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SHEET MOLDING COMPOSITES (SMC), BMC PRODUCTION
Transcript of SHEET MOLDING COMPOSITES (SMC), BMC PRODUCTION
SHEET AND BULK MOLDING COMPOSITES (SMC), (BMC) PRODUCTION
Composite materials are composed of a mixture of two or more constituents, giving them mechanical and thermal properties which can be significantly better than those of homogeneous metals, polymers and ceramics
Typical engineered composite materials include:
Composite building materials such as cements, concrete
Reinforced plastics such as fiber-reinforced polymer
Ceramic Composites (composite ceramic and metal matrices)
Definition of Sheet Molding Compound
The SMC matrix, often termed the SMC paste in its uncured state, is a complex organomineral multimaterial that is generally constituted by;
(i) Thermoset resin,
(ii) Their associated initiators and inhibitors
(iii) Specific thermoplastic polymers
(v) Thickening agents
(vi) Other additives
05090000488 Aynil ÇETİN
05100000459 Nihan AYKANAT
05100000535 Yasin DALMAZ
Figure 2 Various Samples of SMC
SMC is both a process and reinforced composite material. This is manufactured by dispersing long strands (usually >1”) of chopped fiber (commonly glass fibers or carbon fibers on a bath of resin (commonly polyester resin, vinylester resin or epoxy resin). The longer fibers in SMC result in better strength properties than standard bulk moulding compound (BMC) products. Typical applications include demanding electrical applications, corrosion resistant needs, structural components at low cost, automotive, and transit.
Definition of Bulk Molding Compound
Figure 1 Lateral View of Composite Material
Sheet moulding compound (SMC) or sheet moulding composite is a ready to mould glass-fibre reinforced polyester material primarily used in compression moulding. The sheet is provided in rolls weighing up to 1000 kg.
Bulk molding compound (BMC) or bulk molding composite is a ready to mold, glass-fiber reinforced thermoset polyester material primarily used in injection moulding and compression moulding. The material is provided in bulk or logs.
Figure 3 View of a BMC sample
BMC is manufactured by mixing strands (>1”) of chopped glass fibers in a mixer with polyester resin. The glass fibers in BMC result in better strength properties than standard thermoplastic products. Typical applications include demanding electrical applications, corrosion resistant needs, appliance, automotive, and transit.
2.0 Raw Material
Unsaturated polyester resins
Glass (silica or silicate)
Mineral filler materials such as chalk or aluminum trihydrate.
Specific properties such as flame retardancy, surface quality
and paintability can be achieved by adding specific, functional
2.1 The SMC Matrix or Paste;
Today, current research and development work for future improvement of physico-chemical, thermo-mechanical, optical, technological, environmental, and safety properties of SMC is focusing on the following;
The development of low, mid-density, and high strength SMC compounds
The increase of damage and impact resistance properties
The development of carbon reinforcement fibers
High end car parts and civil aircraft applications
The development of high temperature SMC (>140◦C) for power train system applications.
The development of conductive SMC grades.
The formulation of UV-stable formulation
The formulation of SMC, which fulfill more rigid requirements of safety properties such as flame, smoke, and toxicity
The development of anti microbial additives to address water treatment application issues
The use of bio-based resins and natural fibers, which will make SMC greener
2.4 Basic properties for BMC
High temperature resistance Tg>200 ◦C
Very high strength to weight ratio
Chemically resistant to most automotive fluids.
Repeatable molded part dimensions
Excellent dimensional stability
Low warpage/excellent part flatness
Extremely high creep resistance
Excellent flammability resistance
Excellent electrical properties
Low relative cost to alternative high performance materials
High temperature assembly possible
Table 2 Ingredients of SMC and BMC
2.5 Reactions for Unsaturated Polyester
UP resins are widely used in the compositions of thermoset polymer composites Because of their low cost, good physical and mechanical properties in the solid state also their weather ability, and short curing time,
In particular, they are still the most employed resins in the SMC formulations.
The UPs are the chemical products of a linear polycondensation known as polyesterification. This polycondensation takes place in reactors and usually involves saturated acids and diols.
There are numerous UP resin formulations that can be used in polymer composites such as SMC For instance, ortho-resins are made up of glycols
The most used glycols in SMC being the (di)polypropylenes and the (di)ethylene glycols
2.6 Properties for resins
Except the UP resins, other types of thermoset resins can be used in SMC. Such as, vinylester, phenol formaldehyde and epoxy resins
Table 3 Typical Mechanical Properties of the Most SMC Used Thermosets Resins
2.7 Properties for other resins
Phenolic Resins: In order to enhance both mechanical properties at elevated temperatures and the fire resistance, standard UP resins can be replaced by phenol formaldehyde resins.
Vinyl ester Resins: Vinyl ester resins are used for SMC formulations that require higher physical and mechanical properties. For example, structural applications.
Epoxy Resins: For parts requiring high mechanical properties, and when the economic factor is not of first importance (e.g., in the aerospace domain), the SMC paste can also be made up of epoxy resins.
3.1 PROPERTIES OF COMPOSITE PRODUCT
The final properties of produced composite are of two types: the bulk properties and the surface properties.
Bulk Properties: Composite parts are mainly used for structural or semi structural applications. Thus, their mechanical properties, which have been extensively studied in the literature, are of first importance.
To summarize, composites usually behave as anisotropic visco-elastic ‘‘brittle’’ solids undergoing damage that alters their mechanical properties until their rupture.
Surface Properties:Surface quality is comparable in importance to mechanical properties in compression-molded parts, particularly in automotive applications. Several types of defects are frequently encountered such as surface waviness, sink marks, fiber readout, blisters, and pores
3.1 Mechanical Properties for SMC
2.3 Basic properties for SMC-2
2.2 Basic properties for SMC-1
4.0 PRODUCTION METHOD
4.1 SMC Process
Sheet Moulding Compound is an
composition of glass fibre’s, resin and filler.
SMC is made by
metering a resin paste onto a thin plastic carrier film.
The resin is typicall
y thermoset Polyester
but alternatives are available such as vinyl, Phenolic and Acrylic modified depending on the ultimate properties required.
The compound is made by
chopping continuous fibers onto the resin paste as it is conveyed on the film
This glass, resin mix is further covered by another layer of resin on a second carrier film.
Compaction rollers knead the fibers into the resin
for uniform fiber distribution and wetting.
The compound sandwiched between the carrier films is gathered into rolls and stored until it matures.
Flowsheet of SMC Production
4.2 BCM Process
The basic raw materials
resins, additives, catalysts, mould
release agents and fillers
are mixed under high shear to produce a viscous paste similar to SMC process.
To this paste
are added and the kneading process continued for a short period. The fibrous
dough - like
compound is then packed into Styrene proof bags until moulding.
Flowsheet of BMC Production
SMC and BMC product are used in a very broad range of applications, such as:
cars, trucks and other commercial and agricultural vehicles
trains, trams, light railways and monorail
bathroom suites and hygienic surfaces
Building & construction:
civil engineering and household fixtures
coffee machines, toasters, irons, etc.
Electrical & electronics:
housing, fuses, switchgear, etc.
SMC/BMC is safe for the environment and can be handled in the industry in such a way that it has no effect on the human body.
SMC/BMC facilitates the generation of green energy
Heavy metals are pro-actively eliminated from the SMC/BMC industry.
SMC/BMC does not contain halogens to achieve good fire properties.
SMC/BMC has the potential to be 100% bio-based
Continuous filament glass fibers are not respirable and not classified as a suspected carcinogen
The environmental benefits of metals are only based on the possibility to recycle metals. SMC/BMC has much more environmental arguments, such as light weight, low energy consumption, long lifetime AND recyclability.
SMC/BMC parts have a long lifetime, without the need of maintenance
SMC and BMC electrical cabinets have a long track record as durable application. Outdoor exposed cabinets are already in service for more than 30 years, without the need for maintenance.
In comparison with traditional materials, such as steel, aluminum and concrete, SMC and BMC products have a low environmental impact, which is given by a total set of arguments:
Low energy content in production
Low emissions in production
These arguments make products made in SMC and BMC an excellent construction material to contribute to a better world.
Advantages of SMC & BMC
Excellent mechanical properties
even at very high and low temperatures
Low thermal expansion coefficient comparable to steel
Low weight means energy saving over the lifetime of a part; greater fuel efficiency and reduced CO2 emissions through the life of vehicle.
High temperature paintability
• Chemical resistance
Resistant to acidic and alkaline chemical environments, water, moisture.
Excellent dimensional accuracy and stability
• Low system cost through integration of parts and functions
Flame retertand and low smoke emissions, halogen free formulations
Fire safety in mass transit vehicles and public buildings.
• Superior sound demping compared to aluminium and steel
SMC/BMC are highly versatile materials that can be custom formulated and moulded to meet exact performance.
5.1 Economic Aspect
The European Alliance for SMC/BMC released the European market figures for 2010 & 2011 related to products and market
Based on the 2009 – 2010 comparison, the production volume of SMC/ BMC in Europe increased to around 10%.
Concerning 2011 figures, the market data is foreseeing an estimated additional growth of around 7% which brings the total volume to around 240.000 tons
5.0 INDUSTRIAL RELATIONS
The market data in figure below shows the 2008 – 2011 compared market data for BMC and SMC.
Concerning market applications of SMC/ BMC , the 2010 & 2011 data showed a stable volume.
Electrical & electronics
applications continue to lead SMC/BMC market segments
(42%), followed by transportation (40%), construction & household (12%) and others (6%).
Compared to 2010, SMC/BMC applications in transportation increased slightly.
China has been left relatively untouched by the recession in the composites sector and is continuing to draw on this growth.
In 2010, its production represented 28% of global production, the largest share.
In the same year, the USA represented in excess of 22% of global production, and Europe represented 20%. The rest of the world produces 29% of composites.
Companies In the World
IDI Composites International
Retterbush Fiberglass Corporation
Chattahoochee Specialty Composites,Inc.
Molding Technologies Inc.
Companies In Turkey
Alpin Kimya Sanayi ve Ticaret A.Ş
Gamafrp Kompozit Teknolojileri Sanayi
Definition of Composite Material
Table 4 SMC/ BMC Production Volumes in Europe
Table 5 Trend European SMC/ BMC Production (2010- 2015)
Figure 4 Market Application in 2011