Holste Says: |
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The manufacturing assembly plant model provides a structured approach that supports high levels of automation while reducing the incremental labor component. |
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What Do You Say?
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Previous Columns by
Cliff Holste |
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In today’s typical high volume DC, integrated into the maze of material handling equipment and systems is a pick-and-pass order assembly operation not all that dissimilar, at least functionally, from the typical flow-through manufacturing assembly line. The major difference is the huge variety and diversity of customer orders assembled across hundreds of pick faces in the order assembly path.
But even with this additional degree of complexity, customer orders are being picked, assembled, packed and shipped in a flow-through process that has a lot in common with manufacturing assembly operations. To begin with, order fulfillment in the DC is a highly repetitive process, which is a common characteristic of manufacturing assembly lines. Another interesting observation is that many operations that typically have been performed in manufacturing, such as kitting, packaging bulk items into minimum sales quantities, building customer specific displays, and assembling mixed SKU pallet loads (just to mention a few) are being push downstream into the DC. In addition, there has been a proliferation of labor intensive end-user value-added-services (VAS) such as, monogramming, gift wrapping, insertion of sales materials, etc.
Because most DCs today are equipped with fixed-path material flow systems, customer orders requiring special handling are routed into a Work-in-Process (WIP) area. The result is that VAS and all other special operations are handled as exceptions and as such, not integrated into the normal system flow pattern. Scheduling is further complicated in DCs equipped with automated batch order picking and sorting systems due to the unpredictable amount of time required to complete the batch. All of which is both costly and problematic.
Going Forward – There Can Be No Exceptions
For logistics companies and distribution planning professionals, the opportunity going forward is to begin treating DC operations and system design the same as if it were a manufacturing assembly plant. First, special operations must be integrated into the overall materials flow operation. This requires applying “lean” process analysis to the picking and assembly of customer orders. For example: looking at it from the productivity prospective, the goal may be to keep all processing areas running at their “target design rates”. However, from a “lean manufacturing” prospective it is OK to have slack or under-utilized capacity for some of the slowest processes (such as VAS) as long as they are fully utilized.
Lean manufacturing analysis strive to minimize WIP (work-in-process) which is the primary function for accumulation conveyor – queuing WIP between picking and assembly processes with different production rates. DC operations planners should start by focusing on increasing the capacity of the slowest process, i.e., VAS (and located them at the beginning of the serial order-assembly process) with all other downstream processes having a higher throughput capacity. The closer the DC system operation gets to this “pull verses push” model the more lean (efficient & productive) it will become.
DCs that are associated with the company’s manufacturing operations often have access to staff Industrial Engineers (IE). This specialized engineering resource provides DC planners the opportunity to better understand the “real” cost drivers and more easily adopt appropriate lean process analysis. For standalone DCs, IE resources are available through industry experts and independent consulting firms.
To get the ball rolling, DC executives need to seek answers to (3) strategic questions:
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