Technical potential of nano-enhanced SMC.
Technical potential of nano-enhanced SMC.

The National Composite Center (NCC) is mixing up some new 'recipes' for an old technology to help manufacturers expand market applications and achieve lower operating costs. NCC announced it has established a new Sheet Moulding Compound (SMC) Center for Excellence at its Dayton Campus for Advanced Materials Technologies (DC-AMT). In addition to looking at materials that include nano-particles, bio-resins and high strength fibres, NCC will develop efficient scale-up processes for the innovative combinations. Yet the new chemistries and process developments will target traditional SMC manufacturing systems eliminating the need for companies to recapitalise.

Foundation equipment will include a 36-inch SMC line, a cure analysis system and a surface analyser for surface reflectivity. The SMC Center is expected to be set up and fully operational by early 2008. NCC is funding its new SMC Center with an Ohio Third Frontier Project capital equipment grant totalling US$1 800 000.

New chemistries

Conventional processing typically refers to moulding a part's final shape.

“The end product and the moulding equipment used to produce SMC sheets will look relatively the same,” says Harry Couch, Senior Technical Consultant for NCC. “Our goal will be to change the materials or chemistries and the way those materials are combined (see box). We plan to test different ingredients, if you will, such as nanoparticles, higher modulus glass, bio-fibres and bio-resins as application drivers like viscosity, specific gravity, aging and fibre loading capability against the physical property requirements of finished products. We’ll prototype these formulations, test them against standard methodologies and evaluate whether we have achieved critical performances such as modulus, tensile strength and surface quality.”

Markets

Transportation remains the largest market for SMC materials, with applications in the agricultural equipment, construction, and electrical industries. Market size for transportation (automotive and heavy truck) industry in the US is around 400 million lbs of SMC. Yet despite the continued demand for products, the SMC market has become flat as a result of the challenges associated with developing new ideas and competition from other processes. Time horizons for profits, capital expenditures typicallyrequired for development projects and lack of access to other knowledge sources prohibits most companies from pursuing new approaches.

The SMC Center's comprehensive lineup of advanced equipment will allow technical specialists to extensively study and create new chemistry combinations and processing technologies that take advantage of today's emerging materials. The SMC Center also expects to reduce development dollars for industrial partners that want to share the cost of creating and certifying new technologies.

“We’ll also have the capability to analyse work being done in other countries to help make processes here in the US more robust,” Couch says. “With its network, NCC is really a consortium of companies. The ability to tap government, academic and industry knowledge and equipment gives us a much wider source for possible solutions, something the majority of manufacturers don’t have available to them.”

With a new crop of materials and processes to use, the SMC industry will have the opportunity to expand its market reach, enhance process efficiencies and produce lower mass products. For moulders making parts and producing sheet materials, less weight means reduced operating costs.

Nano-particles

Nano-platelets or nano-clays are just one field with potential to optimise SMC material by replacing amounts of conventional filler and glass fibre. Until now, equipment for bench scale work with these materials has been available in academic institutions but lacked the capacity to produce actual parts.

Nano-platelet fillers can consist of anywhere from units of tens to several hundred platelet layers stacked together irregularly. The ability to separate the stacks into individual platelets could dramatically improve stiffness as well as flame retardancy and surface finish.

“The potential of nano-particles to reinforce polymers must still be proven,” Couch says. “Our specialists will use microscopic analysis to look at methods for achieving nano-exfoliation and dispersion in the resin. Without platelet separation and the wet-out of the interface between the resin and the platelets, you can’t achieve improvement in critical mechanical properties. Introduction of nano-particles has been shown to give improved properties but this will need to be demonstrated on full scale manufacturing processes. In addition to new materials like nano-particles, we plan to thoroughly explore available technologies to see if production processes or materials can be effectively translated into practices the average company and its customers can use.”

NCC targeted materials and market opportunities

Materials

  • Survey nano-reinforcement in thermosets: measurement of exfoliation; decreased water absorption
  • Stronger reinforcements: thinner SMC; glass; carbon
  • Lower density using natural materials: reinforcements; fillers
  • Use of biobased resins for cost control and other benefits: thickening mechanisms for consistency; oleophillic absorbers; other industry mechanisms
  • UV stable SMC

Process

  • Process changes for consistency: in-line compounding – direct moulding

Markets

  • Common design methodology: database of SMC/BMC design and modelling
  • New market applications: fuel cell membranes; lawn and turf equipment

There are also a number of lower specific gravity materials being produced today for limited applications. SMC specialists will study ways to further reduce specific gravity while lowering product costs to expand the material's range of applications and offer another avenue for increasing the market's size.

Process challenges

The SMC Center also hopes to provide solutions for some of the processing challenges SMC manufacturers face. Traditionally, the SMC sheet – a high viscosity composite paste – must be chemically thickened in order to be moulded into manufactured parts. If this thickening process isn’t controlled by temperature and time the result is inconsistent part quality. The SMC Center will examine these process variables and explore technologies that will provide repeatable, reliable part quality.

As the cost for petroleum-based materials continues to escalate, it is expected that bio- materials will offer a cost effective alternative. Also as a part of the trend toward green manufacturing, the use of natural fibres continues to command attention (see chart). Yet for SMC applications, the fibres pose problems due to their tendencies to pick up water. Moisture pickup must be managed throughout the processing to avoid process problems and to protect against end use product deterioration. The SMC Center will investigate methods for controlling this problem with natural fibres.

Aside from developing new materials and processes, the industry's need for assistance in the area of end use design will be addressed.

“Many manufacturers still don’t really understand how to design for SMC applications,” Couch said. “Strengthening manufacturers’ design capabilities will make it easier for customers to readily specify SMC.”

With an infrastructure that can turn ideas into practical applications, the opportunity to reinvigorate an established technology provides the potential for market expansion, new jobs and improved products.