The project report includes Present Market Position and Expected Future Demand, Market Size, Statistics, Trends, SWOT Analysis and Forecasts. Report provides a comprehensive analysis from industry covering detailed reporting and evaluates the position of the industry by providing insights to the SWOT analysis of the industry.
Bulk moulding compounds represent a family of chopped fibre thermoset or thermoplastic based composite materials. Fibre lengths are typically 1/2 inch, 1 inch or 2 inch (6 to 50 mm). Longer fibres provide higher tensile strengths while shorter fibres allow more complex shapes to be moulded. Standard modulus and intermediate modulus fibres are utilized as is S2 glass. TenCate offers a complete line of epoxy based thermosets and also offers a line of thermoplastic resins such as PEEK, PEKK, PPS and PEI. Thermoplastic based resins offer low moisture uptake, good impact resistance and low flame, smoke and toxicity. Thermoset resins are precision coated and designed to be low flow for optimal high fibre/resin content.
Premix is generally known as Dough Moulding Compound (DMC), flow mix or Bulk Moulding Compound (BMC). Premix has been defined as “A fiber reinforced thermo set molding compound not requiring advancement of cure, drying of volatiles, or other processing after mixing to make it ready for use at the molding press”. To this might be added “and which can be molded without reaction by products under only sufficient pressure to flow and compact the material”*. If the word “mixing” in the above is changed to “manufacture” the definition can apply equally to sheet molding compound. The principal differences between premix and SMC are in the manufacturing methods and in the form in which they reach the molder. Each can be formulated of the same basic ingredients.
Premix is formulated by combining all the ingredients in an intensive mixing process. It emerges from the mixer in a fibrous putty form, and it can be used directly, the operator merely weighing out charges. Some formulations can be compacted and extruded into bars or “logs” of simple cross section to facilitate handling.
* In contrast to phenolic melamine or urea compounds that have water as a reaction product and require high pressure to prevent steam formation and consequent voids in the molding.
Premix:-
Premix first became a practical possibility when glass fiber rovings came on the market in 1949. Prior to this some reinforced polyester molding compound was made by chopping fiberglass fabric prepare into small pieces. In spite of many disadvantages high cost, residual solvents, no internal release agent no fillers, etc. some useful products offering properties available in no other known material were successfully molded.
It is difficult to track down the first premix compound of the new breed. The earliest were probably made about 1950, employing a process of impregnating roving strand with the resin, filler etc. blend and chopping them to length in the wet stage. Wetting glass fibers with a resin containing much filler is a difficult and slow business consequently these premixes had a high glass content.
Sometime in the early 1950’s the concept of adding prechopped glass fibers to a resin-filler mixture was conceived and by the mid-1950’s premix molding was a going business. It was however, delayed in development by the fact that neither the compounders nor the molders were experienced in the kind of business in which they found themselves. No compounders of conventional thermo set compounds were initially interested. As a result such simple things as internal mold release were a long time coming. And no compression molders would contaminate their premises with the sticky, smelly stuff, so their extensive knowledge of mold construction, ejector mechanisms, heating devices, etc. ws denied the fledgling industry.
The first move to high volume occurred with the development of a premix based on sisal fibers and the molding of automobile heater housings the largest (in area) items ever made in volume production from a molding compound up until that time. While this type of compound was not outstanding in its physical properties, the unique character of the sisal fiber permitted intensive mixing without fiber damage and promoted homogeneity throughout a large molding, which was not possible with the glass fibers then available.
While the easy molding, low cost sisal premix continued to dominate the high volume automobile market, the development of a resin coating for glass fiber strands that preserved their integrity, i.e. kept them intact as bundles of fibers through the mixing process, made possible large area molding with strength, chemical resistance, electrical insulation values, and other desirable properties. Consequently heavy, large area electrical and chemical items as well as a few commercial products such as internal parts of appliances, where surface quality was secondary consideration became commonplace. Surface wavines and coloring problems limited product applications to items and/or parts not normally exposed to the consumers’ view.
To obtain water and stain resistance not offered by sisal and glass fiber reinforced compounds, the use of chopped nylon rag was introduced in the early 1960’s. This material has brought about high volume manufacture of such items as shower bases with dimensions up to 3 feet X 6 feet and weighing as much as 75 pounds each.
As mentioned earlier, the applications of glass fiber reinforced premix were seriously limited by irregular waviness of the molded surface. Developments in Germany and England about 1960 in the use of chemical thickening agents and thermoplastic additives markedly reduced cure shrinkage, resulting in improvement in the quality of the surface as well as limitation of other distortions. These improvements unfortunately required some compromises, and efforts to produce a distortion free premix without sacrifice of other properties continue up to the present.
Other significant stages in the history of premix are: the use of hydrated alumina as an additive to provide either self-extinguishing or nontracking qualities, the development of last cure resins, and very recently the molding of premix in injection transfer type “automatic” presses that give promise of putting
Premix in direct price competition with low cost thermo sets and thermoplastics.
BMC is a doughy mass that can be produced from any conventional thermoset matrix system and is also processed by reaction injection molding. The BMC part can be produced as soon as the BMC compound has been mixed. The main difference from SMC is the fiber content and length.
