Casting often contain various imperfections which often contribute to normal quality variations. These defects not only give a bad appearance to the castings but also decrease their strength and practical utility. Casting defects generally occur due to improper control of the manufacturing cycle.
Defects in castings occur due to different causes. Practically it is quite difficult to establish a relationship between defects and causes. Roughly, casting defects can be classified into the following groups:
-Defects caused by patterns and moulding boxes.
-Defects due to improper moulding or core making materials
-Defects due to improper sand mixing
-Defects due to moulds, cores, runners and risers
-Defects due to improper metal temperature
-Defects due to improper pouring.
(Manufacturing Process, Yazar: H.S. Bawa,P.76)
Guillotines Shears (02,04)
Guillotine shears are used to cut sheet materials such as metal, plastic, paper, card and composite material and may be treadle operated or power driven. Before using any machine, the operator should be fully conversant with the controls, ensure that all the guards are in position and know the the emergency stop procedure. On some power driven machines a photo-electric cell is positioned in front of the blade to prevent operation if any object breaks the beam. For efficient use, the blades should be kept sharp and the clearence between the blades should be adjusted to suit the type and thickness of the material being cut.
(Basic Manufacturing, Yazar: Roger Timings, P.157)
Matrix Material (03,04 - 00.25)
The matrix phase can be any of three basic material types; polymers, metals, or ceramics. The secondary phase may also be one of the three basic materials, or it may be an element such as carbon or boron. Possible combinations in a two-component composite material can be organized as a 3 * 4 chart. We see that certain combinations are not feasible, such as a polymer in a ceramic matrix. We also see that the possibilities include two-phase structures consisting of the same material type, such as fibers of Kevlar (polymer) matrix. In other composites the imbedded material is an element such as carbon or boron.
(Mikell P.Groover, Fundamentals of Modern Manufacturing , page 188-189)
Mechanical Fasteners (03,04- 00.38)
The mechanical fastening generally requires that the components to be joined have holes through which fasteners such as bolts, screws, rivets, pins, etc. may be inserted and the jointing or clamping results either by screwing the nut on the threaded bolt or by riveting the head of the pin. Mechanical fasteners are preferred over other methods of jointing for the following reasons.
-Ease in manufacturing (drilling or tapping)
-Joint is not permanent and has ease of assembly and disassembling for repairing or maintenance
-Easy to create designs of joints requiring moveable joints such as hinges
-Lower overall cost
-Joints are easy to design to resist tensile and shear loads.
(Manufacturing Processes, Yazar: Kaushish, p.535)
Matrix Material (03,04 - 00.25)
The matrix phase can be any of three basic material types; polymers, metals, or ceramics. The secondary phase may also be one of the three basic materials, or it may be an element such as carbon or boron. Possible combinations in a two-component composite material can be organized as a 3 * 4 chart. We see that certain combinations are not feasible, such as a polymer in a ceramic matrix. We also see that the possibilities include two-phase structures consisting of the same material type, such as fibers of Kevlar (polymer) matrix. In other composites the imbedded material is an element such as carbon or boron.
(Mikell P.Groover, Fundamentals of Modern Manufacturing , page 188-189)
Mechanical Fasteners (03,04- 00.38)
The mechanical fastening generally requires that the components to be joined have holes through which fasteners such as bolts, screws, rivets, pins, etc. may be inserted and the jointing or clamping results either by screwing the nut on the threaded bolt or by riveting the head of the pin. Mechanical fasteners are preferred over other methods of jointing for the following reasons.
-Ease in manufacturing (drilling or tapping)
-Joint is not permanent and has ease of assembly and disassembling for repairing or maintenance
-Easy to create designs of joints requiring moveable joints such as hinges
-Lower overall cost
-Joints are easy to design to resist tensile and shear loads.
(Manufacturing Processes, Yazar: Kaushish, p.535)
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