Polyhedrika

  Test and Repair are Non-Value-Add operations: defective products should not be produced on the first place. Unfortunately the state of the art in many processes is not there so tests and controls need to be part of the value stream.  Ideally as the value stream becomes more robust some of these controls can be removed. On the mean time we need a test and repair plan (if repair is possible). A Test/ Repair loop can become a bottleneck for the whole Value Stream when Test First Pass Yield is lower than planned. A drop in FPY is normally caused by problems upstream in the Value Stream as seen in   Defect generation and detection Test/ Repair loops are often absent in Value Stream Maps in spite of the potential to become the bottleneck for the total process. Download this Excel example file   TestRepair.xlsm   to your PC from OneDrive folder   Polyhedrika You must close all open Excel files before you open this one and you should enable Macros . To ...

  The Theory of Constraints is a process improvement methodology that emphasizes the importance of identifying the " system constraint " or bottleneck. By leveraging this constraint, organizations can achieve their financial goals while delivering on-time-in-full to customers, avoiding stock-outs in the supply chain, reducing lead time, etc. Manufacturing Process Example With this simple value stream above, to produce products A and B, we want to illustrate the way to maximize profit taking into account the system constraints . Each product is made by assembling two sub assemblies, one of them common to both products. The process consists of three sequential operations for which there are special purpose workstations with a corresponding operator each trained for the specific job: Manufacturing Test Assembly We want to know how many products A and how many B we should produce to maximize profit. System Constraints Product Margin We want to maximize overall profit so we calcu...

Analyzing our Value Stream we identify a number of constraints that limit its effective capacity. The most visible constraints are the capacity of the different steps. But there are other, not so obvious, constraints such as the capacity variation of some steps. Process variation has been described as a virus infecting the value stream: it causes chaos and it is often undetected.     Dice Throwing Exercise A bottleneck limits the effective capacity of the whole line. Bottlenecks caused by variation are more subtle and difficult to detect and act upon. Process simulation can help us experience the effects of different types of constraints, try solutions and detect possible side effects. Process simulation helps us understand the value stream dynamic behavior: how variation affects key process metrics such as WIP, Lead time, Throughput, Cycle time, On Time Delivery, etc. Understanding these dynamic effects will enable us to get to the root cause of problems implementing def...