Parent Sheet Layout Optimization and Deckle Trim Yield Analysis
Optimal parent sheet layout selection balances master machine deckle coverage against converting gripper margins and fiber grain orientation to lower total package expense.
Layout Efficiency Arithmetic
Yield Calculation
Sheet layout design in the printing and converting industries uses specific mathematical equations to determine the percentage of a substrate that is converted into finished products rather than waste. This analysis, known as layout efficiency arithmetic, divides the total area of the required blanks by the total area of the raw sheet. The resulting percentage indicates the economic viability of the layout and helps select the most appropriate stock sheet size for the production run.
Optimization Variable
Calculating this value requires the designer to account for the necessary gripper areas and trim allowances that must be trimmed away. When multi-up layouts are planned, the spacing between blanks must also be included to allow for die lines and stripping tools. Choosing the correct orientation of the blanks relative to the grain direction of the board further constrains the calculation but is necessary to ensure the structural strength of the finished cartons.
In addition, the nesting of irregular carton shapes must be calculated carefully to exploit nested angles and reduce the skeleton waste between the rows.
Economic Consequence
Minimizing the percentage of unused board is the primary method for reducing material costs in packaging production. A difference of only two or three percent in yield can determine the profitability of a high-volume run. Accurate calculations allow the purchasing department to order custom-sized sheets directly from the mill when standard merchant sizes result in unacceptable waste levels.