Common Problems and Solutions in Sheet Metal Machining

Sheet metal is a comprehensive cold processing technology for sheet metal (usually less than 6mm) which includes cutting, stamping/cutting/compounding, folding, welding, riveting, assembly, and forming (such as body panels). Its notable characteristic is that the thickness of the same part is consistent. This is called sheet metal machining. Different industries refer to different sheet metal components, mainly used for assembly.

Sheet metal components have the characteristics of lightweight, high strength, electrical conductivity (suitable for electromagnetic shielding), low cost, and good performance in mass production. They are widely used in electronics, communications, automotive industries, medical devices, and other fields. For example, sheet metal components are essential parts in computer casings, mobile phones, and MP3 players. As the application of sheet metal components becomes more widespread, the design of sheet metal components has become an important part of the product development process. Mechanical engineers must master the design skills of sheet metal parts to ensure that the designed sheet metal not only meets the functional and aesthetic requirements of the product but also simplifies the manufacturing of the sheet metal stamping die and reduces costs.

Steps of Sheet Metal Processing:

Generally, the three important steps in sheet metal fabrication are CNC sheet metal cutting, stamping/cutting, and folding. Sheet metal is sometimes also referred to as "sheet metal." This term in English is derived from "sheet metal." In general, some metal sheets are pressed by hand or with the aid of molds to undergo plastic deformation to form the desired shape and size, while more complex parts can be formed through welding or a small amount of machining, such as chimneys, tin stoves, and commonly used automotive shells in households. Metal sheet processing is referred to as sheet metal fabrication. Specifically, for example, the production of chimneys, iron barrels, oil tanks, oil pots, ventilation ducts, different-sized end caps, circular positions, funnel shapes, etc., using sheet metal. The main processes involved are shearing, bending, flanging, forming by bending, welding, riveting, etc., which require a certain understanding of geometry.

Problems and Causes in Sheet Metal Fabrication and Stamping:

1. Burrs: Excessive material that is not completely removed during the stamping or cutting process results in burrs on the cross-section of the steel plate. When the burr height exceeds 0.2mm on the cross-section, the mold can be damaged, resulting in uneven surfaces.

2. Unevenness: Abnormal unevenness on the surface of the material, which is caused by the uncoiling line.

3. Roll marks: Caused by the presence of foreign objects (iron filings and dust) mixed in. Generally, the foreign objects on the paper roll marks can be removed.

4. Skidding: Skid marks appear when the rollers suddenly stop or accelerate. Crushed rollers may cause wrinkling at the edges: guide rollers on the uncoiling line may cause wrinkling due to the small gap between the guide rollers on the mold.

5. Skew: Skew during sheet metal fabrication refers to the incomplete alignment of the mold and the press, resulting in displacement of the stamped part in the vertical or horizontal direction. This may result in inaccuracies or incomplete forming of the part. To solve the skew problem, careful inspection and alignment of the position of the mold and the press are necessary.

6. Scratches: The main cause of part scratches is sharp scars on the mold or metal dust falling into the mold. Preventive measures include polishing the scars on the mold and removing metal dust.

7. Cracking at the bottom: The main reason for cracking at the bottom of the part is that the material has poor plasticity or the blankholder of the mold is pressed too tightly. The preventive measure is to replace the material with good plasticity or loosen the edge holder.

8. Wrinkling of the side wall: The main reason for the wrinkling of the side wall of the part is that the material thickness is not enough (if it is relatively small, the thickness is allowed to be thinner) or the eccentricity occurs during the installation of the upper and lower molds, resulting in a large gap on one side and a small gap on the other side. The preventive measure is to change the material immediately and readjust the mold.

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