Defects are likely to result in castings, Other Engineering

Q. What kind of defects are likely to result in castings due to the following? 

       (i) Core prints on the core are undersigned.

       (ii) Core prints on the core are oversized

       (iii) Molten metal is poured at inadequate temperature.

Ans. A properly designed casting, a properly prepared mould and correctly melted metal should result in a defect free casting. But due to lack of proper exercise and surrounding there are some defects in casting. The defects may be of various types. For the given results in casting the following defects occurs :

       (i) Core prints on the core are undersize. Due to this result the defects are :

       (a) Mismatch

       (b) Uneven wall thickness

       (c) Crush

       Mismatch : Mismatch is a shift of the individual parts of a casting with respect to each other. This may occur due to mould shift or core shift. The causes can be an inexpert assembling of the two halves of the mould, from wear of pin bushes and pins and dimensional discrepancy between the core prints of the pattern and the core prints of the core.

      (ii) Core prints on the core are oversized. Due to this result the defects are

      (a) Crushes           (b) Uneven wall thickness

      Crushes : A crush is a deformation of mould surface due to pressing or scrapping of the sand during setting of core or assembly of the mould boxes. Setting of over sized cores in undersized core prints and lack of care in assembly often lead to the occurrence of crushes.

       (iii) Molten metal is poured at inadequate temperature :

       Due to this result, the defects are :

       (a) Hot tears         (b) Shunts

       (c) Misrun or Short run

       Hot tears : Hot tears are hot cracks which appear in the form of irregular crevices with a dark oxidized fracture surface. They arise when the solidifying metal does not have sufficient strength to resist tensile forces produced during solidification. They occur chiefly from an excessively high temperature of casting metal. This defect can be avoided by improving the design of the casting and by having a mould of low hot strength and large hot deformation. 

Posted Date: 8/3/2012 2:40:58 AM | Location : United States

Related Discussions:- Defects are likely to result in castings, Assignment Help, Ask Question on Defects are likely to result in castings, Get Answer, Expert's Help, Defects are likely to result in castings Discussions

Write discussion on Defects are likely to result in castings
Your posts are moderated
Related Questions
if the response of a signal is h(t) then the cascading of two responses h1(t) and h2(t) is given by

Function intersect - set operations: The function intersect returns, additionally to the vector having the values in the intersection of v1 and v2, an index vector into v1 and

Continuous Casting : In essential, the process consists of pouring molten metal into a short vertical metal die or mould (at a controlled rate), which is open at both ends, coolin

R-134a is compressed in an adiabatic compressor from saturated vapor at 100kPa to a final state at 1 MPa and 50 degrees Celcius. Before entering the compressor, the R-134a receive

What''s the principles of surveying?

1. The cantilever beam-like structure shown below is modeled using a 2 x 10 mesh of rectangular four-node plane stress elements of equal size. Geometric boundary conditions at x ?

Analog digital converter  Analog digital converter digitises the conditioned signal and presents it in a digital form, which is more convenient for long distance transmission,

What is the standard deviation of return if we have the following two possible outcomes: a rise of 8.00 per cent with 0.58 probability or a fall of -6.00 per cent?

explain amplitude resonance