About Engineering & Plastic Technology

Design Guidelines 1.   Use of uniform wall thickness throughout the part. This will minimize sinking, warping, residual stresses, and improve mold fill and cycle times. 2. Use generous radius at all corners.           The inside corner radius should be a minimum of one material thickness.           3. Use the least thickness compliant with the process, material, or product design requirements. Using the least wall thickness for the process ensures rapid cooling, short cycle times and minimum   shot weight. All these result in the least possible part cost. 4. Use ribs or gussets to improve part stiffness in bending. This avoids the use of thick section to achieve the same, thereby saving on part weight, material costs, and cycle time costs. 5. Design parts to facilitate easy withdrawal from the mold by providing draft in the direction of mold opening or closing. Wall Thickness The typical plastic part ma...

 HISTORY The aerospace industy was among the first to realize the benefits of composite materials. The Voyager, which without refueling in 1986 , was constructed from graphite and aramid-reinforced plastics. INTRODUCTION Airplanes , rockets, and missiles all fly higher, faster, and farther with the help of composites. The major reasons for the use of composite materials in spacecraft applications include weight savings as well as dimensional stability in wide range of temperature variation from -100 to +100. Carbon-epoxy composite laminates can be designed to give zero coefficient of thermal expansion. Although the terms 'carbon' and 'graphite' are used interchangeably. The term carbon is used for any fiber carbonized to 90% or more. Graphite fibers are more accurately defined as fiber that are carbonized around 99%. APPLICATIONS These fibers are used to reinforce polymers in the constuction of strong, rigid, lightweight and highly durable products such as car bodies, b...

 INTRODUCTION Nylon is one of the most important polymers that can be formed into sheets, rods, fibers, bristles, tubes, coatings and molding powder. MANUFACTURING Carothers synthesized a salt from extremely pure diamine and diacid reactants. Then he removed the impurities by crystallization of the salt followed by heating to produce a high molecular weight polymer, poly-hexamethylenadipamide . This polymer is called as nylon 6,6 because both reactants have six carbon atoms. This polymer was term as "super polyamide". Nylon 6,6 fiber has application in dress, parachutes, tire cord, carpets, socks, fishing line, bristles for brushes, surgical threads. Chemical formula for Nylon 6,6 Other nylons have also been used in fiber formation such as Nylon-6 . Nylon-6 is polycaprolactum, which has the follwing chemical formula [NH(CH2)5-CO]n

 INTRODUCTION asbestos is the fibrous form of magnesium silicate which is a natural inorganic polymeric material. asbestos is not a single mineral but a group of materials that yield soft, threadlike fibers. it consists of alternate sheets of magnesia (Mg(OH)2) and silica with an overall formula as: Mg3Si2O5(OH)4 Egyptians used asbestos cloth to prepare bodies for burial. Marco Polo described its use in the preparation of fire-resistant textiles in the thirteen century. Because of its toxicity, asbestos has been replaced by other fibers.  Asbestos holds less than 1% share in the fiber-composite market. It has tensile strength of 2100 kg/cm2 and has elongation of 25%.

 INTRODUCTION Additives are those  substances which are added into the resin matrix during composite fabrication process. PURPOSE Additives are added to meet  various end-use properties in the polymer and processing and handling needs of polymer TYPES OF ADDITIVES Monomer  Catalyst Accelerators Mould Release agents Fillers Pigments MONOMER Monomer is the smallest unit of a polymer chain which  has capability to form chain like structure. Therefore monomer is used for linking polymer chain to get a 3-dimentional network structure of polymer. Such process is extensively utilized in curing of polyester resin during composite fabrication. For the curing of polyester resin , styrene is added The amount of styrene ranges at 30- 50% by weight. The carbon-carbon double bonds in unsaturated polytester molecule and the carbon-carbon double bonds in the styrene molecules work as the cross-linking site. CATALYST Catalyst are used for curing purpose. Cure rates of a polymer ...