Cryogenic Machining of Inconel 718 VS. Dry and MQL Machining
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Questions and Answers

What is the primary impact of elevated temperatures on cemented carbide tools during machining?

  • Increased hardness of the tool
  • More than 50% decrease in tool hardness at 800 °C (correct)
  • Decrease in tool’s frictional shear stress
  • Improved tool life

    • How does cryogenic cooling affect the cutting forces in machining according to the content?

  • It increases cutting forces for selected conditions (correct)
  • It decreases chip contact area
  • It eliminates flank wear
  • It reduces all three cutting force components

    • Which factor is notably influenced by flank wear during machining?

  • The cutting edge retreat (correct)
  • The material composition of the tool
  • The temperature at the tool's cutting edge
  • The type of cryogenic coolant used

    • What can be a consequence of not having an appropriately designed cutting tool for cryogenic machining?

    <p>Severe notching and flank wear</p> Signup and view all the answers

    What relationship exists between tool–chip contact length and measured cutting forces?

    <p>Strong direct relationship</p> Signup and view all the answers

    At what cutting speed was progressive flank wear observed alongside crater wear?

    <p>60 m/min</p> Signup and view all the answers

    Which cooling method may inadvertently lead to increased tool wear rate?

    <p>Cryogenic cooling with improper tool design</p> Signup and view all the answers

    What role does the delivery of liquid nitrogen play in cryogenic machining?

    <p>It may cause additional issues in cutting</p> Signup and view all the answers

    What is the primary advantage of using cryogenic cooling at higher cutting speeds in machining?

    <p>Reduced thermal distortion</p> Signup and view all the answers

    At what cutting speed is MQL recommended for improved machining performance?

    <p>Low cutting speeds</p> Signup and view all the answers

    Which method demonstrated the lowest surface roughness value among the cooling techniques evaluated?

    <p>Cryogenic machining</p> Signup and view all the answers

    What effect does using MQL have on the force components during machining?

    <p>Reduces all force components significantly</p> Signup and view all the answers

    What is a significant drawback observed in dry machining as compared to MQL or cryogenic methods?

    <p>Increased tool wear</p> Signup and view all the answers

    What is the primary effect of cryogenic cooling on the pitch generated during machining?

    <p>It generates a pitch approximately three times larger than dry and MQL conditions.</p> Signup and view all the answers

    How does chip thickness relate to the shear angle in cryogenic cooling conditions?

    <p>Thicker chips may result from a reduced shear angle caused by cutting temperatures.</p> Signup and view all the answers

    What factor may contribute to the higher cutting forces observed in cryogenic cooling?

    <p>Higher chip thickness from reduced shear angle.</p> Signup and view all the answers

    In comparison to dry and MQL conditions, how does the valley formed in chips during cryogenic machining differ?

    <p>The valley in cryogenic conditions is smaller than in dry and MQL.</p> Signup and view all the answers

    What role does cutting temperature play in the variation of chip thickness?

    <p>Cutting temperature directly influences the shear angle.</p> Signup and view all the answers

    What characteristic of chips does thermal softening influence during high cutting speeds?

    <p>Shear-localized deformation in the chip.</p> Signup and view all the answers

    Which of the following factors was previously investigated for their effect on machining performance?

    <p>Cutting speed and hardness of work material.</p> Signup and view all the answers

    What observation can be made about chip serration in different cooling situations?

    <p>Chip serration varies significantly with cutting conditions.</p> Signup and view all the answers

    What is a necessary area of investigation for correlating chip thickness and force components?

    <p>Measuring and predicting shear angle.</p> Signup and view all the answers

    What is a common outcome of using cryogenic cooling compared to dry machining?

    <p>More effective chip flow and reduced wear.</p> Signup and view all the answers

    What effect does cryogenic cooling have on chip flow under higher cutting speeds?

    <p>It reduces the tool-chip contact due to lower effective contact.</p> Signup and view all the answers

    In what way does cryogenic cooling influence force components compared to dry and MQL conditions?

    <p>It reduces force components more effectively than dry or MQL conditions.</p> Signup and view all the answers

    What primarily contributes to the reduction in force components during cryogenic machining?

    <p>The decrease in tool-chip contact length.</p> Signup and view all the answers

    What is the likely impact of increased cutting speed under the same cooling conditions?

    <p>It alters the lubrication effectiveness significantly.</p> Signup and view all the answers

    What is a consequence of the hydrodynamic action observed in higher cutting speeds during cryogenic machining?

    <p>It sweeps lubricant away from the interface more effectively.</p> Signup and view all the answers

    What potential factors might not be adequately considered in the evaluation of forces during machining?

    <p>Hydrostatic pressure and compressive stress.</p> Signup and view all the answers

    What was the primary observation regarding tool wear in relation to the types of cooling?

    <p>Tool wear mainly affects the flank area during machining.</p> Signup and view all the answers

    How does the length of tool-chip contact change under high cutting speeds compared to other conditions?

    <p>It was found to be smaller than in dry and similar to MQL.</p> Signup and view all the answers

    Which of the following is a major reason for reduced force components when applying cryogenic cooling?

    <p>Reduced tool-chip contact due to increased cutting speed.</p> Signup and view all the answers

    Which of the following describes the impact of the applied pressure from cryogenic jet cooling on chip flow?

    <p>It can slightly enhance chip flow behavior under cryogenic conditions.</p> Signup and view all the answers

    Study Notes

    Cryogenic Machining of Inconel 718

    • Effect of Cryogenic Cooling on Tool Hardness: Cryogenic cooling significantly decreases the hardness of cemented carbide tools. At 800 °C, the hardness reduction is more than 50% compared to room temperature.
    • Elevated Temperatures and Tool Wear: High temperatures at the cutting edge lead to tool impairment, plastic deformation, severe notching, and flank wear.
    • Flank Wear: Flank wear is a common wear mechanism in machining, where the cutting edge retreats, which impacts the workpiece accuracy.
    • Cryogenic Cooling and Flank Wear: Cryogenic cooling generates larger chip pitch and smaller valley compared to dry and MQL machining. This is attributed to the shear angle influenced by the reduced cutting temperature.
    • Cryogenic Cooling and Cutting Force: Cryogenic cooling leads to thicker chip thickness due to reduced shear angle, which can also contribute to higher cutting forces. However, further investigations are needed to correlate chip thickness and force components with shear angle.
    • Chip Morphology and Cryogenic Cooling: Cryogenic cooling can influence chip morphology and seration, but further investigation is needed to consider strain hardening and thermal softening behaviors.
    • Effect of Cutting Speed: Increasing cutting speed, under constant cooling/lubrication, changes the force components. Cryogenic cooling can reduce force components at higher speeds compared to dry and MQL conditions. This is attributed to tool-chip contact length and tool wear.
    • Cryogenic Cooling and Lubrication Effects: Cryogenic cooling can significantly reduce cutting forces. However, the lubrication effects may diminish if too much cryogenic liquid is used, causing a decrease in effective contact between the tool and chip.
    • Cryogenic Cooling and Surface Quality: Cryogenic cooling improves the surface quality, especially at higher cutting speeds, due to reduced tool wear and thermal distortion. At lower cutting speeds, some surface defects may occur in dry machining.
    • Recommendation: Cryogenic cooling is recommended for machining Inconel 718 at higher cutting speeds. MQL machining is recommended for lower speeds to improve machining performance.

    Forces, Chip Morphology, and Cutting Speed

    • Effect of Cryogenic Cooling on Cutting Force : Cryogenic cooling affects all three force components. Cryogenic cooling with two nozzles leads to increased cutting force components, so design modifications are necessary to accommodate liquid nitrogen delivery.
    • Factors Affecting Chip Morphology: Shear angle and shear localized behavior are key factors in chip morphology, which can be affected by thermal softening, strain hardening, and cutting temperature.
    • Chip Flow and Cryogenic Cooling: Cryogenic liquid jets can pressure the tool face, potentially impacting chip flow. At higher speeds, chip flow may override the liquid application pressure.
    • High Speed Machining and Lubrication: At high cutting speeds, lubrication effects may diminish.
    • Tool Wear and Force Components: Changes in tool wear, especially at the nose of the tool, can contribute to variations in force components.

    Summary of Findings

    • Cryogenic Cooling : Cryogenic cooling effectively reduces cutting forces and improves surface quality at higher speeds but requires design considerations to accommodate liquid nitrogen delivery.
    • MQL Machining: MQL machining is suitable for lower speeds as it can reduce force components and improve surface quality.
    • Overall: Cryogenic cooling demonstrates its potential for improved machining performance, but selection of suitable cutting parameters and lubrication methods is crucial.

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    Related Documents

    Evaluation of Cryogenic Machining of Inconel 718 (PDF)

    Description

    Explore the fascinating effects of cryogenic cooling on the machining of Inconel 718. This quiz covers the impact of reduced temperatures on tool hardness, wear mechanisms, and cutting forces. Understand how cryogenic techniques can improve machining performance and tool longevity.

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