Analysis of flatness in case of different cutting technologies

The geometric tolerancing (GPS or GD&T) has increasing importance in machine design, manufacturing and measuring. The geometric tolerances define the deviation of the different kinds of geometric elements in more sophisticated way, than dimensional tolerances. Nevertheless, the application of them requires more wariness in design process, manufacturing process planning and measuring. The key element is the measuring, when the requirements have to be inspected according to the standards, and striving to the maximal productivity and accuracy. The paper presents a new method to evaluate the flatness deviation by limited number of measured points and it uses regression analysis based on partial point sets. The method considers the observation, than the number of measured points increases the evaluated flatness values. The article presents the new method, the results of test, which support it and the result of verification tests also.

As far as machine parts are concerned, accuracy can be defined in many aspects. In order for a workpiece to be functional, dimensional and surface roughness requirements are not enough. Accuracy of geometric elements and position tolerances is necessary information. The notation, definitions, interpretations and general values of geometric tolerances are defined by standards. Nevertheless, there are several mathematical methods of calculating values based on data measured by means of coordinate measuring machines. Standards demand the use of the minimum zone method in assessing form deviation without mentioning the way of obtaining it. In this paper, the minimum zone method, which is an iterative algorithm, was investigated. Thus, the result of flatness measurement was calculated by continuous approximation. There are various methods of defining the steps of iteration, affecting the length of time and accuracy of the flatness value. The aim of the research was to examine the characteristics of two non-commercial software solutions for assessing the minimum zone in comparison with the commercial CMM software. Based on the analysis, it can be concluded that the developed software solutions are efficient in assessing flatness error and that the differences between these and the commercial software are negligible.

The use of geometric tolerances has increasing importance in the industry, but the correct application of it needs deeper understanding. Several aspects should be considered like the work of the product, material properties, manufacturing and measuring circumstances, and the regulations of concerning standards. The article presents the measuring and evaluation problems through the example of flatness. The effect of different point sampling strategies is investigated: twelve methods are compared in case of eight test surfaces, and a modification method is suggested.

Measurement and evaluation of the flatness error of a milled plain surface Abstract – The accuracy requirement of a machine part means not only the dimensional accuracy, but the surface quality, the accuracy of shape and the position of a geometric feature. Because of the increasing industrial requirements, the meaning, measuring and manufacturing of shape and position tolerances come into the limelight. In this article the effect of the different measuring strategy on the coordinate measuring machine is investigated in case of a milled plain surface. The question is, how can be minimized the number of measured points beside the right measured value. From the viewpoint of the measuring process the aim is to create an appropriate strategy, which can ensure the real value of the errors and short measuring time.

During the production process several factors have influence to the accuracy of the product, therefore based on functional requirements tolerances are defined in the design phase. Beside the dimensional tolerances the surface roughness and geometrical tolerances can be defined. The current article presents the application and design process of these tolerances and the uncertainties and problems of the application, the manufacturability and the measurability. A gyártási folyamat során a termék pontosságát számos tényező befolyásolja, ezért a funkcionális követelmények figyelembe vételével tűréseket definiálunk a konstrukciós tervezés során. A mérettűrések mellett felületi érdességet, valamint alak- és helyzettűréseket adhatunk meg. Jelen cikk e tűrések alkalmazási lehetőségeit és tervezési folyamatát ismerteti, foglalkozik a tűrésezés során jelentkező problémákkal és bizonytalanságokkal, a gyárthatóság és mérhetőség kérdésével.