Defects are likely to result in castings, Other Engineering

Assignment Help:

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. 


Related Discussions:- Defects are likely to result in castings

Communication overhead.., what is communication overhead in networking?what...

what is communication overhead in networking?what are the types of overhead?How to reduce communication overhead in broadcasting?

Boroscope inspections of air craft engine, Boroscope inspections: Boros...

Boroscope inspections: Boroscope inspections involve looking at components within an engine using an optical probe. The probes are inserted in to the engine through ports in th

Summing amplifier, Summing amplifier: As the title implies, this is an ...

Summing amplifier: As the title implies, this is an adding device.  The circuit can take any number of voltage inputs, and the output voltage is simply the sum of these inputs.

Post graduation, i am doing be in mechanical engg in india. so can i do my ...

i am doing be in mechanical engg in india. so can i do my masters in geoophysic ?

Armature cipl, in which type of armature winding Equaliser ring dummy coils...

in which type of armature winding Equaliser ring dummy coils are used

Blade twist - aircraft engine, BLADE TWIST: Rotational velocity and its...

BLADE TWIST: Rotational velocity and its effect on the Angle of Attack depends on the radius of the blade element in question. A blade element near the blade root (hub) will h

Acfi385, Seven years ago, after 15 years in public accounting, Stanley Book...

Seven years ago, after 15 years in public accounting, Stanley Booker, CPA, resigned his posiition as Manager of Cost Systems for Davis, Cohen, and O''Brien Public Accountants and s

Oil pumps - aircraft engine, OIL PUMPS The oil pumps fitted in a recirc...

OIL PUMPS The oil pumps fitted in a recirculatory system are normally gear-type or Gerotor type pumps. The pumps are usually mounted in a pack containing one pressure pump and

How will you make finance forecasting ?, how will you make finance forecast...

how will you make finance forecasting ? First I will evaluation the past seasons fiscal reports to get an Idea about the economical functions. Then will talk about with the cont

Payback period method, Non-discounted cash flow method, Payback period met...

Non-discounted cash flow method, Payback period method In this method, time value of money is not considered. It takes into account the number of years required to recover the in

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd