Podcast
Questions and Answers
The most widely used casting process is ______.
The most widely used casting process is ______.
sand casting
In expendable mold processes, the mold is ______ to remove the part.
In expendable mold processes, the mold is ______ to remove the part.
sacrificed
Permanent mold processes can produce ______ castings due to metal molds.
Permanent mold processes can produce ______ castings due to metal molds.
many
Castings produced through sand casting can range in size from small to very ______.
Castings produced through sand casting can range in size from small to very ______.
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Almost all alloys, including high melting temperature metals like ______, can be sand casted.
Almost all alloys, including high melting temperature metals like ______, can be sand casted.
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The first step in sand casting is to pour the ______ metal into the sand mold.
The first step in sand casting is to pour the ______ metal into the sand mold.
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After the metal cools, the next step in sand casting is to clean and ______ the casting.
After the metal cools, the next step in sand casting is to clean and ______ the casting.
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Sometimes, heat treatment of the casting is required to improve its ______ properties.
Sometimes, heat treatment of the casting is required to improve its ______ properties.
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The basic permanent mold process uses a metal mold constructed of two sections designed for easy, precise opening and ______.
The basic permanent mold process uses a metal mold constructed of two sections designed for easy, precise opening and ______.
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Molds used for casting lower melting point alloys are commonly made of ______ or cast iron.
Molds used for casting lower melting point alloys are commonly made of ______ or cast iron.
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Molds used for casting steel must be made of ______ material, due to the very high pouring temperatures.
Molds used for casting steel must be made of ______ material, due to the very high pouring temperatures.
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In die casting, molten metal is injected into the mold cavity under high ______.
In die casting, molten metal is injected into the mold cavity under high ______.
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The advantages of permanent mold casting include good dimensional control and surface ______.
The advantages of permanent mold casting include good dimensional control and surface ______.
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More rapid solidification caused by the cold metal mold results in a finer grain structure, so castings are ______.
More rapid solidification caused by the cold metal mold results in a finer grain structure, so castings are ______.
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The molds used in die casting are referred to as ______.
The molds used in die casting are referred to as ______.
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Permanent mold casting is generally limited to metals of ______ melting point.
Permanent mold casting is generally limited to metals of ______ melting point.
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Die casting machines are designed to hold and accurately close two mold ______.
Die casting machines are designed to hold and accurately close two mold ______.
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Hot-chamber die casting utilizes a ______ to inject liquid metal into the die.
Hot-chamber die casting utilizes a ______ to inject liquid metal into the die.
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Due to high mold cost, permanent mold casting is best suited to high volume ______.
Due to high mold cost, permanent mold casting is best suited to high volume ______.
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Typical parts produced using permanent mold casting include automotive ______, pump bodies, and certain castings for aircraft.
Typical parts produced using permanent mold casting include automotive ______, pump bodies, and certain castings for aircraft.
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High production rates in hot-chamber die casting can reach up to ______ parts per hour.
High production rates in hot-chamber die casting can reach up to ______ parts per hour.
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Applications of hot-chamber die casting are limited to low ______-point metals.
Applications of hot-chamber die casting are limited to low ______-point metals.
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Some common casting metals used in hot-chamber die casting include zinc, tin, and ______.
Some common casting metals used in hot-chamber die casting include zinc, tin, and ______.
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The two main types of die casting machines are hot-chamber and ______-chamber machines.
The two main types of die casting machines are hot-chamber and ______-chamber machines.
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In the expanded polystyrene casting process, the foam pattern is placed in a mold box and sand is compacted around the ______.
In the expanded polystyrene casting process, the foam pattern is placed in a mold box and sand is compacted around the ______.
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During the casting process, molten metal is poured into the portion of the pattern that forms the pouring cup and ______.
During the casting process, molten metal is poured into the portion of the pattern that forms the pouring cup and ______.
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One advantage of the expanded polystyrene process is that the pattern need not be ______ from the mold.
One advantage of the expanded polystyrene process is that the pattern need not be ______ from the mold.
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The economic justification of the expanded polystyrene process is highly dependent on the cost of producing ______.
The economic justification of the expanded polystyrene process is highly dependent on the cost of producing ______.
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The investment casting process involves a pattern made of wax coated with a ______ material.
The investment casting process involves a pattern made of wax coated with a ______ material.
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In investment casting, the term 'investment' refers to the process of ______ completely with refractory material.
In investment casting, the term 'investment' refers to the process of ______ completely with refractory material.
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The investment casting process is capable of producing castings with high ______ and intricate detail.
The investment casting process is capable of producing castings with high ______ and intricate detail.
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Automated and integrated manufacturing systems are used to mold the polystyrene foam ______ and feed them to the downstream casting operation.
Automated and integrated manufacturing systems are used to mold the polystyrene foam ______ and feed them to the downstream casting operation.
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The most commonly used furnace in foundries is the ______.
The most commonly used furnace in foundries is the ______.
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Direct fuel-fired furnaces are generally used for melting ______ metals.
Direct fuel-fired furnaces are generally used for melting ______ metals.
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Crucible furnaces are sometimes referred to as ______ fuel-fired furnaces.
Crucible furnaces are sometimes referred to as ______ fuel-fired furnaces.
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The charge in a cupola consists of iron, coke, ______, and possible alloying elements.
The charge in a cupola consists of iron, coke, ______, and possible alloying elements.
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At the bottom of a direct fuel-fired furnace, there is a ______ to release molten metal.
At the bottom of a direct fuel-fired furnace, there is a ______ to release molten metal.
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Crucible furnaces are used for metals such as ______, brass, and alloys of zinc and aluminum.
Crucible furnaces are used for metals such as ______, brass, and alloys of zinc and aluminum.
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Cupolas are primarily used for melting ______ iron.
Cupolas are primarily used for melting ______ iron.
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The three types of crucible furnaces are: lift-out type, stationary, and ______.
The three types of crucible furnaces are: lift-out type, stationary, and ______.
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In cold-chamber die casting, molten metal is poured into an unheated ______.
In cold-chamber die casting, molten metal is poured into an unheated ______.
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The piston in the cold-chamber die casting machine injects metal under high ______ into the die cavity.
The piston in the cold-chamber die casting machine injects metal under high ______ into the die cavity.
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Cold-chamber die casting is not usually as fast as ______ machines due to the pouring step.
Cold-chamber die casting is not usually as fast as ______ machines due to the pouring step.
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Casting metals commonly used in cold-chamber die casting include aluminum, brass, and ______ alloys.
Casting metals commonly used in cold-chamber die casting include aluminum, brass, and ______ alloys.
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Molds for die casting are usually made of tool steel, mold steel, or ______ steel.
Molds for die casting are usually made of tool steel, mold steel, or ______ steel.
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Ejector pins are required to remove the part from the ______ when it opens.
Ejector pins are required to remove the part from the ______ when it opens.
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One advantage of die casting is that it allows for good ______ and surface finish.
One advantage of die casting is that it allows for good ______ and surface finish.
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Die casting is generally limited to metals with low melting ______ points.
Die casting is generally limited to metals with low melting ______ points.
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Study Notes
Manufacturing Process [Week 6]
- This week's topic is metal casting processes, specifically focusing on sand casting.
- Metal casting processes are categorized as expendable mold processes and permanent mold processes.
- Expendable mold processes involve sacrificing the mold to remove the part, enabling more complex shapes, but producing parts at a slower rate.
- Permanent mold processes employ reusable molds, leading to higher production rates, but with limitations on part complexity.
- Sand casting, the most prevalent casting procedure, accounts for a substantial portion of metal castings.
- It accommodates a wide array of alloys, including high-temperature metals like steel, nickel, and titanium.
- Castings vary greatly in size, spanning small to very large dimensions.
- Production quantities can range from a single piece to several millions.
Quiz on Metal Casting
- Diagrams were included showing the components of a sand mold for a casting. This is for a quiz.
- The diagram labels included "pouring cup," "downspru", "flask," "Cast metal in cavity," "Cope," "Parting line," and "e" (unlabeled part).
Metal Casting Processes
- Sand Casting
- Other Expendable Mold Casting Processes
- Permanent Mold Casting Processes
- Foundry Practice
- Casting Quality
- Metals for Casting
- Product Design Considerations
Two Categories of Casting Processes
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Expendable mold processes:
- Advantage: accommodate complex shapes
- Disadvantage: mold creation time is often a limiting factor in production rate.
-
Permanent mold processes:
- Advantage: high production rate
- Disadvantage: part geometry limited by need to open the mold
Overview of Sand Casting
- It's the most widely used casting process.
- Nearly all types of alloys are cast in sand (including those with high melting temps).
- Castings are available from small to extremely large sizes.
- Productions quantities range from one to millions.
Steps in Sand Casting
- Pour molten metal into sand mold.
- Allow the metal to solidify.
- Break up the mold to remove the casting.
- Clean and inspect the casting.
- Gating and riser systems might require heat treatment to improve metallurgical properties.
Making the Sand Mold
- The sand mold cavity is formed by packing sand around a pattern.
- The pattern is removed, leaving the mold cavity.
- The mold includes a gating and riser system.
- Cores may be included for internal surfaces in complex casting geometries.
- A new mold must be made for each part.
Sand Casting Production Sequence
- The sequence includes steps in pattern making and mold making, in addition to the casting operation itself.
- Stages include core making (if needed), pattern making, mold making, sand preparation, melting, pouring, solidification/cooling, sand removal, cleaning, and inspection to produce finished casting.
The Pattern
- The pattern is a full-sized model of the part (often slightly larger), allowing for allowances for shrinkage and machining during the casting stage.
- Commonly made of wood due to ease of use.
- Metal patterns are more durable but more costly to create.
- Plastics represent a balance between wood and metal.
Types of Patterns
- Diagrams illustrating various types of patterns used in sand casting: solid pattern, split pattern, match-plate pattern, and cope and drag pattern.
Core
- Cores are used to create interior surfaces.
- They are placed in the mold cavity before pouring molten metal.
- Molten metal solidifies between the mold cavity and the core to define the internal surfaces of the casting.
- Cores often require chaplets for support in the mold cavity.
Core in Mold
- Illustration of core placement and chaplet design within the mold cavity.
Desirable Mold Properties
- Strength: Resistance to erosion and shape maintenance.
- Permeability: Allowing hot air and gases to escape.
- Thermal stability: Resistance to cracking from molten metal contact.
- Collapsibility: Ability to yield and facilitate casting shrinkage.
- Reusability: Capacity to reuse sand from broken molds.
Foundry Sands
- Usually silica, mixed with other minerals.
- Good refractory properties for withstanding high temperatures.
- Small grain size leads to better surface finish on the cast part.
- Larger grain size enhances permeability for gas escape during pouring.
- Irregular grain shapes are advantageous for mold strength via interlocking (compared to round grains).
- Interlocking reduces permeability—a drawback.
Binders Used with Foundry Sands
- Mixtures of water and bonding clay, in a typical mix of 90% sand, 3% water, and 7% clay.
- Other binders include organic resins (e.g., phenolic resins) and inorganic binders (e.g., sodium silicate and phosphate).
- Additives can be combined to enhance strength and permeability.
Types of Sand Mold
- Green-sand molds: Sand, clay, and water mixture; moisture remains in the mold during pouring.
- Dry-sand molds: Organic binders instead of clay; molds are baked to improve strength.
- Skin-dried molds: Green-sand molds partially dried: the mold cavity surface is dried using torches or heating lamps.
Buoyancy in Sand Casting Operation
- Molten metal buoyancy tends to displace cores, potentially causing casting defects.
- The buoyant force exerted on a core is equal to the difference between the weight of molten metal displaced and the weight of the core itself (Buoyant force = Weight of displaced molten metal – Weight of the core).
Other Expendable Mold Processes
- Shell molding
- Vacuum molding
- Expanded polystyrene process
- Investment casting
- Plaster mold and ceramic mold casting
Shell Molding
- A casting process that creates a thin shell-like mold, from sand bonded by thermosetting resin.
- Involves a heated pattern placed over a sand mixture with resin.
- The process involves inverting and repositioning the mold box to create a hard shell, then heating the mold in an oven to complete curing and stripping the mold from the pattern.
- Two mold halves are assembled for pouring.
Vacuum Molding
- Uses vacuum pressure to bind sand molds.
- This process involves a different method compared to chemical mold binders.
- Mold regeneration methods separate it from previous techniques.
- It has advantages on recoverability and avoidance of moisture-related defects from sand mixtures, but a disadvantage due to its slower process.
Expanded Polystyrene Process
- A mold of sand packs around a polystyrene foam pattern.
- The foam vaporizes when molten metal is poured, forming the casting in the mold cavity.
- Other names for the process are lost-foam method, lost pattern casting, evaporative-foam casting, and full mold casting.
- The polystyrene foam pattern contains sprues, risers, gating systems, and internal cores (if needed).
- The mold doesn't require separation into cope and drag.
Investment Casting (Lost Wax Process)
- A wax pattern is coated with a refractory material to create a mold.
- The wax is melted away before pouring molten metal.
- The coating process is named "investment" — to completely coat the entire wax pattern with refractory material.
- It is a precision casting process capable of producing high accuracy and intricate castings.
- The pattern is usually constructed from wood or metal.
Investment Casting
- Steps in the process have been provided in separate diagrams.
Plaster Mold Casting
- This method creates molds with plaster of paris (gypsum).
- A plaster and water mix is placed over a mold pattern to form a rigid mold.
- Wood patterns are rarely used owing to prolonged contact with water.
- Plaster casting materials readily fill the mold cavity, capturing fine details nicely.
Ceramic Mold Casting
- Mold is constructed from refractory ceramic materials, capable of enduring higher temperatures than plaster.
- They are used in cast steels, cast irons, and high-temperature alloys.
- Applications are analogous to plaster molding, except for specific metals.
- Advantages include high accuracy and good surface finish.
Permanent Mold Casting Processes
- An economic disadvantage of expendable mold casting is that a new mold requires creation for each casting.
- Permanent molds enable repeated use, leading to greater efficiency.
- Processes include basic permanent, die, and centrifugal casting.
The Basic Permanent Mold Process
- A two-section metal mold facilitates easy and precise opening/closing.
- Molds for lower melting point alloys, like cast iron or steel, are typically made from steel.
- Casting molds for steel employ refractory materials due to steel's high melting point.
Permanent Mold Casting
- Stages in the application have been presented in separate diagrams.
Advantages and Limitations of Permanent Mold Casting
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Advantages:
- Precise dimensional control.
- Good surface finish.
- Rapid solidification produces finer grain structure, yielding strong castings.
-
Limitations:
- Primarily limited to lower-melting-point metals.
- Part geometries are relatively simpler to accommodate mold opening/closing.
- Relatively higher mold cost.
Applications of Permanent Mold Casting
- Suitable for high-volume production, often automated.
- Common parts include pistons, pump bodies, and those for aircraft/missiles.
- Commonly cast materials include aluminum, magnesium, copper-based alloys, and cast iron.
Die Casting
- A permanent mold casting process utilizing high pressure.
- Molten metal is injected into the mold cavity under high pressure.
- This pressure assists with solidification.
- The mold components (dies) are reusable, unlike in expendable mold processes.
Die Casting Machines
- Designed to accommodate and precisely close mold halves.
- Main types are hot-chamber and cold-chamber machines.
Hot-Chamber Die Casting
- Metal melting occurs in the machine's container.
- A piston injects molten metal under pressure into the mold cavity.
- High production rates (e.g., 500+ parts/hour) are typical.
- Metals used are typically low-melting-point metals (zinc, lead, tin, and magnesium) unsuitable for high-temperature chemical reactions with the machine's components.
Hot-Chamber Die Casting
- Stages in the process have been presented with diagram.
Cold-Chamber Die Casting Machine
- Molten metal is supplied from an external melting unit.
- A piston forces metal into cold, sealed die halves.
- High production rates are typical, though not as high as in hot-chamber machines.
- Suitable materials include aluminum, brass, and magnesium alloys. Low melting point metals are favored due to the external melting method.
Cold-Chamber Die Casting
- Stages of the process are given in separate diagrams.
Molds for Die Casting
- Mold materials typically comprise tool steel, mold steel, or maraging steel.
- Tungsten and molybdenum are favored due to their refractory and high heat resistance.
- Ejector pins are necessary to dislodge castings once the mold opens.
- Lubricants are applied to the mold cavity to reduce sticking between internal mold components and castings.
Advantages and Limitations of Die Casting
-
Advantages:
- Economically advantageous for large-scale production.
- Accurate dimensions and good surface finishes.
- Enables production of thin sections.
- Rapid cooling leads to a fine grain structure, producing strong castings.
-
Disadvantages:
- Primarily applicable with low melting-point metals.
- Part geometries need to accommodate ease of casting removal from the mold's dies.
Centrifugal Casting
- A family of metal casting processes, involving rotated molds.
- Centrifugal forces aid molten metal distribution from the mold's axis to its outer regions.
- Subtypes involve true centrifugal casting, semicentrifugal casting, and centrifuge casting—each having differences in their application scenarios and geometrical constraints.
True Centrifugal Casting
- Molten metal is poured into a rapidly rotating mold to create a tubular part.
- Mold rotation often begins after pouring, as opposed to prior.
- Components producible via this method include pipes, tubes, bushings, and rings.
- The outside shape of the casting may be irregular (octagonal, hexagonal, etc.), while the inside shape of the casting is ideally perfectly circular, owing to forces acting radially from the axis of rotation.
True Centrifugal Casting
- Diagrams provided that describe the application methodology for true centrifugal casting.
Semicentrifugal Casting
- Aims to produce solid castings rather than tubular ones.
- Molds are configured with risers centrally located to facilitate metal flow.
- Metal density tends to be higher in the casting's outer segments compared to its center.
- Parts are frequently machined to eliminate central sections of lower quality casting.
Centrifuge Casting
- Mold design directs casting material away from the axis of rotation.
- Molten metal flowing into the mold distributes to far sections radially.
- This process is tailored for producing small components.
- The part doesn't need to exhibit radial axis symmetry, unlike in true centrifugal casting.
Furnaces for Casting Processes
- Cupolas
- Direct fuel-fired furnaces
- Crucible furnaces
- Electric arc furnaces
- Induction furnaces
Cupolas
- Cylindrical furnaces fitted with a tapping spout near the base.
- Primarily used for cast iron production.
- Compared to other casting furnaces, cupolas have significantly higher cast iron production volume.
- Load "charge materials", consisting of iron, coke, flux, and possible additives, through a charging door.
Direct Fuel-Fired Furnaces
- Small open-hearth furnaces heated by natural gas located on the furnace's sides.
- Furnace roofs reflect flames toward the charge, assisting the heating process.
- A tap hole at the furnace's bottom releases molten metal.
- Predominantly used for nonferrous metals (copper alloys and aluminum).
Crucible Furnaces
- Metal melting occurs without direct flame contact.
- Referred to as indirect fuel-fired or crucible type.
- Refractory material or high-temperature steel alloys constructs the crucible.
- Diverse metals (bronze, brass, alloys of zinc and aluminum) are producible.
- Foundries commonly employ lift-out, stationary, or tilting crucible furnaces.
Crucible Furnaces
- Diagrams highlighting lift-out, stationary, and tilting crucible furnace designs are included.
Electric-Arc Furnaces
- Heat generated from electric arcs melts the charge.
- Electric furnaces can be designed for higher melting capacity.
- Primarily employed for melting steel.
Electric-Arc Furnaces
- A diagram describing an electric arc furnace and important components is given.
Induction Furnaces
- Alternating current flowing through a coil produces a magnetic field within the metal.
- Induced currents lead to fast heating and melting.
- Electromagnetic forces aid metal mixing within the furnace.
- Environment control is superior compared to other heating techniques.
- Common applications include steel, cast iron, and aluminum alloys.
Induction Furnace
- Diagram illustrating the components of an induction furnace
- Key aspects of the process and the physical set up are highlighted via a diagram
Ladles
- Use to transfer molten metal from the furnace crucible to the mold.
- Crane ladles and two-man ladles are representative examples for the purpose.
Additional Steps After Solidification
- Trimming: Removal of excess metal (sprues, runners, risers, flash, fins).
- Core removal: Removing cores from the casting.
- Surface cleaning: Removing defects and extraneous materials.
- Inspection: Determining casting quality.
- Repair: Repairing imperfections.
- Heat treatment: Adjusting mechanical properties, via heat treat, for service application.
Trimming
- Excess metal (sprues, gates, risers, and flash) is removed.
- Brittle metals can be broken off; others might require mechanical methods such as sawing, hammering, shearing, abrasive wheels, or torches.
Removing the Core
- Removing the cores, if used in the process, is necessary.
- Bonded cores frequently fall out as the binder deteriorates.
- Manually shaking or mechanically vibrating the casting releases some cores.
- Chemically dissolving the bonding agents is another option for removing cores in some applications.
Surface Cleaning
- Sand, debris, or other extraneous material removal yields smoother, cleaner surfaces.
- Methods for surface cleanup include: tumbling, air blasting, coarse sand, metal shot; wire brushing or chemical pickling.
- Surface cleaning is crucial, and for permanent mold processes the step is often not explicitly needed.
- Defects in castings are possible and need inspection techniques to determine their presence.
Heat Treatment
- Enhancing casting qualities via heat treatment.
- Heat treats castings to improve subsequent processing (e.g., machining).
- To impart specific properties for service applications.
Casting Quality
- Defects can happen throughout the casting process; categories include general casting defects applicable for any type of casting process, and those more specific for sand-casting procedures.
General Defects: Misrun
- Molten material failed to fill the mold cavity entirely resulting in incomplete castings
General Defects: Cold Shut
- Non-union of casting segments that results in a seam, frequently an indication of insufficient flow.
General Defects: Cold Shot
- Casting inclusions that result from insufficient metal fluidity and flow characteristics, often an indication of poor flow conditions.
General Defects: Shrinkage Cavity
- Depressions or voids caused by shrinkage during solidification, indicating that the mold cavity didn't have enough molten metal for total solidification.
Sand Casting Defects: Sand Blow
- Entrapment of air within the sand mold cavity resulting in the formation of a void.
Sand Casting Defects: Pin Holes
- Small, roughly cylindrical voids caused by entrapped gases in the form of bubbles within the castings.
Sand Casting Defects: Penetration
- High fluidity of molten metal caused the molten metal material to seep or embed into the sand cavity, resulting in a mixture of metal and sand within the casting.
Sand Casting Defects: Mold Shift
- The mold halves did not properly align, resulting in misaligned sections, mismatched shapes, etc.
Foundry Inspection Methods
- Visual inspection of castings for obvious defects such as misruns, cold shuts, or surface flaws.
- Dimensional measurements to ensure tolerances.
- Metallurgical, chemical, and physical tests to evaluate the cast metal quality.
Metals for Casting
- Most commercial castings use alloys, rather than pure metals, for improved castability and desirable properties.
- Casting alloys are categorized as ferrous (iron-based) or nonferrous (non-iron-based).
Ferrous Casting Alloys: Cast Iron
- Cast iron is a significant metal for casting, with high production volume compared to other metals.
- Types of cast iron include gray, nodular, white, malleable, and alloy cast irons.
- Typical pouring temperatures range between 1400°C (2500°F).
Ferrous Casting Alloys: Steel
- Steel possesses high strength and complex geometry production potential, making it a preferred material.
- Difficulties in steel casting include elevated pouring temperatures and tendency towards oxidation, requiring specific casting techniques to manage.
Nonferrous Casting Alloys: Aluminum
- Highly castable, aluminum's low melting point facilitates casting.
- Properties: light weight; heat treatment can manipulate strength; easy machinability.
Nonferrous Casting Alloys: Copper Alloys
- Bronze, brass, and aluminum bronze are copper-based alloys known for corrosion resistance.
- These alloys also have attractive appearance and good bearing properties.
- Applications span pipeline fittings, marine propellers, pump components, and ornamental items.
Nonferrous Casting Alloys: Zinc Alloys
- Highly castable; have low melting points (419°C or 786°F).
- Good fluidity aids casting processes.
- Low creep, so castings cannot withstand prolonged high stress levels.
Product Design Considerations
- Geometric simplicity: Simplifying part design facilitates casting.
- Avoid unnecessary complexities: Simplifying mold making, reducing core needs, and improving casting strength.
- Corners: Avoid sharp corners and angles on parts to minimize stress concentrations and hot cracking. Use fillets (rounded corners) for smoother transitions.
- Draft Guidelines: Allow for draft angles for part removal from the sand or permanent mold. Draft angles are commonly around ±1° for sand casting. Higher draft—2° to 3°—is standard for permanent mold casting.
- Draft: Adapting part design to eliminate reliance on cores.
- Dimensional Tolerances and Surface Finish: Varying tolerances and surface finishes can be achieved based on the specific casting procedure (e.g., Sand, Die, Investment Casting).
- Machining Allowances: Extra material for subsequent machining, typically 1.5-3 mm (1/16-1/4 inch).
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Description
Test your knowledge on various metal casting processes, including expendable and permanent molds. Explore the characteristics and applications of sand casting and die casting in this comprehensive quiz. Perfect for students and professionals in metallurgy or manufacturing!
