應用TOC的補貨機制改善以MRP為存貨管理機制之研究~以無線通訊廠為例

Abstract

在面對電信市場需求不確定性極高的產業動態下，讓以預測為MRP生產補貨基礎的存貨管理經理人，大都有多備庫存才會有好交期的傳統迷思，但卻也十分頭痛過多流動遲緩的存貨侵蝕了公司的利潤，因此存貨管理系統之補貨機制已成為該產業供應鏈競爭力之關鍵所在。在研究個案中，M公司為了降低預測不準確所導致的營運風險，而預設了安全庫存，並將需求預測與材料做分類，根據不同時間點的預測與實際需求予以陸續補貨投料…等管理改善方案設置於M公司的MRP存貨管理機制裡，其存貨績效也如預期的持續改善中，但是在與同業的存貨績效相比後仍有段差距。因此如何突破MRP系統存貨管理的困境，進而強化企業之競爭力，這是個案公司必須面對的嚴肅課題。本研究以實際個案的存貨數據為基礎，以限制理論所提的動態需求拉動與緩衝管理模式 (Demand-pull & Buffer management) 的邏輯架構與方法論之分離程序 (de-couple)，將存貨異常的材料從產品BOM中予以分離出來，經模擬配銷管理程式模擬各個產品壽命週期的需求變化驗證後，確認TOC的存貨績效確實比原個案運作的MRP系統來得好。另外，本研究並不否定以預測方式來規劃未來的存貨生產計畫，畢竟預測可以讓管理者了解未來需求的趨勢，但經由預測方式所獲的資訊可以與TOC做結合，使企業不再落入是否要多備庫存來維持客戶服務水準的矛盾衝突中。

In telecommunications industry, the demand uncertain is the interfering factor on replenishment system of MRP that is a big headache issue. The errors of forecast bothering the inventory manager needs to prepare more inventory meeting customer services, but also concern to erode the benefit of company. That means the replenishment system of inventory management is the critical path keeps the enterprises competition. In case, Company M performs some compromises modifying MRP system that including more efficiency forecast, flatten the BOM, safety stock setting and manual work around proliferation to reduce the operational risk, but also as expected to get some improvements. But compared with the performances of the others competitors that there is still gap need to overcome. Therefore, it needs the managers to find the constraint on MRP system, and take actions to break it to enhance the competitiveness of enterprises. This study based on the idle inventory report of Company M to identify some material parts, through methodology of TOC (Demand-pull & Buffer management), de-couple the BOMs to individually manage their inventory. After simulating some scenario of product life cycle, confirm the inventory performances are better than the MRP system. In addition, this study does not deny using the forecast way to plan future inventory. After all, through forecasting the demand is important. That makes the managers to understand the demand trend, but the information obtained by the prediction method can be combined with TOC. TOC can help the company never falls into the conflicts between the customer services and the company profits.