Engineering Questions with Answers - Multiple Choice Questions
Manufacturing Processes – Abrasive Jet Micromachining – 6
1 - Question
Powder flowability is affected by particle size and surface texture.
a) True
b) False
View Answer
Explanation: Powder flowability and compatibility are greatly influenced by particle size, size distribution, moisture content, and surface texture.
2 - Question
Adhesion between particles can be increased by moisture.
a) True
b) False
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Explanation: Inter particle adhesion is further enhanced by moisture that adsorbs readily onto these hygroscopic (having a tendency to absorb moisture) surfaces.
3 - Question
Relative humidity can affect adhesive forces.
a) True
b) False
View Answer
Explanation: The relative humidity of stored air can have a major influence on the adhesive forces at the interface of particles. But one of the major difficulties with the AJMM process is the handling of very fine abrasive particles.
4 - Question
Movement of powder leads to stratification.
a) True
b) False
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Explanation: It is well known that the movement of powder leads quickly to stratification and the creation of gradient of particle size and/ or shape. Such problems result in alteration of the powder mass flow rate during the course of AJMM experiments.
5 - Question
Powder feed control of micro-blasting systems is divided into _____
a) 2
b) 3
c) 4
d) 5
View Answer
Explanation: The powder feed control of two micro-blasting systems is considered into two types. • Pressurized powder feed system • Fluidized bed powder spray system.
6 - Question
Vibratory or screw feeding systems are another approach to control the powder mass flow rate.
a) True
b) False
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Explanation: Other approaches to the control of powder mass flow rate include vibratory and screw or auger feeding in which the powder is fed to the conveying air through an auger (similar to the tool used for boring earth).
7 - Question
In powder feeding systems, powder bridging, compaction, and agglomeration are desirable.
a) True
b) False
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Explanation: Introducing a vibrator to a screw system improve the steadiness of the powder feed But the improvement diminishes with fine, more cohesive materials such as zeolites and cement powders due to phenomena such as powder bridging, compaction, and agglomeration.
8 - Question
In AJMM, the powder is fed _____
a) through air stream
b) through a water pipe
c) along with a gel, which improves the adhesion between particles
d) in the form of batches
View Answer
Explanation: The powder is fed through the air stream from a pressurized reservoir through an orifice and mixing chamber. The system utilizes an oscillating valve that splits the operation cycle into two halves.
9 - Question
The operation cycle is activated when the entire system is pressurized.
a) True
b) False
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Explanation: The operation cycle is activated by a switch only after the entire system, including reservoir, has initially been pressurized by closing the nozzle end and opening the oscillating valve to the main air supply.
10 - Question
During powder feeding, the oscillating valve is open for the first half of the operation cycle.
a) True
b) False
View Answer
Explanation: During the first half of the operation cycle, the oscillating valve is open, allowing air to flow from the pressure regulator to the mixing chamber while some enters the powder reservoir and the rest flows out through the opened nozzle.