Plastic injection moulding offers clear advantages over CNC milling and 3D printing for series production: low unit costs, high dimensional accuracy, and excellent reproducibility. But when do those advantages truly outweigh the mould investment? In this article, we outline the main benefits of plastic injection moulding and compare the process fairly with the alternatives.

Kunststof spuitgieten is een fabricageproces dat wordt gebruikt om kunststof onderdelen te produceren door gesmolten kunststof onder hoge druk in een mal te injecteren.

By the injection moulding process Molten plastic is injected into a mould under high pressure. After cooling, you have a product that has taken on the exact shape of that mould. This sounds simple, but the power lies in the details. The mould determines the tolerances, the surface structure, and the geometry of each part.

Because the same mould can be used thousands to millions of times, the reproducibility of the process is exceptionally high. Every product that comes out of the mould is identical to the previous one. That is a characteristic that CNC milling and 3D printing do not offer on the same scale.

In CNC milling, each part is the result of a separate machining process. In 3D printing, layer build-up plays a role, which can cause slight variations between products.

Comparison with CNC, 3D printing and milling

To fully understand the benefits of injection moulding, comparing it with alternative manufacturing methods is useful. Each technique has its strengths, but the choice depends on volume, accuracy, and cost.

CNC milling is extremely suitable for metalworking, low volumes and parts with complex internal structures. The processing time per part is relatively high. With a batch of a thousand pieces or more, the costs rise quickly. Injection moulding reverses that ratio: a higher upfront investment in the mould, but a low unit price at high volumes.

3D printing offers great design freedom and is ideal for prototypes or small batches. However, its accuracy is less precise than injection moulding, and the material choices are more limited. Furthermore, the production time per part is considerably longer with 3D printing. For functional batches of over five hundred pieces, 3D printing quickly loses its advantage.

Milling and injection moulding are sometimes combined. After injection moulding, a component can be post-processed via CNC milling to achieve specific tolerances or surfaces. Eurotechniek 2026 advises on the most efficient combination based on your design. Your end application is always the starting point.

Low unit price for high volumes

The cost structure of plastic injection moulding differs from that of milling or printing. Tooling costs are higher, but this investment is recouped over the entire production run. The higher the volume, the lower the cost per unit.

Suppose you need an enclosure for an electronic device. For a series of ten thousand units, the unit price via injection moulding is considerably lower than via CNC milling. The mould has already been made, and each cycle costs only a fraction of the total investment. With milling, you start again for each part. This makes injection moulding the standard choice for large-scale production in almost every sector.

Eurotechniek 2026 will help you calculate the break-even point. From what volume will the mould investment be recouped? This analysis will make it clear if injection moulding is the right step for your situation.

High accuracy and reproducibility

One of the strongest properties of plastic injection moulding is its consistency. Tolerances of plus or minus 0.1 millimetres are routinely achievable, depending on the material and the geometry of the part. In demanding applications, such as medical devices or automotive parts, even tighter tolerances are possible.

The reproducibility is virtually unlimited. Whether you are producing the first or the hundred thousandth part, the dimensions do not vary. This is different with milling. There, tool wear, temperature fluctuations and changing clamping can cause small deviations. With 3D printing, the layer thickness always influences the surface quality and dimensional accuracy.

For products requiring flawless fit, interchangeability, or standardised assembly, injection moulding is the most reliable method. Eurotechniek 2026 works with certified moulds and monitors quality through fixed measurement procedures per production run.

Wide choice of materials and multifunctional design

Plastic injection moulding is not restricted to one material type. Depending on the application, you can choose from technical plastics such as PA, POM, PP, ABS, or PEEK. Each material has specific properties in terms of temperature resistance, chemical resistance, hardness, and flexibility.

Furthermore, the 2K process offers the ability to process two different materials or colours in a single cycle. A housing with a hard core and a soft grip part can be produced in one step using 2K injection moulding. This eliminates assembly steps and reduces overall production costs.

Metal inserts, such as nuts or bushings, can be integrated directly into the component during injection moulding. This increases the functional value of the final product without additional post-processing steps. Milling does not offer these integration possibilities in the same way. 3D printing supports this to a limited extent, but the material performance is not as good as with injection moulding.

Sustainability in the supply chain

Plastic injection moulding has lower material wastage than milling. With CNC milling, you start with a block of material, a large part of which is removed as chips. With injection moulding, you only inject the material that makes up the part itself. Excess from the injection channels can be recovered and reused in non-critical applications.

Eurotechniek 2026 uses recycled and bio-based plastics wherever possible. This is not a marketing choice, but a concrete responsibility within the production chain. Where quality requirements permit, the company actively advises on more sustainable material options without compromising functionality.

The energy efficiency of modern injection moulding machines has also improved significantly. Electric injection moulding machines consume up to fifty percent less energy than hydraulic variants. This not only makes the process cheaper, but also better aligns with your organisation's sustainability goals.

Frequently asked questions about plastic injection moulding

What is the minimum volume at which injection moulding becomes interesting?

The mould costs make an investment at low volumes financially less attractive. In general, injection moulding becomes cost-effective from around five hundred to a thousand units per year, depending on the complexity of the mould and the unit price. Eurotechniek 2026 will perform a volume analysis for you to make the break-even point clear. Below that threshold, 3D printing or CNC milling is in many cases a better alternative.

What is the difference between injection moulding and milling for complex geometries?

Milling is better suited for parts with deep internal channels or features that need to be machined from multiple directions. Injection moulding can handle complex external shapes and thin-walled constructions well, but has limitations with undercuts without sliding mechanisms in the mould. An experienced party such as Eurotechniek 2026 will assess which process is most suitable for your part during the design phase.

How accurate is plastic injection moulding compared to 3D printing?

Injection moulding achieves standard tolerances of plus or minus 0.05 to 0.1 millimetres. 3D printing averages plus or minus 0.2 to 0.5 millimetres, depending on the technology and material. For functional parts where fit and dimensional stability are critical, injection moulding offers significantly higher accuracy. For prototypes or design validation, 3D printing is a faster and cheaper first step.

Injection moulding as the basis for your series production

Plastic injection moulding combines low unit costs, high accuracy, and a wide choice of materials in one process. It’s not a universal solution, but for mass production of plastic parts, it’s hard to beat. The comparison with CNC milling and 3D printing makes it clear that each process has its own area of application. Injection moulding wins in terms of volume, consistency, and cost per unit.

Would you like to know if injection moulding is suitable for your part? Contact Eurotechniek 2026 or view the full range at euro-techniek.nl.