Designing Non-Standard Sheet Metal Products: 5 Key Principles

Generally, sheet metal is a term used to describe materials that have a uniform thickness.

Commonly used sheet metal materials include stainless steel, galvanized steel, copper, aluminum, and iron.

Let’s examine the fundamental design principles for sheet metal products.

Principle 1: select appropriate sheet metal thickness

The thickness of sheet metal parts can vary from 0.03 mm to 4.00 mm. However, it is important to note that as the thickness increases, processing becomes more challenging and the likelihood of defects also rises.

The appropriate thickness should be selected based on the functional requirements of the product.

In general, thinner sheet metal is preferable as long as it still meets the strength and stiffness requirements.

For most products, the thickness of sheet metal parts is kept below 1.00 mm, and the thickness of industrial sheet metal products is typically between 1.0 and 2.0 mm.

Principle 2: the design of sheet metal parts should be oriented to sheet metal technology

The design of a part must align with the processing technology, as products that are not compatible with the technology cannot be manufactured.

Sheet metal processability refers to the level of difficulty in performing processes such as blanking and bending.

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The fundamental methods of sheet metal processing include: blanking, bending, stretching, and forming.

Principle 3: the shape of blanking parts should be as simple as possible to avoid slender cantilever and slot

As a general rule, the depth and width of any convex or concave part in a blanking piece should be greater than 1.5/t (where t represents the plate thickness), and narrow and long cuts or narrow grooves should be avoided in order to enhance the strength of the corresponding part of the die, as illustrated in the following figure.

increase the edge strength of the corresponding part of the die

Principle 4: the shape and inner hole design of blanking parts should avoid sharp corners

The sharp corners on a sheet metal blanking part can have a significant impact on the lifespan of the die. When designing the product, it is important to pay attention to the transition at the corner connection, with a radius of R ≥ 0.5T (where T is the plate thickness), as demonstrated in the following figure.

the transition at the corner connection

Principle 5: Determination of minimum bending radius

When a material is bent, the outer layer is subjected to stretching and the inner layer is compressed in the fillet area.

When the material thickness is constant, the smaller the inner fillet, the more severe the tensile and compressive stress on the material.

If the tensile stress on the outer fillet exceeds the material’s ultimate strength, cracks and fractures will occur.

If the bending radius is too large, it can result in material rebound, which can negatively impact the accuracy and shape of the product.

Common material bending radius values can be found in the following table for reference.

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Materials Min Bending Radius bending radius values of common materials
GI, CR sheet R≥2.0t
MS, brass plate R≥1.0t
SS. R≥1.5t
Aluminum plate R≥1.2t

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