- 學位論文
物流中心走道設計與儲位指派對揀貨績效影響之研究
Aisle configuration and storage assignment on order picking performance in the distribution center
摘要
近年來網路消費的快速發展與便利性，使得顧客的購物需求轉變為少量多樣化，且具時效性商品在配送上需額外加以考量，再加上原油價格不斷上升等原因，導致物流中心成本提升與營運的壓力。為了減少成本與壓力，過往學者分析人工揀貨作業成本佔物流中心總成本15至20%，而影響倉儲績效的相關因子有走道設計、儲位指派、訂單揀取及揀貨路徑規劃，其中走道設計為設置後較難大幅度變更之因子，且對於後續作業具有一定程度之影響，故走道設計為規劃倉儲時重要之一環。近年來學者提出非傳統走道設計：Flying-V與魚骨佈置，這些走道設計打破以往舊有的觀念：『較高儲存密度代表較短的揀貨距離』，學者實驗此兩種走道設計在單元負載倉儲的揀貨表現均比傳統走道設計有著不錯表現。 本研究提出不同之倉儲走道設計、儲位指派、作業型態與需求型態等不同因子搭配，分別探討對於單元負載與訂單揀貨倉儲作業績效的影響。本研究提出與Flying-V和魚骨佈置主體設計相似的平行走道斜橫走道與直交走道斜橫走道，最大的差異點在於PD點設置在角落，其主體設計相似於Flying-V與魚骨佈置之右半部。在單元負載作業考量不同倉儲長寬比、倉儲大小、需求型態及比較隨機指派與週轉率指派的表現差異，藉以找到最適倉儲長寬比。在訂單揀貨作業依最適倉儲長寬比設計不同倉儲大小，比較不同揀取品項數與需求型態對於訂單揀貨作業的差異。針對實驗的結果進行統計分析，盼能在不同的因子下找出最佳組合，並且分析那些因子對於揀貨距離會造成影響，藉以提高倉儲作業的效率。 研究結果發現在單元負載作業時，非傳統走道設計相較於傳統走道設計大多表現較佳，但是當PD點在底部中央之倉儲長寬比大於1.5時，傳統走道設計反而表現較佳，因此使用非傳統走道設計時需評估倉儲長寬比。在訂單揀貨作業時，非傳統走道設計表現並沒有如同在單元負載作業佳，相反的擁有橫走道的傳統走道表現最佳；但若考量實際上使用訂單揀貨的情境，非傳統走道設計在訂單揀貨作業仍然具有一定的潛力。整體而言，使用週轉率指派相對於使用隨機指派能夠有效地減少揀貨距離，並依據貨品的需求型態不同而有所差異，最後本實驗統整在特定情境因子下的走道設計推崇，以供倉儲作業人員參考。
並列摘要
Warehouse operation is an important factor for the efficient and effective supply chain management. Order picking process is the most laborious and most costly activity in a typical warehouse. Among those factors that affect the order picking efficiency, most research addresses the issues of the storage assignment and routing policy. The aisle configuration within storage areas is also an important factor but not many papers consider this factor. Motivated by this, a different aisle configuration is discussed with other major factors. A recent trend in design of warehouse configuration is the consideration of different designs for the pick aisles and the cross aisles. Flying-V and fishbone layout are the two new configurations proposed in the literature. They can save the total travel distance in unit-load operation over the traditional aisle configuration. In this research, we developed another two similar configurations with PD point at the bottom left position, which could be considered as half of Flying-V and fishbone layout, respectively. Storage assignment strategy (random and turnover based) and warehouse operation (unit-load and order picking) are also considered to evaluate the performance of the new aisle configurations over the traditional layouts. Three different experiments in different scenarios are conducted to evaluate the effect of the aisle configuration and storage assignment on the picking performance in this research. Four different demand distributions are also considered in the experiments. Based on the results, we found that the new aisle configuration with turnover based assignment can reduce the travel distance up to 26.16% and 20.37% for the single-command and dual command operation at the unit-load warehouses, respectively. Regarding the order picking operation, the traditional layout with a cross aisle can provide shortest travel distance. However, the fishbone and half-fishbone layout provide shorter distance when mixed size orders are picking. When implementing the new aisle configuration, one should observe that the travel savings are offset by a reduction in storage density. In the future, we could collect real data to test the performance of the new aisle configurations. Another possible extension is to evaluate multiple PD points and locate the best positions for these PD points.