ENG08034 2019 Polymer Processing and Mould Analysis

Demonstrate an understanding of the theory, concepts and methods and apply practical experience in relation to the injection moulding process.

Demonstrate an understanding of the theory, concepts and methods of the polymer extrusion, vacuum forming, rotational moulding and blow moulding processes.

Evaluate simple plastic component designs for manufacturability and recommend improvements.

Employ injection moulding simulation software to analyse injection moulding of plastic components and deduce potential problems.

Demonstrate a detailed of knowledge and understanding of mould flow analysis.

Fulltime

Lectures, tutorials, exercises and practicals.  Visits to moulding shops/toolrooms to examine moulding machines and moulds.  Practicals with software, videos and multimedia presentations.  Injection moulding laboratory.

Online

This module will be delivered using blended learning techniques. The theoretical and background material will be presented through a series of online lectures. Students will complete assignments during the semester and attend an end of semester practical day for relevant parts of the module content.

Final Exam

Assignments

Project Work

This will consist of a final exam and/or resubmission of assignments and project work.

Injection moulding
Construction of machines and types available. Types of mould locking systems and tie bar less machines. Screw and nozzle shut off designs. Injection moulding of non-standard materials such as elastomers and thermosets. The effects of moulding conditions and process variables on products, e.g. shrinkage and orientation. Systematic approach to correction of moulding faults.  Heating and cooling requirements.  EUROMAP specifications and standards.  Machine safety, requirements and types of safety mechanisms.

Extrusion
Screw types, overview of the main extrusion processes, introduction to screw and die characteristics and design considerations, fault diagnosis of common processing problems.

Vacuum Forming
Positive, negative, drape, air slip, snap back, and plug assist. Mould design, draft angles and venting for vacuum forming etc. Choice of mould making materials. Manual, semi automatic and fully automatic machines.

Rotational Moulding
Principles, equipment and processing. Material selection. Determination of the optimum moulding area diagram for a range of engineering materials. Optimising vacuum forming parameters. Effects of extrusion variables on the dimensions of an extruded profile. Use of parison programming on the material distribution of a blow moulded bottle.

Blow Moulding

Principles of injection and extrusion blow moulding. Parison formation, blowing systems, effects of material properties and processing parameters on the product.

Rheology of Polymers
Newtonian and Non Newtonian liquids.  Pseudoplastic.behaviour.  Pressure Volume Temperature  curves.  Effects of shear and shear rates on polymers.  Use of viscosity and shear rates curves. Factors affecting viscosity.  Applications of rheological data.  Application of rheological properties to moulding conditions.

Injection Mould Design
Basic mould construction, feed systems, runner profiles and freeze characteristics, gate types including size and choice of gating position. Surface vs submarine gates. Runner balancing. Hot runner / insulated runner systems. Cooling channel design, size and layout. Heat transfer requirements. Venting, including the role of venting, choice of vent location, problems with poor venting.

Application of Plastic Flow Analysis Software
Factors affecting filling, cooling characteristics, warp analysis, effects of gate position, viscosity effects.

Mould Analysis
Pressure drops in the mould cavity, including within the runner system.  Runner design, including runner balance.  Pressure build up in the cavity.  Design of runners for two and three plate moulds.

Moulded Part Design
Common quality problems, e.g., weld lines, air-traps, warpage, short shots and how to address them.