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Questions and Answers
What is the most common method of casting?
What is the purpose of pattern allowance in sand casting?
What is the type of sand that is moist and easy to work with, but fragile?
What is the name of the process that uses a wax pattern, which is melted out during the casting process?
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What is the purpose of the refractory material in investment casting?
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What is the name of the casting process that uses high pressure to force molten metal into a mold?
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What is the name of the metal casting technique that uses a vacuum to remove air from the mold?
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What is the type of molding process that creates a sand mold around a pattern?
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What is the main characteristic of a Horizontal Milling Machine?
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Which type of milling cutter is used for milling curved surfaces?
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What is the advantage of Upmilling machine?
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What is the purpose of a Negative Rake Angle in milling cutters?
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Which type of milling machine is used for general-purpose milling?
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What is the advantage of using Diamond-coated Cutters in milling?
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What is the difference between Upmilling and Downmilling?
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What is the main characteristic of a Universal Milling Machine?
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Study Notes
Casting Machine
Sand Casting
- A casting process that uses sand as the molding material
- Most common method of casting
- Sand is mixed with clay and water to form a workable mixture
- Patterns are created and placed in the sand, and molten metal is poured in
- After cooling, the sand is broken away to reveal the cast part
Molding Processes
- Coping: creating a sand mold around a pattern
- Drag: creating a sand mold without a pattern
- Two main types of sand:
- Green sand: moist sand, easy to work with, but fragile
- Dry sand: dry and compacted sand, stronger than green sand
Investment Casting
- Also known as lost-wax casting
- Uses a wax pattern, which is melted out during the casting process
- Steps:
- Create a wax pattern
- Coat the pattern with a refractory material (investment)
- Melt out the wax
- Pour in molten metal
- Break away the investment to reveal the cast part
Die Casting
- A casting process that uses high pressure to force molten metal into a mold
- Uses a permanent mold (die) made of steel or other metal
- Fast production rates and high accuracy
- Often used for aluminum, zinc, and copper alloys
Metal Casting Techniques
- Vacuum casting: uses a vacuum to remove air from the mold
- Centrifugal casting: uses centrifugal force to fill the mold
- Pressure casting: uses high pressure to force metal into the mold
- Squeeze casting: uses a combination of pressure and vacuum to fill the mold
Pattern Allowance
- The process of creating a pattern that is slightly larger than the desired casting
- Allows for shrinkage of the metal during cooling
- Types of pattern allowance:
- Shrinkage allowance: accounts for metal shrinkage during cooling
- Draft allowance: allows for easy removal of the pattern from the mold
- Machining allowance: allows for additional material to be removed during machining
Sand Casting
- Uses sand as the molding material
- Most common method of casting
- Sand mixture consists of sand, clay, and water
- Patterns are created and placed in the sand, and molten metal is poured in
- After cooling, the sand is broken away to reveal the cast part
Molding Processes
- Coping: creating a sand mold around a pattern
- Drag: creating a sand mold without a pattern
- Two main types of sand:
- Green sand: moist sand, easy to work with, but fragile
- Dry sand: dry and compacted sand, stronger than green sand
Investment Casting
- Also known as lost-wax casting
- Uses a wax pattern, which is melted out during the casting process
- Steps:
- Create a wax pattern
- Coat the pattern with a refractory material (investment)
- Melt out the wax
- Pour in molten metal
- Break away the investment to reveal the cast part
Die Casting
- Uses high pressure to force molten metal into a mold
- Uses a permanent mold (die) made of steel or other metal
- Fast production rates and high accuracy
- Often used for aluminum, zinc, and copper alloys
Metal Casting Techniques
- Vacuum casting: uses a vacuum to remove air from the mold
- Centrifugal casting: uses centrifugal force to fill the mold
- Pressure casting: uses high pressure to force metal into the mold
- Squeeze casting: uses a combination of pressure and vacuum to fill the mold
Pattern Allowance
- The process of creating a pattern that is slightly larger than the desired casting
- Allows for shrinkage of the metal during cooling
- Types of pattern allowance:
- Shrinkage allowance: accounts for metal shrinkage during cooling
- Draft allowance: allows for easy removal of the pattern from the mold
- Machining allowance: allows for additional material to be removed during machining
Milling Machine Types
- Horizontal Milling Machine: used for heavy-duty milling operations, with spindle parallel to worktable.
- Vertical Milling Machine: used for precision milling operations, with spindle perpendicular to worktable.
- Universal Milling Machine: combines horizontal and vertical milling capabilities.
- Knee-type Milling Machine: features a vertical column (knee) supporting the worktable, suitable for general-purpose milling.
- Bed-type Milling Machine: has a horizontal bed supporting the worktable, used for heavy-duty milling.
Milling Cutters
Types of Milling Cutters
- End Mill: for milling slots, pockets, and faces.
- Face Mill: for milling large flat surfaces.
- Slab Mill: for milling large surfaces.
- Ball Mill: for milling curved surfaces.
Cutter Angles
- Positive Rake Angle: provides a stronger cutting edge, used for soft materials.
- Negative Rake Angle: provides a weaker cutting edge, used for hard materials.
Cutter Materials
- High-Speed Steel (HSS): used for general-purpose milling.
- Cemented Carbide (WC): used for high-speed milling and hard materials.
- Diamond-coated Cutters: used for milling hard materials and precise surfaces.
Upmilling Machine
- Upmilling: also known as conventional milling, where the cutting tool moves in the same direction as the feed motion.
Advantages of Upmilling
- Produces a better surface finish.
- Reduces tool wear and extends tool life.
- Easier chip removal and less clogging.
Disadvantages of Upmilling
- Requires more power and can lead to vibrations.
- Generates more heat, affecting tool life and workpiece quality.
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Description
Learn about the sand casting process, a common method of casting that uses sand as the molding material. Understand the process of creating a sand mold and pouring in molten metal.
