Simon Adams

The design, manufacture and optimisation of a prototype injection moulding machine

From a young age, I’ve had a passion for making things and I devoted my spare time before university to learning as many practical skills as possible. While at university, I found a further engineering passion in the academic side of my subject, and for my final year project, I decided to utilise both my academic and practical engineering skills.

This led to me drawing from my experience in the design and modelling modules at university and applying them to a further passion of engineering a sustainable future by exploring the engineering required to construct a machine which can use recycled plastic to manufacture new components.

Introduction

Global warming and climate change are widely acknowledged as one of the biggest issues the world currently faces. This project set out to investigate the main causes and find ways of combatting the issue. I found that implementing a circular economy is an ideal solution to the world’s climate crisis.

To apply a circular economy on a small local scale, the decision was to engineer an injection moulding machine which would be able to use recycled waste plastic to produce new components. The main challenge of this project was to design improvements to an open-source design, manufacture the designed prototype and assess its functionality.

Project aims and objectives

The main aim of this project is to create a functioning prototype injection moulding machine which will allow shredded recycled plastic to be made into new plastic products.

To achieve the aim the project must meet the following objectives:

• Use CAD, to produce 3D and 2D models and drawings to fully design the injection moulding machine and improve the existing design
• Manufacture mechanical components to the designed specification and tolerance
• Assemble the mechanical and electrical components into a safe and functioning prototype
• Produce a product to test the functionality of the injection moulding machine

Method

The process to produce the prototype injection moulding machine was to follow the engineering design process which in this case consisted of:

Design

• Project Definition
• Product Definition
• Conceptual Design
• Product Development

Production and delivery

• Manufacture
• Assembly
• Distribution
• Installation

Use

• Operation
• Cleaning

The design of the injection moulding machine was based on an open-source design with the aim of engineering improvements and changes. The main changes were:

• Split the machine into multiple sub-assemblies to allow for safer manual handling and to aid in maintenance and cleaning
• Replace the plunger arrangement for a design which can reduce the risk of entrapment and allow for the variation of the tolerance of the material manufacturer
• Redesign the hopper to allow for manufacturing efficiency and ease
• Adjustments due to availability of raw materials
• Improved mould attachment point

The manufacture of the injection moulding machine required: fabrication, welding, waterjet cutting, machining, and laser cutting, to produce the electrical and mechanical assemblies required for the machine.

Testing and results

In testing, the machine was tested to produce recycled plastic components. This was achieved by experimenting with different temperatures using HDPE plastic. An aluminium mould was used for testing the production capabilities and the machine performed well, producing molten plastic at a sufficient and consistent temperature and viscosity for injection moulding.

Conclusion

This project has successfully produced a functional injection moulding machine for use with recycled plastic, through the use of engineering design, manufacture and analysis. The machine could be improved by introducing metal guards, improving the mechanical designs further, and further testing. This would result in increased reliability, improve the yield from manufacture and a deeper understanding of how to operate the machine utilising different types of plastics.