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a) Answer any three of the following: (i) Identify two cutting tool materials used on a centre lathe; (ii) Describe the process of up-cut milling; (iii) Explain the differences between forming and generating; (iv) Outline two reasons for wheel dressing a grinding wheel; (v) Distinguish between a clearance fit and an interference fit - Leaving Cert Engineering - Question 7 - 2010
Question 7
a) Answer any three of the following: (i) Identify two cutting tool materials used on a centre lathe; (ii) Describe the process of up-cut milling; (iii) Explain... show full transcript
Worked Solution & Example Answer:a) Answer any three of the following: (i) Identify two cutting tool materials used on a centre lathe; (ii) Describe the process of up-cut milling; (iii) Explain the differences between forming and generating; (iv) Outline two reasons for wheel dressing a grinding wheel; (v) Distinguish between a clearance fit and an interference fit - Leaving Cert Engineering - Question 7 - 2010
Step 1
Step 2
Describe the process of up-cut milling
Answer
Up-cut milling, also known as conventional milling, is a method where the cutting tool rotates against the direction of the workpiece's movement. The key steps in this process are:
- Setup: The workpiece is securely clamped to the milling machine.
- Cutting: As the cutter ascends, it bites into the workpiece from its bottom, leading to smoother cutting action.
- Result: This method is effective for removing material but requires precise clamping to avoid movement of the workpiece.
Step 3
Explain the differences between forming and generating
Answer
Forming and generating describe two distinct machining processes:
- Forming: This is a process where the surface of the material being machined takes the shape of the tool itself. This method often involves techniques such as contour work or screw cutting.
- Generating: In contrast, generating involves the creation of a surface by moving a cutting tool along a specified path. Examples include turning and tapering operations where the final shape is created by the relative motion between the tool and the workpiece.
Step 4
Outline two reasons for wheel dressing a grinding wheel
Answer
Wheel dressing is critical for maintaining grinding wheels. Two reasons for this process include:
- Restoration of Cutting Surface: Dressing removes any embedded foreign materials and irregularities, restoring the wheel’s sharp cutting surface for efficient grinding.
- Self-Dressing: Some grinding wheels are designed to self-dress during operation, but regular dressing maintains surface integrity and improves performance.
Step 5
Distinguish between a clearance fit and an interference fit
Answer
The key differences between clearance fit and interference fit are:
- Clearance Fit: This occurs when the shaft is smaller than the hole it fits into, allowing for easy assembly and disassembly.
- Interference Fit: In this scenario, the shaft is larger than the hole, requiring force for assembly. This fit is typically used when a tight connection is necessary.