What is SMC Composite, a Detailed Explanation Guide

What is SMC Composite

Sheet Moulding Compound (SMC) is a high-strength glass reinforced thermoset moulding material which is normally a compression moulded. It combines long glass fibre and unsaturated Polyester/ Phenolic/ Vinyl and Acrylic modified resins to produce a high-strength moulding compound. These materials are usually formulated to meet the performance requirements of the part to be moulded. 

Sheet Moulding Compound (SMC) is ideal for large structural components due to its high strength-to-weight ratio. SMC offers additional benefits in part design allowing localised rib reinforcement and bosses for fastening attachments and sub-assemblies. Significant tooling investment and overall component cost savings result from part consolidation. With the same coefficient of thermal expansion as Steel and excellent corrosion resistance, SMC is an ideal alternative to steel and can be used in the same fluctuating temperature environments. The main benefit, however, is a typical 25% weight reduction achieved at a similar strength to steel.

About the Manufacturing Process of SMC Composites

Paste reservoir dispenses a measured amount of specified resin paste onto a plastic carrier film. This carrier film passes underneath a chopper which cuts the fibers onto the surface. Once these have drifted through the depth of resin paste, another sheet is added on top which sandwiches the glass. 

The sheets are compacted and then enter onto a take-up roll, which is used to store the product whilst it matures. The carrier film is then later removed and the material is cut into charges. Depending on what shape is required determines the shape of the charge and steel die which is then added to. 

Heat and pressure act on the charge and once fully cured, this is then removed from the mold as the finished product. Fillers both reduce weight and change the physical properties, typically adding strength. Production challenges include wetting the filler, which could consist of glass microspheres or aligned fibers rather than random chopped fibers; adjusting die temperature and pressure to provide the proper geometry, and adjusting chemistry to end-use.

About the Advantages of SMC Composite Materials

Compared to similar methods, SMC benefits from a very high volume production ability, and excellent part reproducibility, it is cost-effective as low labor requirements per production level are very good and industry scrap is reduced substantially. Weight reduction, due to lower dimensional requirements and because of the ability to consolidate many parts into one, is also advantageous. The level of flexibility also exceeds many counterpart processes.

• The most important and most frequently talked about the advantage of sheet molding compound is its light weight when compared to other substances, including metals and even other polyesters such as bulk molding compound (BMC). For this reason, SMC has replaced metal components as the primary material used for a number of automotive parts. It has also seen use in the manufacture of baths, spas, arenas, cinemas,s and stadium seating.

• In addition to its lightweight, SMC is easy to produce and can be manufactured in high volume. Combined with the straightforward nature and short production cycle of the compression molding process, parts made using SMC can be created in similarly high volumes in a small amount of time.

• However, SMC’s lightweight nature does not necessitate any sacrifice in strength. It is sturdy and durable, capable of resisting impact even at high speeds. The compound is even approved for use in the outer shells of passenger vehicles, where it regularly receives high scores in crash tests.

• Lastly, the sheet molding compound is an extremely economical choice. Manufacturers can save money on all aspects of the production process, from minimal labor costs to reduced waste. As a further bonus, SMC is time-efficient as well – it can be primed in the mold rather than needing to wait until after the molding process has finished.  However, to achieve class A finishes, a post-mold painting process is required.

Physical Properties of SMC Materials

Properties vary depending upon filler and resin types, with compounds using aligned fibers (especially long fibers) being subject to greater anisotropy. Typical ranges are listed below.

Main Uses of SMC Composites

• Automotive & Transportation

• Electric & Communication Engineering

• Building & Construction

• Others

Frequently Asked Questions About SMC Composites

What car parts commonly use SMC?

Several outer-vehicle body parts utilize SMC — this goes for passenger vehicles and lightweight trucks. SMC parts include door assemblies, body panels, roof panels, spoilers, fenders, and bumpers.

What damage does an SMC experience in an accident?

During an accident, the most common damage to SMC is cracking. In severe situations, part of the panel might be torn off completely.

What does FRP mean?

FRP is an abbreviation for fiber-reinforced plastics. They are composite substances that are made of a polymer matrix and strengthened by fibers. SMC is a type of FRP.

How is SMC repaired?

When repairing SMC, a repair adhesive specifically designed for it can be used. It can either be a two-part urethane or epoxy adhesive. Loose or damaged fibers are removed and, in the case of a hole, a piece of scrap material can be used as a patch it if it’s the same kind of material. Proper sanding techniques are then used to ensure a quality repair.

How to Buy SMC Composite Materials

HAMC is a leading global SMC composites company serving more than 100 global customers. We provide advanced composite solutions and molded products.

With us, you can find the best SMC composite materials, if you need our help or products, please contact us now. We will give a reasonable price!