The number of pickers and stock-keeping unit arrangement on a uni-directional picking line

Hagspihl, Robert ; Visagie, Stephan E. (2014-11)

CITATION: Hagspihl, R. & Visagie, S.E. 2014. The number of pickers and stock-keeping unit arrangement on a uni-directional picking line. South African Journal of Industrial Engineering, 25(3):169-183, doi:10.7166/25-3-886.

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The order picking process is often the single largest expense in a distribution centre (DC). The DC considered in this paper uses a picking line configuration to perform order picking. The number of pickers in a picking line, and the initial arrangement of stock-keeping units (SKUs), are two important factors that affect the total completion time of the picking lines. In this paper, the picking line configuration is simulated with an agent-based approach to describe the behaviour of an individual picker. The simulation is then used to analyse the effect of the number of pickers and the SKU arrangement. Verification and validation of this model shows that the model represents the real-world picking line to a satisfactory degree. Marginal analysis (MA) was chosen to determine a ‘good’ number of pickers by means of the simulation model. A look-up table is presented to provide decision support for the choice of a ‘good’ number of pickers to improve completion times of the picking line, for the properties of a specific picking line. The initial SKU arrangement on a picking line is shown to be a factor that can affect the level of picker congestion and the total completion time. The greedy ranking and partitioning (GRP) and organ pipe arrangement (OPA) techniques from the literature, as well as the historical SKU arrangements used by the retailer under consideration, were compared with the proposed classroom discipline heuristic (CDH) for SKU arrangement. It was found that the CDH provides an more even spread of SKUs that are picked most frequently, thus decreasing congestion and total completion time.

Die opmaak van bestellings is meestal die enkele grootste uitgawe in ʼn distribusiesentrum (DS). Die DS wat hier beskou word gebruik ʼn opstelling in die vorm van ʼn uitsoeklyn om bestellings vir die winkels op te maak. Die aantal werkers en die rangskikking van voorraadeenhede in die uitsoeklyn is twee belangrike faktore wat die totale afhandelingstyd beïnvloed. In hierdie artikel word ʼn uitsoeklyn met behulp van agent-gebaseerde simulasie gemodelleer om die gedrag van ʼn individuele werker te simuleer. Hierdie simulasie word dan gebruik om die effek van die aantal werkers en die voorraad se rangskikking te analiseer. Verifiëring en validering van die model wys dat die model wel die werklike uitsoeklyn bevredigend naboots. Grensontleding word gebruik om ʼn goeie aantal werkers vir ʼn uitsoeklyn te bepaal. ʼn Tabel word verskaf om die regte aantal werkers vir ʼn nuwe lyn na te slaan. Die aanvanklike rangskikking van die voorraadeenhede in die uitsoeklyn beïnlvoed die kongestie en die totale afhandelingstyd. Die gulsige rangskikking-en-verdeling en die orrelpyp rankskikkings uit die literatuur, sowel as die historiese rankskikking deur die kleinhandelaar, word vergelyk met die voorgestelde klaskamer-dissipline-heuristiek (KDH) vir voorraad rangskikking. Die bevinding word gemaak dat die KDH ʼn beter verspreiding van voorraadeenhede oor die lyn bewerkstellig, wat lei tot die verlaging van die totale kongestie en afhandelingstyd van ʼn uitsoeklyn.

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