Plastic injection moulding is often praised for its speed, precision, and ability to mass-produce identical parts. But beneath that glossy exterior, there are drawbacks that catch many businesses by surprise—especially smaller firms or start-ups expecting a quick win. Here’s a closer look at the negatives that come with this manufacturing process.

Why can injection moulding be expensive to start with?

The biggest hurdle is tooling cost. Moulds are carved from hardened steel or aluminium with exacting precision, and depending on complexity, a single mould can cost tens or even hundreds of thousands of dollars. For a company testing a new product idea, that’s a risky investment if demand doesn’t materialise.

Beyond tooling, there are machine and maintenance costs. Industrial injection moulding machines aren’t just plug-and-play units; they require skilled operators, regular calibration, and in some cases, climate-controlled facilities. Anyone who’s set foot in a factory knows the hum of those machines comes with a hefty power bill.

Does injection moulding limit design flexibility?

Yes—despite its reputation for versatility. Moulds demand uniform wall thickness, draft angles, and avoidance of undercuts. That means designs often need to be adjusted—or compromised—to fit the process. Creative freedom shrinks when engineers are told, “the mould can’t handle that curve.”

Additionally, once a mould is made, changes are costly and slow. Unlike 3D printing, where you tweak a CAD file and try again, injection moulding locks you into a path that’s expensive to deviate from.

What about environmental drawbacks?

Injection moulding relies heavily on plastics—materials already under global scrutiny. While recycling is possible, not all resins are easy to reuse, and rejected parts, test runs, and excess sprues often end up as waste. Add to that the high energy consumption of the machines, and the environmental footprint becomes harder to ignore.

A study from ScienceDirect highlights that energy intensity and plastic waste are two of the largest environmental concerns tied to injection moulding, particularly in regions still reliant on fossil-fuel-heavy electricity grids.

Is injection moulding ideal for small production runs?

Not really. The process shines when producing high volumes, where the upfront tooling costs are spread thin over thousands or millions of parts. But for short runs or prototype batches, it’s usually uneconomical compared to methods like 3D printing or CNC machining.

Small businesses that rush in often find themselves with a warehouse full of stock they don’t need, or worse—moulds they can’t justify using again.

Are there risks in quality and defects?

Absolutely. While the process is precise, it’s not foolproof. Issues like warping, sink marks, flow lines, and voids can appear if parameters like temperature, pressure, or cooling time aren’t dialled in correctly. Fixing these requires technical expertise, rework, and sometimes retooling—none of which come cheap.

And here’s the irony: the more intricate the part, the higher the risk of defects, which often negates the very precision that makes injection moulding attractive.

FAQ

Is injection moulding always the best option?
No. It’s best suited to large-scale production of uniform parts. For custom or low-volume projects, other methods are often more practical.

How long does it take to make a mould?
Depending on complexity, anywhere from 4 to 12 weeks. That lead time can stall projects waiting to go to market.

Can recycled plastics be used?
Yes, but not all plastics are easily recyclable, and performance may be compromised depending on the mix.

Injection moulding remains a powerhouse for industries needing millions of consistent parts. Yet, its high upfront costs, design limitations, environmental footprint, and unsuitability for low volumes make it a double-edged sword. Anyone weighing up their options—whether in aerospace, medical devices, or consumer goods—should tread carefully, especially in regions where production costs are rising. For instance, businesses considering Injection Molding Greater Vancouver will want to factor in both the financial and environmental costs before committing.