考慮回收及保固策略之不良品存貨模式

Inventory Models of Imperfect Items with Return and Warranty Policies

滕慧敏(Hui-Ming Teng)

中原大學/電機資訊學院/工業與系統工程研究所/博士(2011年)

https://doi.org/10.6840/CYCU.2011.00115

摘要

經濟全球化的趨勢與科技的快速發展下，產品必須不斷的推陳出新。企業為了更具競爭優勢，必須整合製造商與零售商的供應鏈，使得供需雙方都能够獲得最佳利潤。但在整合的過程中，有幾個議題值得我們注意：
1、相關的文獻裡，大多都假設供應商所提供的貨品為良品。但在實務界，供應商會因生產製程不盡完善、人為疏忽等問題，導致不良品的產生，這個現象會影響到零售商的存貨水準及訂購的次數，更進而影響企業的商譽。因此、降低不良品的產生以求取成本的最小化，是一個重要的議題；而改善製造設備，降低不良品發生的比率則又是另一項值得注意的議題。
2、近年來隨著環保意識的抬頭，保護環境所耗用的成本占企業總成本的比重日益增加。環保是為了不浪費資源，並減少廢料對於環境所造成的負擔。因此，如何利用資源回收與再生來降低相關的物料成本，是企業在提高市場競爭力上另一項考量的重點。
3、由於消費者意識抬頭，消費者對所購買的產品品質有更嚴格之要求，因此廠商對售後產品所提供的保固，就變得相當重要。在不完美的製造或訂購系統下，適當的對產品檢測以降低不良品的產生，對製造商而言是相當重要的。
本論文整合以上幾項議題，建立數學模式，並以數學範例的結果證明可獲得最佳解。本文主要獲得之研究結果為：
在第三章中，我們利用更新理論（renewal theory），來發展在考慮缺貨後補狀況下的經濟訂購模式；數學範例則顯示為確保在檢驗期間內無缺貨，不完美產品產生的比例必須受到限制。在第四章中，我們同時考慮回收及缺貨後補的兩階存貨模式。同時，本文亦考慮為刺激購買意願而增加貨品上架數量時的訂價策略。
另外、由於檢驗率的制訂，會對存貨成本造成影響。因此在第五章中，本研究將檢驗率的制訂，加入允許部份補貨的不良品生產過程中探討。
第六章中，本研究針對保固議題進行探討。另外、為了瞭解各參數對數學模式所造成之影響，本研究在各章中都進行敏感度分析。有別於以往的分析方法，本研究在第七章中建構一個新的分析方法，該方法是將要進行分析的參數視為變數，然後再利用該函數的性質以梯度來進行分析。第八章則為結論。

關鍵字

保固策略 ； 定價策略 ； 整合 ； 回收策略 ； 不良品

並列摘要

In light of globalization of the economic entity, and rapid growth of the technology, manufactures of products are constantly advanced. Companies will need to integrate the supply chains between manufacturers and retailers to better equip themselves in the business competition, and to maximize profits of all parties. In the path of integration, several issues need to be addressed:
1. In most of the previous literature, it is assumed that manufactured products are without deficiency. In reality, suppliers sometimes provide defective products due to imperfect production process or employees’ negligence. It lowers the retailers’ inventory quality and order requests, and harms the company’s reputation. Thus, reducing defective products and minimizing the cost is a critical task.
2. According to the growth of environmental consciousness in recent years, the cost related to environmental protection takes a larger and larger proportion in the company’s total cost. Environmental protection aims at saving resources, and reducing the damage to the earth caused by waste materials. Thus, minimizing related material cost by recycling and reprocessing is another important concern for the business competition.
3. Due to the growth of consumer awareness, consumers have higher expectation towards product quality. Thus, product warranty becomes a critical element. While the production and ordering processes are imperfect, conducting assessments on product quality is very important to the manufacturers.
This study covers aforementioned issues and establishes a mathematical model, and then applies numerical examples to derive optimal solutions. The main conclusions are as follows. In chapter 3, we adopt this renewal theory, and develop an economic ordering strategy which involves backorders. Numerical examples are provided to demonstrate that the portion of defective items should be minimized so that no shortage could occur during the screening time. In chapter 4, we establish a two-echelon inventory system for the returns and shortage backordering. In the meantime, the paper also develops another pricing strategy for situation where the inventory is increased just to encourage consumption. The screening rate fairly affects both the inventory holding cost and the feasibility of model, especially in the situation of shortage backordering when the defective items and imperfect production processes were considered in chapter 5.
We develop an optimal replacement period by considering minimizing the expected warranty cost in Chapter 6. Then in order to understand the effect of each parameter on the mathematical model, this paper conducts sensitivity analysis in each chapter. Accordingly, a new analytical method is developed in the chapter 7. This method considers the parameters which would have been analyzed as variables, and then analyzes them by gradients with properties of that function. Conclusion and further research are given in Chapter 8.

並列關鍵字

Warranty strategy ； Pricing strategy ； Integration ； Return policy ； Imperfect quality

參考文獻

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