DIMENSIONAL ACCURACY PROFESSIONAL ENGLISH IN USE FOR ENGINEERING

 

PROFESSIONAL ENGLISH IN USE FOR ENGINEERING UNIT 7. DIMENSIONAL ACCURACY

 

A Precision and tolerance It is impossible to produce components with dimensions that are absolutely precise, with sizes exactly the same as those specified in a design. This is because all production processes are imprecise to a certain extent. Therefore, the sizes of several components produced from the same design will vary (differ). Although the variation may only be a few of hundredths of a millimetre, sizes will not be 100% accurate (exact) compared with the design. B Fit When one component goes through another, such as a shaft or a bolt going through a hole, the two must fit together – their sizes and shapes must match. They key question is, how tightly (or loosely) should they fit together? There are two main types of fit:   EXERCISES 7.1 Find words and expressions in A opposite with similar meanings to the words and expressions below (1-10). Sometimes there is more than one possible answer. The first one has been done for you. 1. allowed  permissible 2. exact 3. differ 4. exactness 5. not exact 7.2 Match the related sentences. Look at B opposite to help you. 1 It’ll bind a The bolt will have to turn in the hole 2 It’ll contract. b The bolt won’t be able to turn freely enough in the hole. 7.3 Complete the article about engine blueprinting using the words in the box. Look at A and B opposite to help you. clearances minus plus range variation fit permissible precise tolerances within

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