Chapter 6 Machining Accuracy
Abstract
The machining accuracy of machine parts is the quality foundation of the whole machine. It is usually measured with two indices: machining accuracy and surface quality and their value size will directly affect the performance and life of the whole machine. This chapter mainly involves the machining accuracy.The basic concepts,factorsthat are related with the machining accuracy, the comprehensive analysis of machining errors, and the methods of raising the machining accuracy are discussed in this chapter.
Index
7.1 Basic concepts of machining accuracy
7.2 factors affecting the machining accuracy7.3 statistic analysis of machining errors7.4 methods of raising the machining accuracy
6.1 Basic concept of machining accuracy
6.1.1Machiningaccuracyandmachiningerror
Machining accuracy：The degree of the practical dimensions after
machining conforms to the desired geometrical parameters.The higher the degree conforms, the higher the machining accuracy.
Machining error：The degree of the practical dimensions after machining deviates from the desired geometrical parameters. The size of the machining error denotes the size of the machining accuracy.
“Machining accuracy”and“Machining error”are two different concepts to evaluate the accurate degree of the part geometries. In production
practice, the accuracy is ensured by controlling the machining error or active adapting method 。
6.1.2 The method to study the machining accuracy
Therearetwomethodstostudythemachiningaccuracy.Oneisthesinglefactoranalysismethod,inwhichthemachiningaccuracyisanalyzedbycalculation,experimentorinspectionsoastodecidethesinglefactor’sinfluencinglawtothesingleerror.Anotheroneisthestatisticmethod,inwhichthestatisticaltheoryisusedtoprocesstheinspecteddataofabatchofworkpiecefromthepracticesoastocontroltheprocessrunninginnormalcondition.
Thesetwomethodsareoftenusedtogetherinpractice.Generally,thestatisticmethodisfirstusedtofindoutthelawoftheerror,andjudgethecauses,thenfactoranalysismethodisusedtofindoutthekeyfactorswhichinfluencethemachiningaccuracy.
