Workpiece Cutting
After receiving the drawings, different cutting methods are chosen based on the unfolding diagram and batch requirements. These methods include laser cutting, CNC punching, shearing, and mold cutting. The corresponding unfolding is made according to the drawings. CNC punching is affected by the tool and may result in significant burrs on the edges when processing irregular shapes and irregular holes. Post-processing is required to remove the burrs, which also affects the accuracy of the workpiece. Laser cutting, on the other hand, has no tool restrictions, produces smooth sections, and is suitable for processing irregular shapes. However, it is time-consuming when processing small workpieces. Placing a workbench next to the CNC and laser machines facilitates the placement of sheet metal for processing, reducing the workload of lifting the sheets. Some usable leftover materials are placed in designated locations to provide material for trial bending.
After the workpiece cutting, necessary adjustments such as deburring, chamfering, and smoothing of contact points are performed. Flat files are used to adjust the contact points at the tool interface, while grinding machines are used for workpieces with significant burrs. Small internal hole contact points are adjusted with corresponding small files to ensure a pleasing appearance. The shaping of the outer surface also guarantees consistent positioning during bending, ensuring the dimensional consistency of batch products.
Next Process
After the cutting process is completed, the workpieces move on to the next process, where different workpieces enter corresponding procedures based on processing requirements. These procedures include bending, riveting, flanging, tapping, spot welding, convex package forming, and segmental differences. In some cases, nuts or bolts need to be tightened after one or two bending processes. It is important to consider processing convex package forming and segmental differences with molds first to avoid interference with subsequent processes that could prevent the required processing. When there are hooks on the upper cover or lower shell, pre-processing should be done before bending to prevent interference with welding after bending.
During bending, the selection of tools and slots is determined based on the dimensions and material thickness specified in the drawings, avoiding collisions between the product and the tool that could cause deformation. The selection of the upper die is crucial (different models of upper dies may be used for the same product), while the selection of the lower die depends on the thickness of the sheet metal. The bending sequence is then determined, typically starting with internal bends before external bends, smaller bends before larger ones, and special bends before regular ones. For workpieces that require edge flattening, the workpiece is first bent to 30°-40° and then flattened using a flattening die.
During riveting, the selection of molds depends on the height of the bolts. The pressure of the riveting machine is adjusted to ensure that the bolts and the surface of the workpiece are flush, avoiding insufficient or excessive pressure that could result in the rejection of the workpiece.
Welding methods include argon arc welding, spot welding, CO2 shielding welding, and manual arc welding. For spot welding, the welding positions on the workpiece are carefully considered. In batch production, positioning fixtures are used to ensure accurate spot welding.
To ensure a strong weld, convex points are created on the workpiece to ensure uniform contact with the flat plate before electric welding, heating each point consistently. This also helps determine the welding position. Proper adjustment of pre-press time, holding time, maintenance time, and rest time is necessary to ensure a secure spot weld.
Post-Spot Welding, welding scars may appear on the surface of the workpiece, which need to be treated with a flat grinding machine. Sub-arc welding is mainly used when connecting two large workpieces or when handling the edges and corners of a single workpiece to achieve a smooth and polished surface. The heat generated during argon arc welding can easily cause workpiece deformation. Therefore, after welding, grinding machines and flat grinding machines are used for post-treatment, especially for edges and corners with more imperfections.
Surface Treatment
After bending, riveting, and other processes, surface treatment is carried out on the workpieces. Different surface treatment methods are used for different types of sheet metal. After cold plate processing, surface electroplating is generally performed. After electroplating, no spray treatment is applied; instead, phosphating treatment is conducted, followed by spray coating. For electroplated sheet metal, the surface is cleaned and degreased before spray coating. Stainless steel plates (mirror panels, matte panels, brushed panels) undergo brushing treatment before bending and do not require spray coating. If spray coating is necessary, a matte finish is applied. Aluminum plates are generally subjected to oxidation treatment, and the choice of oxidation base color depends on the desired spray coating color.
Surface pretreatment is performed to ensure a clean surface, significantly improve the adhesion of the coating, and enhance corrosion resistance. The cleaning process involves first washing the workpieces by hanging them on a production line. They pass through a cleaning solution (alloy degreaser) and then enter a water rinse. Next, they go through a spray zone and a drying zone before being taken off the production line.
Spray Coating
After surface pretreatment, the workpieces enter the spray coating process. When spray coating is required after assembly, threads or certain conductive holes need to be protected. For threaded holes, soft rubber rods or screws can be inserted, and high-temperature adhesive tape is used to protect holes that require conductivity. In the case of large-volume production, protective fixtures are used for positioning to prevent overspray inside the workpieces. For visible nut (flanging) holes on the outer surface of the workpiece, screws are used for protection to avoid the need for re-threading after spray coating.
Some large-volume workpieces also require the use of protective fixtures. When the workpiece is not assembled for spray coating, areas that do not require coating are covered with high-temperature adhesive tape and paper, and exposed nut holes are protected with screws or high-temperature rubber. If both sides of the workpiece need to be spray-coated, the same method is used to protect nut (bolt) holes. Small workpieces are bundled together with lead wires or paper clips before spray coating. Some workpieces require high surface quality and need to be scraped before spray coating. Special high-temperature adhesive stickers are used to protect grounding symbols on certain workpieces.
During the spray coating process, the workpieces are hung on a production line, and compressed air is used to blow off any dust particles on the surface. They then enter the spray zone for coating. After spraying, they move along the production line to the drying zone and are finally taken off the line as completed spray-coated workpieces.
There are two types of spray coating: manual and automatic, each requiring different fixtures.
Assembly Process
After spray coating, the workpieces enter the assembly process. Before assembly, the protective stickers used during the coating process are removed, and it is ensured that no paint or powder has entered the threaded holes. Throughout the process, gloves are worn to prevent dust from the hands from adhering to the workpieces. Some workpieces may also require cleaning with compressed air.
Packaging Stage
After assembly, the workpieces are ready for packaging. They are inspected and then placed in specialized packaging bags for protection. Workpieces without specialized packaging are wrapped in bubble wrap or similar materials. Before packaging, the bubble wrap is cut to the appropriate size to avoid delays in the packaging process. For large-volume production, custom-made cardboard boxes, bubble bags, foam pads, trays, or wooden crates are used. Once packaged, the workpieces are placed in cardboard boxes, and the corresponding finished or semi-finished product labels are affixed to the boxes.
After receiving the drawings, different cutting methods are chosen based on the unfolding diagram and batch requirements. These methods include laser cutting, CNC punching, shearing, and mold cutting. The corresponding unfolding is made according to the drawings. CNC punching is affected by the tool and may result in significant burrs on the edges when processing irregular shapes and irregular holes. Post-processing is required to remove the burrs, which also affects the accuracy of the workpiece. Laser cutting, on the other hand, has no tool restrictions, produces smooth sections, and is suitable for processing irregular shapes. However, it is time-consuming when processing small workpieces. Placing a workbench next to the CNC and laser machines facilitates the placement of sheet metal for processing, reducing the workload of lifting the sheets. Some usable leftover materials are placed in designated locations to provide material for trial bending.
After the workpiece cutting, necessary adjustments such as deburring, chamfering, and smoothing of contact points are performed. Flat files are used to adjust the contact points at the tool interface, while grinding machines are used for workpieces with significant burrs. Small internal hole contact points are adjusted with corresponding small files to ensure a pleasing appearance. The shaping of the outer surface also guarantees consistent positioning during bending, ensuring the dimensional consistency of batch products.
Next Process
After the cutting process is completed, the workpieces move on to the next process, where different workpieces enter corresponding procedures based on processing requirements. These procedures include bending, riveting, flanging, tapping, spot welding, convex package forming, and segmental differences. In some cases, nuts or bolts need to be tightened after one or two bending processes. It is important to consider processing convex package forming and segmental differences with molds first to avoid interference with subsequent processes that could prevent the required processing. When there are hooks on the upper cover or lower shell, pre-processing should be done before bending to prevent interference with welding after bending.
During bending, the selection of tools and slots is determined based on the dimensions and material thickness specified in the drawings, avoiding collisions between the product and the tool that could cause deformation. The selection of the upper die is crucial (different models of upper dies may be used for the same product), while the selection of the lower die depends on the thickness of the sheet metal. The bending sequence is then determined, typically starting with internal bends before external bends, smaller bends before larger ones, and special bends before regular ones. For workpieces that require edge flattening, the workpiece is first bent to 30°-40° and then flattened using a flattening die.
During riveting, the selection of molds depends on the height of the bolts. The pressure of the riveting machine is adjusted to ensure that the bolts and the surface of the workpiece are flush, avoiding insufficient or excessive pressure that could result in the rejection of the workpiece.
Welding methods include argon arc welding, spot welding, CO2 shielding welding, and manual arc welding. For spot welding, the welding positions on the workpiece are carefully considered. In batch production, positioning fixtures are used to ensure accurate spot welding.
To ensure a strong weld, convex points are created on the workpiece to ensure uniform contact with the flat plate before electric welding, heating each point consistently. This also helps determine the welding position. Proper adjustment of pre-press time, holding time, maintenance time, and rest time is necessary to ensure a secure spot weld.
Post-Spot Welding, welding scars may appear on the surface of the workpiece, which need to be treated with a flat grinding machine. Sub-arc welding is mainly used when connecting two large workpieces or when handling the edges and corners of a single workpiece to achieve a smooth and polished surface. The heat generated during argon arc welding can easily cause workpiece deformation. Therefore, after welding, grinding machines and flat grinding machines are used for post-treatment, especially for edges and corners with more imperfections.
Surface Treatment
After bending, riveting, and other processes, surface treatment is carried out on the workpieces. Different surface treatment methods are used for different types of sheet metal. After cold plate processing, surface electroplating is generally performed. After electroplating, no spray treatment is applied; instead, phosphating treatment is conducted, followed by spray coating. For electroplated sheet metal, the surface is cleaned and degreased before spray coating. Stainless steel plates (mirror panels, matte panels, brushed panels) undergo brushing treatment before bending and do not require spray coating. If spray coating is necessary, a matte finish is applied. Aluminum plates are generally subjected to oxidation treatment, and the choice of oxidation base color depends on the desired spray coating color.
Surface pretreatment is performed to ensure a clean surface, significantly improve the adhesion of the coating, and enhance corrosion resistance. The cleaning process involves first washing the workpieces by hanging them on a production line. They pass through a cleaning solution (alloy degreaser) and then enter a water rinse. Next, they go through a spray zone and a drying zone before being taken off the production line.
Spray Coating
After surface pretreatment, the workpieces enter the spray coating process. When spray coating is required after assembly, threads or certain conductive holes need to be protected. For threaded holes, soft rubber rods or screws can be inserted, and high-temperature adhesive tape is used to protect holes that require conductivity. In the case of large-volume production, protective fixtures are used for positioning to prevent overspray inside the workpieces. For visible nut (flanging) holes on the outer surface of the workpiece, screws are used for protection to avoid the need for re-threading after spray coating.
Some large-volume workpieces also require the use of protective fixtures. When the workpiece is not assembled for spray coating, areas that do not require coating are covered with high-temperature adhesive tape and paper, and exposed nut holes are protected with screws or high-temperature rubber. If both sides of the workpiece need to be spray-coated, the same method is used to protect nut (bolt) holes. Small workpieces are bundled together with lead wires or paper clips before spray coating. Some workpieces require high surface quality and need to be scraped before spray coating. Special high-temperature adhesive stickers are used to protect grounding symbols on certain workpieces.
During the spray coating process, the workpieces are hung on a production line, and compressed air is used to blow off any dust particles on the surface. They then enter the spray zone for coating. After spraying, they move along the production line to the drying zone and are finally taken off the line as completed spray-coated workpieces.
There are two types of spray coating: manual and automatic, each requiring different fixtures.
Assembly Process
After spray coating, the workpieces enter the assembly process. Before assembly, the protective stickers used during the coating process are removed, and it is ensured that no paint or powder has entered the threaded holes. Throughout the process, gloves are worn to prevent dust from the hands from adhering to the workpieces. Some workpieces may also require cleaning with compressed air.
Packaging Stage
After assembly, the workpieces are ready for packaging. They are inspected and then placed in specialized packaging bags for protection. Workpieces without specialized packaging are wrapped in bubble wrap or similar materials. Before packaging, the bubble wrap is cut to the appropriate size to avoid delays in the packaging process. For large-volume production, custom-made cardboard boxes, bubble bags, foam pads, trays, or wooden crates are used. Once packaged, the workpieces are placed in cardboard boxes, and the corresponding finished or semi-finished product labels are affixed to the boxes.
