1.What is the material utilization rate of cold-rolled coils?
Material utilization rate of cold-rolled coil refers to the percentage of the total weight (or total area) of the final finished part (or product) to the total weight (or total area) of the cold-rolled coil raw materials consumed. It is a core economic indicator for measuring whether materials are used effectively.
2.In the processing of cold-rolled coils, what are the specific components of material utilization? Where does the loss occur?
Product scrap (stamping/blanking scrap): This is the largest loss component. It refers to the scrap generated after parts are laid out, between parts (overlap), between parts and the strip edge (edge distance), and in the holes within parts. This typically accounts for 15%-30% of the incoming material weight.
Process scrap:
Head and tail trimming: The heads and tails of cold-rolled coils often have poor shape or unstable performance, requiring the trimming of a certain length (e.g., 1-2 meters).
Trial die scrap: Scrap generated during die debugging.
Geometric scrap: Remaining portions (edges) that cannot be fully utilized in the width direction due to a mismatch between the coil width and the unfolded part width.
Quality scrap: Scrapped products caused by defects in raw materials (such as inclusions, holes) or processing defects (such as scratches, cracks).
3.What are the differences between calculating material utilization within the steel mill and calculating it at the user's (stamping plant) site?
The two have different calculation methods and applications, so they need to be distinguished:
Internal calculations at the steel mill (yield):
Definition: The metal yield from steel billet to the final cold-rolled coil.
User-side calculation (material utilization rate):
Definition: The degree of material utilization from cold-rolled coil to the final stamped part.
4.In practical calculations, how can we accurately measure and statistically analyze material utilization rates?
Weighing Input: Record the actual weight of each cold-rolled coil put into production (from the weighing system).
Output Statistics:
Count the number of qualified stamped parts produced in this batch.
Randomly select a certain number of qualified parts and weigh their net weight (or calculate the unfolded area × thickness × density of the part using CAD software).
Calculate the total weight of qualified parts = Net weight per part × Number of qualified parts.
Scrap Material Classification and Weighing (Optional, for analysis):
Collect and weigh edge wire scrap, overlap scrap, punching scrap, head and tail scrap, and defective products separately.
This allows you to calculate the specific proportion of each type of loss, facilitating targeted improvements.
5.Could you provide an example of how computational optimization can improve material utilization?
Taking the production of a reinforcing plate by an auto parts factory as an example:
Initial state:
Part unfolded dimensions: 400mm × 300mm.
Selected cold-rolled coil width: 1250mm (standard width).
Layout: 3 pieces per row, overlap 5mm.