Metal stamping is a process that converts flat metal sheets into specific designs and shapes. Unlike machining, 3D printing, or manual fabrication, stamping transforms raw sheet metal into mission-critical parts with unmatched speed, consistency, and economy. For OEMs across automotive, aerospace, electronics, and medical sectors, the choice isn't just about manufacturing – it's about securing sustainable competitive advantage.
The biggest reason is Cost Efficiency-the yield rate.
In the metallurgical industry, the yield rate is the most significant factor influencing its cost, accounting for approximately 85% to 90% of the production cost. For automobile manufacturing, the body-in-white is an important component of the entire vehicle, accounting for 15% to 20% of the total vehicle cost. Moreover, the weight of stamping parts in the total weight of the body-in-white accounts for over 90%. It is evident that reducing the development cost of stamping parts for the body-in-white is of great significance for lowering the overall vehicle development cost. Among the components of the cost of stamping parts, the cost of stamping materials accounts for the largest proportion, approximately 70%. Therefore, improving the utilization rate of stamping materials (yield rate) is an important way to reduce the development cost of body-in-white. According to estimates, for every 1% increase in the yield rate of stamping aluminum alloy from coil to sheet, the cost per vehicle can be reduced by 105 RMB (calculated based on a 350kg all-aluminum body). The improvement in the yield rate of coil not only enhances economic benefits but also affects the production process of the stamping development line and the stamping production line. A concentrated manifestation of quality control and optimization of management level.
The main factors affecting the yield of rolled plates
- Process fixed loss
It mainly includes: Poor removal of the coil head and tail. Due to the fact that the alloy is transported over long distances in coil form to the uncoiling and blanking line after the rolling process, the outer circle of the coil head directly contacts the outer packaging, gets entangled or is damaged during transportation, which damages the cleanliness, appearance quality, oil film, etc. of the strip, thus affecting its use. The inner part of the roll tail cannot be used due to the silver mark of the material factory's curling, the core shaft mark of the unwound line, transportation damage, cleanliness and tension issues, etc. The commonly used standard for the cutting of the head and tail of a coil in the industry is "three on the outside and five on the inside". Taking the side-walled 6-series alloy as an example, if the coil width is 1740mm, the thickness is 0.9mm, and the standard weight of the coil is 11t, then according to the standard of three on the outside and five on the inside, a length of 30 meters needs to be cut, which affects the yield of a single coil by approximately 1.13%
Fluctuation in roll width tolerance: The delivery of strip materials is based on the given dimensional tolerance standards. For instance, for roll widths less than 2000mm with a tolerance of (0, +3), the actual amount of sheet metal that can be sheared under the same roll weight conditions varies when delivered according to the lower and upper limits of the tolerance.
Process quality inspection scrapping: Process quality inspection includes the mechanical property inspection of coil plates and the quantity of process spot checks carried out in accordance with CP. The mechanical property test of the original coil is conducted by taking samples from the material head shear before leveling, with a sample width of 300mm. The leveling process uses the leveling system to perform cyclic up and down bending with a small radius of curvature, which enables the strip to obtain a consistent "fiber" length and thus achieve a good plate shape. During this process, the internal skin force state of the material changes, thereby affecting the original performance of the strip. Therefore, it is necessary to retest the mechanical properties of the sheet metal after leveling.
2. Wear and tear due to equipment and tooling reasons
The relevant losses are mainly manifested in the following two aspects
The first is the wear and tear caused by the failure of equipment and tooling. This type of loss is uncertain and mainly includes adjustment losses caused by unstable feeding accuracy, such as the phenomenon of the size of the swinging material; secondary adjustment losses of the leveling parameters due to the performance or plate shape differences of some alloy tail materials, such as the inlet/outlet of the high-strength 6-series aluminum alloy's coil head part using 0.8/1.8 numbers, and the tail material part using the same parameters due to a smaller coil half diameter The problem of edge lifting at both ends of the sheet metal: deformation caused by the failure of the slapping device at the end of the line (such as slapping marks, etc.) or loss caused by the failure of slapping. Quality defect losses caused by the failure to maintain molds or shearing knives in a timely manner or poor maintenance, such as burrs on the cutting edge, aluminum powder and aluminum wire on the cutting edge, etc. Quality issues and losses caused by the wear of the conveyor belt and rollers in the line body, such as the cutting effect between the belt and the polyurethane rollers inside the line body during high-speed transmission, resulting in irregular black or other foreign substances. Additional losses caused by insufficient production experience of operators, misjudgment, and incorrect operation, etc. These uncertain faults not only lead to the loss of sheet metal, but also greatly affect the production efficiency of the production line.
The second is the wear and tear of the flipping equipment. The symmetrical side panels on both sides, such as the left and right sides of the outer panels of the side panels, the left and right sides of the inner panels of the four doors, and the left side of the outer panels of the wheel covers, are mostly balanced and used by using a flipping machine. The entire pallet stack (with pallets placed on both the top and bottom) is loaded onto a C-type or O-type turnover machine. After being pressed and fixed by the clamping force of the upper and lower pallets under hydraulic pressure (at least 1.5 times the weight of the stack), it is flipped 180 'to form another stack. During the flipping process, due to the strong external force held in place, the cleanliness, oil film or appearance of the upper and lower sheet materials that are in rigid contact with the tray are all damaged to varying degrees and cannot be used, especially for the outer sheet parts or deep-drawn parts that are strongly related to the thickness of the oil film, such as the inner panels of deep-drawn aluminum four-door panels.
3. Loss due to quality accidents
The scrap and loss of the first and last materials of the pallets, especially the first and last materials of the outer sheet parts, after being stacked on steel or wooden pallets, are cleaned, packed and stored in the warehouse, and then transferred to the stamping production line for use. The first and last sheet materials of the material stack often come into direct contact with the binding straps of the outer packaging. After storage and transportation, their appearance cleanliness deteriorates, the oil film is damaged, or the last sheet materials are wrapped in the packaging skin. The last sheet materials come into contact with the pallets, causing problems such as pallet marks or indentations, which makes the first and last sheet materials unusable.
4. Other quality issues and losses caused by returns. It mainly includes the scrapping of parts caused by occasional problems of sheet metal quality (such as oil marks, scratches, deformations, pits, pockmarks, peeling, indentations, etc.) during the stamping production process. Returns and empty returns when the number of material stacks on the left and right sides is inconsistent during co-mold production of left and right parts. Returns or empty returns that occur when the actual quantity of a single pallet does not match the set quantity due to counter errors or human intervention during the process.
