How to Calculate Blanking Force

Blanking force is a term used in the metalworking industry to describe the force required to punch or cut a piece of material (such as sheet metal) into a specific shape using a tool called a blanking die. The blanking force is the amount of force required to shear the material along the die's edges and form the desired shape. The amount of force required for blanking is determined by various parameters, including the material's thickness and hardness, the size and shape of the blanking die, and the type of press or machine employed. Blanking force must be calculated and controlled correctly to ensure the quality and accuracy of the finished product while also minimizing wear and tear on the equipment.

Blanking force refers to the force required to cut or punch a material during the blanking process. Blanking is a manufacturing process that involves removing flat pieces of material from a larger sheet or strip of material, usually metal. A variety of factors influence the blanking force, including the type and thickness of the material being cut, the size and shape of the blanking die, and the speed of the punching operation. The force required to cut a material during blanking is typically high, so it is critical to ensure that both the blanking machine and the material being cut can withstand the force without deformation or cracking.

Type of Blanking Force

There are generally two types of blanking force:

1. Punching force:  The force needed to punch a hole or shape out of a sheet of material with a punch and die. The punching force is determined by the thickness of the material, its hardness and strength, the dimensions of the punch and die, and the clearance between the punch and die.

2. Shearing force:   The amount of force required to cut a sheet of material in a straight line with a pair of cutting blades. The shearing force is determined by the thickness of the material, its hardness and strength, the blade clearance, and the sharpness of the blade.

Both types of blanking force can be affected by a number of variables, including the press's speed and stroke, the lubricant applied during cutting, and the ambient temperature and humidity. To guarantee consistent and precise cutting results and increase the tool's lifespan, it is essential to adjust the blanking force properly.

Method of Calculate Blanking Force

The general approach for computing blanking force may involve more complex calculations or adjustments for factors like as tool wear and tear, friction, and lubrication. The steps that follow provide a general method for estimating blanking force:

1. Determine the workpiece's material parameters, such as thickness, yield strength, and ultimate tensile strength.

2. Using the dimensions and shape of the punch and die, calculate the cutting area. This is the workpiece region that will be cut or punched out.

3. Using the ultimate tensile strength of the material, calculate its shear strength. Shear strength is typically approximately 0.7 times ultimate tensile strength.

How to Calculate Blanking Force

The calculation of blanking force depends on various factors such as the material properties of the workpiece, the dimensions and shape of the punch or die, and the design of the cutting process.

Here is a general formula for calculating the blanking force:

Blanking Force = Perimeter of the Cut × Plate Thickness × Shear Strength

F = Pl × t × St

Hole perimeter is depend on hole shape as like -

Hole perimeter _(Round) (PL) = π × d 

The method for estimating the perimeter of a shape relies on the shape in question. The perimeter of typical 2D shapes can be calculated using the following generic formulas:

The method for calculating the perimeter of a shape depends on the specific shape being considered. Here are some general formulas for calculating the perimeter of common 2D shapes:

·    1.  Rectangle:              Perimeter = 2(length + width)
2.  Square:                   Perimeter = 4 x side length
3.  Triangle:                 Perimeter = sum of all three sides
4.  Circle:                     Perimeter = 2 x pi x radius (where pi ≈ 3.14)
5.  Regular polygon:   Perimeter = number of sides x length of one side

The perimeter of an irregular shape can be computed by adding the lengths of all the sides or curves that make up the shape's boundaries.

A material's shear strength can be determined using several testing methods, such as torsion or shear testing. If you don't have access to testing equipment or data, you can estimate shear strength based on the ultimate tensile strength of the material (UTS). Following is a general formula for calculating shear strength:

Shear force = 0.7 x UTS

The figure 0.7 is a commonly used factor that describes the approximate ratio of many materials' shear strength to ultimate tensile strength. However, the real value may differ based on the material and its properties.

It is important to understand that this formula provides an estimate of the required blanking force, and the actual force required may vary based on the cutting process parameters. As a result, it is best to consult a tooling provider or conduct experiments to identify the best blanking force for a certain application.

Application of Blanking Die

        Blanking die has a wide range of applications in manufacturing and metalworking industries. Some of the common applications include:

1. Cutting and punching of sheet metal parts in the automotive, aerospace, and appliance industries.

2. Manufacturing of electronic components such as printed circuit boards and connections.

3. Production of metal packaging and containers such as cans and drums.

4. Production of precision parts for machinery and equipment.

5. The manufacture of consumer goods such as jewellery and watches.

6. Cutting and punching of gaskets, seals, and other industrial materials.

Major Factor of The Blanking Force Calculation

The shape of the blanking tool, including the punch and die, can influence the blanking force calculation. The following are some of the major tool shape factors that can be employed in blanking force calculations:

1. Cutting area:   The surface area of the tool that comes into contact with the workpiece during the cutting operation is referred to as the cutting area. It is normally determined using the punch and die's shape and size.

2. Clearance:   The gap between the punch and die during the cutting operation is referred to as clearance. It influences the amount of material sheared or punched, as well as the computation of blanking force.

3. Punch and die shape:   The punch and die shape defines the shape of the cut or punch in the workpiece. It can have an impact on the blanking force estimate, especially if the shape is complex or many punches are necessary.

4. Tool material attributes:   The punch and die's material properties, such as hardness and strength, can influence the amount of force required for cutting or punching. This can have an effect on the estimation of blanking force.