Sheet Moulding Compound

PRAZASTINAV manufactures Sheet Moulding Compounds (SMC) that are primarily used in compression moulding. PRAZASTINAV offers SMCs that are suitable for moulding a wide range of parts from very small to very large, from flat panel to very complex shapes. Through our Engineered Solutions, SMCs are tailored to specific customer needs providing part performance as well as manufacturing efficiency. The pliable sheet allows enough body for handling and cutting but enough rigidity for manual charge building or automation.

The SMC manufacturing process allows glass percentages from 15% to 65% to be incorporated into the matrix. The glass length can also be increased up to 2″ vs. a BMC that may range between 1/8″ and 1/2″. SMC also offers the possibility of continuous strand or matte. SMC’s come in a wide range of colours and can often be colour matched. SMC’s have excellent physical, thermal, flame and chemical resistance properties.

As with other thermosets, SMC is a mixture of polymer resin, inert fillers, fiber reinforcement, catalysts, pigments, stabilizers, release agents, and thickeners. Manufacturing of SMC is a continuous in-line process. The base components of liquids and solids (paste) are bulk mixed and continuously metered onto to the surface of a carrier/barrier film, coating the film surface. Two mirror imaged metering stations operate simultaneously. One of the paste-coated carrier films are then layered with chopped fibers. The 2 carrier webs, paste & fiber are then brought together in the compaction section, where the sandwich-like layered components are kneaded into one homogenous compound sheet. The sheet is then fan folded into a container and stored in a controlled environment where maturation takes place, on its way to a specified viscosity.

SMC Product Overview

Our PRAZASTINAV SMC products are adaptable to your needs. All our formulations are designed according to your specific requirements.

Sheet Molding Compound Offers Superior Strength and Electrical Insulation

Designed, formulated and manufactured to perfection using the Schmidt-Heinzmann, Germany machines, we are one of the excellent and leading manufacturers and suppliers of Sheet Moulding Compound. Formulated by top of the line composites scientists with more than combined 90 Years of industry experience from across the globe, manufactured as per international quality standards and norms, the moulding compounds manufactured by PRAZASINAV Compositech Pvt Limited, Vadodara are acknowledged for their high tensile strength, fine finishing and longer life, which can be used for any type of applications, starting from Electrical applications to Automotive to Aerospace/Avionics.

Sheet Moulding Compound (SMC) is a thermoset, glass-fibre reinforced semi-finished plastic. PRAZASINAV Compositech Pvt Limited produces SMC both for use in its own moulding department and for third parties. In our fully dedicated Research and Development Centre we have developed a large number of application-specific formulas, using our many years of expertise.

Sheet moulding compound (SMC), is a composite sheet material made by sandwiching chopped fiberglass between two layers of thick resin paste. The SMC is cut into smaller sheets and is assembled (specific dimensions and number of layers) on a heated mould. The mould is closed and clamped, and 30 to 80 bar pressure is applied. Material viscosity drops and the SMC flows to fill the mould cavity. After cure, the mould is opened and the part is removed.

Fibre reinforced polyester systems in the form of Sheet Moulding Compound (SMC) are moulded into various parts in a lot of application areas. Typically these are automotive, electrical, construction and sanitary due to their excellent performance regarding heat stability, mechanical and electrical properties.

Sheet molding compounds (SMC) are fiber-reinforced thermosetting semifinished products. They are produced in thin uncured and thickened sheets between 1 and 3 mm thick that can be handled easily. To a larger extent, SMC is a generic term that designates such types of compounds, together with the process to convert them into large composite parts (average area of 0.7 m2, with a maximum area of up to 4 m2), which mainly display shell-like geometry (average thickness of 2.5–3 mm). This process is usually achieved through compression molding. It is industrially profitable for medium volume production. Also note that SMC can be injected. Roll forming was also reported as an interesting process to make SMC parts. SMC compounds include short, that is, discontinuous, fibers or fiber bundles that are impregnated between two layers of a resin paste. Various types of fibrous reinforcement can be utilized: glass fiber bundles, that is, a strand of individual glass filaments, which are most common, carbon fiber bundles, plant-based fibers, or hybrids. The typical length of the reinforcement is about 25–50 mm. The volume fraction of the fibrous reinforcement ranges between 10% and 65%. The resin paste, that is, the composite matrix, consists of a mixture of thermosetting resin (usually polyester but also vinylester and epoxy), fillers (calcium carbonate, alumina, etc.), and additives such as initiators, inhibitors, thickeners, mold release agents, and low profile additives (LPAs). The resin paste is thickened before molding: the paste viscosity is increased so that the SMC is a ‘‘putty-like’’ material. This is a fundamental point of the SMC technology concept, which allows the sheets to be easily handled and the paste to drift the fibers during compression molding. This feature makes a clear distinction between SMC and other comparable thermosetting compounds such as bulk molding compounds (BMC) and continuous impregnated compounds (CIC). The SMC process comprises two major distinct steps: compounding and compression molding.

SMC is a mixture of polymer resin, inert fillers, fiber reinforcement, catalysts, pigments, stabilizers, release agents, and thickeners. Manufacturing of SMC is a continuous in-line process. Sheet Molding Compound (SMC) is a compression molding compound often used for larger parts where higher mechanical strength is needed. SMC is a fiber reinforced thermoset material. Glass reinforcement is between 10% and 60%, and glass length is slightly longer than Bulk Molding Compound (BMC) – between 1/2-inch and 1-inch (25mm).

The systems are custom – made to all kinds of needs by changing the basic formulation. Central focus is always the application.

Properties SMC

Due to an extremely high chemical resistance, strength and temperature resistance, SMC is very suitable for products which have to meet stringent requirements. Its ageing properties are so good that even after many years of outside use with a high UV-load, the mechanical properties of SMC are barely affected. SMC products are impact- and scratch-resistant, colourfast, maintenance-free, temperature and corrosion-resistant. By adding special additives SMC achieves a high level of flame-retardancy and low waste gas emission.

Sheet molding compounds can be molded into complex shapes. Superior mechanical properties and surface appearance, plus excellent electrical insulation make this thermoset material ideal for automotive Class A body panels, high-strength electrical parts, business equipment cabinets, personal watercraft, and various structural components.

SMC compounds

As with BMC, thermoset Sheet Molding Compound (SMC) is a mixture of polymer resin, inert fillers, fiber reinforcement, catalysts, pigments and stabilizers, release agents, and thickeners and possesses strong dielectric properties. The SMC slurry is spread on a foil, whereupon the glass fibres are added, which can vary in length and quantity, depending on the required properties and geometry of the product. Then a second layer of slurry is added and covered with foil. Finally, the whole mat is impregnated. Before SMC can be processed, it must be ripened under controlled conditions. Manufacture of sheet molding compounds is a continuous in-line process. The material is sheathed both top and bottom with a polyethylene or nylon plastic film to prevent auto-adhesion. The paste is spread uniformly onto the bottom film. Chopped glass fibers are randomly deposited onto the paste. The top film is introduced and the sandwich is rolled into a pre-determined thickness. The sheet is allowed to mature for 48 hours.

Custom specification

PRAZASINAV Compositech Pvt Limited produces SMC for both own use as for third parties with customized specifications and in small series.

Major Advantages of SMC are versatile materials: their formulation can be adjusted and tailored to meet the requirements of a diverse range of applications. Compression molding of SMC allows processing complex and large shapes on a rapid cycle time. Features such as inserts, ribs, bosses, and attachments can be molded in. This process needs little mold preparation and generates few scraps, thus reducing the cost of trimming operations. Good surface finishes are obtainable, contributing to lower part-finishing cost. This process can also be automated. Compared, for instance, to steels, SMC provide design freedom and flexibility by accommodating shape complexity and geometric details; reduced manufacturing complexity through part integration in a single assembly; and combining structural, assembly, and integration functions (e.g., antennae embedment); substantial weight reduction (∼20–35% lighter than equivalent steel parts); superior corrosion resistance; and reduced tooling costs (40% less than tools for steel stamping). SMC also offer enhanced damage resistance from dents and dings, especially in exterior cladding (body panels), as compared to aluminum alloys and steels; good harshness properties; and good noise and vibration properties. The benefits of using SMC are also: in-mold coloring and powder priming for painted parts with the requirement of high temperature resistance from 150 to 200◦ C for e-coat application. Compared with injection molded parts, particularly those produced using the BMC process, SMC parts have better mechanical properties. For instance, equivalent parts exhibit typically an average thickness of 2.5 mm in the SMC case, whereas this thickness is about 3.5 mm in the case of injection molded BMC to meet the same mechanical requirements. This is due to the highest length of the fibers used in SMC. Even if fibers having the same length can be used in both processes, it is known that injection processes have a clear tendency to damage the fibrous reinforcement resulting in a drastic length reduction. This shows a limitation and an inefficiency in the injection processes. On the contrary, compression molding allows a lower freedom of design and complex geometry to be molded. This can be seen as an advantage when comparing SMC with prepreg fabrics: the latter indeed offer higher mechanical properties, but the parts have simpler geometry. For many applications, SMC compete with fiber-reinforced thermoplastic materials. Those materials can be injection molded or compression molded as GMT. SMC parts have better mechanical properties, heat resistance, better than usual dimensional stability and environmental resistance, and cost-effective thermoplastic composite parts. SMC can be used for the structural parts of the assembly, whereas visible skins can be composed of thermoplastic composites. This type of solution is currently implemented in the automotive industry. Nevertheless, painted SMC body panels are still being produced without major insoluble industrial problems.

Custom Formulated Sheet (SMC) & Dough Moulding (DMC)/ Bulk Moulding Compounds (BMC)

Material Performance	Material Description
General Purpose	General purpose composite materials with a wide range of applications. Suitable applications are typically structural in nature with no flammability requirements.
Heat and Corrosion Resistant	Composite materials intended for use in sanitary, cookware, appliance and indirect food contact applications.
Low Shrink Materials	Low shrink composite materials. Well suited for applications requiring shrink <0.1%.
UV Stable	These materials are suitable for use in applications requiring superior colourfastness & physical property retention upon exposure to UV and visible light.
Low Flame & Smoke Toxicity	These materials provide low flame & smoke toxicity in accordance with ASTM E162 and E662 standards
Corrosion Resistant	These composites are typically unsaturated polyester or epoxy vinyl ester materials formulated to meet the strict performance requirements of pumps, pipe flanges & underground applications that are impacted by corrosive environments.
Dielectric & Flame Resistant	These materials are suitable for electrical applications requiring a composite material that possesses a UL Yellow card and flammability performance from UL94 HB, V-0 & 5VA. These materials can be found in Underwriters Laboratory file E53587.
Electrical Insulators & Flame Resistant	These high strength Prazastinav DMC/ BMC composites are suitable for use in electrical applications requiring materials that possesses dielectric properties and flammability performance from UL94 HB, V-0 & 5VA. These materials can be found in Underwriters Laboratory file E53587.
Flame Resistant & Low Smoke Toxicity	This composite is certified as a low smoke toxicity material with a UL94 V-0 flame rating. It's physical characteristics have been certified to meet several specifications.

Manufacture of SMC

Electrical & Electronics Thermoset composite materials exhibit excellent dielectric strength due to the network of cross-linked molecules that create a rigid structure, where molecules are held in place by chemical bonds. Compounds made with thermoset binders. Thermosets are currently widely used in an array of electrical parts and applications for strong electric property benefits such as low arc and creep, high dielectric strength, and heat resistance. Additionally, thermosets can be UL rated at V0 or 5VA for flammability resistance, offering a high-performance material at much lower material cost per pound vs similarly performing thermoplastics such as PA66, PC, or PPS. Enclosures housing PCB boards or supercapacitors must be physically strong as well as electrically insulative to protect internal components from damage. Aside from strong material properties and the geometric benefits of molding vs. casting, thermoset enclosures offer an excellent cost comparison compared to a cast aluminum enclosure. Thermosets are an excellent economic alternative alleviate costly secondary operations and bring down overall program costs of an assembly through part consolidation and light weighting. Thermosets are much lighter than metallic materials, saving shipping costs and creating a much more friendly installation vs. heavy cast enclosures. Where a cast enclosure may incur secondary machining and protective painting costs, thermosets offer molded-in material color options and tight molding tolerances, ensuring product meets performance, dimensional, and aesthetic requirements.

Some Common examples of Thermoset plastic components are:
• Transmission components
• Motor houses
• Valve housings
• Appliance knobs and handles
• Circuit breakers
• Switch plates
• Relays
• Standoff insulators
• Brush holders
• Bases and end caps
• Crack balls, cement and wiper plugs
• load rings
• Electrical connectors, shrouds, circuit breaker housings, and contact blocks
• Motor mounts, brush cards, brush holders, and starter housings
• Electric switchgear
• Electrical insulator parts
• Electrical junction boxes
• Satellites Aerials / Dish Antennas
and other components which are in danger of exposure to high heat and corrosion.

Typical structural FEA properties for SMC

Properties	Unit	SMC- 20 – 40 % Glass Content
Coefficient of Thermal Expansion	⁰C	17.78
Flexural Modulus	GPa 10.34 – 13.10	10.34 – 13.10
Specific Gravity	g/cm³ 1.6 – 2.0	1.6 – 2.0
Poisson’s Ratio	–	0.32 – 0.36
Shear Strength	MPa	55.17 – 82.76
Tensile Modulus	GPa	9.66 – 12.41
Young’s Modulus	GPa	11.03 – 13.79

Transportation

Thermoset Sheet Moulding Compounds (SMC) meet the requirements of the Rapid Transit industry about low smoke generation and low flammability ratings, making them ideal for rapid transit, suburban commuter, and light rail systems' third rail electrical applications. These composite materials offer superior electrical insulation and heat resistance, allowing them to withstand prolonged exposure to the elevated temperatures and high voltage common in transit applications. Thermoset materials have Comparative Tracking Index (CTI) values exceeding 600 volts and dielectric strength in excess of 15 KV/mm. This, along with their excellent thermal properties, makes SMC moulding compounds an ideal choice for the insulative needs of the Rapid Transit industry.

Applications for SMC in the Rapid Transit market include: • Train / Tram interior & body parts
• High speed train driving cabin
• High speed train wind deflector
• Various train interior decoration parts
• Various train structural parts
• Tunnel cable bracket
• Third rail insulators
• Third rail canopies
• Contactors
• Traction motor brush holders
• Stand-off insulators
• Contactors
• Traction motor brush holders

Automotive

In the automotive and heavy truck market, designer struggle to meet many different and sometimes conflicting requirements. Parts must have the physical properties to handle the loads and environments of demanding vehicle applications. At the same time, must be relatively light, cost effective, and manufacturable in the time allowed by tight production schedules. In some cases, they must also have a pleasing appearance that will help attract buyers and differentiate a vehicle from its competitors. Some specific applications where SMC materials are currently being used by the automotive and heavy industry include:

• Headlamp housings (DMC/BMC)
• ETC valve housings (DMC/BMC)
• Engine housings (DMC/BMC & SMC)
• Various interior parts (DMC/BMC &SMC)
• Trunk covers (SMC)
• Bumpers (SMC)
• Front Faces (SMC)
• Deflectors (SMC)
• Fenders (SMC)
• Gasoline tank bottom shells (SMC)
• Truck step panels (SMC)
• Tractor roofs (SMC)
• Tractor exterior shells (SMC)
• Battery enclosures for BEV & Hybrid-Vehicle (SMC)
• Air deflectors and spoilers (DMC/BMC)
• Frames for windows/sunroofs (SMC)
• Air-intake manifolds (SMC)
• Front-end grill opening panels (SMC)
• Battery casings and covers (SMC)
• Headlamp housings (DMC/BMC)
• Bumpers and bumper beam (SMC)
• Heat shields (engine, transmission) (SMC/DMC)
• Cylinder head (e.g. valve, rocker, cam) cover (SMC)
• Pillars (e.g. 'A' and 'C') and coverings (SMC)

Medical Devices

Medical applications require many special considerations that make thermoset Sheet Moulding Compound (SMC) the perfect choice over metals and thermoplastics. These applications often require a material that can stand up to harsh cleaning solvents, high-temperature sterilization, and even X-ray radiation exposure. Thermoset SMC composite materials have many material characteristics that make it ideal for medical applications, such as; Instrumentation covers, bases, and components Standard and contagious/biohazard trash cans and receptacles X-ray film containers Surgery equipment Dental medication systems Antibacterial components

General Design Guidelines
Minimum Radius	1 mm (0.0625 in)
Minimum Draft	4 degrees
Minimum Thickness	3 mm (0.125 in)
Maximum Thickness	13 mm (0.500 in)
Typical Reinforcement Loading	10 – 60 %
Density (GP resin)	1938 kg/m³ (0.070 lb./in³)
Die Lock (Reverse Draft)	Yes