Views: 8 Author: Site Editor Publish Time: 2024-07-13 Origin: Site
Sheet molding compound (SMC) or sheet moulding composite is a ready to mould glass-fibre reinforced polyester material primarily used in compression moulding. Alternatively the resin and related materials may be mixed on site when a producer wants greater control over the chemistry and filler.
Sheet molding compound (SMC) is manufactured by dispersing long strands (usually >1") of chopped fiber (commonly glass fibers or carbon fibers on a bath of thermoset resin (commonly polyester resin, vinyl ester or epoxy resin)). The longer fibers in SMC result in better strength properties than standard bulk molding compound (BMC) products. Also we provide long and continuous fiber or woven roving for extra reinforcement.
SMC is usually sold in rolls and then cut into smaller pieces called "loads." In a process called compression molding, heat and pressure are applied to the charge to create a wide range of products from simple designs to complex components.
The slurry reservoir dispenses a dosed amount of the specified resin slurry onto a plastic carrier film. The carrier film passes through a chopper, which cuts fibres into the surface. Once these fibres have drifted through the depth of the resin paste, another layer is added on top to sandwich the glass. These sheets are compacted and loaded into a winder for storing the product as it matures. The carrier film is then removed and the material is cut into various shapes. The shape of the charge and the mould are determined according to the desired shape and the charge is then added to the mould. Heat and pressure are applied to the charge and once fully cured, the charge is removed from the mould and becomes the finished product. Fillers can both reduce weight, change physical properties and often increase strength. Challenges in the production process include wetting the filler, which can consist of glass microspheres or neatly aligned fibres rather than randomly chopped fibres; adjusting the mould temperature and pressure to provide the right geometry; and adjusting the chemistry to suit the end use.
Electrical applications, corrosion resistant needs, structural components at low cost, automotive, sanitary, transit.
The most important and frequently cited advantage of sheet moulding compound is its low weight compared to other substances, including metal and even other polyesters such as block moulding compound (BMC). As a result, SMC has replaced metal parts as the primary material for many automotive components. It is also used in the manufacture of bathtubs, hydrotherapy pools and seating for arenas, cinemas and stadiums.
In addition to being lightweight, SMC is easy to manufacture and can be produced in large quantities. Combined with the simplicity of the compression moulding process and the short production cycle, parts made from SMC can also be mass-produced in a very short period of time.
However, the lightweight nature of SMC does not mean that strength must be sacrificed. It is robust and can withstand impacts even at high speeds. The compound is even approved for use in the housings of passenger cars, where it regularly scores highly in crash tests.
Finally, sheet moulding compound is an extremely economical option. Manufacturers can save money on all aspects of the production process, from minimal labour costs to reduced waste. In addition, SMC is very time efficient - it can be primed in-mould rather than waiting until the end of the moulding process. However, a post-mould painting process is required to achieve a Class A finish.
