Gauge Repeatibility and Reproducibility (Gauge R&R) : (Previous) (Better)
GR&R
methodology consist of quantifying the measurement error due to
equipment and operators. Data is collected by several operators
measuring the same set of parts on the same equipment. The average
ranges of the part measurements determine the equipment variability, and
the differences in the measurement averages determine the operator's
(apparaisers) variability. The methodology for attaining the GR&R of
a measurement system is as follows:
1.
The parts to be used in the GR&R study should be identified. Up to
10 parts are normally used from the same production proces.
2.
Up to three skilled operators should be identified to make the
measurements. They should be familiar with the parts and measurement
equipment.
3. Each
operator then measures each part on the same equipment several times;
these measurements are called trials. Usually up to three trials are
made by each operator.
4. The errors are thus generated by n parts, which are measured and repeated r times by different operators.
GR&R represents 99% of the measurement error caused by either operator or equipment.
(S. G. Shina, Siz Sigma for Electronics Desingn and Manufacturing, pp. 158-159)
Gauge Repeatibility and Reproducibility (Gauge R&R) : (New) (Measurement Standart)
An important aspect of six sigma is the recognition of the effects of measurement error on performance metrics. With a target of 3.4 DPMO, small measurement errors can be significant in the final assessment of performance. The approach developed by six sigma quality professionals is to include the evaluation of measurement error in the statiscal analysis. Applying analysis of varience (ANOVA, see Chapter 5), the evaluation of measurement variation is termed gauge repeatibility and reproducibility (Gauge R&R), and the approach assesses the amount of variability measurements due to the measurement system and compares this variation to the total observed variability to determine the extend to error included in the measurements. Several components affect a measurement system!s variability.
(Advanced Performance Improvement in Health Care: Principles and Methods, Donald E. Lighter, p.303)
Electrochemical Discharge Grinding (ECDG) : (New) (Grinding Type)
Electrochemical or electrolytic grinding is a process used for metal removed by an electrochemical decomposition of the work material aided by the cutting action of an abrasive (mechanical). 78-1 (Page 408).
In the electrochemical process, a metal bonded wheel is used as the cathode(—) and the workpiece is electrically connected to a DC power source and used as the anode ( + ). 78-2. The DC current from the power supply unit passes through the electrolyte between the wheel and the workpiece and electrochemically attacks the workpiece.
An abrasive wheel continuously removes an electrically resistant film which would otherwise remain on the workpiece and stop the electrochemical action.
Electrochemical grinding(ECG) is done without burr or heat or metallurgical damage. 78-3. NOTE: A great deal more power is required to remove a given amount of material by this method than in conventional grinding. The electrolyte has two primary functions: (1) to pass high current from the workpiece to the wheel and (2) to combine chemically with the workpiccc material. These functions require that the electrolyte completely fill the gap area. It is necessary that a continuous controlled supply of filtered electrolyte be distributed evenly over the cutting area.
Power supplies generally range from 50 to 3,000 ampere DC capacities. The power supply must be able to provide constant voltage under varying load conditions.Two abrasives are commonly used in electrolytic wheels: diamond and aluminum oxide. Diamond wheels are used when machining tungsten carbide, and aluminum oxide wheels arc used when machining other materials.The electrochemical machinc must be a good quality machine tool with adequate corrosion protection, a good electrolyte system, and a variety of speeds and feeds.
There are several facets of the grinding operation which offer definite advantages over conventional methods:
1. There is a savings in wheel costs. Since 90% of metal removal is accomplished by electrochemical action and only 10% by abrasive action, there is considerable reduction in wheel wear.
2. Trueing of the wheel is done less frequently due to low wheel breakdown.
3. High production rates arc obtained when machining hard materials such as cemented carbides or Stellite.
4. Cutters ground by this method generally have increased life due to the elimination of the rough edges that arc obtained in conventional tool grinding operations.
5. Freedom from workpicce distortion is due to the “cold machining" characteristic of this type of grinding.
A comparison of three processes, clcctric discharge machining, electrochemical machining, and electrochemical grinding, is shown. 78-4.
(21st Centuty Manufacturing: National Initiative For Product Data Exchange, DIANE Publishing Company, p.408)
There is no old answer !!!
(Advanced Performance Improvement in Health Care: Principles and Methods, Donald E. Lighter, p.303)
Electrochemical Discharge Grinding (ECDG) : (New) (Grinding Type)
Electrochemical or electrolytic grinding is a process used for metal removed by an electrochemical decomposition of the work material aided by the cutting action of an abrasive (mechanical). 78-1 (Page 408).
In the electrochemical process, a metal bonded wheel is used as the cathode(—) and the workpiece is electrically connected to a DC power source and used as the anode ( + ). 78-2. The DC current from the power supply unit passes through the electrolyte between the wheel and the workpiece and electrochemically attacks the workpiece.
An abrasive wheel continuously removes an electrically resistant film which would otherwise remain on the workpiece and stop the electrochemical action.
Electrochemical grinding(ECG) is done without burr or heat or metallurgical damage. 78-3. NOTE: A great deal more power is required to remove a given amount of material by this method than in conventional grinding. The electrolyte has two primary functions: (1) to pass high current from the workpiece to the wheel and (2) to combine chemically with the workpiccc material. These functions require that the electrolyte completely fill the gap area. It is necessary that a continuous controlled supply of filtered electrolyte be distributed evenly over the cutting area.
Power supplies generally range from 50 to 3,000 ampere DC capacities. The power supply must be able to provide constant voltage under varying load conditions.Two abrasives are commonly used in electrolytic wheels: diamond and aluminum oxide. Diamond wheels are used when machining tungsten carbide, and aluminum oxide wheels arc used when machining other materials.The electrochemical machinc must be a good quality machine tool with adequate corrosion protection, a good electrolyte system, and a variety of speeds and feeds.
There are several facets of the grinding operation which offer definite advantages over conventional methods:
1. There is a savings in wheel costs. Since 90% of metal removal is accomplished by electrochemical action and only 10% by abrasive action, there is considerable reduction in wheel wear.
2. Trueing of the wheel is done less frequently due to low wheel breakdown.
3. High production rates arc obtained when machining hard materials such as cemented carbides or Stellite.
4. Cutters ground by this method generally have increased life due to the elimination of the rough edges that arc obtained in conventional tool grinding operations.
5. Freedom from workpicce distortion is due to the “cold machining" characteristic of this type of grinding.
A comparison of three processes, clcctric discharge machining, electrochemical machining, and electrochemical grinding, is shown. 78-4.
(21st Centuty Manufacturing: National Initiative For Product Data Exchange, DIANE Publishing Company, p.408)
There is no old answer !!!
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