IJERT-Comparative Study of Three-Dimensional Measurement between CMM and CN Machine Tool -Case: Flatness and Cylindricity (original) (raw)

Geometric Measurements on a CNC Machining Device as an Element of Closed Door Technology

Sensors

The article discusses the quality testing of a measuring system consisting of a CNC machine with measuring probes. The research was conducted in a broader context regarding the implementation of the closed door technology, i.e., production without human intervention, in an aviation plant manufacturing aircraft gearbox systems. This technology may involve automated measuring operations performed in machining centers, and not in measuring laboratories, provided that the quality of the measurements is appropriate. The aim of the study was to investigate whether the CNC machining device can be used to measure the geometric features of aircraft gearbox housing. For this purpose, measurement experiments were carried out with the use of three different probes. Measurements were carried out using four sequences of increasing complexity, so that, after error analysis, it was possible to find the causes of possible irregularities. A reference ring with known dimensions and position in the wor...

3D Measurement - Comparison of CMM and 3D Scanner

DAAAM Proceedings, 2020

Continuous improvement and optimization of products, which is the most often reflected in more complex geometrical and dimensional characteristics of products and increasing market demands for quality, lead to the development of new solutions in quality control. In industry today, the control of geometric characteristics is most often performed by the tactile method of probe stylus, i.e. using 3D coordinate measuring machines (CMM). Coordinate measuring machines have long been the only option in quality control of various products and have become generally accepted in industrial quality. In recent years, the development of digital technologies, i.e. the development of a new generation of hardware and software, has enabled the development of other methods of 3D measurement such as 3D scanner, which has proven to be a good alternative to CMM machines. The aim of this review is to provide insight into the areas of application of both devices as well as their advantages and disadvantages and possible future solutions and application of devices in this area.

Laine Mears Quality and Inspection of Machining Operations: CMM Integration to the Machine Tool

Dimensional measurement feedback in manufacturing systems is critical in order to consistently produce quality parts. Considering this, methods and techniques by which to accomplish this feedback have been the focus of numerous studies in recent years. Moreover , with the rapid advances in computing technology, the complexity and computational overhead that can be feasibly incorporated in any developed technique have dramatically improved. Thus, techniques that would have been impractical for implementation just a few years ago can now be realistically applied. This rapid growth has resulted in a wealth of new capabilities for improving part and process quality and reliability. In this paper, overviews of recent advances that apply to machining are presented. More specifically , research publications pertaining to the use of coordinate measurement machines to improve the machining process are discussed.

CMM Measurement Variability Analysis: A Comparison Between Two Metrological Laboratories Measuring Three Industrial Workpieces

2008

Quality may be defined as a set of requirements a system should satisfy in order to meet customer's needs. Control of these requirements assures satisfaction of relevant standards, and consequently the performance levels of a manufacturing/transactional stream. In this context it is fundamental to define control procedures and reliable measurement systems adequate for adopting improvement action as soon as anomalies and dysfunctions are detected. This paper deals with a study of measurement variability occurring during practical exploitation of CMMs (Coordinate Measuring Machines). These measurement systems are designed to probe selected points of workpiece surface, and compare the relevant coordinates or derived quantities with specified values; capability and versatility of CMMs justify their widespread use in industry. Evaluation of CMM measurement variability is however often awkward owing to a number of factors, such as e.g. measurement task, environment, operator and measurement procedures. A round robin exercise involving two industrial laboratories was planned in order to address these issues. Three typical machine tool parts were circulated among participants, who were asked to measure linear dimensions as well as tolerances at specified locations, according to an agreed upon schedule. Results of measurements, performed by experienced CMM industrial users, were analyzed in order to bring out discrepancies, and suggest remedial actions in the light of information gathered. Several factors involving metrological as well as other aspects were observed to cause major discrepancies, yielding in turn information on where to look for potential sources of trouble. Conclusions were drawn in terms of operating procedure, leading to improved information on origin and components of variability.

The role of measurement and modelling of machine tools in improving product quality

2013

Manufacturing of high-quality components and assemblies is clearly recognised by industrialised nations as an important means of wealth generation. A "right first time" paradigm to producing finished components is the desirable goal to maximise economic benefits and reduce environmental impact. Such an ambition is only achievable through an accurate model of the machinery used to shape the finished article. In the first analysis, computer aided design (CAD) and computer aided manufacturing (CAM) can be used to produce an instruction list of three-dimensional coordinates and intervening tool paths to translate the intent of a design engineer into an unambiguous set of commands for a manufacturing machine. However, in order for the resultant manufacturing program to produce the desired output within the specified tolerance, the model of the machine has to be sufficiently accurate. In this paper, the spatial and temporal sources of error and various contemporary means of modelling are discussed. Limitations and assumptions in the models are highlighted and an estimate of their impact is made. Measurement of machine tools plays a vital role in establishing the accuracy of a particular machine and calibrating its unique model, but is an often misunderstood and misapplied discipline. Typically, the individual errors of the machine will be quantified at a given moment in time, but without sufficient consideration either for the uncertainty of individual measurements or a full appreciation of the complex interaction between each independently measured error. This paper draws on the concept of a "conformance zone", as specified in the ISO 230:1-2012, to emphasise the need for a fuller understanding of the complex uncertainty of measurement model for a machine tool. Work towards closing the gap in this understanding is described and limitations are noted.

Investigation of Functional Dependency between the Characteristics of the Machining Process and Flatness Error Measured on a CMM

Measurement Science Review, 2021

Numerous studies have shown that the choice of measurement strategy (number and position of measurement points) when measuring form error on a coordinate-measuring machine (CMM) depends on the characteristics of the machining process which was used to machine the examined surface. The accuracy of form error assessment is the primary goal of verification procedures and accuracy is considered perfect only in the case of the ideal verification operator. Since the ideal verification operator in the "point-by-point" measuring mode is almost never used in practice, the aim of this study was to examine a relationship which had not been examined in earlier studies, namely how the machining process, surface roughness and a reduced number of points in the measurement strategy affect the accuracy of flatness error assessment. The research included four most common cutting processes applied to flat surfaces divided into nine different classes of roughness. In order to determine functional dependency between the observed input variables and the output, statistical regression models and neuro-fuzzy logic (artificial intelligence tool) were used. The analyses confirmed the significance of all three input parameters, with surface roughness being the most significant one. Both the statistical regression models and neuro-fuzzy models proved to be adequate, matching the experimental results. The use of these models makes it possible to determine flatness error measured on a CMM if input variables considered in the paper are known.

Performance of a five-axis machine tool as a coordinate measuring machine (CMM)

Journal of Advanced Mechanical Design, Systems, and Manufacturing

The use of machine tools for on-machine coordinate measurement on the workpiece is becoming commonplace. However, numerous errors can adversely affect the measurement accuracy. For instance, the inter-axis parameters are major contributors to the overall machine tool's inaccuracy hence estimation and compensation of such errors are prerequisite to fully exploit the machine's measurement capability. This paper presents a scheme to assess the accuracy of coordinate measurement by probing a precision sphere mounted on the machine table for different rotary axes indexations. Only the sphericity of the reference sphere is assumed and neither its size nor position. All individual probing data from all indexations are used for the assessment of the apparent out of sphericity of the reference sphere. Machine readings are processed either directly, using the machine nominal model, or using a compensated model. This provides a fast method to validate on-machine measurement before and after compensation with the exception of isotropic scale effects.