COQ--质量成本分析

•We cannot reduce cost without affecting quality. 我們不能削減成本而不影響品質 •We can improve quality without increasing cost.我們可以不增加成本而改善品質. We can reduce cost by improving quality.我們可以通過改善品質而降低成本. •We can reduce cost by reducing variations.我們可以通過減少差異而降低成本. Taguchi QLF strive for minimal variation around target values without adding cost. He defines loss as “…the lost imparted to society from the time the product is shipped”, this loss includes Taguchi QLF 努力达致接近目标值的最小差异而不增加成本。 他将损失定为： “从产品装运时流失的那部分损失“这种损失包括 ： customer dissatisfaction, 客戶不滿意 added warranty cost to the producer, 生产商增加担保成本 loss due the company’s bad reputation, 公司信譽恶劣引致的损失
动态
回复有賴於輸入，如風扇的變速必須根据引擎溫度而變化。
Taguchi Quality Loss Function (QLF) Taguchi 品质损失运算 L = k ( y - T )² (QLF
LSL USL
Loss $
Value of quality characteristics 品质特性值 L k y T = Loss in $’s以美元计的损失 = Cost coefficient 成本系数 = Value of quality characteristics 品质特性值 = Target val成 本
IF COQ high, 如果COQ高
Poor Quality… Poor Business ! 品質差，生意差 !
It is a time bomb waiting to
Explode!
COQ高，是一顆等待爆炸的定時炸彈！
Tip of the Ice Berg 冰山一角
Effect of Good Preventive Activities
60
良好的預防活動產生的效果
Old Total 舊的總成本
50
40
Cost
30
20
A
New Tota 新的總成本 l Controllable Cost 可控成本
10
B
0
Resultant Cost 結果成本
Controllable Effort
Why Examine the Cost of Quality? 为何要审视品质成本?
1. Get management attention引起管理层的关注 2. Change the way employee think about errors 改变雇员看待错误的方法 3. Provide better return on the quality improvement program 提供更好的回报 4. Provide a tool to measure impact of corrective actions 为改正行动提供量度的工具 5. Provide a tool to measure the impact of poor-quality on profits 为恶劣品质对利润的影响提供量度的工具
Design: 1 $ 設計: 1 $
QFD
Design 設計 Process Control 工藝控制 Inspection 檢 查 Field Service 服 務
DOE
SPC
Production: 100$ 生產: 100$
Customer: 1000$ 到客戶手中: 1000$
Cost of Quality
Nominal the best. Achieving a desired target value with minimal variations, such as dimensions & output voltage. 名义上的最好 达致理想的目标值，差异最小，如尺寸和输出电压。 Smaller the better. Minimizing a response, such as shrinkage and wear. 越小越好 如收缩和磨损 Larger the better. Maximizing a response, such as pull off force and tensile strength. 越大越好 如拉力和张力 Attribute. Classifying and/or counting data, such as appearance. 属性 澄清并且/或者清点数据，如外观 Dynamic. Response varies depending on input, such as a fan drive speed should vary with engine temperature.
y
Basic Premises for Quality Cost: 品质成本基本前提:
1. It is less expensive to prevent rather than detect nonconformity 预防比检测更省钱。 2. Process and product performance can be appraised (measured) 工序和产品性能可以评估(量度) 3. The causes for nonconformance can be identified and their effects can be reduced or eliminated 产品不符的原因可以确认，其影响可以减小或消除
Poor Quality is Poor Business
60
品質差即是生意差
Total Cost 總成本
50
40
Cost
30
20
A
Controllable Cost可控成本
10
Resultant Cost 結果成本
0
Low
Controllable Effort
High
Resultant Cost 結果成本 = Failure Cost 失效成本， Defect Cost 次品成本. Controllable Cost 可控成本 = Prevention and Appraisal Cost. 預防和評估成本.
Taguchi Quality Loss Function (QLF) Taguchi 品质损失运算(QLF)
The way QLF is established depends on the type of quality characteristics involved. A quality characteristics is whatever we measure to judge performance (quality). QLF的建立有赖于有关的品质特性。 品质特性是用来判断性能(品质)而进行的一切量度。 There are five types of quality characteristics. 有五种品质特性.
通常量度的失效成本只是真正失效成本中的冰山一角。
• Scrap報廢 •Rework 翻工 •Warranty保證 • Engineering time 工程設計時間 • Management time管理時間 • Shop and field downtime工場壞機時間 • Increased inventory增加存貨 •Decreased capacity 削弱生產能力 • Delivery problems 交貨問題 • Lost orders訂單減損
Low
High
Good Preventive activities usually begin at front end of process with better effect on resultant cost. 良好的預防活動通常開始于工序前沿，對結果成本產生較好的影響。
Taguchi Quality Loss Function (QLF) Taguchi 品質損失運算 (QLF)
which would lead to eventual loss of market share. 这种损失终將导致市场份额的丧失。
Taguchi Quality Loss Function (QLF) Taguchi 品质损失运算(QLF)
Quality cost are usually quantified in terms of tangible cost such as rework and scrap cost, and customer warranty. These losses constitute only the tip of the iceberg. 品质成本通常以有形成本如翻工，报废，给客户提供担保等等而被量化，这些损失只 是冰山一角。 What about the intangible costs such as management/engineering time, inventory, customer dissatisfaction, and loss market share? 那些无形的成本代价如管理/设计时间，存货，客户的失望，市场份额损失等，又怎样 呢？ QLF is a method used to approximate these hidden and long term losses. QLF 是用 于估算这些隐藏的而且是长期损失的方法。