Working smarter has been a goal of manufacturers throughout time. From the earliest days of handcrafting tools to the rise of mechanised production, each era has sought ways to increase efficiency, reduce waste, and improve quality. Today’s organisations strive to deliver a compelling value proposition by operating with greater precision, building a culture of continuous improvement, and leveraging technology, data, and collaboration to drive measurable results.
Injection moulding allows for the rapid production of functional end-use parts at lower per-unit costs compared to manual or substitute methods. Once configured, it can produce a high volume of parts per hour using a wide variety of plastics, as well as materials such as liquid silicone rubber (LSR), which offers ease of processing. Injection moulding plays a decisive role in the manufacturing of millions of products, including but not limited to sunglasses, TV bezels, insulation seals, smartphones, and electromechanical enclosures.
It’s possible to plan for outsourcing when the projected capacity for a defined interval falls short of requirements. Outsourcing is a business practice in which you contract an external, specialised manufacturer—often referred to as a custom moulder—to produce the plastic parts rather than doing it yourself in-house. At first glance, it may appear to be a relatively benign process, but in reality, there are deeper considerations.
Key Moments to Outsource Injection Moulding for Operational Excellence
Love it or hate it, outsourcing is now an integral feature of business life. As manufacturers search for cheaper and more effective ways of working, handing over processes such as injection moulding to reputable providers can be an alluring prospect for ensuring business continuity by providing access to specialised expertise. Businesses that capitalise on outsourcing can achieve dramatic savings and build the much-needed capacity to grow in a way that wouldn’t be possible with in-house resources.
There are several key indicators that it may be time to outsource your injection moulding needs:
High Upfront Capital Investment
Meticulous planning and sound decisions can help prevent high unit costs. Molds are commonly produced through CNC machining, using either steel or aluminium. For long-lasting, high-volume production moulds with complex geometries, stainless steel is typically employed, often manufactured with advanced techniques such as wire EDM and die-sinking EDM. The moulding/tooling cost is by far the most significant upfront expense.
Simple aluminium moulds for prototyping or low-volume runs fall within the range of €1,000 and €5,000, whereas standard production moulds, which are suitable for moderate volume production with basic geometries, are priced between €10,000 and €50,000. Complex multi-cavity steel moulds designed for long-term use, tight tolerances, and complex parts typically run from €30,000 to €150,000. Once the mould is made, the marginal (variable) cost is relatively low, meaning the average cost per part decreases as more units are produced.
Low Or Sporadic Production Volume
Not all businesses are the same. Some produce only a small number of units or fabricate them sporadically rather than in a steady, continuous flow due to trade issues such as tariffs, low investment spending, supply chain issues, and internal inefficiencies, including a lack of skilled labour. If you find yourself in a similar situation, consider partnering with a specialised third party because your cost per part is much higher than a dedicated, large-volume moulder can achieve. You can reallocate the internal resources to core functions or growth initiatives.
Lack Of Specialized Expertise
Injection moulding is a completely different way of manufacturing compared to additive (3D printing) or subtractive (CNC machining) technologies. It’s a formative process because it creates parts by forcing molten materials under pressure into a mould cavity, where they solidify to take on the mould’s shape. How the material flows and solidifies during injection greatly affects the main design restrictions of this method. According to the experts at HSV TMP (https://www.hsv-tmp.com/) it’s a highly technical process, so it requires specialised knowledge and experience.
Changing one aspect for better results may have a negative effect on other influencing factors, such as mould design. Knowledge and expertise of more than one specific area are indispensable to have an optimum solution, and unfortunately, the growing demand for experienced designers and engineers far exceeds the supply. Outsourcing is a practical method to address knowledge gaps in the workplace because it guarantees access to external expertise, niche capabilities, and a global talent pool that may be prohibitively expensive or impractical to cultivate internally.
Process-Induced Inconsistencies
Common issues in injection moulding include, but aren’t limited to:
- Black specks: Black specks are unmixed particles that pigments usually conceal in opaque parts, but they’re fully visible in transparent ones. They can be caused by machine contamination, which often results from degraded plastic residues or burnt material accumulating. You should conduct a comprehensive purge utilizing a resin with high thermal stability or a specialized purging compound.
- Brittleness: Brittleness can be related to moisture and other factors that degrade the plastic’s molecular structure, leading to a tendency to crack or break. One solution would be to ensure dew points are – 20°F.
- Contaminations: Contaminants frequently manifest as black specks or streaks of discoloration. You should review the resin handling system to preserve the chemical and physical consistency of virgin and regrind polymers by eliminating foreign material intrusion.
- Deformation: Parts sometimes stick to the mould during ejection, which can deform their shape as they’re pushed out. Overpacking can lead to part deformation, flash, internal stresses, and reduced dimensional accuracy. It’s recommended to lower the injection and holding phase velocities and pressures accordingly to minimise material compaction during the packing phase.
- Discoloration: Equipment that hasn’t been properly cleaned can lead to streaks or off-colours parts. This is why it’s important to flush the injection unit until all residual material is cleared and the resin runs clean.
If you’re struggling to maintain consistent part quality, it may be time to reassess your process parameters, mould design, and even material selection.
Closing Insights
Outsourcing injection moulding is one of the best ideas that allows you to focus on what you do best. By shifting production to specialized partners, you can reduce overhead costs, avoid expensive equipment investments, and eliminate the need to manage complex tooling and quality control in-house. It’s something to think about.
