Note:
Metal pouring defects (mis run and cold shuts) are caused due to following
>>Lower fluidity of the molten metal; remedy: increase pouring temp
>>If the section thickness of the mould is too small; remedy: proper casting design
>>Castings with large surface area to volume ratio
>>Back pressure due to gases in the mould which are not properly vented
Hot tear is caused by unwanted cooling stress(metals have low strength at high temp)leading to the rupture of the casting, usually caused by poor casting design
Hot spots are caused by chilling of the casting. Proper metallurgical control and chilling practices are essential for eliminating hot spots
syllabus of mech?
Casting:
The internal cracks in casting can be easily found by ultrasonic method
The surface and sub surface cracks in non-magnetic alloys can be easily located and detected by dye-penetratrant testing
The internal hot tear defects in castings can be inspected by radiography
Honey combing/sponginess refers to formation of number of cavities in close proximity in casting
Sand with high moisture content results in scab
Pin holes in casting can occur because of sand with higher moisture content
Rat tails are common in investment casting
Invar is the metal which has negative shrinkage allowance
In case of expendable pattern total casting allowance is P+Q
In case of metal pattern the total allowance is P+Q+R-S
P:shrinkage allowance, Q:machining allowance, R:draft allowance, S:shake allowance
Silica gel is used in C02 moulding
Best process for mass production of small plastic components is injection moulding
Atomization is the stage , molten metal is used as input in powder metallurgy
The main purpose of chaplets is to support the cores
Investment casting is used for shapes which are very complex and intricate and cannot be cast by any other method
Slush casting: hallow castings like lamp shades
Dry sand moulding: cast iron shoe brake
Centrifugal casting: rain water pipes
What was isro 2015 cutoff for mechanical?
Any one having source for 2006-2012 answer key?
Plz solve
which of the following process would produce strongest components?
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can any one provide key to isro 2006 to 2012
number of force acts on a rigid body each force is replaced by equal and parallel force acting through a fixed point together with a couple for a rigid body to be in equilibrium?
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Isro 2013 .
A is a squar. Matrix order 3 then product of A and its transpose is..unit matrix, zero matrix,identity matrix, symmetric matrixAnswer for 11th question pls
[https://www.google.co.in/url?q=http://isro.gov.in/sites/default/files/pdf/recruitment/icrb2014-01/Mechanical-BE002-key-2014-revised.pdf&sa=U&ved=0ahUKEwicl-u-ybnNAhVFuo8KHTP4CX0QFggRMAE&usg=AFQjCNGbMMppvGS0hTkBQ4DyN36XGe4Jxw] 2014 revised answer key
[https://www.google.co.in/url?q=http://www.isro.gov.in/sites/default/files/answer_keys_for_web-mechanical.pdf&sa=U&ved=0ahUKEwicl-u-ybnNAhVFuo8KHTP4CX0QFggWMAM&usg=AFQjCNF-_Le3GDaIGHfE6O0S69mgTxzbzA] 2015 revised answer key
Plz few of u provide exam pattern....subjectwise how much priority isro give to each subject??
also how to go for RAC & IC.couldn't attend classes for them
in a simple micrometer with a screw pitch 0.5mm and divisions on thimble 50, the reading corresponding to 5 divisions on barrel and 12 div on thimble is
a, 2.620 mm b. 2.512
A piece of lead is contained in the block of ice which is kept in water tub . If the ice melts, then level of water
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centrifugal tension in belt
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vapour condenses to liquid
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Expected isro cut off for mechanical 2016??
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