Summary Question and Answers Table Explanation Practical Casting Fundamentals of Metal Casting Introduction; Solidification of Metals; Pure Metals; Alloys; Structure-Property Relationship; Fluid Flow; Sprue Design; Modeling and Flow Characteristics; Fluidity of Molten Metals; Heat Transfer; Solidification and Shrinkage Defects and Porosity; Metal Casting Process and Equipment Introduction; Casting Techniques; Expendable Molds • Utilizing materials like sand, plaster, and ceramics mixed with binders, expendable molds are used once and then broken to reveal the cast product Permanent Molds • Crafted from high-temperature-resistant metals, permanent molds are employed for multiple castings. • They offer superior dimensional tolerances and surface finish compared to expendable molds. Composite Molds • Merging the strengths of different materials, such as sand, graphite, and metal, composite molds enhance mold strength, cooling rates, and overall casting economics. Sand Casting; Types of Sand Molds; Employing organic and inorganic binders, these molds yield accurate shapes at a higher cost. Cost-effective and recyclable, these molds offer flexibility and are suitable for larger castings Using synthetic liquid resin, these molds solidify at room temperature, eliminating heat bonding needs. Pattern and cores; Sand Molding Machine; Sand Casting Operation; Mold Ablation; •Shell molding, with its precise dimensions and excellent surface finish, is a popular technique for manufacturing intricate mechanical components. • The ceramicmold casting process employs refractory mold materials to withstand high temperatures, producing castings with excellent dimensional accuracy and surface finish • Evaporativepattern casting (EPC) uses vaporizing polystyrene patterns to create casting cavities, offering advantages like simplicity and reduced finishing operations. •Plaster mold casting, known for high precision, utilizes plaster of paris combined with talc and silica powder to create molds suitable for materials like aluminum, magnesium, zinc, and certain copper-based alloys. Some More Casting Like THAT; Directionally Solidified Blades; Single Crystal Growing; • It involves pulling a seed crystal from molten metal. • It grows a single crystal on a rod of polycrystalline silicon. Rapid Solidification; Inspection Casting; Melting furnaces and Practices; Foundries and Foundry Automation; Differ Between Pattern and Core; Pattern In the metalworking industry pattern is a replica that has similar shape and dimension to the casting. The casting pattern are used to press into sand mold to create the hollow cavity that allowing molten metal to be poured into and forming the casting. Core A core is an insert that will be placed into the mold. The sand is poured over the pattern while being compacted and pressed. The core purpose is to direct where the molten metal will go to fill the cavity in the mold. Some cores can be very intricated. • The cavity is the space within the mold where the molten metal is poured to create the final shape of the casting. • It defines the external geometry of the casting and includes the outer surfaces and contours. Core Cavity Differ between Cavity and Core; • The core is a pre-formed sand shape placed inside the mold cavity to create internal features or voids within the casting. • It defines the internal geometry, passages, and voids that cannot be achieved solely with the mold cavity. What is the material for core in sand casting? How is a core made? Core Box Preparation Casting Cooling and solidification Sand Mixing Mold Creation Casting Removal Core Box Filling Hardening Core Assembly Core Removal Discuss different types of patterns for sand casting and how they are used; Solid Patterns Spilt Pattern Match Plate Pattern Cope and Drag Pattern Solid patterns are full-size replicas of the final casting. They are made from materials like wood, plastic, or metal. Split patterns consist of two or more parts that can be separated to create complex shapes with undercuts or projections. Match plate patterns are constructed with the pattern on one side and a flat plate on the other. Cope and drag patterns consist of two separate patterns—one for the top (cope) and one for the bottom (drag) part of the mold. Solid patterns are used for simple, solid castings without any internal voids or cavities. They are used when the casting design has features that would prevent the pattern from being removed from the mold in a single piece. These patterns are used to make multiple mold cavities in a single molding operation, increasing production efficiency. They are used in two-part molds to create more complex castings that require a parting line. Take an example part and draw/show the steps used to make it using sand casting; Create a pattern of the keychain medallion's design using materials like wood, plastic, or metal. This pattern is a replica of the final part and will be used to create the mold. Place the pattern in a box called a flask. Fill the flask with special molding sand, compacting it around the pattern to create the top and bottom halves of the mold. Carefully remove the pattern from the compacted sand mold, leaving a void in the shape of the medallion. For parts with internal cavities or intricate shapes, a core made of sand or other materials may be inserted into the mold to create these features. Place the top half of the mold over the bottom half, ensuring that the two halves align properly and create a complete mold cavity. Heat the desired metal (such as aluminum, bronze, or brass) to its melting point in a separate furnace Allow the molten metal to cool and solidify within the mold. The metal takes on the shape of the medallion as it solidifies. Once the metal has cooled and solidified, the mold is carefully broken apart, revealing the rough cast medallion within. Remove any excess material, called "risers" and "gates," from the cast part. Trim any rough edges or irregularities to achieve the desired final shape. The finished medallion is inspected for any defects or imperfections. If necessary, any issues are addressed to ensure the quality of the final product. Identify the three sources of contraction in a metal casting after pouring; Solidification Contraction Solid-State Contraction Pattern Shrinkage • The metal atoms arrange themselves in a more ordered pattern, resulting in a decrease in the overall volume of the casting. • When molten metal cools and transforms into a solid state, it undergoes a reduction in volume due to the inherent properties of the crystalline structure of the solid. • As the temperature decreases, the metal contracts further as its particles lose thermal energy and move closer together. • As the solidified metal continues to cool down to room temperature, it may undergo additional contraction due to thermal contraction. • Before pouring metal into a mold, a pattern or mold is used to create the desired shape of the casting. • Patterns are typically made slightly larger than the desired final size to compensate for the expected shrinkage during solidification and cooling. What properties must a riser possess? Why are these allowances required in metal casting: (a) shrinkage allowance, and (b) draft allowance? Shrinkage Allowance This allowance compensates for the reduction in size that occurs during the cooling and solidification of molten metal, preventing defects in the final casting. Draft Allowance This allowance involves tapering the vertical sides of a pattern or mold to facilitate the removal of the casting without damaging its surfaces, as well as ensuring smooth and accurate casting production. Why are hot-chamber and cold-chamber die casting processes so named? Cold-Chamber Die Casting: In this process, the molten metal is held in an external melting furnace separate from the die-casting machine. A ladle is used to transfer the molten metal from the furnace to the machine's shot chamber. The "cold" in "cold-chamber" refers to the fact that the molten metal is not in direct contact with the diecasting machine and is brought in from an external source. Why is it that the high pressure die casting can produce the smallest parts? Mold Precision: The molds used in high pressure die casting are intricately designed and manufactured with exceptional precision. This allows for the creation of intricate details and fine features, crucial for small parts. Material Flow Control : The high pressure applied during the injection process ensures optimal material flow into even the most intricate sections of the mold. This control prevents any voids or imperfections, which are more likely to occur in small-scale components. Consistency and Reproducibility: The controlled nature of high pressure die casting guarantees consistent part quality and dimensions. This level of consistency is particularly important for small parts where even minor variations can lead to functional issues. Reduced Cooling Time: Small parts have a relatively smaller volume, which means they can cool down more quickly. High pressure die casting's rapid cycle times and efficient cooling systems help prevent distortion or defects caused by prolonged cooling. What is flash in a casting process? List at least five parts of a car that you think are made using metal casting. Mention specifically which casting process will you recommend for each part and why? Engine Block: Transmission Housing: • Casting Process: Sand Casting • Reason: Engine blocks are typically large and complex components. Sand casting is suitable for producing these parts due to its ability to handle intricate designs and larger sizes. The sand molds can accommodate the complex shapes and internal passages found in engine blocks. • Casting Process: Die Casting • Reason: Wheel hubs often have intricate designs and need to be lightweight yet strong. Investment casting allows for detailed designs and can produce lightweight parts with good mechanical properties. This process is suitable for producing smaller, more intricate par Wheel Hub: Intake Manifold: Brake Caliper: •Casting Process: Investment Casting •Reason: Wheel hubs often have intricate designs and need to be lightweight yet strong. Investment casting allows for detailed designs and can produce lightweight parts with good mechanical properties. This process is suitable for producing smaller, more intricate parts •Casting Process: Permanent Mold Casting •Reason: Intake manifolds are medium-sized parts that require good dimensional accuracy and surface finish. Permanent mold casting offers better dimensional control compared to sand casting and is more efficient for producing medium-sized parts with consistent quality. •Casting Process: Centrifugal Casting •Reason: Brake calipers require uniform material distribution and strength. Centrifugal casting is ideal for creating cylindrical parts like brake calipers. It ensures consistent density and mechanical properties due to the centrifugal force pushing the molten metal towards the mold walls. Make pictures of at least five products from your surroundings that you think are made using some metal casting process. Why do you think casting was used to make these products? Door Knobs and Handles Automobile Engine Block Statues and Sculptures Cookware (Casting Iron Skillet) Jewelry (Gold or Silver Rings) With the help of figures, briefly explain the working and use of these furnaces: cupolas, crucible furnaces, electric-arc furnaces, induction furnaces. Cupola Furnaces • Cupola furnaces are used for melting cast iron. • Working: Coke and iron ore are charged from the top. Air is blown in from the bottom to ignite the coke, creating high temperatures. The iron ore is reduced to molten iron, which collects at the bottom and is tapped. Electric Arc Furnaces (EAF) • Electric arc furnaces are used for melting and refining steel • Working: Scrap steel and other materials are charged into the furnace. Electricity is passed between the electrodes, creating an electric arc that generates high temperatures, melting the scrap. Crucible Furnaces • Crucible furnaces are used for melting small quantities of metals, alloys, and precious metals. • Working: The metal or alloy is placed inside a crucible within the furnace. The crucible is heated either directly or indirectly, causing the metal to melt. Induction Furnaces • Induction furnaces are used for melting and heating metals using electromagnetic induction. • Working: An alternating current (AC) passes through the coil, creating a magnetic field. This induces electric currents, called eddy currents. Excel Engineering (Pvt.) Ltd; What are the casting processes and equipment being used? Write details about specific features of the processes and equipment: What are the products it is making? Select any three products for each organization and explore their function. Then answer the question: Why this product is being made using a specific casting process? Carrier Clutch • The function and purpose of a carrier clutch is to transmit torque from a rotating driving motor to a transmission. Clutches require a mode of actuation in order to break the transmission of torque. • Die Casting Lower Link • Its function is to tandem to control the pitch, yaw and the fore and aft movement • Sand Casting Elbow Vertical Exhaust • The exhaust system collects the exhaust gases from the cylinders, removes harmful substances, reduces the level of noise and discharges the purified exhaust gases at a suitable point of the vehicle away from its occupants. • Centrifugal Casting Matchless Engineering (Pvt.) Ltd; What are the casting processes and equipment being used? Write details about specific features of the processes and equipment. What are the products it is making? Select any three products for each organization and explore their function. Then answer the question: Why this product is being made using a specific casting process? Power flow inside the differential, the pinion gear drives the ring gear, which rotates the carrier. The carrier then drives the smaller pinon gears, which in turn drive the side gears. The drive axles are splined into the side gears, which then drive the wheels. Die Casting A hydraulic lift is a device for moving objects using force created by pressure on a liquid inside a cylinder that moves a piston upward. Forging The flywheel's ring gear also serves as an engagement point for the pinion of the starter motor when cranking the engine. Because of the lightweight design of the flywheel or flex plate, it does not help to smooth out power pulses Sand Casting Qadri Foundry;
