Types of Engineering Materials Testing - Essay Example

?Experimental report Introduction Materials testing is the actual process of assessing the properties of the material. It is a lengthy process that aims at determining the finer property details of the materials. Engineering materials are tested for their strain so as to determine their failures. The testing involves analysis of both the chemical and physical properties of a material. The testing of the materials is done to ascertain whether the material meets required standards. Most of the testing is carried out in a highly controlled materials laboratory. Quality assurance plays an active role in materials testing. Quality assurance carries out calibration test and manufacturing test. Calibration test is carried out to determine the workability of the measuring properties. Manufacturing test is carried out to determine the adherence to standardization. Some of the tests through which engineering materials are subjected to can be categorized as follows; Mechanical test These tests are carried out on the engineering materials to determine their strength, elastic constants, material properties and performance properties. Mechanical test involves testing the test specimen. The test specimen is obtained through the breaking of the original sample materials. Tensional test These are quasi-static test carried out on the engineering materials to determine the properties of these materials. This test is carried out by exposing the sample material to uniaxial loading conditions. Hardness test The resistances to penetration by most engineering materials are determined by hardness test. Hardness test is carried out using three different methods that are scratch test, rebound test, indentation test. Scratch test involves progressive scratching of a hard material. Rebound test involves the ability to determine the material resilience. Material resilience is determined by measuring the potential energy of the material. Indentation test involves production of a permanent impression on the surface of the materials. The size and the force of the impression determine the material hardness. Hardness test can further be categorized as macro hardness test or micro hardness test. The macro hardness test includes Brinell, Vickers and Rockwell tests. Micro hardness test includes Knoop and Tukon test. Torsion test This is a test that is carried out to obtain the stress-strain relationship for the metal. Torsion test is able to generate both the shear stress and shear strain of the material. Impact test This test is conducted to determine the static properties and the mechanical behavior of the engineering material. Heat treatment and the stress concentrations of the material are carried out under impact test. When the drill (Osaki CD 1202 12V) was stripped down, the following material components were identified; Polystyrene polymer Polystyrene is a vinyl polymer structurally made up of very long hydrocarbon chain. The polystyrene polymer has a phenyl group attached to its carbon atom. This polymer is hard and it is a clear plastic. Polystyrene is made from free radical vinyl polymerization of the monomer styrene. This polymer is hard and it is used for making of the drill handle. Due to its hard nature, it is able to withstand a lot of heat. Nylon This is a thermoplastic polymer which is used as a fiber. Nylons are made from diacid chlorides and the diamines.One of the nylon polymer that is nylon 6, 6 is produced from the combination of two monomers. The two monomers are adipoyl chloride and hexamethylene diamine. Another form of nylon is the nylon 6. Nylon 6 is made from a ring opening polymerization. These nylons are used in making the casing for the ball bearing. It is preferred because of its ability to be fabricated into any shape. Diamond This is the hardest engineering material. They are gem-quality carbon crystals. They are highly refractive crystalline carbon types and are used in abrasives, cutting tools and drilling operations. They have slight impurities in their structures, but they are purely carbon. Due to their hard nature, they are used in the manufacturing of the drill bit used in the drilling operations. Carbide This is an engineering material composed of carbon and little electronegative material. They are categorized according to their chemical bonding. They can be classified as salt-like, covalent structures, interstitial structures and transition metal carbides. The various types of carbides are; calcium carbides, tungsten carbide and silicon carbide. Due to their heat resistance nature, they are used in the making of the drill bits. Besides their heat resistance nature, they are also hard and therefore used for making cutting tool bits. Cellulose Cellulose is a polymer found in plant materials. It is one of the engineering materials made of repeated units of glucose monomer. Cellulose is used in the making of the synthetic polymers. One of the derivatives of cellulose is the hydroxyethylcellulose. Cellulose is used for making the tool handles. They provide insulation from electric shock. Mega steel polymer The drill bit used in the holes drilling operation has a matrix head and a mating body pin. A locking ring is provided for the fastening of the pin body and the matrix head. At times, mega steel polymer is applied to the threads so as to provide sealing and also to add strength to the connection. When a mega steel polymer is used then the locking rings are not used. Literature review Introduction Some of the artifacts studied were; metal artifacts such as carbide and diamond and also polymer artifacts such as polystyrene, nylon, cellulose and mega steel. All the polymers were thermoplastic and the metal artifacts were high strength steel carbons. History of Carbide and Diamond Carbide polycrystalline cutters were invented in the year 1971 by General Electric. The technology of the carbide and the diamond cutting has significantly changed the industrial segment material removal. The cutting technology of both carbide and diamond was first tested by Hughes Tool Company in the year 1972 by General Electric. The early carbide cutters were available as carbide disc of about 8.38 mm diameter, 2.8 mm thickness and un-chamfered 0.5mm polycrystalline diamond cutter. The early drill bits were large (Wentorf, 1971). History of the thermoplastic polymers Modified polymers such as nitrated cellulose were the first synthetic polymers to be used .Polymerization of styrene started in the year 1839. Ethylene glycol and ethylene succinate were first synthesized in the year 1960.First commercial synthetic polymer was phenol formaldehyde resin also known as Bakelite. This synthetic polymer was developed in the early 1900s by Leo Baekeland. Polyester paints and polybutadiene later followed. The relationship between intermolecular forces and the properties of polymers was first echoed by a German chemist called Hermann (Balcannon, 1950). Experimental procedure The metal sample was tested for magnetism so as to confirm whether it was ferrous. The sample was washed and bathed in alcohol. Drying was done using the hot air gun. The sample was put into a mounting machine and a heat spoon of graphite was added. This was followed by non-stick powder which was placed on the lid. After the machine has mounted the sample on the bakelight, the sample was cooled and ground on a silicon car byte belt. 240 grip were used and increased to 400 and then to 800 and finally to 1200.All the scratches were erased after grinding close to 100 times. The sample was then held at 90 degrees to the direction of the polish. The sample was then washed, drenched in alcohol and dried using a hot air gun. A 6 micron diamond was put into a polishing machine and a suspension liquid was put onto the diamond and spinning was done in the opposite direction. After a time period of 5 minutes, the sample was washed, drenched in alcohol and dried. The relative lines on the sample were then checked under the microscope. Etching was done the sample by submerging the sample into a 2% solution of Nital and left for 5-10 minutes. The sampled was then soap washed, drenched in alcohol and dried. Later it was observed under the microscope. Results The Vickers hardness test carried out showed that the handle of the drill was made up of a polymer. The polymer in question was polystyrene. The bearing casing of the drill was found to be made up of nylon polymer. The microscopic observation revealed that the drill bit was made up of tungsten carbide and diamond. This was due to the shiny metal particles which were visible under the microscope. Name of the plastic part Density/drop Test/scratch test Burn Flame Identified as Green plastic cover of the drill Sinks/high pitch/scratch test: found out to be a thermosetting resin Highly flammable, black smoke with flying black particles, melt none, bubbling Yellow flame=acidic Polystyrene Drill head plastic cover (keyless drill chuck) Sinks/dull pitch/not easily scratch Lower flammable, no smoke, no melt, no bubble, no drop Yellow flame Mega steel polymer Battery cover Sinks/high pitch sharp noise/easily scratched Highly flammable , melt, black smoke, bubbling Yellow flame Nylon Plastic frame for the drill head Sinks/low pitch/easily scratched Highly flammable, melt, bubble Yellow flame Cellulose Name of the part Surface appearance Microscopic test Density Identified as Metal part Smooth and shiny Shiny and bright particles, densely compacted Sinks in both water and alcohol Carbide Ball bearing Smooth and shiny Shiny and bright particles, densely compacted Sinks in water and alcohol Carbide Drill wheel Rough and dull Black particles, the particles are very close Sinks in both water and alcohol Diamond Discussions The scratch test done on the green cover of the drill head indicated that the material for the drill head was made up of a polymer. This conclusion was arrived at having studied the behavior of the material. Most of the polymer materials such as polystyrene is heavy and therefore would definitely sink in water. Besides sinking, polystyrene also produces high pitch sound when dropped. The burning nature of the material also proved that the material was polystyrene since it burnt with a sooty flame and had fallen particles. The falling black particles were the carbon elements of the polystyrene. Most polymers are made up of hydrocarbons. Hydrocarbons most of the time burns with a yellow flame and leaves traces of black substances (Hadal & Misra, 2005). The drill head plastic cover was found to be mega steel polymer. This conclusion was arrived at after the series of scratch test and the flame test. Most mega steels are heavy and therefore they would sink when put in water. Due to their heavy nature, these materials would drop with the low pitch sound. They are hardened and therefore not easily scratched. They burn slowly and do not melt during burning. All these are the test for mega steel polymer. The test on the battery cover indicated the material in question was nylon. Some nylon like nylon 6, 6 sinks when put in water. When touched or rubbed then they give high pitch noise sound. They are also easily scratched and they burn with a yellow flame and leaves behind no chars since they always melt. The black sooty smoke is due to the carbon in their composition and structure. They bubble when burnt. The test on the plastic frame for the drill head indicated that the material was indeed a polymer. This polymer was cellulose. Most cellulose is hardened fibers. They sink when put in water. They have a low pitch due their compacted nature. Their fibers are completely compacted. Vickers scratch test on them shows they are easily scratched. These materials are also highly flammable and they melt and bubbles when exposed to heat above 45oC.They burn with a yellow flame due to the fact that they are polymers. They burn with sooty flames .The sooty flames are the unburnt carbons since they are made of hydrocarbons (Browning et al, 2006). On the microscopic test, the metal which appeared to be shiny and densely spaced can be said to be carbide. The tungsten carbide has a shiny and smooth appearance. Most carbide particles are densely spaced so as to increase their metallic bond. The metallic bond is like a sea of electrons. The shiny appearance is due to the high polishing of their surfaces. They are heavy and therefore would sink in both water and alcohol. The other microscopic test showed the presence of black particles. The surface of the material was dull and rough. The spacing between the particles was close and the particles appeared as black specks. The material was also able to sink in both water and alcohol. The material under test can be deduced to be a diamond. Due to its hard nature, diamond is generally rough and dull. The dullness is due to the presence of carbon. As said earlier, Diamond is made purely of carbon and carbon is black, hence the dull nature. Diamond is heavy and therefore it sinks in both water and alcohol. Bibliography Browning, R., Lim, G., Moyse, A., Sun, L., Sue, L., &Sue, H.J. 2005. Materials science and Engineering. London: critical publishers pp. 252-261 Balcannon, 1950.History of polymers and early uses of polymers. New York; engineering Science review pp. 231-237. Hadal, R. & Misra, RDK 2005. Materials science and engineering. Ottawa: Mac mills experts pp 252-261. Wentorf, 1971. History and early uses of carbides and diamonds. Rome: Indis publishers pp 104-110. Read More