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Questions and Answers
What does the term 'manufacture' derive from in Latin?
What does the term 'manufacture' derive from in Latin?
Which processes are classified as primary shaping processes?
Which processes are classified as primary shaping processes?
What is the main characteristic of deforming processes in manufacturing?
What is the main characteristic of deforming processes in manufacturing?
In machining or removing processes, what is the primary operation performed?
In machining or removing processes, what is the primary operation performed?
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Which of the following methods is not typically associated with joining processes?
Which of the following methods is not typically associated with joining processes?
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What is the purpose of surface finishing processes?
What is the purpose of surface finishing processes?
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Which statement best describes primary shaping processes?
Which statement best describes primary shaping processes?
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Which option accurately describes the relation between forming processes and material removal?
Which option accurately describes the relation between forming processes and material removal?
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What is the primary purpose of porosity in moulding sand?
What is the primary purpose of porosity in moulding sand?
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Which property of moulding sand allows it to easily fill a molding box?
Which property of moulding sand allows it to easily fill a molding box?
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What does collapsibility in moulding sand prevent?
What does collapsibility in moulding sand prevent?
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What characteristic is essential for sand to cling to moulding boxes?
What characteristic is essential for sand to cling to moulding boxes?
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How can the flowability of sand be improved?
How can the flowability of sand be improved?
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Which property of moulding sand refers to the ability of sand particles to stick to each other?
Which property of moulding sand refers to the ability of sand particles to stick to each other?
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What is refractoriness in the context of moulding sand?
What is refractoriness in the context of moulding sand?
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What is the consequence of inadequate porosity in moulding sand?
What is the consequence of inadequate porosity in moulding sand?
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What classification is used for metals in a pressurized gating system?
What classification is used for metals in a pressurized gating system?
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Which gating ratio indicates a pressurized gating system?
Which gating ratio indicates a pressurized gating system?
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What is the primary control method in an unpressurized gating system?
What is the primary control method in an unpressurized gating system?
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Which statement is true about the turbulence in gating systems?
Which statement is true about the turbulence in gating systems?
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How does the flow of metal behave in an unpressurized gating system?
How does the flow of metal behave in an unpressurized gating system?
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What effect does the back pressure have in a pressurized gating system?
What effect does the back pressure have in a pressurized gating system?
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What happens to the total cross-sectional area in an unpressurized gating system?
What happens to the total cross-sectional area in an unpressurized gating system?
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Which of the following is a characteristic of a pressurized gating system?
Which of the following is a characteristic of a pressurized gating system?
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What is a significant disadvantage of shell mold casting?
What is a significant disadvantage of shell mold casting?
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Which of the following is an application for shell mold casting?
Which of the following is an application for shell mold casting?
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What material is used for creating the shell mold in shell mold casting?
What material is used for creating the shell mold in shell mold casting?
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What is the typical thickness of an industrial shell mold used in the casting process?
What is the typical thickness of an industrial shell mold used in the casting process?
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At what temperature range is the metal pattern heated during the shell mold casting process?
At what temperature range is the metal pattern heated during the shell mold casting process?
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What happens to the loose sand during the shell mold casting process?
What happens to the loose sand during the shell mold casting process?
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What is the purpose of the parting agent applied to the metal pattern?
What is the purpose of the parting agent applied to the metal pattern?
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Why is shell mold casting particularly suitable for manufacturing steel castings?
Why is shell mold casting particularly suitable for manufacturing steel castings?
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What is the primary cause of pinholes in molten metal?
What is the primary cause of pinholes in molten metal?
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Which of the following is NOT a remedy for reducing pinholes in casting?
Which of the following is NOT a remedy for reducing pinholes in casting?
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Which of the following best describes a cold shut defect?
Which of the following best describes a cold shut defect?
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What is the recommended remedy for preventing misrun defects?
What is the recommended remedy for preventing misrun defects?
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What causes shrinkage cavities in casting?
What causes shrinkage cavities in casting?
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Which of the following is a cause of slag inclusion in casting?
Which of the following is a cause of slag inclusion in casting?
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How can the issue of cold shuts be mitigated?
How can the issue of cold shuts be mitigated?
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Which practice is advised to increase the quality of pouring for preventing misruns?
Which practice is advised to increase the quality of pouring for preventing misruns?
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Study Notes
Manufacturing Processes
- Manufacturing is the application of physical and chemical processes to alter the geometry, properties, and/or appearance of a starting material.
- Derived from Latin words "manus" (hand) and "factus" (make), meaning "made by hand".
Classification of Manufacturing Processes
- Primary Shaping Processes: Manufacturing of solid body from a molten or gaseous state or from an amorphous material (gases, liquids, powders, fibers, chips).
- Deforming Processes: Use stresses like compression, tension, shear to cause plastic deformation without changing mass or composition.
- Machining/Removing Processes: Utilize suitable relative motion between workpiece and tool to generate a desired surface, removing material from unwanted regions.
- Joining Processes: Unite two or more pieces of metal parts through fusing, pressing, rubbing, riveting, or other methods to create sub-assemblies or final products.
- Surface Finishing Processes: Provide intended surface finish on a job.
Moulding Sand Properties
- Porosity/Permeability: Allows gases to pass through easily, preventing gas trapped in molten metal during solidification, which causes holes/pores in castings.
- Flowability: Moulding sand's ability to behave like a fluid during ramming. High clay/water content increases flowability.
- Collapsibility: The sand's ability to collapse after metal solidification allowing for free contraction, preventing tearing/cracking.
- Adhesiveness: The ability of sand particles to stick to another body, ensuring sand clings to molding boxes.
- Cohesiveness/Strength: The ability of sand particles to stick to each other for mold strength.
Gating Systems
- Pressurized System: Designed for reactive metals (magnesium alloy) using a specific gating ratio (1:2:1 or 1:0.75:0.5). Back pressure is maintained, reducing aspiration and leading to high velocity and turbulence.
- Unpressurized System: Used for normal metals (brass, steel, aluminum) with a gating ratio like 1:2:2, 1:3:3, or 1:1:3. Flow is not full and less turbulence occurs.
Shell Mold Casting
- Shell mold casting uses a thin hardened shell of sand and thermosetting resin as the mold.
- Suitable for steel castings less than 30 kg.
- The process involves:
- Using fine-grained sand mixed with a thermosetting resin binder.
- Coating the metal pattern with a parting agent for shell removal.
- Heating the pattern (175°C-370°C) and pouring/blowing the sand mixture over it.
- Allowing the shell to harden onto the pattern in an oven.
Casting Defects
- Pinholes: Small holes left behind by escaping hydrogen gas during solidification.
- Causes: High moisture content in sand, hydrogen/carbon monoxide gas absorption by molten metal, pouring from wet ladles.
- Remedies: Reduce moisture, good fluxing practices, increased permeability.
- Shrinkage Cavity: Cavity formed due to volumetric contraction during metal solidification.
- Causes: Uneven solidification, high pouring temperature.
- Remedies: Directional solidification techniques, use of chills (promote solidification), and padding.
- Cold Shut: Line on a casting surface formed when two streams of molten metal fail to fuse properly at a low temperature junction.
- Causes: Poor gating system, low melting temperature, lack of fluidity.
- Remedies: Improved gating system, proper pouring temperature.
- Misrun: Molten metal solidifies before completely filling the mold, leaving a space.
- Causes: Low fluidity (from low metal temperature), too thin sections, improper gating system.
- Remedies: Increase pouring temperature, proper gating system, avoid thin sections.
- Slag Inclusion: Slag particles trapped in the molten metal during solidification.
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Description
Explore the various manufacturing processes that transform materials through physical and chemical means. This quiz covers primary shaping, deforming, machining, joining, and finishing processes. Test your understanding of these critical techniques in manufacturing.
