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Answer any three of the following: (i) Explain the term tolerance used in metrology - Leaving Cert Engineering - Question 7 - 2017
Question 7
Answer any three of the following: (i) Explain the term tolerance used in metrology. (ii) Outline the difference between loading and glazing of grinding wheels. (... show full transcript
Worked Solution & Example Answer:Answer any three of the following: (i) Explain the term tolerance used in metrology - Leaving Cert Engineering - Question 7 - 2017
Step 1
Explain the term tolerance used in metrology.
Answer
Tolerance refers to the allowable deviation in the dimensions of a part from its nominal size. For example, if a part is designed to be 20.00 mm, a tolerance of ±0.15 mm means the actual size can range from 19.85 mm to 20.15 mm. This ensures that parts fit together during assembly while considering manufacturing variability.
Step 2
Outline the difference between loading and glazing of grinding wheels.
Answer
Loading occurs when abrasive particles on the grinding wheel become clogged with material, preventing effective cutting and reducing efficiency. In contrast, glazing happens when the grinding wheel develops a shiny surface due to the abrasive particles losing their cutting edges, leading to ineffective grinding. Both conditions can adversely affect the grinding process.
Step 3
Describe the function of a reamer in machining.
Answer
A reamer is a precision tool used to enlarge and finish existing holes to a specific diameter with high accuracy. It smooths the hole's surface and achieves tight tolerances that drilling alone cannot provide. Reamers are essential for achieving precise fits in mechanical assemblies.
Step 4
State two advantages of a keyless chuck.
Answer
Keyless chucks offer the advantage of convenient operation since they can be tightened and loosened by hand, eliminating the need for a key. Additionally, they provide greater ease of use, especially in environments where quick tool changes are essential, like manual machining or mobile applications.
Step 5
Explain the term rancidity in relation to cutting fluids.
Answer
Rancidity in cutting fluids refers to the degradation of the fluid due to the growth of bacteria and other microorganisms over time. This process can lead to the formation of unpleasant odors and the production of harmful byproducts. Managing rancidity is crucial for maintaining the effectiveness of cutting fluids and ensuring machine performance.
Step 7
Describe the impact of cutting fluids on metal cutting machines and metal cutting efficiency.
Answer
Cutting fluids help prolong the life of metal cutting machines by reducing heat buildup, which can lead to wear and tear. They also enhance machining efficiency by improving tool life, reducing friction, and achieving better surface finishes, which ultimately leads to lower production costs and improved product quality.
Step 8
Explain, with the aid of a diagram(s), the basic operation of a magnetic chuck.
Answer
A magnetic chuck holds ferromagnetic workpieces securely during machining processes. It typically comprises a top plate and embedded magnets that can be switched on and off to secure the workpiece. When the magnets are activated, they create a strong magnetic field, holding the workpiece firmly in place against the chuck's surface.
Step 9
State one advantage and one disadvantage of magnetic chucks.
Answer
Advantage: Magnetic chucks provide a firm grip on metal workpieces, allowing for stable machining processes. Disadvantage: They require the workpiece to be magnetic; thus, non-ferrous materials cannot be clamped using magnetic chucks.