Manufacturing and Mechanical Engineering Quiz

Carbon monoxide is not used as a refrigerant due to its toxicity and chemical properties. Ammonia (despite the typo 'amonia') is widely used in industrial refrigeration systems. Sulphur dioxide was historically used as a refrigerant. Carbon dioxide (CO2) is increasingly used in modern eco-friendly refrigeration systems. Only carbon monoxide serves no purpose as a refrigerant.

Freon (chlorofluorocarbon or CFC) compounds were the standard refrigerants in domestic refrigerators for decades. While sulphur dioxide was used historically, modern domestic refrigerators primarily use various types of freon (R-12, R-134a, etc.). Air and methane are not practical refrigerants for household cooling applications.

A shaper machine uses quick return motion mechanism - the ram moves forward slowly during the cutting stroke and returns rapidly during the return stroke (non-cutting). This improves efficiency since cutting happens only in one direction. Lathe, drilling, and grinder machines do not use this mechanism.

Draft (or taper) on a pattern is provided to accommodate the shrinkage of metal during cooling and solidification in the casting process. It also facilitates easy withdrawal of the pattern from the sand mold. The slight angular taper (typically 1-3 degrees) accounts for volumetric contraction.

Slotting cannot be performed on a lathe - it requires a slotter machine or shaper. Lathes are designed for rotating workpieces and perform operations like facing (surfacing the end), drilling (with tailstock support), and thread cutting (using lead screw). Slotting involves linear reciprocating motion, incompatible with lathe operation.

Centrifugal pumps have the lowest initial cost and maintenance cost among common pump types. They have few moving parts (mainly the impeller), no valves, and simple construction compared to gear pumps, bucket pumps, or double-acting piston pumps which have complex mechanisms with more wear parts requiring frequent maintenance.

Mandrels are used to hold hollow workpieces for machining operations on a lathe. They expand or grip the inner diameter of tubular parts, providing support during turning, facing, or other operations. Mandrels do not hold cutting tools, face plates, or drill bits - those have their own holding mechanisms.

Boring is the operation of enlarging an already existing hole to achieve precise diameter and surface finish. Drilling creates a hole from solid material. Counter sinking creates a conical seat for screw heads. Reaming slightly enlarges and finishes a hole for close tolerance. Only boring specifically enlarges an existing hole.

In upcut milling (conventional milling), the workpiece is fed against the rotation of the cutter. This means the cutter teeth engage the material at the thickest part first. This is opposite to downcut (climb) milling where feed is in the same direction as cutter rotation. The direction affects tool life and surface finish.

To answer this question, the user needs to know the definition of the term "sprue." A sprue is a passage or channel that allows molten material to flow into a mold during casting.

Now, let's go through each option and explain why it is right or wrong:

A. Outflow: This option is incorrect because a sprue is not a passage for outflow. Instead, it is a passage for inflow of molten material.

B. Smooth flow: This option is incorrect because a sprue is not a passage for smooth flow. It is specifically designed to allow controlled and directed flow of molten material into a mold.

C. Inflow: This option is correct. A sprue is a passage or channel that allows molten material to flow into a mold during casting. Thus, option C is the correct answer.

D. Solidification of the molten material: This option is incorrect because a sprue is not related to the solidification of the molten material. Instead, it is related to the initial introduction of molten material into the mold.

The Answer is: C

After Albert Einstein's death in 1955, pathologist Thomas Harvey removed his brain during the autopsy without the family's permission. The brain was preserved and sectioned for scientific study, with Harvey keeping portions of it in jars for decades. This controversial act led to extensive research on Einstein's brain structure to understand his exceptional intellect.

To solve this question, the user needs to know about the basic terminologies and operations of a lathe machine.

The feed rate in a lathe machine refers to the distance that a cutting tool advances into the workpiece with each revolution of the lathe spindle. It is typically expressed in millimeters per revolution (mm/rev).

Option A is correct because feed rate is generally given in millimeters per revolution (mm/rev). This means that for every complete revolution of the lathe spindle, the cutting tool advances a certain distance along the workpiece.

Option B is incorrect because the feed rate is not typically given in millimeters per degree. Degrees are used to measure angles, not distances.

Option C is incorrect because simply giving the distance in millimeters does not take into account the number of revolutions of the lathe spindle that are required to move the cutting tool that distance.

Option D is incorrect because RPM (revolutions per minute) is a measurement of the speed of the lathe spindle, not the feed rate.

Therefore, the correct answer is:

The Answer is: A. mm per revolution

Rapping allowance on a pattern is provided to ensure easy withdrawal of the casting from the mold. Rapping involves loosening or vibrating the pattern slightly before removal to break the adhesion between the pattern and the sand mold, preventing damage to either the pattern or the mold cavity during withdrawal.

Upsetting is a forging operation where the length of a workpiece is reduced while increasing its cross-sectional area. It is typically performed by hammering or pressing the end of a hot metal workpiece to create an enlarged section, commonly used in making bolt heads, rivet heads, and other fasteners.