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Sheet Metal Design Interview Questions Part-2

This article covers commonly asked sheet metal design interview questions and answers. For design engineer position. Interviewer can ask questions on sheet metal design guidelines, materials, manufacturing  process and finish operations.

 We suggest you to read this article on sheetmetal design guidelines before reading these questions and answers. This article can help you in answering below interview questions

What is the difference between sheet metal blanking, punching & piercing operation?

Blanking is a process in which the punch operation removes a final product from a larger piece of sheet metal.

Punching is a material removal process in which the punch operation removes material from a final piece of sheet metal.

Piercing is process in which punch operation cuts a hole / material by tearing operation from a final piece of sheet metal. Piercing is a blanking operation

Check out in detail about the difference between blanking, punching and piercing here

What are the various steps to manufacture sheetmetal parts?

Following operations are performed during sheet metal part manufacturing:

Step-1 : Flat pattern calculations. Check sheet metal flat pattern calculator here.

Step-2 : CNC Punching Process Programming 

Step-3 : Cutting operations. It includes CNC Punching, laser or water cutting e.t.c

Step-4: Deburring

Step-5: Hardware assembly ( PEM Hardware, Weld Nut, Rivet hardware)

Step-6 : Press Bending

Step-7 :  Joining operations (welding/riveting)

Step-8 : Grinding 

Step-9 ; Finish operations such as anodizing, plating, powder coating

Step-10 : Packing

What are various sheet metal materials ?
  • CRCA
  • HRCA
  • Aluminium
  • Galvanised Iron (GI)
  • Stainless Steel

 Check out in detail about sheet metal materials here.

What is the difference between hot rolled & cold rolled steel sheets?

Hot rolling process involves steel rolling above re-crystallisation temp. During the cooling process steel will shrink. Therefore the size and shape of the steel will be less predictable.

Whereas cold rolling involves steel rolling below re-crystallisation temp (at room temp). 

Check out in detail the difference between hot and cold rolled steel

What are Sheet Metal Joining Operations ?

Sheet metal Joining Operations can be classified in two categories.

A) Permanent Joints:

  1. Welding
  2. Adhesive Bonding
  3. Riveting
  4. Clinching

B) Reusable Joints:

  1. Metric Screws
  2. Self Cutting Screws
  3. Sheet metal tabs
  4. Hemming
What are various sheetmetal cutting operations?
  1. Shearing
  2. Punching
  3. Blanking
  4. Nibbling
  5. Perforation
  6. Trimming
  7. Deburring
Why punching is preferred over laser cutting process?

Sheet metal forming operations such as extruded hole, lancing, cut and bend are not feasible with laser cutting.

What is  minimum possible hole diameter using sheet metal turret punching press?

Minimum diameter of hole that can be punched in sheet metal should be equal to sheet thickness. 

What are various press bending operations on sheet metal parts?
  • 90 degree bend
  • Z bend
  • Hem bend
  • Tab Bend
What are various welding operations done on sheet metal parts ?
  • TIG welding
  • MIG Welding
  • Gas Welding
  • Spot welding
  • Seam welding
What is Sheet metal gauge thickness?

Sheet Metal gauge represents standard sheet thickness for specified material. Different material with same gauge number has different sheet thickness. Gauges are defined based on material weight and rolling mills. Check out sheet metal gauge chart here.

What is neutral axis in sheet metal?

When metal is bent the top section is going to undergo compression and the bottom section will be stretched.  The line where the transition from compression to stretching occurs is called the neutral axis.

Check out in detail about neutral axis in sheet metal here.

Conclusion

To sum up, knowledge of sheetmetal design, materials, manufacturing and assembly process is required to  crack the interview. 

Got Question?  We will be happy to help.

If you think we missed Something?  You can add to this article by sending message in comment box. We will do our best to add it in this post.

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