First Article Inspection Protocols for Custom Pack Stamping Dies
First article approval for pack stamping dies requires free-state optical scanning coupled with micro-sectioned edge burr verification below 0.03 mm.
Rollover Depth
Meaning
This dimensional characteristic refers to the rounded edge formed on the punch side of a sheet metal part during the blanking or piercing process. It represents the initial plastic deformation that occurs before the material begins to shear and fracture. The depth of this rollover is measured from the original surface of the sheet to the point where the cut edge starts.
Engineers monitor rollover depth to ensure that the clearance between the punch and die is correctly set for the material thickness. It stops being a rollover when the edge becomes a vertical burnish zone. The measurement is an indicator of the quality and precision of the stamping operation for battery housing components.
Deformation Mechanics
Metal flow into the die opening occurs as the punch makes contact with the sheet, creating a curved profile at the edge of the part. Because rollover depth is a result of the material ductility and the tool geometry, it varies based on the alloy grade and the temper. This specific deformation is more pronounced in softer materials such as annealed aluminum or copper used for electrical busbars.
The magnitude of the rollover affects the final contact area available for welding or mechanical fastening. Engineering teams use finite element analysis to predict the shape of the edge and to optimize the design of the stamping tools. This predictive approach allows for the creation of parts with the desired edge profile and structural integrity.
Understanding the mechanics of the forming process is essential for high quality manufacturing.
Clearance Influence
Distance between the cutting edges of the punch and the die determines the timing of the fracture and the size of the rollover. Since rollover depth increases as the tool clearance becomes larger, it serves as a measure of the setup accuracy and the tool wear. An excessive rollover can reduce the functional width of the part and interfere with the assembly of the battery cells.
Monitoring this dimension allows the production team to identify when the tools need to be reground or replaced. It also helps in the selection of the correct stamping parameters for different sheet thicknesses. Proper control of the clearance ensures that the edge quality remains consistent throughout the entire production run.
This precision is necessary for the automated assembly of the battery modules.
Assembly Impact
Fitment of the stamped components within the battery enclosure depends on the absence of excessive edge deformation and burrs. While rollover depth is a natural part of the shearing process, it must be managed to ensure a flat surface for sealing and bonding. Sourcing teams review the edge quality of the supplied parts to verify that they meet the strict requirements of the design.
The data collected from edge measurements supports the optimization of the assembly process and the reduction of scrap. Proper handling of the parts is required to prevent damage to the rounded edges during the transport and the installation phases. Choosing the right stamping strategy ensures that the mechanical and the electrical properties of the battery system are maintained.
Accurate edge profiles prevent the formation of gaps and the loss of seal integrity. .