Why size matters in injection moulding
25 May 2026
From 25T to 1300T – Choosing the Right Injection Moulding Machine
At TEX Plastics, we operate a vast range of injection moulding machines, from 25 tonnes for micro-medical components to 1300 tonnes for large industrial housings. While many assume machine selection is simply about “fitting the part,” the reality is far more nuanced. Choosing the correct machine is critical for part integrity, production efficiency, and energy optimisation.
Understanding Machine Tonnes and Shot Sizes
Two key factors determine how well a moulding machine suits your project:
- Clamping Force (Tonnage): Measured in tonnes, this is the force the machine applies to keep the mould closed during injection. Too little force can cause flash (excess material at parting lines), warping, or incomplete fill; too much can stress the mould unnecessarily and waste energy.
- Shot Size: This is the maximum volume of plastic the machine can inject in a single cycle. Selecting a machine with a shot size close to the part’s requirement ensures consistent quality without overloading the machine or wasting energy.
Right-Sizing Your Production
The benefits of matching machine size to part requirements go beyond fit:
1. Precision and Part Quality
- Using a 25T machine for small, intricate medical parts allows precise control over injection speed and pressure, maintaining tight tolerances.
- Conversely, a 1300T machine ensures large industrial housings are filled uniformly, minimising the risk of voids, warping, or defects.
2. Optimised Cycle Times
- Right-sizing reduces unnecessary delays in mould filling and cooling.
- Overpowered machines for small parts can lead to slower cycles and energy inefficiency; underpowered machines for large parts risk incomplete fills and increased scrap.
3. Energy Efficiency and Sustainability
- Selecting the correct machine reduces electricity consumption and carbon footprint.
- Smaller machines use less energy for small parts, while larger machines are engineered for high-volume, high-tonnage efficiency—maximising output with minimal waste.
4. Tool and Material Longevity
- Correct tonnage protects moulds from excessive pressure, extending tool life.
- Proper shot sizing ensures material is injected consistently, reducing rework and scrap.
How TEX Plastics Delivers Flexibility
With a comprehensive range of machines across two UK facilities, TEX Plastics can handle projects of all sizes:
- Micro-medical components requiring precision under 25T
- Small to medium parts for automotive or consumer goods using 100–500T machines
- Large industrial housings and assemblies on 1000–1300T machines
This flexibility allows engineers to select the optimal machine for their project, balancing quality, speed, cost, and environmental impact.
Educating Engineers for Better Outcomes
At TEX Plastics, we work closely with design and production teams to advise on machine selection, tooling design, and process optimisation. Understanding how tonnage and shot size interact with part geometry is essential to achieving:
- High-quality, consistent parts
- Shorter lead times
- Reduced energy usage and carbon footprint
- Lower total production costs
Ensuring part integrity, optimising energy use, and delivering cost-effective production
“Size matters” in injection moulding—not just in fitting the mould, but in ensuring part integrity, optimising energy use, and delivering cost-effective production. By leveraging the full spectrum of TEX Plastics’ machine capabilities, customers can confidently manufacture everything from precision micro-parts to large, complex housings—efficiently, sustainably, and to the highest quality standards.