Sheet metal is a comprehensive cold working process used for sheet metal (typically less than 6mm) that involves a series of operations including shearing, punching/cutting/compositing, folding, riveting, welding, plastic spraying, foaming, and assembly to meet the needs of users.
It is widely known that optimizing the process can not only control processing costs and improve the profit margin of products, but also save costs for customers. Broadly speaking, process optimization is an important means of promoting technological progress in the industry.
However, optimizing the process is not a small challenge and is a test for every sheet metal expert. In fact, it is not easy for enterprises to do so.
Bending process improvement cases
Bending is the process of altering the angle of plates or sheets, including bending them into V-shape or U-shape.
It is a crucial step in sheet metal processing, and a well-executed bending process can ensure the accuracy and surface quality of the product while allowing for efficient flow into subsequent processes. This, in turn, facilitates the quick and effective operation of the production line.
“Square to Round” (Fig. 1) is a classic workpiece in sheet metal processing that has been widely adopted. However, traditional manufacturing methods typically involve multiple bending or butt welding, both of which yield suboptimal results.
Fig. 1 “Square to Round” workpiece
Adopting the method of multiple bending may lead to unqualified appearance and low efficiency of the product due to the inaccurate positioning of bending. Similarly, butt welding may not meet the standard product size due to the inability of accurate positioning.
To address these problems caused by a high volume of orders, our company has decided to use a special bending die for bending. After communication with the supplier, we have purchased a set of special dies specifically designed for “Square to Round” production. These dies can be formed at one time through four knife bending, and the final product quality meets the customer’s requirements.
Considering the difficulty in ensuring product forming quality with ordinary bending dies for other large batches, our company will actively use special bending dies for production while comprehensively considering the die cost. This approach not only ensures product quality but also promotes the reduction of production costs.
Welding process improvement cases
Welding plays a vital role in the sheet metal process as it connects various parts together. It is particularly crucial for workpieces that cannot be processed through bending or stamping and can only be accomplished via welding.
However, the welding process can also lead to several issues such as bubbles, weld beading, shrinkage cavities, cracks, incomplete penetration, weld black ash, and severe oxidation in the welded joints.
A well-executed welding process can make a significant difference in the outcome. For instance, consider the example of a dishwasher (Fig. 2). The plates utilized in this product are usually 0.8mm thick stainless steel plates that can easily deform during welding due to their thinness.
Fig. 2 Dishwasher
In order for the dishwasher to maintain waterproofing under certain water pressure, a full welding process is required. However, full welding can often lead to deformation which deviates from the desired product requirements of a flat surface and a beautiful appearance.
To protect the appearance of the product, all wire drawing plates used in this product must have the protective film with a width of about 20mm around the weld removed prior to welding. After welding, all protective film of the wire drawing plate must be removed to ensure a beautiful external surface.
To control welding deformation, the corners of the product should be fixed symmetrically and small current pull welding and full welding should be used on the periphery.
Spot welding should be used on the inner side, and the welding current of the argon arc welding machine should be constantly adjusted until the welding parameters meet the customer’s needs. This not only solves the problem of welding deformation but also ensures a flat, firm, and beautiful welding appearance.
Welding and post-treatment cases
Later processes such as spraying, assembly, and packaging have a significant impact on product quality.
Common problems that arise include metal spraying, surface rating of paint coating not meeting the required standards, inadequate protection grade, and overall corrosion rating falling short of the required level.
If these problems are not effectively addressed, they can pose major hidden dangers to product quality. This can severely impact the company’s reputation and result in incalculable losses to customers.
To illustrate, consider the example of our company’s photovoltaic combiner box (Figure 3). The product must meet the IP67 standard, which entails complete prevention of the intrusion of foreign objects and dust.
Fig. 3 Combiner box
To prevent the negative effects of immersion for up to 30 minutes in water at depths of up to 1m, effective control of product flatness within 0.5mm is necessary during the welding process.
Our company has successfully tackled the issue of flatness by continuously adjusting the welding current.
Furthermore, our products meet the C5 standard for anti-corrosion ability. To achieve this, we use methods such as spraying, electroplating, hot plating, and others to create a protective layer on the product surface, enhancing its anti-corrosion properties.
The entire sheet metal processing process has a significant impact on product quality, service life, and aesthetics. Therefore, continuous optimization of the existing process is necessary to improve the manufacturing level of the enterprise.
After years of technical accumulation and progress, our company has developed a set of process standards and optimization systems tailored to our own development.
Conclusion
As the sheet metal industry continues to expand and manufacturing standards improve, the level of sheet metal processing technology required is becoming increasingly higher.
Currently, there remains a gap between traditional sheet metal processing technology and the actual needs of the industry. This necessitates continuous improvement of the sheet metal process, and optimizing it will further promote the development of the sheet metal industry.
