Force and Work done in Punching and Blanking

Q. $10$ mm diameter holes are to be punched in a steel sheet of $3$ mm thickness. Shear strength of the material is $400$ $N/m{m}^2$ and penetration is $40$%. Shear provided on the punch is $2$ mm. The blanking force during the operation will be

1. $22.6$ kN
2. $37.7$ kN
3. $61.6$ kN
4. $94.3$ kN

Q. Determine the load required to punch a $20mm$ diameter hole in a $2mm$ thick sheet. The properties of the material of the sheet are:
Tensile strength $-580MPa$
Yield strength in tension $-410MPa$
Shear strength $-350MPa$
Yield strength in shear $-250MPa$
The load is $kN$ is

1. $31.40$
2. $43.98$
3. $64.40$
4. $91.10$

Q. The shear strength of a sheet metal is $300$ MPa. The blanking force required to produce a blank of $100$ mm diameter from a $1.5$ mm thick sheet is close to

1. $45$ kN
2. $70$ kN
3. $141$ kN
4. $3500$ kN

Q. Circular blanks of $10$ mm diameter are punched from an aluminium sheet of $2$ mm thickness. The shear strength of aluminum is $80$ MPa. The minimum punching force required in kN is

1. $2.57$
   
2. $3.29$
3. $5.03$
4. $6.33$

Q. A hole of 50 mm diameter is to be punched on a 2 mm thick sheet. The shear stress for the material can be taken as 3.1 $kN/m{m}^2$. Assuming gradual variation of load with punch travel and penetration to thickness ratio = 0.5, the energy required to punch the hole is

1. 973.89 J
2. 1216.21 J
3. 1947.78 J
4. 2609.76 J

Q. A rectangular hole of size $100$ mm $timses$ $50$ mm is to be made on a $5$ mm thick sheet of steel having ultimate tensile strength and shear strength of $500$ Mpa and $300$ MPa, respectively. The hole is made by a punching process. Neglecting the effect of clearance, the punching force (in kN) is

1. $300$
2. $450$
3. $600$
4. $750$

Q. A $\varphi 25mm$ hole is pierced in a $t=2.5mm$ thick steel sheet having shear strength $\tau =350MPa$. If the diametral clearance is given by the expression $c=0.0064\sqrt{\tau }$, the die diameter (in $mm$), punch diameter (in $mm$) and punch force in $\left(kN\right)$ respectively are

1. $25.0,25.3,171.8$
2. $25.0,24.7,68.75$
3. $24.7,25.0,171.8$
4. $25.3,25.0,68.75$

Q. For $50\%$ penetration of work material, a punch with single shear equal to thickness will

1. reduce the punch load to half the value
2. increase the punch load by half the value
3. maintain the same punch load
4. reduce the punch load to quarter load

Q. In a blanking operation to produce steel washers, the maximum punch load used is $3\times {10}^{5}N$. The plate thickness is 5 mm and percentage penetration is 25. What is the work done during this shearing operation?

1. 325 J
2. 475 J
3. 375 J
4. 350 J

Q. A hydraulic press is used to produce circular blanks of $100mm$ diameter from a sheet o $2mm$ thickness. If the shear strength of the sheet material is $400N/m{m}^2$, the force required for producing a circular blank is

1. $8kN$
2. $25.13kN$
3. $31.42kN$
4. $125.66kN$

Q. The punching force required in a blanking operation of mild steel sheet is 500 kN. The diameter of blank is increased by 20% and thickness is reduced by 4%, then punching force will be:

1. 434 kN
2. 576 kN
3. 634 kN
4. 676 kN

Q. The punching force required in a blanking operation of mild steel sheet is 500 kN. The diameter of blank is increased by 20% and thickness is reduced by 4%, then punching force will be:

1. 434 kN
2. 576 kN
3. 634 kN
4. 676 kN