everything you Need to Know
X Rapid Technologies provides you with the guide to rapid injection moulding(molding). Learn about everything from the molds used to the process of RIM here.
Rapid injection molding: bringing part designs to life
Thousands and millions of companies in the demanding industries over the world use it to bring their parts designs to life. X Rapid Technologies’ rapid injection molding is a great solution, meeting particular conditions like customers who require low quantity plastic parts quickly.
Designing plastic parts which could be molded has always been quite important for the process of traditional injection molding. When there is a need for engineers to produce parts very quickly, they prefer rapid injection molding. Rapid injection molding ensures quality and speed remain constant at the time of manufacturing.
On this planet, the most famous technique for manufacturing parts of plastic is Rapid Injection Molding.
This process has scope for growth in the future. The parts that are produced in this process are used to create prototype parts for analysis of design. In this article, we are going to understand the meaning of rapid injection molding. The working of rapid injection molding and its benefits will also be discussed.
What is Rapid molding?
The process of rapid injection molding incorporates a swift tooling technique for delivering production-grade injection molded parts rapidly. The cost is quite low in comparison to standard tooling and the turnaround time is really fast. This rapid injection molding technology is great for buyers who require their parts with minimal investment and in less than two weeks.
Rapid injection moulding is called low-pressure injection molding. Rapid injection moulding is best for trial production of small-batch at the time of product development, products will be uneven, and large wall thickness, and production of simple-structured that are short-run. Some famous examples of rapid injection moulding are medical syringes, bottle caps, and Lego bricks.
How does rapid molding work?
The rapid injection moulding process mainly has three components, namely the machine mould, raw plastic, and a rapid injection moulding machine. In the rapid injection moulding machine, normally, the raw material plastic is injected into the mold. To become the final required part, it then hardens and cools there. After the part has been cooled, it will then be removed, and the process is completed. The process is relatively recently developed that is applied in the production of low–volume rapid injection moulding products.
Two polyurethane materials are injected into the rapid mold at low pressure and room temperature.
The items are formed through physical and chemical processes like material curing, cross-linking, and polymerization. In the procedure of rapid injection molding various cores and cavities share the same base of mold which reduces the lead time. It is also referred to as low volume production mold and prototype mold.
Benefits of using rapid molding
- Quick lead time: By taking the benefit of easy machinability of aluminum and CNC machining research and development engineers are enjoying the swift process of the making of rapid injection molding.
- Flexibility and strength: Rapid Injection Moulding offers a perfect balance between flexibility and strength using a single material. Material selection, gussets, and ribs can be used by the designer to control flexibility and rigidity.
- Low labor cost: Thanks to its reduced requirements, Rapid Injection Moulding does not need complex processes. Few molding batches and a single CNC machining can perform Rapid Injection Moulding. Supervision is also not required in these quick processes.
- Low material waste: Low scrap rate of preservative manufacturing like 3D printing can be matched with Rapid Injection Molding. A limited amount of materials are used by Rapid Injection Moulding, so only flash, gates, runners, and sprue generate resin waste.
- Consistent and complex part design: By using CNC machining for creating mold cavities, Rapid Injection Moulding can produce complex features and parts. It also gives uniformity, thus providing the ability to create various virtually the same pieces. A bridge of mass production can be made with Rapid Injection Moulding like tooling design and material.
Reasons you need a rapid molding service
- Rapid injection molding service is in demand because it lessens the lead time and production cost in comparison to the traditional mold
- It is quite possible to customize the molding as per the design of the product and the color consistency of the products is maintained
- Various surfaces can be accessed, which include sandblasting, polishing, texturing, etc.
- Rapid injection moulding is the best solution for low as well as high volume production
Where to buy Rapid molding for your project?
In a nutshell, Rapid injection molding is affordable yet the best solution. Various manufacturers provide effective solutions. However, at X Rapid Technologies, we combine our advanced technology, engineering capabilities, and experience to producing high- quality, quick tooling solutions for short production runs and prototypes. Our professional team is constantly working with every customer to ensure perfect solutions. The team is well equipped to handle the mass production of rapid injection moulding. To get assistance, contact us today.
Reaction Injection Moulding (RIM) is also known as low-pressure injection molding. It is a relatively newly developed process applied to the production of rapid prototypes and low-volume rapid injection moulding products.
It injects two polyurethane materials into the rapid mold at room temperature and low pressure. The products are formed through chemical and physical processes such as polymerization, cross-linking, and materials curing.
Its advantages are high efficiency, a short production cycle, simplicity, and low production costs. In this case, rapid reaction injection moulding is an excellent choice for small-batch trial production during product development, short-run production of simple-structured coverings, and products with large and uneven wall thicknesses.
1. Molds for RIM
ABS molds (20-50 pcs), resin molds (50-500 pcs), aluminum alloy molds (500-5,000 pcs), and steel molds (10,000-50,000 pcs).
2. Materials for RIM
The material for RIM is called polyurethane, PU in short. It can be divided into three types.
- Foamed PU. They can be soft foam and dense foam, which are used to make sound insulation covers, heat insulation layers, etc.
- Micro-foaming PU. Its density is generally 0.6-0.7 kg/m³. They can be applied to thick-walled and high-strength products.
- Non-foaming PU. The material performance is similar to PP or ABS with a density of about 1.1-1.2 kg/m³. They are suitable for various thin-walled shell products, with aging resistance, strong impact resistance, high cohesion, easy to load and unload, etc.
3. Injection pressure of RIM
The injection pressure is about 10MPa with a flow rate of 600g/s.
4. General working time of RIM
Each part takes 15-30 minutes to make. The demoulding temperature is usually controlled below 40℃, and after demoulding the parts are cured in an 80℃ environment for 2-4 hours for best performance. The materials and the sizes of the product determine the curing time.
5. Standard tolerances of RIM
According to its structure, the wall thicknesses of the product are different and their tolerances vary as well. The tolerance is usually within ±0.20mm/100mm. By designing the tooling, the part can be processed a second time to ensure tolerances of the position with particularly high precision requirements.
6. Thickness of the part injected
3mm or more.
7. Maximum size of the parts
Up to 30 kg of weight and up to 2500x1500x1000 mm in size.
8. The process of RIM
Initially, the monomer or prepolymer is mixed in a liquid state with a metering pump at a certain ratio into the mixing head. After the mixture is injected into the mold, it reacts rapidly and is cross-linked and cured in the mold. Then, after demolding, the part is complete. Finally, the RIM parts will be post-finished. Nearly all surface treatments are available, including painting, plating, screen printing, hand transfer printing, etc.
This process can be simplified as follows: storage → metering → mixing → mold filling → curing → demolding → post-treatment.
9. Applications of RIM
As one of the low-volume rapid injection moulding manufacturing methods, RIM is widely used for small-batch production of car models and accessories, medical equipment shells, toys, digital products, home electronics, fitness equipment, etc. If you need to make large-sized plastic products, but the quantity did not reach the MOQ of injection molding, you can turn to rapid reaction injection moulding.

To better understand RIM’s applications, let's look at the top three most commonly applied industries.
The shell production of medical carts, CTs, ophthalmic treatment instruments, medical B ultrasound devices, color ultrasound devices, reagent instruments, hematology analyzers, cell analyzers, virus detection instruments, tumor detection instruments, laser treatment instruments, environmental detection instruments, gas chromatographs, liquid chromatographs, beauty instruments, etc.

The production of bumpers, car dashboards, car door panels, side trim panels, modified cars, etc.

The shell production of service robots, industrial robots, etc.
As a low-volume rapid injection moulding manufacturer, X Rapid Technologies provides a one-stop RIM service. Feel free to get in touch with us and discuss your requirements. You will get free quotes within 24 hours and kick-start your projects soon.