以模擬驗證TOC Demand pull可改善IC設計公司庫存管理

Abstract

台灣IC產業發展歷史已超過30年，在政府積極支持和產業界的協助努力下，台灣已成為全球IC產業的重鎮，而台灣IC設計在全球的市占率成長躍居全球第二， IC製造能力在全球半導體市場更扮演舉足輕重的角色，成為全球第四大生產國。台灣IC設計業者的營運模式多以無晶圓（Fabless）為主，並不需要擁有自己的製造工廠，把生產交給專業的代工廠來執行。因為本身無自有工廠，在所有生產活動皆必須委外代工的情況下，僅能依據市場的銷售預測提早投單，也因為無自有產能，所有的產能必須與各家代工廠協調，一旦代工廠產能接近滿載時，委外生產的交期則會變得更不可靠。而當景氣不好時，安全庫存量及在製品將造成資金成本積壓，庫存成本增加等。IC產品生命週期短、產業景氣循環大，在傳統供應鏈運作，常以預測的方式進行生產規劃，然而我們知道預測通常是不準的，往往造成倉庫堆積著大量的存貨，而卻總是缺少客戶所需要種類的產品。然後再以急單或是以插單生產的方式來補足客戶實際需求，讓整個供應鏈的運作變得更加不穩定。有鑑於預測的不確定性對供應鏈運作所造成的干擾，本研究將依據限制理論(Theory of Constraints, TOC)，以預測驅動的操作模式改變成以實際賣出量之拉式需求「Demand pull」驅動的操作模式，用「目標庫存水準」的操作方式來控管庫存水準；透過理論的探討與實際資料的驗證，希望能改善整體的庫存水準，同時能滿足客戶要貨有貨的高可得性，可以更低的庫存來滿足客戶，提昇企業競爭之彈性能力，提高獲利與投資報酬率。

IC Industry has been developed more than 30 years in Taiwan. As a result of Government support actively and under the Industrials support, Taiwan became the 2nd large base for the Fabless IC design houses in the world. And also became the 4th large production country from the excellent manufacturing capacity and play a decisive role in the globe semiconductor market. The operation strategies were focus on Fabless IC design and without their own manufacturing plant. The professional subcontractors were in charge of the manufacturing. All of the production activities must to outsourcing cause of they did not have their plant and plan the production schedule was according to the forecast of market ahead of time only. They must to negotiate with subcontractors for production capacity. Outsourcing production delivery day became unreliable when the subcontractors production capacity near to full loading. When the market trend turn down, safety stock and WIP will affect the money overstocks accumulated and inventory cost was been increased. Under the violent market changed and short product lift time, the traditional supply chain management was base on the sales forecast to plan the production schedule. And then, we know the forecast was always not accurate, there was always having a lot of inventory in the warehouse but without the product that customer need. And then, released the super hot run to fulfill the customer actual demand became normal afterward make the supply chain executed become unstable. In consideration of the interfere in supply chain management from the forecast uncertainty, this paper will base on the Theory of Constraint and implement Demand Pull in stead of the forecast production; and use the target inventory level to manage inventory. According to the literatures discuss and the company’s history data verify, we are trying to improve the inventory level and also fulfill the customer’s demand with lower inventory level. And then to enhance the company’s competition flexibility, increase its profit and return on investment rate.