Edge and Corner Processing: The treatment of edges and corners in bending. There are many methods, but there's not enough time to write about all of them. Corner rounding refers to overlapping two corners. Here's an image I found for you related to sheet metal processing:
Sheet metal, up to now, does not have a comprehensive definition. According to a definition from a professional journal abroad, sheet metal can be defined as a comprehensive cold working process for metal sheets (usually below 6mm), including shearing, punching/cutting/compound, bending, welding, riveting, joining, forming (such as automotive bodies), etc. Its notable characteristic is the consistent thickness of the same part.
In general, a sheet metal factory's basic equipment includes shearing machines, CNC punching machines/lasers, plasma, waterjet cutting machines, combination machines, bending machines, and various auxiliary equipment such as uncoilers, levelers, deburring machines, spot welders, etc.
Typically, the three most important steps in a sheet metal factory are shearing, punching/cutting, and bending.
The operation between departments in a sheet metal factory is not significantly different from that of a general manufacturing enterprise. Here, we will only introduce the manufacturing process of products in the workshop.
Usually, the three most important steps in a sheet metal factory are shearing, punching/cutting, and bending.
1.1 The first step is the blanking process (also known as material dropping). Typically, on-site workers will use shearing machines to cut suitable-sized parts from large sheets based on the unfolded drawings provided by the technical department. If using a punching machine, the dead zone of the clamp must be considered. After the blanking process, workers will mark the part numbers on the surface of each material with a marking pen.
Note: Some factories skip this step and directly lay out on standard sheets, followed by punching/cutting.
1.2 Then the material will be sent to a CNC punching/cutting machine for punching/cutting operations. In this process, NC (Numerical Control) codes need to be generated for the processed parts. Nowadays, most machine tool manufacturers provide automatic programming software (domestic manufacturers mostly cooperate with foreign software companies for OEM sales since they don't have their own software development team), which greatly facilitates programming engineers. Factors that punching/cutting programming engineers need to consider include material utilization, tooling, efficiency, accuracy, etc. After punching/cutting, the parts are separated from the micro-connections and then sent to the bending machine for bending.
1.3 In the bending process, the main considerations are tool selection, bending sequence, bending compensation, bending interference, etc. Bending programming software is also available for sale, but most domestic CNC bending machines still rely on manual programming, often relying heavily on the experience of skilled workers. On the other hand, there is still some distance between domestic manufacturing processes and international standards, so the efficiency has not improved, and the performance of CNC bending machines has not been fully utilized.
1.4 Finally, depending on the product requirements, additional processes such as welding, grinding, painting, assembly, packaging, etc., may be required, which will not be described in detail here.
1. Increased demand for production capacity: The demand for metal processing capabilities continues to grow, and electrical control boxes and machine enclosures in the metal processing industry are generally sheet metal parts. Therefore, the demand for sheet metal processing capabilities is also increasing.
2. Low precision requirements and easy to start: In terms of metal processing, precision within a few thousandths of an inch is common, and the processes can be quite complex, with some parts requiring dozens of steps. Therefore, metal processing companies typically need a variety of machinery and equipment to meet different process requirements. On the other hand, sheet metal punching accuracy is generally around ±0.25mm, and bending accuracy can generally reach ±0.5mm, which is much lower compared to metal processing.
3. High profitability: Stamping can generally achieve a profit margin of around 30%, while laser cutting can reach 50% or even more.
For thin sheets, simple cutting can be done with shearing machines, while complex or large-scale production cutting can be done with punching machines. Thick sheets can be cut using CNC cutting machines.
In situations where precision requirements are not high, shearing machines are sufficient. For high precision requirements, plasma cutting machines or laser cutting machines are used.
In industrial mass production, steel coils are usually purchased, and a production line for cutting and punching is established. An automatic uncoiler is used to uncoil the steel coils, and a fast shearing machine is used to cut rectangular or trapezoidal materials. To improve material utilization, an arc cutting machine can be used to cut arc-shaped materials. For medium-scale production, rectangular materials can be directly ordered from steel mills. Laser/plasma cutting is only used for trial production (due to high costs and low productivity), and waterjet cutting is used for cutting certain special materials that are not hot-rolled or cold-rolled, with low productivity as well.
