Three influences of sheet thickness on punching process

There are many factors that affect the punching process of the punching machine. Today we will focus on the thickness of the sheet. The thickness of the sheet is relative. Generally, we call the sheet material below 4mm thin sheet, and we name the sheet above 4mm thick sheet.

The influence of sheet thickness on the blanking process is manifested in the following aspects:

(1) The thickness of the sheet material directly affects the reasonable gap of the die.

The thicker the sheet is, the larger the reasonable gap of the die will be. The thinner the sheet is, the smaller the die gap is required. The small required clearance will bring a series of problems, such as changes in die accuracy. For medium hardness steel with a sheet thickness of 0.2mm, the required reasonable clearance is 0.012-0.016mm (double-sided clearance).

（2）The thickness of the sheet metal has a positive relationship with the punching pressure

Such a positive relationship has brought a series of specific problems to actual production.

When punching thin sheets, the punching resistance is less than or equal to the nominal pressure of the punch. While punching thick materials, the situation is just the opposite.

If the operator punches small holes in a thick sheet with a general structure, the punch is easy to break. It is necessary to adopt a punch with the characteristics to solve the punch breakage: the punch is placed between the guide sleeves with great strength and rigidity so that the punch is protected. This brings difficulties to die manufacturing.

(3) The thickness of the sheet material affects the accuracy of the blanking parts. The elastic rebound of blanking parts is larger for thin materials than thick ones

Due to the large elastic rebound of the thin-material blanking parts, its accuracy is reduced; however, due to the small blanking gap of the thin-material blanking parts, the cross-section of the blanking parts is relatively perpendicular to the surface. The elastic rebound of the thick material blanking parts is small, but due to the large gap of the thick material blanking, the section of the blanking parts is not only rough but also has an obvious slope.

Based on the above influence, the conclusion is that the dimensional accuracy of blanking parts decreases with the increase of sheet thickness.

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