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Quality Control and Improvement, Reliability, Liability P. King/Chapter 13 overview
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Reliability is: A characteristic that describes how good a device is. Must be planned for, designed in both in terms of the initial product and in maintenance of that product.
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Failure is: The degradation of the performance of a device (process) outside of a specified value AND non-performance or inability to perform its function for a given time period within specified conditions. Defect: imperfection Deficiency: lack of conformance to specs Fault: Cause of failure Malfunction: unsatisfactory performance
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Failure Measures Real life failure: fact of life, define normal operation, anticipate worst, try to design out. Failure rate typically = #failures/unit time = failures/million hours for devices.
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Unreliability is: A measure of the potential for failure of a device (or process.) Leads to high cost, wasted time, inconvenience, poor reputation, unsafe operation, … - 9/9/99 more than 10,000 stepladders recalled by Home Depot – steps too short, improperly attached (RIDGID ladders, Louisville Ladder Co, Louisville KY)
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Quality is: The ability to provide stated needs NOW (and is implied during warranty period.) Warranty period: that period of time that you guarantee to refund/replace/fix your product.
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Safety & Quality in Health Care: HHS Secretary Tommy G. Thompson today (10/11/2001) announced the release of $50 million to fund 94 new research grants, contracts and other projects to reduce medical errors and improve patient safety. This research initiative is part of HHS' broader efforts to improve the quality of care in America and better assure safety across health care settings.
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Reliability Implies: MTBF of x years (for example, e -1 fail in 5 years), proportional to the probability of service over a period of time, T. = performs stated function, without failure (even with misuse) in the stated environment, for a specified period of time.
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Vanderbilt: Reliability & Risk Engineering & Management NSF IGERT awarded 2001 $2.7 M over 5 years BME/ChE/CE/EECS/MT/Math/ME/Owen 2 year support toward PhD Sankaran Mahadevan, CE
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Infant Mortality Wearout Joints, Welds, Contamination, Misuse Corrosion, Cracking, Wear, Crazing, Shorts Screening, Design, Burn-in -- Design, Preventive Maintenance, Replacement, Repair Time -> Failure Rate
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Time-> Friction, Fatigue, Erosion, Corrosion, Cracking, Lack of PM PM, Replacement Misassembly
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Failure Rate Time -> Debug errors, Spec. Errors, Special Cases
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Failure Rate Time -> QI PM Lawsuit
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Is this a reliable ventilator?
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Product Liability Negligence - legal Strict Liability - legal Breach of warranty – legal Defects Failure to warn
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Negligence You owe a duty of care to another The standards for that care have been breached As a result a compensable injury results There are damages or injury to the plaintiff
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Strict Liability The PRODUCT is defective or dangerous. Risk is too high (risk/benefit higher than competition, etc.)
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Breach of Warranty Implied Merchantability (“King’s Pacemakers”) Implied Warranty for particular purpose (pacemaker) Breach of express warranty (written or oral contract: cures 100%)
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Defect Actual defect (sharp edges, …) Consumer expectations Risk/benefit State of the art Defective warnings Inadequate guarding…
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Failure to warn! You have a duty to warn. If you do not warn that coffee is hot, you are likely to get in trouble…
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Examples Coffee burn “found with head trapped in side rails…” Stepladder recall Fluidized air therapy bed X-ray/Cobalt therapy accident Morphine infusion 3 hours not 24 LMA – cyanosis (see MAUDE)
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Some final key phrases Misuse Negligent selection Failure to inspect Use with knowledge of defect Alterations Disclosure through MAUDE (FDA) Disclosure through CPSC (non-FDA)
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