The Main Guide to Low‑Volume Injection Molding

Traditionally, injection molding is a manufacturing process used for mass production. It has high tooling costs. Initially longer waiting times. But what happens when you’re between rapid prototyping to full scale production, and want to quickly produce plastic parts in higher volume?

The answer lies in low‑volume injection molding. It's a molding technique suitable for 100 to 10,000 pieces. How is that possible? It uses less complex molds and softer steel to speed up the process to mill the core and cavity.

In this article, we’ll dive into how low-volume injection molding can produce hundreds of functional prototypes and parts, why they're becoming increasingly popular for injection molding online platforms. And what limitations you should be aware of when you’re using it.

How Low‑Volume Injection Molding Works

At its core, low‑volume injection molding follows the same four‐step cycle as its high‑volume counterpart. Namely, clamping, injection, cooling, and ejection (but with tooling and machines optimised for short runs).

First, the tooling is created by using aluminum or a soft/semi‑hardened steel mold. This costs a fraction of hardened mold steel. Secondly, the mold is mounted in a compact press designed for rapid changeovers. The plastic pellets are then poured into the hopper, where a heated barrel melts them into a uniform melt.

A reciprocating screw builds up pressure until it “shoots” molten polymer through runners and gates into the mold cavity. After a 20-60‑second cool cycle (depending on wall thickness and resin choice), ejector pins or, for severe undercuts, sliders, lifters, or manual hand loads, releasing the part with minimal flash.

Low‑volume runs typically use cold‑runner systems for cost savings. However, hot‑runners may be available for tight‑tolerance or cosmetic needs.

What Are the Key Advantages of Low‑Volume Injection Molding?

Low‑volume injection molding delivers the best of both worlds. The speed of rapid prototyping + material integrity and repeatability of large‑scale production. Here are the primary benefits:

1. Cost‑Effective Short Runs

Thanks to the soft/semi-hardened steel molds, you can spread modest tooling investments across lower quantities. You’ll avoid larger molding bills of high-volume production molding yet experience a price advantage compared to post-processed 3D prints.

2. Production‑Grade Materials and Properties

Low‑volume molds support the same engineering resins and high‑performance polymers as full‑scale runs. For example ABS, PC, PBT, PEEK, PPSU, and more. All of these deliver tensile strength, fatigue resistance, and thermal stability with zero porosity or directional weakness.

3. Rapid Turnaround

From CAD approval to first shot, low‑volume molds can be in production within 10–14 days. That way, you can validate form, fit, and function far faster than with traditional tooling timelines.

Steel Molds versus Aluminium in Low Volume Injection Molding

Oftentimes low volume injection molding companies use aluminum molds because it offers fast machining and lower upfront costs. This makes them attractive for very short runs or cosmetic prototypes. However, their softer nature leads to faster wear when molding abrasive or filled materials. At the same time, their lower thermal mass sometimes results in uneven cooling and minor warpage.

By contrast, steel molds take longer to machine and carry a higher tooling investment. But they excel in durability and maintaining sharp details, draft angles, and polished surfaces throughout cycles.

For low‑volume runs that demand production‑grade accuracy and repeatability, it’s worth considering steel molds, as it would give you a real preview of mass-production conditions. Regardless of your choice. Aluminum molds still serve well for quick and lower‑stress applications.

Conclusion: Guide to Low‑Volume Injection Molding

Low‑volume injection molding bridges the gap between one‑off prototypes and mass production. It’s used in quantities from 100 to 10,000 and avoids costly tooling investments that of hardened-steel molds. However, soft/semi‑hardened steel inserts wear faster than hardened tooling. And it only supports single‑cavity designs, so per‑part costs remain higher than large‑volume runs.

For production needs above roughly 10,000 parts, hardened‑steel molds with multi‑cavity tooling become more cost‑effective. The tooling investment is spread over larger volumes and cycle times per part is reduced.

Are you ready to weigh the trade‑offs and find your best option? Submit a request to get quotations for low volume injection molding services on Haizol. Generally, the low volume injection molding cost is far more competitive in Asia, than in your home country.