Low volume plastic injection moulding: a practical guide

Low volume plastic injection moulding is becoming an increasingly popular solution for companies that need high-quality parts without committing to the high costs of traditional mass production. By combining modern technologies such as 3D printing and precision machining, low volume injection moulding allows designers and engineers to produce small batches of functional parts efficiently, accurately, and cost-effectively.

Low volume vs. traditional injection moulding

Traditional injection moulding excels in mass production, offering high repeatability and ability to manufacture large series of identical parts with tight tolerances. However, the significant upfront investment in steel or aluminium moulds, combined with long lead times of 8-12 weeks, makes it impractical for low volume injection molding for prototypes or small runs.

Low volume injection moulding, on the other hand, leverages alternative mould fabrication methods like 3D printed polymer moulds or lightweight aluminium tooling to drastically reduce costs and timelines (3-10 days). These solutions enable production from a handful of prototypes to hundreds of functional parts, ideal for product development, pilot runs, or niche markets where demand is volatile.

Workflow for low volume production

The process of low volume plastic injection moulding closely mirrors traditional procedures but prioritizes speed, flexibility and supports quick iterations and material tests before scaling to mass production.

• Mould Design: CAD software is used to design the part and the mould, adhering to best practices for injection moulding and 3D printing.
• Mould fabrication: depending on the volume, the mould can be 3D printed in high-strength polymers or machined in aluminium to balance cost, durability, and precision.
• Assembly and setup: the mould is assembled in a frame, equipped with ejector pins or inserts, and mounted on the injection machine.
• Injection and cooling: thermoplastic pellets are injected at optimised temperatures and pressures, followed by cooling, accelerated using compressed air for polymer moulds.
• Demoulding and inspection: parts are demoulded manually or automatically, and quality checks are carried out to ensure dimensional accuracy and repeatability.
  

Applications

Low volume plastic injection moulding shines in key applications across demanding sectors:

• Rapid prototyping: functional prototypes can be produced with end-use materials, enabling realistic testing and validation of designs.
  
• Short-run production: manufacture small batches for pilot studies, market testing, or niche products, perfect for low volume molding services in volatile markets.
  
• Custom and on-demand manufacturing: create tailored parts without high tooling costs, minimizing inventory in sectors like IdeaStampi specializes.
  
  

These uses make this practice a versatile tool for startups, product developers, and companies looking to bring products to market faster and more efficiently.

Best practices for low volume injection moulding success

To maximize results, follow these proven tips - drawn from real-world low volume projects:

• Design with uniform wall thickness to avoid warping;
• Use draft angles for easy demoulding;
• Select materials matching end-use (e.g., PP for flexibility, PC for transparency);
• Avoid undercuts or add inserts for complex geometries.
• Test multiple iterations early to refine tolerances.
  

Why choose Idea Stampi

At Idea Stampi, with over forty years of experience, we deliver reliable low volume injection molding services through fully in-house mould production and cutting-edge 3D printing/aluminium tooling. Our DFM (Design for Manufacturability) consultations and expertise in various sectors like automotive, medical and electronics, ensure high precision, repeatability, and compliance.

From prototype validation to small series, our team keeps you agile in competitive markets.