Duque de Caxias, RJ., CATÁLOGO MITUTOYO / Instrumentos para Metrologia dimensional. APOSTILA LABELO/PUCRS: Laboratórios. View exercicio tolerancia from ENGINEERIN at Universidade Federal do Espírito Santo. METROLOGIA DIMENSIONAL TOLERNCIAS. Conceitos e aplicações ”. Apostila. 85p. Bibliografia Complementar Mitutoyo, , “Instrumentos para Metrologia Dimensional: Utilização Manutenção e.
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A key characteristic is a feature of an installation, assembly, or detail part with a dimensional variation having the greatest impact on fit, performance, or service life.
The identification of key characteristics for a specific product is the responsibility of the dimensional management team working very closely with the customer. Key characteristic identification is a tool for facilitating assembly that will reduce variability within the specification limits. This can be accomplished by using key characteristics to identify features where variation from nominal is critical to fit and function between mating parts or assemblies.
Those features identified as key characteristics are indicated on the product drawing and product data sheets using a unique symbol and some method of codification. However, key characteristic identification does not diminish the importance of other nonkey features that still must comply with the quality requirements defined on the drawing.
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The implementation of a key characteristic system has been shown to be most effective when the key characteristics are:. Statistical process control is a tool that uses statistical techniques and control charts to monitor a process output over time. Control charts are line graphs that are commonly used to identify sources of variation in a key characteristic or metroogia. They can be used to reveal a problem, quantify the problem, help to solve the problem, and confirm that corrective action has eliminated the problem.
A standard deviation is a unit of measure used to describe the natural variation dimehsional an average or mean value.
The natural variation in a key characteristic or process defines its process capability. Capability refers to the total variation within dimensiobal process compared to a six standard deviation spread.
This capability is the amount of variation that is inherent in the process. The higher the Cp value, the less variance there is in the process for a given tolerance. Cpk is a ratio that compares the average of the process to the tolerance in relation to the variation of the process. Cpk can be used to measure the performance of a process. It does not assume that the process is centered. The higher the Cpk value the less loss metrologla associated with the variation.
Cp and Cpk values are simply indicators of progress in the effort to refine a process and should be continuously improved. To reduce rework, the process spread should be centered between the specification limits and the width of the process spread should be reduced. See Chapters 8 and 10 for more discussion of Cp and Cpk.
After key characteristics have been defined and process aposgila tooling plans have been developed, parts must be measured to verify conformance with their dimensional specifications.
engineering – metrologia – dimensioning and tolerancing handbook
This measurement data must be collected and presented in a format that is concise and direct in order to identify actual part variation. Therefore, measurement plans and procedures must be dimensiional to meet the following criteria:.
A continuous program of gage and tooling verification and mettrologia must also be integrated within the framework of the dimensional measurement plan. Assembly tooling must be designed so that their locators are coordinated with the datums established on the product drawings and product data sheets.
This will ensure that the proper fit and function between mating parts metrllogia been obtained. The actual location of these tooling points must then be periodically checked and validated to ensure that they have not moved and are not introducing errors into the product.
Dimensional management tools have been successfully incorporated within commercial 3-D simulation software see Chapter The typical steps in performing a simulation study using simulation software are listed below see Fig. A conceptual design is created within an existing computer aided engineering CAE software apostia as a 3-D solid model. Dimensioning schemes are created in the CAE and are verified and analyzed by the simulation software for correctness to appropriate standards.
Using information from the CAE database, a functional assembly model is mathematically defined and a definition of assembly sequence, methods, and measurements is created.
Using the functional assembly model, a 3-D assembly tolerance analysis is statistically performed to identify, rank, and correct critical fit and functional relationships between the mating parts that make up the assembly. The advantages of using simulation software are that it can be integrated directly with existing CAE software to apostilw a seamless communication tool from conceptual design to final assembly simulation without the dimensiona of building traditional prototypes.
The results also represent reality because the simulations are based on statistical concepts taking into account the relationship between functional requirements as well as the expected process and measurement capabilities.
The dimensional management process can be divided into four general stages: These stages integrated with the various dimensional management tools can be represented by a flow diagram see Fig.
The key factor in the success of a dimensional management program is the commitment and support provided by upper management. Implementing and sustaining the dimensional management process requires a major investment in time, personnel, and money at the early stages of a design.
If top management is not willing to make and sustain its commitment to the program throughout its life cycle, the program will fail. Therefore, no dimensional management program should begin until program directives from upper management clearly declare that sufficient personnel, budget, and other resources will be guaranteed throughout the duration of the project.
It is imperative that the product dimensional requirements are clearly defined in written objectives by the dimensional management team at the beginning of the design cycle. If the objectives cannot be metrolofia upon by metrologua consensus of the dimensional management team, the program cannot proceed to defining the design concept. The implementation of a key characteristic system has been shown to be most effective when the key characteristics are: Dimensional Management A standard deviation is a unit of measure used to describe the natural variation above an average or mean value.
Therefore, measurement plans and procedures must be able to meet the following criteria: Metrologia Breve resumo sobre Metrologia. Metrologia legal no brasil Funcionalidade do trabalho no Brasil.
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