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Questions and Answers
What does truing do to a grinding wheel?
What does truing do to a grinding wheel?
Which grinding operation is primarily used for grinding flat surfaces?
Which grinding operation is primarily used for grinding flat surfaces?
What is a primary purpose of dressing grinding wheels?
What is a primary purpose of dressing grinding wheels?
Which method is used for high production cylindrical surface grinding?
Which method is used for high production cylindrical surface grinding?
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What do grinding fluids primarily help to achieve?
What do grinding fluids primarily help to achieve?
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How does ultrasonic machining primarily remove material?
How does ultrasonic machining primarily remove material?
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What is the main use of honing in manufacturing?
What is the main use of honing in manufacturing?
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What is the difference between superfinishing and honing?
What is the difference between superfinishing and honing?
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What is a characteristic of portable grinders?
What is a characteristic of portable grinders?
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Which type of grinding employs an abrasive belt rotating over rolls?
Which type of grinding employs an abrasive belt rotating over rolls?
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What is the primary purpose of abrasive machining operations?
What is the primary purpose of abrasive machining operations?
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Which abrasive machining operation is primarily used to achieve a high-quality, smooth finish with a mirror-like appearance?
Which abrasive machining operation is primarily used to achieve a high-quality, smooth finish with a mirror-like appearance?
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What type of abrasive is known for its exceptional hardness and ability to enhance surface quality?
What type of abrasive is known for its exceptional hardness and ability to enhance surface quality?
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In grinding operations, what is indicated by a high grinding ratio?
In grinding operations, what is indicated by a high grinding ratio?
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Which of the following is NOT an application of abrasive operations?
Which of the following is NOT an application of abrasive operations?
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What is the purpose of dressing a grinding wheel?
What is the purpose of dressing a grinding wheel?
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Which materials are considered conventional abrasives?
Which materials are considered conventional abrasives?
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What is commonly used to improve the grinding ratio in abrasive operations?
What is commonly used to improve the grinding ratio in abrasive operations?
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Which of the following operations primarily uses a honing stone to improve surface finish?
Which of the following operations primarily uses a honing stone to improve surface finish?
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What is the main purpose of lapping in finishing operations?
What is the main purpose of lapping in finishing operations?
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In which scenario is Chemical Mechanical Polishing (CMP) most commonly used?
In which scenario is Chemical Mechanical Polishing (CMP) most commonly used?
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What distinguishes electropolishing from other finishing processes?
What distinguishes electropolishing from other finishing processes?
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Which of the following describes the main goal of deburring?
Which of the following describes the main goal of deburring?
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How do costs generally change with the level of surface finish in finishing operations?
How do costs generally change with the level of surface finish in finishing operations?
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What type of tool is used in buffing to achieve a smooth finish?
What type of tool is used in buffing to achieve a smooth finish?
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What is a common method for vibratory deburring?
What is a common method for vibratory deburring?
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Study Notes
Abrasive Machining and Finishing Operations
- A machining operation systematically removing material from the surface in very small amounts.
- Utilizes abrasive particles, small, hard particles with sharp edges and irregular shapes.
- Examples include sand, sandpaper, and emery cloth.
- Used to smooth surfaces, remove sharp corners, improve surface finish, and create dimensional accuracy.
Types of Abrasive Machining Operations
- Grinding: The predominant abrasive machining operation.
- Honing: Improves surface finish.
- Lapping: Achieves precise dimensional accuracy and highly polished finishes.
- Buffing: Removes fine scratches and imperfections, improving surface finish.
- Polishing: Creates a high-quality, smooth, mirror-like finish.
Applications of Abrasive Operations
- Finishing heat-treated hard surface metals and alloys.
- Finishing ceramic surfaces and sunglasses.
- Cutting off lengths of parts, structural shapes, masonry, and concrete.
- Removing unwanted weld beads and splatters.
- Creating smooth and flat surfaces on silicon wafers used in the semiconductor industry.
- Polishing bearings and races.
- Cleaning surfaces with jets of air and water containing abrasive particles.
Abrasive Materials
- Conventional Abrasives: Aluminum oxide and silicon carbide.
- Super Abrasives: Cubic boron nitride and diamond, exceptionally hard, enhancing surface quality.
Grinding Wheels
- Formed by bonding abrasive grains.
- Each particle removes tiny chips from the workpiece.
- The wheel wears out due to particle removal.
- Wheels require reconditioning.
Grinding Ratio
- Relationship between workpiece and grinding wheel material removed.
- Ranges from 2 to 200, depending on materials and parameters.
- Grinding fluids significantly improve the ratio (by a factor of 10 or more).
- High ratio means efficient material removal and less wheel wear.
Reconditioning Grinding Wheels
- Dressing: Conditions the wheel to create fresh, sharp grain edges.
- Truing: Restoring a true circular shape to the wheel surface.
Grinding Wheel Problems
- Glazing: Shiny surface due to excessive abrasive particle wear.
- Loading: Workpiece material clogging the wheel pores.
- Both glazing and loading require wheel reconditioning.
Dressing Grinding Wheels
- Uses a dressing tool to create a fresh abrasive surface on the wheel.
Grinding Operations
- Surface Grinding: Grinding flat surfaces with a horizontal spindle.
- Cylindrical Grinding: Grinding external cylindrical surfaces with parallel axes.
- Centerless Grinding: High-production cylindrical surface grinding, workpiece supported by a blade and regulating wheel.
- Internal Grinding: Grinding internal diameters and profiles with a smaller wheel.
- Creep Feed Grinding: Large depth of cut (up to 6mm) and slow feed rate for large-scale metal removal.
Grinders
- Universal Tool and Cutter Grinders: Grinding single and multipoint tools, cutters precisely.
- Toolpost Grinders: Attaches to lathes to grind lathe-mounted tools.
- Swing Frame Grinders: Used in foundries for large casting grinding.
- Portable Grinders: Handheld for weld bead grinding and flash cutting.
- Bench or Pedestal Grinders: General-purpose for off-hand grinding of tools and small parts.
Grinding Fluids
- Reduce workpiece temperature, improve finish and accuracy, increase grinding ratio, reduce wheel wear, minimize loading, and lower power consumption.
Ultrasonic Machining
- Material removal: microchipping and erosion using vibrating abrasive grains in a water slurry.
- Tool (sonotrode) vibrates at high frequency (20 kHz) with small amplitude (10 micrometers).
- Vibration gives high velocity to abrasive grains, causing erosion.
- Can create intricate shapes and small-diameter holes in hard materials (e.g., glass, graphite, epoxy composites).
Rotary Ultrasonic Machining
- Variation using a metal-bonded diamond abrasive tool instead of slurry.
- Tool vibrates and rotates simultaneously.
Finishing Operations
- Refining surface finish and reducing roughness for improved part quality.
Coated Abrasives
- Sandpaper: Backing material with abrasive coating and sizing to hold grains.
- Manual surface finishing.
Belt Grinding
- Uses a rotating abrasive belt on rolls to remove material for high-speed, good-finish removal.
Power Brushing
- Circular wire brush creates longitudinal scratches, improving surface finish.
Honing
- Improves surface finish of inside diameters, holes, and internal shapes.
- Rectangular honing stones reciprocate to create smoother, more precise circular surfaces.
Superfinishing
- Similar to honing, but with lighter pressure and shorter strokes for an ultra-fine finish.
Honing
- Uses a honing stone oscillating or reciprocating on the workpiece with light pressure for surface finish enhancement on cylindrical and centerless workpieces.
Lapping
- Uses a soft, porous tool (lap) like cast iron, copper, leather, or cloth to finish flat, centered, and curved surfaces with embedded or slurry-carried abrasive particles, often used for glass lenses. The lap moves parallel to the workpiece surface enhancing surface finish.
Polishing
- Produces a smooth finish by softening and smearing surface layers with fine abrasives through friction. The shiny appearance results from this smearing action.
Chemical Mechanical Polishing (CMP)
- Polishing semiconductor substrate surfaces in integrated circuits.
- Rotating workpiece disc with abrasive slurry between. Involves both physical abrasion and chemical reactions with the slurry. Creates perfectly flat surfaces.
Electropolishing
- Produces a mirror-like finish, the reverse process of electroplating.
Buffing
- Similar to polishing but with finer abrasives on soft cloths or felt disks; abrasive is supplied externally from a stick.
Deburring
- Removes thin, triangular ridges (burrs) from workpiece edges.
- Methods include vibratory deburring, thermal energy deburring, and robotic deburring.
Cost of Finishing Operations
- Finishing cost increases with surface finish quality.
- Rough turning is least costly, with finishing turning increasing the cost.
- Grinding and honing are the most expensive finishing operations, with finishing operations only carried out if necessary for required tolerances.
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Description
Test your knowledge on abrasive machining and finishing operations. This quiz covers various types of operations such as grinding, honing, and polishing, along with their applications in metal and ceramic finishing. Discover how these processes achieve precise dimensional accuracy and superior surface finishes.
