【正文】 50%84%98%50% + ??50% + ??安全庫存 = ?*服務(wù)水準(zhǔn) *(MCT)?這里 ? = 變異系數(shù) CV = s/x=Sigma/Average Demand（ CV,用數(shù)量計算 WIP， ,用等價物數(shù)量或時間， , 用時間表示，詳見 W306 Generic Pull System章節(jié)縱軸是顧客需求量橫軸是時間序列39Replenishment Pull SystemsImproveSafety Stock (SS): Service Level Service Level:uThe service level is essentially the number of standard deviations, relative to the mean, carried as safety stock. u It is, literally, the calculated number of times that you expect a stock out to occur.50%84%98%????Demand above and below the meanu Service Level = 1 means that one standard deviation of safety stock is carried, and on average there will be no stock outs 84% of the time (50% below mean + 34%)u Service Level = 2 means that two standard deviations of safety stock is carried, and on average there will be no stock outs 98% of the time (50% below mean + 48%)u and so on...40Replenishment Pull SystemsImprove安全庫存 (SS): 服務(wù)水平服務(wù)水平 :u 服務(wù)水平本質(zhì)上指相對需求平均值而言的標(biāo)準(zhǔn)差的倍數(shù)，在安全庫存中表示 . u 按字面理解，就是你認(rèn)為出現(xiàn)庫存短缺發(fā)生的時間的計算50%84%98%????需求高于或低于平均值u 服務(wù)水準(zhǔn) = 1 意指只有 1個標(biāo)準(zhǔn)差的庫存，平均庫存不出現(xiàn)短缺的次數(shù)將有 84% （50%均值以下 + 34%)u 服務(wù)水準(zhǔn) = 2 意指只有 2個標(biāo)準(zhǔn)差的庫存，平均庫存不出現(xiàn)短缺的次數(shù)將有 98%（ 50%均值以下 + 48%)u 等等41Replenishment Pull SystemsImproveSafety Stock (SS): Service Level 42Replenishment Pull SystemsImproveDate Usage4Jan 995Jan 1006Jan 1007Jan 998Jan 9811Jan 10012Jan 10113Jan 9914Jan 10215Jan 10318Jan 9919Jan 9820Jan 9721Jan 10022Jan 10125Jan 10226Jan 10427Jan 10128Jan 99 Usage Count29Jan 98 96 11Feb 98 97 22Feb 96 98 43Feb 100 99 64Feb 102 100 75Feb 101 101 68Feb 103 102 49Feb 102 103 210Feb 101 104 111Feb 10012Feb 99 均值15Feb 101 16Feb 9717Feb 100 標(biāo)準(zhǔn)差18Feb 99 19Feb 102Average Daily Usage929496981001021041061/4/01 1/11/01 1/18/01 1/25/01 2/1/01 2/8/01 2/15/01UnitsCount of Usages01234567896 97 98 99 100 101 102 103 104Count安全庫存 (SS): 服務(wù)水平 43Replenishment Pull SystemsImproveSafety Stock (SS): Service Level Recall that we assume our demand can be represented by a normal distribution:1? = = % 2? = = %Me anBut, we are always covered when demand is LOWER than the mean, so at:Service Level = 1 which is:1*? = % / 2 + % = % And at:Service Level = 2 which is:2*? = % / 2 + % = % To summarize:Service Level = 1 gives 84% stockout coverageService Level = 2 gives 98% stockout coverageService Level of 1 = 84% stockout coverageService Level of 2 = 98% stockout coverage44Replenishment Pull SystemsImprove安全庫存 (SS): 服務(wù)水平 假定我們的需求可以用正態(tài)分布1? = = % 2? = = %均值但是，當(dāng)需求比平均值低時，我們總是出現(xiàn)短缺，所以 :服務(wù)水平 = 1 意味著 :1*? = % / 2 + % = % 在 :服務(wù)水平 = 2 意味著 :2*? = % / 2 + % = % 總結(jié) :服務(wù)水平 = 1 覆蓋 84% 庫存不短缺服務(wù)水平 = 2 覆蓋 98% 庫存不短缺 服務(wù)水平 1 = 84% 庫存短缺率服務(wù)水平 2 = 98% 庫存短缺率45Replenishment Pull SystemsImproveBOHWork Orders (SumWO)MCTMax Loop* = (MCT * Dmd) + (CTI * Dmd) + SSMin Kanban/Trigger Point = (MCT * Dmd) + SSOrder If: (BOH* + SumWO) = Trigger PointOrder Qty = Max Kanban (BOH* +SumWO)CTISSMCTManufactured Parts AvgBOH* Balance OnHand (BOH) Max Loop = Max KanbanMaxMinBasic Pull Formulas for Manufactured Parts46Replenishment Pull SystemsImprove現(xiàn)有余額現(xiàn)有余額=BOH訂單數(shù)量 =OOQMCT最大看板數(shù)量 Max Loop* = (MCT * Dmd) + (CTI * Dmd) + SS最小看板 / 觸發(fā)點 Min Kanban/Trigger Point = (MCT * Dmd) + SS如果 : (BOH* + SumWO) = Trigger Point 觸發(fā)點時就生產(chǎn)訂單數(shù)量 = 最大看板數(shù)量 (BOH* +SumWO)CTISSMCT制造的零件AvgBOH? Balance OnHand (BOH) 顧客過程中的現(xiàn)有余量? Max Loop = Max Kanban 最大看板數(shù)量MaxMin制造件的拉系統(tǒng)基本公式47Replenishment Pull SystemsImproveOther Key Parameters for Manufactured Partsu Batch Size n Perform analytical batch sizingn Ensure pull design meets capacity limitations of processu Minimum/Maximum/Multiple Order Quantitiesn Challenge based on Batch Sizing and capacity analysis aboven May be based upon container quantity – caution48Replenishment Pull SystemsImprove制造零件的其他關(guān)鍵參數(shù)u 批量 n 實施批數(shù)量的分析n 確保拉動設(shè)計滿足過程的能力限制u 最小 /最大 /多訂單數(shù)量n 基于以上批量和能力分析而挑戰(zhàn)n 還可能基于容器數(shù)量 – 警戒49Replenishment Pull SystemsImproveExample:Manufacturing Replenishment Pull SystemPart Number “XYZ” has the following data:CTI = 15 daysMCT = 30 daysSafety Stock = 100 partsDemand = parts / dayDetermine the Max Loop (Kmax)Max Loop = (MCT x Demand) + (CTI x Demand) + SS = (____ x _______)+ (___ x _______) + (__) = __________50Replenishment Pull SystemsImprove舉例 :制造補充拉系統(tǒng)零件 “XYZ” 已經(jīng)有了如下數(shù)據(jù) :CTI = 15 天MCT = 30 天安全庫存 = 100 個需求 = 個 / 天決定最大看板數(shù) (Kmax)Max Loop = (MCT x Demand) + (CTI x Demand) + SS = (____ x _______)+ (___ x _______) + (__) = __________51Replenishment Pull SystemsMeasureAnalyzeControlImproveLean Six SigmaPurchase Pull Systems MeasureAnalyzeControlImproveLean Six Sigma采購拉系統(tǒng) ImproveStrategicBuffer(onsite)8 WeekVendor Lead Time 12 WeekManufacturing Cycle Time2 Week“Customer Expectation”Replenishment Signal “Purchase Order”ConsumptionVendor ManufacturingPurchase Pull System u Based on consumptionu Onhand quantity function of demand variability, lead time, order frequency, desired service levelu Part shortages reduced/eliminated (reducing expediting)u Inventory reduced (better mix)54Replenishment Pull SystemsImprove戰(zhàn)略緩沖(onsite)8 周供應(yīng)商交貨期 12 周制造周期時間2 周“客戶期望 ”補充信號： “采購訂單 ”消耗供應(yīng)商供應(yīng)商 制造流程采購拉系統(tǒng) u 補充基于消耗u 現(xiàn)有數(shù)量與需求變量、交貨時間、訂單頻次、期望的服務(wù)水平成函數(shù)關(guān)系u 零件短缺減少 /消除 u 庫存減少（更合理的產(chǎn)品組合）55Replenishment Pull SystemsImprovePurchase Pull System ParametersuDemand (average weekly or daily usage)n Based on either history, forecast (backlog) or binationn Recalculated frequently in order to capture changes in trendsuLead Time (LT)n Time from when a release (PO)