ANOVA Gauge Repeatability and Reproducibility (ANOVA Gauge R&R) is a technique of Measurement Systems Analysis.  It evaluates the measurement system using the ANOVA (Analysis of Variance) Random Effects model.  This evaluation is not only limited to gauges, but also applicable to measurement systems like test methods, measuring instruments, and others.

ANOVA Gauge R&R determines the viability of a measurement system by measuring the amount of variability in the measurements, and comparing it with the total variability.  A measurement system may be affected by several factors like:

• Measuring instruments -  the gauge or the instrument, and all supports, mounting blocks, load cells, fixtures, etc.  Examples of variation sources are sloppiness in mating parts, ‘zero’ blocks, machine’s ease of use, etc.  Sources of variation in systems making electrical measurements include analog-to-digital converter resolution and electrical noise.
• Operators -  Efficiency of the people to carry out the verbal/written instructions.
• Test methods -  include how the devices are set up, parts are fixed, data is recorded, etc.
• Specification -  based on which the measurement is being reported.  Though engineering tolerance does not affect measurement, it is vital in the evaluation of the measurement system’s viability.
• Parts -  what are being measured.  While a measurement system may hold good for measuring steel block length, it may not be suitable for measuring rubber pieces.

Gauge R&R consists of the following two important aspects:

• Repeatability -  The variation in measurements taken on the same item, under the same conditions, by a single person or instrument
• Reproducibility -  The variability induced when different operators (or laboratories) measure the same item

Gauge R&R is used only for the precision aspect of a measurement system.  It is an important Six Sigma methodology tool, and is also a PPAP (Production Part Approval Process) documentation requirement.  GRR (Gauge R&R) measures parts under the established measurement system, and aims to report all possible variation sources in measurement, for understanding and assessment.

Multiple operators are needed for getting report on reproducibility errors.  The ASTM E691 Standard Practice requires at least 10 operators or laboratories.  Others demand only 2 or 3 for measuring the same parts.  For accounting repeatability errors, one operator measures the same part several times.  In case of multiple testing of different parts, full set of operations should be included in each measurement cycle.  For accounting operator interaction with different parts, usually five to ten parts are measured.  The GRR matrix enables the Quality Engineer to assess risks based on the vitality of the measurement and its cost.  There are several methods for determining the degree of replication and sample sizes.  The ‘10x2x2’ (ten parts, two operators, two repetitions) is a common sampling for some studies.

The following are some common misconceptions regarding GRR:

• Single GRR is sufficient per family of gauges -  GRR relates to a complete measurement system – including the specification, part, operator, and method – rather than one caliper.
• GRR will not pass using parts -  GRR can assess precision of a device of system. only if that system is measuring standard weights and blocks.  In case of changes in part like deformity occur in measurement, it is taken as a component of measurement system error.
• It is necessary to report GRR results on PPAP documentation for each measurement -  It is not necessary, as usually, the Quality Engineer himself makes a good assessment.  Only if the characteristic is vital to safety, it requires valid GRR.  Otherwise, it is not required for easy measurement of parts with acceptable precision.  During PPAP reviews, customers may require additional GRRs.
• GRR performance is very expensive -  GRR performance is inexpensive for simple devices, and the result can be utilized for assessment of subsequent measurements using the system.  Costs occur for additional measurements only.  Only in case of destructive testing, the costs are higher.
• GRR must be within 10% to pass -  The final decision to accept the precision of measurement system is taken between the supplier and the customer.  GRR is just a tool for assessment, and not a deciding factor whether to accept the level of precision of a measurement system or not.

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ERP vendors are providing built-in configuration tools to enable to customers to change the working of the out-of-the-box core system.  The basic differences between configuration and customization are:

• Configuration like organizational trees, cost/profit center structure setups, purchase approval rules, etc. is required to some extent before making the software work.  But customization always remains an option.
• Configuration is open up to all the customers, whereas customization varies for each individual customer in the level of efforts to capture market.
• The changes to configuration are entered as data in vendor-supplied data tables, whereas changes in customization require some programming and/or table structure changes.
• The effect of configuration changes are predictable, whereas the effect of customization is unpredictable, requiring the implementation team to spend considerable time on stress testing.
• Configuration changes can be easily upgraded to new software versions.  Though some customizations pass through upgrades, they require re-testing.  And if the customizations are more extensive, then the upgrades would overwrite them and they need manual re-implementation.

While customizing ERP packages can be quite cumbersome and expensive, they also provide opportunity for achieving excellence in specific areas of business process.

ERP packages are also suitable for ‘extensions’, i.e., they can be combined with third-party programs which perform reporting, archiving, and republishing, and also for transactional data captures (like tills, scanners, and RFIDs).  But ERP applications have a set of rules to control the creation or changing of data.

ERP system helps in effective interfaces of tasks which include:

• Connection of required software for accurate forecasting
• Integration of functional areas ensuring productivity, efficiency, and effective communication
• Design engineering
• Order tracking, right from acceptance till fulfillment
• Revenue cycle, right from invoice till cash receipt
• Management of inter-dependent complex processes
• Tracking of the triangular process of purchase orders, inventory receipts, and costing
• Tracking accounting tasks at a granular level

The following are the advantages of centralization of data by ERP systems in one place:

• Problem of synchronizing changes between multiple systems is eliminated
• Business processes that cross functional boundaries can be controlled
• Complete top-down view of the enterprise is visible
• Since a single structure contains multiple permissions and security models, loss of sensitive data is greatly reduced

ERP system also has some security features for protection against both outsider crimes like industrial espionage, and also insider crimes like embezzlement.  It has functions for implementation of internal controls.  It provides better integration with other kinds of information security tools.

But the ERP system also has its own disadvantages.  Problems mainly arise due to insufficient investment on training the employees on the ERP system, as well as absence of data protection policies regarding ERP systems.  Some disadvantages are listed below:

• ERP software can be customized only to a limited extent
• Redesign of business processes as suggested by ERP system may effect loss of competitive advantage
• ERP system implementation can be quite expensive
• The rigidity of ERP to adapt to a specific workflow required by some organizations leads to its failure
• There are many integrated links which are effective only if other applications are accurate
• Switching costs of ERP system is very high and reduces flexibility and strategic control at corporate level
• If errors are made with regard to company boundaries, it will affect employees’ morale, accountability, and lines of responsibility
• Resistance of departments to share sensitive internal information among them may render the ERP system ineffective
• In case of large organizations where there are multiple departments, each having their own mission, resources, chains-of-command, etc., consolidating them as a single enterprise would not fetch much benefits

But the advantages of ERP system outrun the disadvantages, and ERP vendors are bringing out more sophisticated system patterns which are sure to benefit organizations.