Composites: Sheet moulding compound
Sheet moulding compound (SMC) is the largest mass manufacturing technique for the production of large composite structures. SMC can be made from many different resins, fillers and reinforcing fibres to achieved many desired material properties.
- SMC paste is applied to a top and bottom sheet of carrier film as they pass under a doctor box.
- SMC paste is a mixture of the resin and any particulate materials.
- The bottom sheet of carrier film passes under a rotary cutter that cuts and randomly applies reinforcement fibre into the paste.
- The top sheet of carrier film then sandwiches the reinforcement between two layers of paste.
- This composite sandwich is then compressed to ‘wet-out’ the fibres with SMC paste and form a homogeneous material.
Compression moulding uses the application of heat and pressure to form and cure SMC materials into complex shapes.
SMC is able to flow during moulding which allows complex part geometries, including ribs and bosses, to be incorporated into a single part.
Our research projects
With a lab-scale system available, X-AT has carried out projects to optimise materials and processes including:
Here at Exeter, TARF-LCV aims to develop advanced polymer matrix composites - sheet moulding compounds (SMC) and dough moulding compounds (DMC) using recyclable natural fibres for LCV structures that are light in weight, sustainable, disposable and have similar performance (mechanical, environmental resistance, surface finish etc) to man-made fibre reinforcement.
Partners: Brunel University, University of Manchester, University of Strathclyde, Imperial College, London, University of Nottingham, Coventry University, Oxford Brookes University
Funded by: EPSRC
The European Union End-of-Life Vehicle (ELV) Directive requires that 85% of a vehicle (by weight) must be capable of recovery or reuse from Jan 2006 and 95% by 2015. These targets cannot be reached by recycling metals alone. The goal of this project is to develop new, high quality, Sheet and Bulk Moulding compounds (SMC/BMC) materials that are derived from recycled SMC/BMC through a granulation process, where the comminuted materials are then used as fillers in other products. It seeks to understand and develop improved SMC/BMC formulations involving recyclate as an active reinforcing agent, rather than just the passive filler as considered in previous studies.
Partners: Sims, Menzolit, Mitras, Gurit, BPF, SMMT, Brunel University
Funded by: DTi
This collaboration proposes new routes to the recycling and remanufacturing of composite materials, and provides solutions to the current problems in the recycling processes of heterogeneous composite materials. The project will focus on glass fibre, carbon fibre, epoxy, polyester and thermoplastic materials. Novel recycling technologies and composite manufacturing processes will be developed for cross-sector use of heterogeneous scrap material. The microstructure-property relationship in waste materials will be thoroughly investigated. The material, cost, water and energy used will be optimised throughout the entire recycling and remanufacturing processes.
Partners: University of Birmingham, Cranfield University, The University of Manchester
Funded by: EPSRC
Sheet and dough moulding compounds (SMC and DMC) are a special class of composite used extensively in the automotive industry and are really the only volume manufacturing methodology for composite materials for automotive applications. Concerns over Impending EU end of life vehicle requirements (ELV) has prompted manufacturers to seek viable routes for disposal at ELV, where the goal of the project was to as far as possible produce SMC and DMC composites from bio-derived carbon-neutral ingredients. 95% of SMC/DMC composites comprise a resin system (25-35%), a filler system (35-55%) and the fibrous reinforcing system (25-35%). MAP-SR examined bio derived alternative materials for three components. The project idea was to develop a whole range of SMC/DMC composites using an organically or bio-derived materials, including by resins the organically derived filler materials, and natural fibre or bio-derived fibre for reinforcement, and to develop combined formulations to produce essentially bio-derived SEM/DMC composites. Since the composites developed materials would be from carbon neutral (bio-derived) sources, the problem of environmental disposal would be removed or substantially negated.
New materials were fabricated as far as possible, from sustainable, bio-derived organic precursors, including the use of bio-resin matrix systems, organic fillers and natural fibre reinforcement. Bio-derived SMC promises three major impacts:
1) Super-lightweight composite structures for all types of vehicles, but especially future electric and hybrid cars, extending range and economy.
2) Provide the car market with the sustainable and disposable alternative materials SMC/BMC grades it has been seeking that will satisfy the requirements of impending EU vehicle disposal legislation.
3) Removal of the barriers to further and wider exploitation of this important class of composite material that has high tensile strength and stiffness, and can provide a class “A” surface finish, and offers the only cost effective volume fabrication alternative to metals for car exterior parts.
Partners: Ford Motor Company Ltd, JCB, DSM Composite Resins (NL), Menzolit Ltd (UK) and Mitras Automotive (UK) Ltd, in collaboration with the University of Exeter
Funded by: TSB - High Value Manufacturing
Savage L, Evans K. (2014) The importance of the mesostructure in toughening cellulosic short fibre composites, Composites Science and Technology, volume 93, pages 97-105
L. Savage, O.R. Ghita, et al (2011) Sheet Moulding Compound (SMC) from Carbon Fibre Recyclate – Composites: Part A) Vol. 41, pp. 1232-1237.