Compendium admissions 2023-25
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- DPMO vs. DPPM
| C pk : β’ It is the resultant process capability as it not only considers variation but also the location of the data by considering the closeness of the mean to the target and specification limits. β’ It compares the width of the specification and the width of the process while also accounting for any change in the process average (location of central tendency) β’ Rule of thumb C pk >1.33 indicates that the processor characteristic is capable in the short term. β’ Values less than this may mean variation is too wide compared to specification, or the process average (location) is away from the target or a combination of width and location. πΆπ = πππΏ β πΏππΏ 6 ο³ πΆππ = min, πππΏβππππ 3 ο³ ) DPMO vs. DPPM: DPMO = Defects per Million Opportunities A measure of quality performance calculated as DPMO= 1,000,000 x amount of defects/number of units x number of opportunities per unit DPPM = Defective Parts per Million A measure of quality performance. One DPPM means one (defector event) in a million or 1/1,000,000. To calculate, for example, letβs say you had 25 pieces defective in a shipment of 1,000 pieces. 25/1000= .025 or 2.5% defective. 0.025 X 1,000,000 = 25,000 PPM. 82 It is important to remember that DPMO and DPPM mayor may not represent the same thing. A defective part can have one or more defects, and apart can have one or more opportunities. If ONE part has 1,000,000 opportunities fora defect, and one defect is found, making the entire PART defective, it is possible to have a 1 DPPM with a DPMO of 0.000001. Typically, most products (and services) have more than one opportunity of going wrong, which leads to the following example If I manufactured two items (wristwatches and pencils, it is obvious the watches have more opportunities for defects. Therefore, if DPPM were lower on my watches, it would be grossly unfair to say it was worse than my pencils. To gain an apples-to-apples comparison, I would then use DPMO to consider the complexity of the watches and to evenly balance it on a scale with the pencils allowing for better assessment. Download 4.08 Mb. Share with your friends:
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