Important Questions and Answers: Sheet Metal Process

SHEET METAL PROCESS

1        What is punching operation ?

Ans : It is the cutting operation with the help of which various shaped holes are produced in the sheet metal. It is similar to blanking; only the main difference is that, the hole is the desired product and the material punched out to form a hole is considered as a waste.

2        What is super plastic forming operation ?

Ans: Superplastic forming is a metalworking process for forming sheet metal. It works upon the theory of superplasticity, which means that a material can elongate beyond 100% of its original size.

3        What is press brake?

Ans: Press brake (bending brake) is an open frame press used for bending, cutting and forming. Generally, it handless long workpieces in the form of strips. Usually press brake have long dies and suitable and suitable for making long straight line bends.

4        Define hydro forming process.

Ans : Hydro forming is a process which can be carried out in two ways:

1)               Hydro - mechanical forming

2) Electro - hydraulic forming Hydro - mechanical forming: In this method , the blank is placed over the punch whose shape is similar to inner of the find workpiece.

Electro - hydraulic forming : This method involves the conversion of electrical energy into mechanical energy in a liquid medium. Electric spark in a liquid produces shock waves and pressures which can be used for metal forming.

5                     Give the difference between punching and blanking.

Ans:

Blanking : It is the cutting operation of a flat metal sheet. The article punched out is known as blank. Blank is the required product of the operation and the metal left behind is considered as a waste.

Punching: It is similliar to blanking; only the main difference is that, the hole is the desired product and the material punched out to form a hole is considered as a waste.

6                     How is hydro forming is similar to rubber forming ?

Ans : In both the sheet metal working processes sheet metal is pressed between a die and rubber block. Under pressure, the rubber and sheet metal are driven into the die and confirm to its shape by

forming the part.

7        What do you mean by minimum bend radius?

Ans: It is the radius of curvature on inside surface of the bend. If the bend radius is too small, then cracking of a material on the outer tensile surface takes place. To prevent any damage to punch and die, the bend radius should not be less than 0.8mm.

8        Define limiting drawing ratio.

Ans : It is the ratio of finished shell diameter (d) to the radius of bottom corner(r).

9        Define Embossing.

Ans : With the help of this operation, specific shapes or figures are produced on the sheet metal.

It is used for decorative purpose or giving details like names, trade marks, specifications, etc. On the sheet metal.

10. What are the factors affecting shearing operation?

Shape and material of punch

Die,speedof punching,lubrication

Clearance between punch & die.

11. Define Blanking.

A finite shape of sheet metal is removed and blocked by shearing the entire contour using a die and a punch. The portion removed, which is the required part is called as blank and the operation is called as blanking.

12.What is meant by Dimpling.

irst hole is punched and then it is expanded into a flange. flange may be produced by piercing with a sharp punch when ther bend angle is less than90⁰, as n fittings with conical ends.this process is also called as

FLAIRING.

13.Define Notching.

It refers to the removing pieces from the edge. In this process, the metal is removed from the side (or) edge of a sheet to get the desired shape.

14.define Stretch forming.

The sheet metal is placed under a tensile load over a forming block and stretching it beyond its elastic limit and to the plastic range, thus cause permanent set to take place.this process is useful in making prototype models of aircraft and automotive parts.

15.Define Wrinkling

It is caused by compressive stresses in the plane of the sheet . It can be objectionable or can be useful in imparting stiffness to parts. It can be controlled by proper tool and die design.