Calculating Line Changeover Costs in Shared Sub Assembly Infrastructure
Subassembly changeover costs must sum direct technician labor, idle station depreciation, downstream line starvation risks, and post-swap calibration scrap.
Purge Loss Calculation
Meaning
Mathematical determination of the volume of material discarded between production runs. Purge loss calculation measures the difference between the total material fed into a machine and the amount that ends up in finished products during a transition. This value helps production managers estimate the total material requirement for a specific job.
It defines the efficiency of the cleaning process for equipment like injection molders or extruders.
Resin Waste
Determining the exact weight of discarded resin or chemical provides the data needed for financial accounting. The calculation starts by weighing the material exiting the machine before the first good part is produced. Because purge loss calculation accounts for the specific density of the material, it allows for accurate comparisons between different product lines.
High density materials often result in a higher weight of waste for the same volume.
Transition Efficiency
Reducing the time and material needed for a color or material change improves the overall factory output. A high result from the purge loss calculation indicates that the machine requires too much cleaning or that the operator is being overly cautious. Optimizing the sequence of production runs can lower this figure by moving from light to dark colors.
This strategy minimizes the amount of purging required to reach a clean state.
Material Recovery
Some discarded materials can be reground and mixed back into the raw supply. The purge loss calculation should reflect whether the waste is truly lost or if it can be reclaimed for lower grade applications. If the material is contaminated, it must be written off as a total loss.