Production assembly manufacturing facilities typically run several, if not dozens of products at the same time. Some of these are not physically distinguishable from one another. In this instance, mixing of the individual units between multiple lots was occurring at nearly all of the assembly manufacturing sites. As a result, after the product had left the manufacturing facilities, passed unnoticed, through the logistics systems and customers’ integrated the units into their final products. Customers reported that they were encountering apparently defective products because their completed assemblies either did not operate at all, or would not operate to specifications. Upon return to the vendor for investigation/retesting, it was found that the units were in fact, fully functional; but were not the type of product that the customer had expected them to be. Further investigation identified the root cause as item level mixing between lots during the assembly manufacturing operation and correct replacement parts had to be shipped to the customers. Additionally, dozens of lots of material had to be returned from the logistics channel, retested at the manufacturing sites to identify any mixed units, which were then quarantined until a determination could be made as to their final disposition.


Management’s request was to eliminate or, if not feasible, minimize lot mixing, customer complaints of defective product caused by this mixing, and the associated “recovery” costs.


It was found that the mixing was generally occurring at only a few, select operations during assembly manufacturing. Since item level, direct part marking was already part of the assembly manufacturing process, it was proposed that a unique 2D data matrix identifier be added to each unit made in each batch to ensure that all units within each of the batches was identifiable. Additionally, at those selected manufacturing steps where mixing could occur, data matrix readers would be installed to ensure that each unit was part of the batch being processed and that no mixing had occurred during processing.


Upon implementation of 2D data matrix marking, reading at the selected operation, with confirmation of data read at these operations through an operational database integrated with the shop floor control system, mixing of product was totally eliminated and customer complaints reduced from a “Top 10 Issues” item to non-existent.

Bonus!  Additionally, the factories which had been providing the manpower and equipment needed to retest/quarantine products no longer had to ensure availability of this manpower or equipment. Finally, the logistics operations which had been handling the mixed material and customer returns found that the system discovered a marked reduction in manpower and time required to manually handle the issues of customer returns.