# 25. mechanical engineering interview questions and answers

## Mechanical Engineering interview questions and answers

### Part 1   Part 2   Part 3   Part 4   Part 5   Part 6 1.What are the different types of fits? Explain? 2. What are the factors that can affect the Factor of safety selection? 3. What is heat treatment and why is it done? 4. What are the rules that must be kept in mind while designing castings? 5. What are the points that should be kept in mind during forging design? 6. Describe briefly the different cold drawing processes. 7. What are the different theories of failure under static load, explain briefly? ## What are the different types of fits? Explain? On the basis of Indian standards fits can mainly be categorized into three groups: > Clearance Fit: These types of fits are characterized by the occurrence of a clearance between the two mating parts. The difference between the minimum size of the hole and the maximum size of the shaft is called the minimum clearance, the difference between the maximum size of the hole and the minimum size of the shaft is known as maximum clearance. > Interference Fit: In these types of fits the size of the mating parts are predefined so that interference between them always occurs. The tolerance zone of the hole is completely below the tolerance zone of the shaft. > Transition Fit: As the name suggests these type of fit has its mating parts sized limited to allow either clearance or interference. The tolerance zone of the hole and the shaft overlaps in case of such fits. For a shaft designated as 40 H8/f7, calculate the tolerances. Given: Shaft designation = 40 H8/f7 The shaft designation 40 H8/f 7 means that the basic size is 40 mm and the tolerance grade for the hole is 8 ( i. e. I T 8) and for the shaft is 7 ( i. e. I T 7). Since 40 mm lies in the diameter steps of 30 to 50 mm, therefore the geometric mean diameter, D = Square root of (30 x 50) = 38.73 mm We know that standard tolerance unit, i = 0.45 x Cube root of (D) + 0.001 D i = 0.45 × 3.38 + 0.03873 = 1.559 73 or 1.56 microns i = 1.56 × 0.001 = 0.001 56 mm ...(1 micron = 0.001 mm) The standard tolerance for the hole of grade 8 (IT8) = 25 i = 25 × 0.001 56 = 0.039 mm The standard tolerance for the shaft of grade 7 (IT7) = 16 i = 16 × 0.001 56 = 0.025 mm ## What are the factors that can affect the Factor of safety selection? The factor of safety is used in designing a machine component. Prior to selecting the correct factor of safety certain points must be taken into consideration such as: > The properties of the material used for the machine and the changes in its intrinsic properties over the time period of service. > The accuracy and authenticity of test results to the actual machine parts. > The applied load reliability. > The limit of stresses (localized). > The loss of property and life in case of failures. > The limit of initial stresses at the time period of manufacture. > The extent to which the assumptions can be simplified. The factor of safety also depends on numerous other considerations such as the material, the method of manufacturing , the various types of stress, the part shapes etc. ## What is heat treatment and why is it done? Heat treatment can be defined as a combination of processes or operations in which the heating and cooling of a metal or alloy is done in order to obtain desirable characteristics without changing the compositions. Some of the motives or purpose of heat treatment are as follows: > In order to improve the hardness of metals. > For the softening of the metal. > In order to improve the machinability of the metal. > To change the grain size. > To provide better resistance to heat, corrosion, wear etc. Heat treatment is generally performed in the following ways: > Normalizing > Annealing > Spheroidising > Hardening > Tempering > Surface or case hardening ## What are the rules that must be kept in mind while designing castings? Some of the points that must be kept in mind during the process of cast designing are as follows: > To avoid the concentration of stresses sharp corners and frequent use of fillets should be avoided. > Section thicknesses should be uniform as much as possible. For variations it must be done gradually. > Abrupt changes in the thickness should be avoided at all costs. > Simplicity is the key, the casting should be designed as simple as possible. > It is difficult to create true large spaces and henceforth large flat surfaces must be avoided. > Webs and ribs used for stiffening in castings should as minimal as possible. > Curved shapes can be used in order to improve the stress handling of the cast. ## What are the points that should be kept in mind during forging design? Some of the points that should be followed while forging design are: > A radial flow of grains or fibers must be achieved in the forged components. > The forged items such as drop and press forgings should have a parting line that should divide the forging into two equal halves. > The ribs in a forging should not be high or thin. > In order to avoid increased die wear the pockets and recesses in forgings should be minimum. > In forgings the parting line of it should lie as far as possible in a single plane. > For ease of forging and easy removal of forgings the surfaces of the metal should contain sufficient drafts. ## Describe briefly the different cold drawing processes. Some of the important cold drawing processes are as follows: > Bar and Rod Drawing: In the case of bar drawing the hot drawn bars are at first pickled, washed and coated to prevent oxidation. Once this is done a draw bench is used for the process of cold drawing. In order to make an end possible to enter a drawing die the diameter of the rod is reduced by the swaging operation. This end is fastened by chains to the draw bench and the end is gripped by the jaws of the carriage. In this method a high surface finish and accuracy dimensionally is obtained. The products of this process can be used directly without any further machining. > Wire Drawing: Similar to the above process the bars are first pickled, washed and coated to prevent any oxidation. After this the rods are passed through several dies of decreasing diameter to provide a desired reduction in the size ( diameter ). The dies used for the reduction process is generally made up of carbide materials. >Tube Drawing: This type of drawing is very similar to the bar drawing process and in majority of cases it is accomplished by the use of a draw bench. ## What are the different theories of failure under static load, explain briefly? The main theories of failure of a member subjected to bi-axial stress are as follows: > Maximum principal stress theory ( Rankine’s theory): This theory states that failure occurs at a point in member where the maximum principal or normal stress in a bi-axial system reaches the maximum strength in a simple tension test. > Maximum shear stress theory ( Guest’s or Tresca’s theory): This theory states that failure occurs when the biaxial stress reaches a value equal to the shear stress at yield point in a simple tension test. > Maximum principal strain theory ( Saint Venant theory): This theory states that failure occurs when bi-axial stress reaches the limiting value of strain. > Maximum strain energy theory ( Haigh’s theory): This theory states that failure occurs when strain energy per unit volume of the stress system reaches the limiting strain energy point. > Maximum distortion energy theory ( Hencky and Von Mises theory): This theory states that failure occurs when strain energy per unit volume reaches the limiting distortion energy. Part 1   Part 2   Part 3   Part 4   Part 5   Part 6 (adsbygoogle = window.adsbygoogle || []).push({}); Write your comment - Share Knowledge and Experience Discussion Board https://shuffleos.com You can read and respond to posts using Google Groups or email, depending on how the group is set up. shuffleos.com 09-10-2020 03:48 PM Mechanical Eng For an experience guys job change make some time critical due to prolong non contact of engineering basic, such thing is easily shown here and well explained this help to brush up me for an Interview.I would like to take this Opportunity to Thanks you for acquiring such material and helping the needy Engineer over here. vijendra shrivastav 10-1-2019 04:33 AM Heat Treatment Thank you for Remembering the basic terms for my interview.It helped me a lot. Ramanandh.H 07-24-2019 01:35 AM interview questions Excellent efforts have been put to prepare the questions and answers which will be helpful to college freshouts and also candidates already in jobs to brushup their subjects.New areas like statutory environment requirement can be added SRINIVASAIAH 01-7-2019 07:03 AM quick caed chyaamfer 2mm, like deeeesh ABDUL CHYYAAAMFER 10-15-2018 12:40 AM questions during an interview Very useful questions.Thanks a lot. ABHIRAM CHANDRA 10-15-2018 12:32 AM Content related Some questions related to Equipments like measuring gage, pressure gauge, and others will definitely help to us. Kishan Rajbhar 07-17-2017 05:11 AM Mechanical interview This question is well define. More questions about mechanical aptitude is also ask in interview. So my humble request is that provide that type of questions and its answer. Hardik prajapati 06-7-2017 02:32 AM interview question all que nd ans are helpful but when i had gone to take interview for production .interviewer ask me question another types relete to our sub for ex what is mechanical engg,nd what is engg etc. HASMAT ALI 02-7-2017 12:37 PM PISTONS, RINGS, PINS Kindly provide some questions regarding Pistons in petrol and Deisel engine Dayashankar A S 12-20-2016 12:19 AM Knowledge Fits are very difficult to understand theoretically and if there will be practical examples also ,then it is very easy to understand Rohit 12-14-2016 02:17 AM Mechanical Engineering this answer is very nice. but write some engine related question. kumaresan.k 10-16-2016 05:38 AM mechanical engineering questions and answers for interview these question are very importantnice questions Chandra prakash 09-20-2016 12:56 PM Suggetion These questions are very helpful for revisen of topics when we have a distance with our subjects so I wanna suggest please mention some interview questions related to quality and producton . Navneet Upadhyay 09-4-2016 06:41 PM Heat treatment Types please add Quenching to heat treatment types.thanks for al information. Abdulelah 08-23-2016 06:09 AM Mechanical engineering I remember correctly what I learn Tq Jeevarathinam S 08-17-2016 07:09 AM job thank you for the basic information about this ritesh mahapatra 08-10-2016 04:19 AM mechanical spr... vengi 07-20-2016 02:22 AM mechaical engg. very nice thank you BESTON.J 06-23-2016 07:49 AM questions and answers Thank you so much the questions that i have read here together with the answers are familiar to wht i have been reading, and are helpful. Lungile Ntuli 06-17-2016 12:10 PM mech_information Thanks to the guys posted the information, its easy to understand things. subramani 06-10-2016 12:14 AM Interview quest(mech) Very useful Anupriya 05-2-2016 05:51 AM doubt ok this all questions and answers are very helpful me thank you and I won't more then abdul 04-29-2016 12:02 PM Great job These questions are very useful to me thanks.. Sai 02-23-2016 07:06 AM mech very good mech 01-19-2016 08:55 AM mechanical yes the questions are quite familiar for me,as i have already attended many interviews.but i just need a clarification that what design package i must learn because as of now iam in lot of confusion whether to take up CREO,UG OR HYPERMESH.IT might be of greater help vishwanath v 01-7-2016 08:42 AM mech. engg thank you...vry useful knowledge get in questions and thanx to supporting Rahul shankar pandit 12-22-2015 09:13 AM thank you you are doing good job.it is helpful to us. santhosh g 12-2-2015 11:49 AM engineer interview questions You r doing a good work for us thank u D.satya praveen 11-8-2015 10:39 AM mechanical engg. very nice questions nd good explainationssss...@@ Naveen 10-27-2015 05:13 PM Mechanical Engg. very nice thanx alot...... Dhiraj 10-12-2015 11:42 PM Heat treatment While defining Heat treatment, we cannot say for obtaining desired characteristics without changing composition. Because in case of case hardening, we are increasing the carbon potential at the surface to get hard case and soft core. Hence the Carbon composition is getting more upto total case depth. Y.D. LENKA 09-17-2015 06:10 AM Design Good Explanation.... Omshree Bagnawar 08-13-2015 03:30 AM mechanical It helps us very much fr interview ....thnx a lot basavaraj hallikhed 07-28-2015 05:40 AM thermodymanics very nice JALAKAM SHIVAJI 07-22-2015 09:04 AM machinal very nice Rakesh khoja 07-11-2015 03:36 AM related to download really nice . how can i download this. mahboob alam 06-22-2015 01:44 AM very nice good explanation haseeb 06-19-2015 02:33 AM about notes appreciable:....thnx for posting this..:) sumit bisht 06-7-2015 05:26 AM mechanical engg Very nice ; thanks alot...... jay prakash 05-30-2015 03:34 PM thanking... Thanx to the sapported & help guys good luck to my all engg,, frendsss anil patil mach,,engg 05-21-2015 04:47 AM Important for Mechanical engineering Students Very Nice Yogesh Ove 04-29-2015 01:49 PM status Very Nice Yogesh Ove 04-29-2015 01:47 PM med Good explanation Melaku Gedefaw 04-2-2015 04:19 AM improve our knowledge Like the questions Mohanraj 04-1-2015 12:57 PM mechanical engineering very usefull......... vikram 03-24-2015 07:56 PM thanking IT WAS very informative in revising the bookish as well as practical knowledge TANAY TRIVEDI 03-18-2015 06:02 AM questions related to mechanical engineering It's very good collection for us but I want. Something new. md sakjad alam 03-6-2015 12:16 PM mechanical engg I'm very happy for your support thank you so much Srinivasarao 03-1-2015 11:20 AM for an view it is for quick view for an interview. sai prasa 02-26-2015 11:54 PM mech. Engineer very usful collection thanks..... chandresh 02-21-2015 07:39 AM mech engineerining Cant get better solution to the quirious questionss...thanxx... provide us with more & more gistss time to time dipanjan deb 02-20-2015 10:22 PM interview question It is very useful and happy to boost knowledge again ...THANK YOU K.Ashik Hameed 02-20-2015 12:57 AM feeedback thanks your knowldge and very helpful for me Aravinth.M 02-19-2015 12:38 AM Mech. Engg. Very imp & helpful. Ashish M. Harinkhede 01-31-2015 04:23 PM mechanical engg Very helpful and appreciable....thnku. gaurav singh 01-16-2015 12:08 PM mechanical engg Very helpful and appreciable....thnku. gaurav singh 01-16-2015 12:08 PM mechanical engg Very helpful and appreciable....thnku. gaurav singh 01-16-2015 12:08 PM good questions Really good questions and answers But download option is not kisan vishnu kale 01-10-2015 07:06 AM AS A MECHANICAL ENGINEER IT IS MUST TO KNOW. REALLY APPRECIATION. NIBAS BEURA 12-20-2014 02:40 AM h Very Nice ishaq 11-16-2014 07:42 AM interview good questions ans explaination is clearly fine but download option is not MOTHILAL 11-5-2014 05:33 AM mech very good question collection........really helpful vikash 10-30-2014 05:24 AM good qustion good soumya parida 06-20-2014 12:33 AM   (adsbygoogle = window.adsbygoogle || []).push({}); (adsbygoogle = window.adsbygoogle || []).push({});

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