Mixed Model Production is the practice of manufacturing multiple product variants on the same line in an interleaved sequence, instead of running one variant for a long batch before switching to the next. It is one of the most demanding but rewarding operational patterns, because it lets a factory match demand mix exactly, in real time.
Traditional batch production runs 500 of variant A, then 300 of variant B, then 200 of variant C. Mixed model production interleaves them: A, B, A, C, A, B, A, sequenced so that the mix in every short interval matches the mix in the actual demand. Inventory of any single variant stays small; the line is always producing something the customer wants right now.
Short changeovers, often measured in seconds, so the switch between variants is invisible in the flow. Stations designed to handle every variant without reconfiguration. Materials for all variants available at every workstation. Skilled operators trained on the full model mix. And a leveling system (Heijunka) to define the sequence.
Finished-goods inventory drops close to zero because you're never building ahead of demand. Response to demand mix changes becomes instant. Lead time to any specific variant shrinks. Overproduction becomes impossible because you're only building what the sequence, driven by real orders, calls for.
Mixed model production is the natural end state of a mature lean factory. It requires investment in changeover reduction, flexibility and leveling, but the operational payoff is a line that produces exactly what customers want, in the exact mix they want it, without carrying inventory as insurance.
