In part 1 of this series, we looked at the process materials and the machines used to deliver high-quality injection moulded components. Design is where injection moulding truly comes to life. Even with the right material and manufacturing capability, small design choices can significantly influence part quality, cycle time and long-term production costs.
In this second part, we look at the design principles that matter most, alongside finishing integration, cost structure and sustainability considerations that shape modern injection moulding projects.
Design principles that matter
Injection moulding demands different design thinking than other manufacturing methods. Wall thickness consistency prevents warping and sink marks as the component cools. Draft angles – a slight taper on vertical surfaces – allow parts to eject cleanly from the mould without drag marks. Corner radii eliminate stress concentrations and improve material flow.
Gate placement, where molten plastic enters the mould, affects how the cavity fills and where any witness marks appear on the finished component. For components that will receive secondary finishing, like gate placement becomes even more critical to ensure surface quality where it matters most.
These design considerations aren’t restrictions, but opportunities to improve part quality, reduce cycle time and lower manufacturing cost. Working with your moulder at the design stage, before tooling commitments are made, typically saves significant time and expense.
The integration advantage
While many of our clients come to us purely for injection moulding capability, some projects benefit significantly from our specialist finishing services. Borough built its reputation on chrome plating components for automotive and premium consumer goods applications.
This combination under one roof eliminates a common supply chain complication. Components don’t travel between separate moulding and finishing facilities, so material handling is reduced and lead times are shortened.
Most importantly, we design and mould components with the subsequent finishing process in mind, ensuring we achieve the surface quality that electroplating demands.
For projects requiring a plated finish, particularly chrome or nickel, this integrated approach delivers quality advantages that single-source suppliers simply cannot match. For projects needing only moulded components, our experience designing for demanding finishing requirements translates to exceptionally high surface quality standards.
Cost structure: understanding the investment
Injection moulding economics divide into tooling investment and piece-part cost. Tool costs range from a few thousand pounds for simple geometries to tens of thousands for complex, multi-cavity moulds or two-shot applications. This upfront investment can appear significant, but it’s amortised across production volume.
Once the tool is cut, piece-part costs can become remarkably low, particularly on longer production runs with high volume demands. Material cost, cycle time and production efficiency determine unit economics. A well-designed part on an appropriately-sized machine can achieve unit costs that make injection moulding the most economical manufacturing method for medium to high volumes.
Design decisions significantly impact both tooling and production costs. Simplifying geometries, eliminating unnecessary features and designing for efficient material use all reduce expense.
These considerations are further reasons to engage your manufacturing partner at the outset – cost-optimisation opportunities exist throughout the design phase and are locked in once tools are cut.
Sustainability considerations
Modern injection moulding has become considerably more sustainable than its reputation suggests. Material waste gets reground and recycled back into production. Our ENGEL machines use tie-bar-less technology that allows larger components to be moulded on smaller, more energy-efficient equipment, reducing our carbon footprint while improving capability.
Energy-efficient heating and cooling systems, optimised cycle times and material waste reduction all contribute to more sustainable production. For clients with specific environmental targets, we can discuss material selection, recycling strategies and production approaches that align with sustainability objectives.
We also demonstrate our environmental commitment, with almost 1,000 solar panels now covering the roof of our facility, generating 405,000 kWh of renewable energy annually, providing lifetime carbon savings of 2,287 tonnes of CO₂ equivalent.
For clients with supply chain sustainability targets, this represents tangible environmental action rather than policy statements – modern manufacturing infrastructure built for long-term partnership.
Getting started
Injection moulding delivers consistent, high-quality components at scale, but success depends on making informed decisions about design, materials and manufacturing approach. Whether you need high-volume production of standard components, specialist capabilities like two-shot moulding, or the integration advantages of in-house finishing, choosing the right partner matters.
When design, material choice, manufacturing expertise, and long-term planning come together early, your components achieve their intended performance, remain cost-efficient, and scale reliably over time. At Borough, we combine over twenty years of injection moulding experience with plant capacity ranging from 70 to 400 tons, specialist finishing expertise, and assembly capability. Our team works with you from initial design through to volume production, optimising your component for manufacturability, cost, and quality.
If you’re ready to discuss your next injection moulding project, get in touch with our team. We’re always happy to talk through design challenges and manufacturing solutions.
