Podcast
Questions and Answers
Which nose radius and feed parameters best describe the roughing process?
Which nose radius and feed parameters best describe the roughing process?
What is a primary purpose of using cutting fluids in machining?
What is a primary purpose of using cutting fluids in machining?
Which factor can help eliminate vibrations in machining processes?
Which factor can help eliminate vibrations in machining processes?
What defines a turret lathe compared to a basic lathe?
What defines a turret lathe compared to a basic lathe?
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In turning, what is the effect of spindle rotation on the cutting process?
In turning, what is the effect of spindle rotation on the cutting process?
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What is a disadvantage of the turning process in machining?
What is a disadvantage of the turning process in machining?
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Which of the following is NOT a benefit of using cutting fluids?
Which of the following is NOT a benefit of using cutting fluids?
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What role does the shape of the cutting tool play in turning?
What role does the shape of the cutting tool play in turning?
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What is the primary purpose of a drilling operation?
What is the primary purpose of a drilling operation?
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What does the term 'blind hole' refer to in drilling?
What does the term 'blind hole' refer to in drilling?
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Which factor is NOT considered to influence the cost of drilling?
Which factor is NOT considered to influence the cost of drilling?
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What is the function of the flutes on a drill bit?
What is the function of the flutes on a drill bit?
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Which of the following statements about reaming is correct?
Which of the following statements about reaming is correct?
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What type of drilling machine provides the most adjustability?
What type of drilling machine provides the most adjustability?
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What is the primary limitation of conventional drilling at depths greater than four times the drill bit diameter?
What is the primary limitation of conventional drilling at depths greater than four times the drill bit diameter?
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Which operation is used to create a stepped hole for hiding a bolt or screw head?
Which operation is used to create a stepped hole for hiding a bolt or screw head?
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What type of hole is created through the process of tapping?
What type of hole is created through the process of tapping?
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Which is NOT a characteristic of an upright drill press?
Which is NOT a characteristic of an upright drill press?
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What is a major advantage of using CNC for machining?
What is a major advantage of using CNC for machining?
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Which of the following is considered a disadvantage of machining?
Which of the following is considered a disadvantage of machining?
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What factor can limit the cutting speed and overall productivity in machining?
What factor can limit the cutting speed and overall productivity in machining?
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Which of the following statements about cutting tools in machining is true?
Which of the following statements about cutting tools in machining is true?
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What can be a consequence of using low-quality cutting tool materials?
What can be a consequence of using low-quality cutting tool materials?
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Which of the following represents a factor affecting the machined surface finish?
Which of the following represents a factor affecting the machined surface finish?
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Why can machining be more time-consuming than other manufacturing methods?
Why can machining be more time-consuming than other manufacturing methods?
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What is a common drawback associated with achieving high dimensional accuracy in machining?
What is a common drawback associated with achieving high dimensional accuracy in machining?
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What is the primary difference between casting and forging processes?
What is the primary difference between casting and forging processes?
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Which of the following processes is classified as material addition?
Which of the following processes is classified as material addition?
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What does the term 'net shape' refer to in manufacturing?
What does the term 'net shape' refer to in manufacturing?
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What is the main purpose of machining in shaping processes?
What is the main purpose of machining in shaping processes?
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Which factor does NOT affect the material removal rate during machining?
Which factor does NOT affect the material removal rate during machining?
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What does the term 'near net shape' indicate?
What does the term 'near net shape' indicate?
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Which of the following best describes machining as a subtractive manufacturing process?
Which of the following best describes machining as a subtractive manufacturing process?
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In the context of shaping processes, which of the following is a characteristic of bulk deformation?
In the context of shaping processes, which of the following is a characteristic of bulk deformation?
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What is an essential requirement for a material to be processed through conventional machining?
What is an essential requirement for a material to be processed through conventional machining?
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Which process uses heat to join separate material parts into a final shape?
Which process uses heat to join separate material parts into a final shape?
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What is the primary goal of manufacturing from an economical perspective?
What is the primary goal of manufacturing from an economical perspective?
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Which factor affects the cost of manufacturing when increasing the complexity of a part?
Which factor affects the cost of manufacturing when increasing the complexity of a part?
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What determines the achievable resolution and surface finish in manufacturing?
What determines the achievable resolution and surface finish in manufacturing?
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How does production volume relate to manufacturing complexity?
How does production volume relate to manufacturing complexity?
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Which of the following materials is typically heavier and more cost-effective for car wheels?
Which of the following materials is typically heavier and more cost-effective for car wheels?
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What is the role of manufacturing support systems?
What is the role of manufacturing support systems?
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What would likely be the consequence of using standard part shapes and sizes in manufacturing?
What would likely be the consequence of using standard part shapes and sizes in manufacturing?
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What is likely to happen to costs as production quantity increases?
What is likely to happen to costs as production quantity increases?
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What aspect of manufacturing is affected by material limits?
What aspect of manufacturing is affected by material limits?
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Which of the following statements regarding flexibility in manufacturing is correct?
Which of the following statements regarding flexibility in manufacturing is correct?
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Which manufacturing process is typically used for creating the general shape of car wheel parts?
Which manufacturing process is typically used for creating the general shape of car wheel parts?
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What does the term 'near net process' refer to in manufacturing?
What does the term 'near net process' refer to in manufacturing?
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Which feature is essential for assessing quality in manufactured parts?
Which feature is essential for assessing quality in manufactured parts?
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What impacts the accuracy and consistency of a manufacturing process?
What impacts the accuracy and consistency of a manufacturing process?
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Study Notes
Manufacturing
- Manufacturing: the transformation of raw materials into products of greater value by one or more processing and/or assembly operations
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Manufacturing System: a coordinated network of people, equipment, facilities, procedures, and information that transforms inputs into outputs.
- Macro View: Manages materials and processes (facilities, people, equipment, procedures)
- Micro View: Individual equipment and operators that perform processing and/or assembly operations on a starting raw material (specific machines, mill, lathe, operators, workpiece, cutting tools)
- Manufacturing Support Systems: Increase productivity but do not make the final product (people and procedures used to manage production operations)
Manufacturing Considerations
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Costs:
- Setup costs (equipment and tooling)
- Running costs (energy and labor)
- Waste/pollution (environmental costs)
- Cost decreases with increasing quantity
- Cost increases with increasing complexity and variety
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Production Rate:
- Parts per unit of time
- Speed of production
- Labor: Number of people required to operate the manufacturing system
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Geometric Complexity:
- Part shape
- Part size
- Number of features
- Geometric transitions
- Holes/cores and non planar surfaces
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Accuracy:
- Achievable resolution, feature size, surface finish
- How accurate and consistent the process is (variation)
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Quantity/Production Volume:
- Product quantity to be made
- Low (1-100): custom
- Medium (100-10,000): jets, exotic cars
- High (10,000+): bottles, cars, phones, laptops
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Material Limits:
- Physical limitations
- Use standard materials (exotic high strength materials are expensive and difficult to process)
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Quality:
- Achievable resolution, feature size, surface finish
- How accurate and consistent the process is (variation)
- Material or part quality (net vs near net process)
- Tolerance: allowable variation in dimensions or size (cost increases with increasing precision)
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Flexibility:
- Scalability to different physical sizes of parts
- Compatibility with different part geometry
- Scalability to different production quantities
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Limitations:
- What processes can/can't be used
- What materials can/can't be worked with
- What shapes can/can't be made
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Manufacturing Plant Capability:
- Manufacturing plant capability
- Number of components
- Use standard part shapes and sizes to reduce cost
- Minimize part complexity
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Product Variety:
- Different product types or models produced in the plant
- Soft: Slight changes, many common parts
- Hard: Great changes, few common parts
- Cannot manufacture many parts if all parts are different across different products due to cost
Shaping Processes
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Solidification Process: Starting material is melted and solidified.
- Casting (metals and ceramics): Molten material is poured into a mold.
- Moulding (plastics): Material is pressed into a die.
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Deformation Process (Bulk): Starting material is shaped by forces exceeding the yield strength of the material.
- Sheet metal forming or stamping: Flat sheet metal is formed into desired shapes.
- Forging: Material is hammered or pressed into shape.
- Extrusion: Material is pushed through a die to create a desired shape.
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Material Subtraction (Machining): Excess material is cut away from a starting workpiece.
- Turning: Material is cut from a rotating workpiece using a single point cutting tool.
- Drilling: Material is cut from a workpiece using a rotating drill bit.
- Milling: Material is cut from a workpiece using a rotating milling cutter.
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Material Addition Process (3D Printing): Material is added together to form the final part shape.
- Particulate processing: Starting materials are metal or ceramic powders which are pressed and sintered (heated near melting temperature).
- Powder bed fusion process: Laser fuses powder together (additive manufacturing or AM).
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Material Joining Process: Separate bulk material parts are joined to form the final shape
- Adhesive bonding/glueing
- Welding/brazing
- Fastening with bolts
Material Removal/Subtractive Manufacturing
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Conventional Machining: Uses a sharp and hard cutting tool to mechanically cut away material to shape and enhance finish of material or add extra details by forming chip.
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Factors:
- Relative motion and trajectory between tool and workpiece
- Shape of cutting tool
- Strength of cutting tool material
- Cost of cutting tool
- Target Material: Typically for metal, but plastic or ceramic materials may be used depending on machinability.
- Target Stage: Typically performed after other basic near-net shape manufacturing processes such as casting, forging, etc.
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Advantages
- Versatile
- High dimensional accuracy
- Good surface finish (net finish)
- Few defects
- Easily automated (CNC)
- Can have replaceable inserts
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Disadvantages:
- Wasteful of material
- Costly to recycle
- More time consuming than other methods (low-medium rate)
- Can leave machining marks
- Shape limited by tool access
- Material machinability
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Considerations:
- Cutting tools wear out or fail (break) over time due to higher loads
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Factors:
Machined Surface Finish
- Can show visible machining marks
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Factors:
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Geometric tool factors: Nose radius (NR) & feed (f)
- Roughing: (High feed, low speed), uses a sharp nose radius to get near-net shape by removing large amounts of material quickly.
- Finishing: (Low feed, high speed), uses a round nose radius to get net shape (final dimensions, tolerance, and surface finish).
- Eliminate vibrations/chatter: Increase stiffness of setup, reduce feeds and depths to reduce forces, change cutter design to reduce forces, use a cutting fluid.
- Process used:
-
Geometric tool factors: Nose radius (NR) & feed (f)
Cutting Fluids
- Machining often requires use of cutting fluids (oil, water):
- To remove heat
- To lubricate the chip-tool interface
- To wash away chips
- To avoid part oxidation
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Contributes to:
- Chip removal
- Reduced stress on cutting tool
- Increased tool life
- Better part accuracy (reduced thermal expansion)
- Less surface damage
Turning
- Uses lathe and single tip tool to create a rotational part (circular cross section).
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Process:
- Material is spinning (primary motion).
- Rotating tool moves horizontally (secondary motion).
- Creates divots into the circular part.
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Factors:
- Relative motion and trajectory between tool and workpiece (cutting speed and feed motion) to achieve various geometries/shapes.
- Shape of cutting tool.
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Types of Lathes:
- Basic lathe: Bed, tool post, chucks, tailstocks.
- Turret lathe: Tailstock replaced by turret that holds several tools, tools rapidly brought into action by indexing the turret, saves changeover time.
- CNC lathe: Advanced programmable “Computer Numerical Control” (CNC) of position, tool change, and tool feeds.
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Advantages:
- Precision and Accuracy
- Versatility
- Flexibility
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Disadvantages:
- Material Waste
- Requires specific machinery
- Knurling: Forming operation to produce patterns in the work surface, no cutting of material, just deformation.
Drilling
- Drilling machine/press uses a drill bit (multiple points) to create a prismatic part (rigid non-rotational cross section).
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Process:
- Material is stationary.
- Rotating tool moves along one axis.
- Creates circular holes into the part.
- Through Hole: Drill exits the opposite side of the work.
- Blind Hole: Drill does not exit the opposite side.
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Factors that influence cost:
- Cutting speed (v)
- Feed rate (fr)
- Depth of cut (d)
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Types:
- Machine Used:
- Upright drill press: Simple manually operated machine with limited adjustability.
- Radial arm drill press: More adjustability (horizontal and vertical), manually operated.
- CNC drill: More adjustability (horizontal and vertical), computer positioning, advanced computer numerical control operated.
- Drill bit used:
- Body of flutes, spiral grooves, used to guide chip removal and deliver cutting fluids.
- Cutting points - number of flutes.
- Reaming: Slightly enlarges a hole, enhances tolerance and surface finish (removes machine marks).
- Tapping: Cuts internal screw threads on an existing hole.
- Counterboring: Creates a stepped hole.
- Countersinking: Used for hiding bolt/screw head.
- Machine Used:
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Advantages:
- High accuracy and repeatability
- Can drill a wide range of hole sizes and depths
- Relatively easy to automate
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Limitations of Conventional Drilling:
- At depths of over 4 times the diameter of the drill bit, chips can accumulate, cutting fluid flow is restricted, interrupted cut drilling (peck drilling).
- Long/deep and narrow holes (small diameter) are difficult/impossible to drill conventionally due to drill bits being fragile and likely to break or wonder/skew.
- Small holes: Difficult to drill conventionally due to smaller drills being fragile.
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