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

Abstract

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 working space of the machine was used for the measurements performed as part of the assessment of the measurement system. The quality of the measurements was evaluated with the use of repeatability and reproducibility testing and statistical process control. The analysis results showed that the tested measurement system ensures adequate accuracy and repeatability, and the measurement process is characterized with adequate efficiency in relation to the manufacturing tolerance of the components produced using the machine. Thus, it was proven that the measurement process can be carried out on a machining device, which enables its integration into the closed door technology.

Comparative Performance Evaluation of Multiconfiguration Touch-Trigger Probes for Closed-Loop Machining of Large Jet Engine Cases

“…The T1, T2, and T5 probes can be used for all application tags as defined: setup, adaptive process, measurement of features, and MT error compensation. However, R&R of the main T1 probe in comparison to a similar probe configuration, as shown in the article [28], is significantly lower. The difference is caused by the process tolerance requirements, machine tool size, and 5-axis configuration (tilting head instead of swiveling table, rigid column).…”

“…The R&R method was used for the definition of the repeatability and reproducibility index value of the measuring system for the T1 probe, the most important probe in the system. The R&R evaluation has been performed for both MTs #2 and #3 according to the methodology as proposed in the article [28]. Initial test setup is presented in Figure 6.…”

“…Initial test setup is presented in Figure 6. R&R measurement evaluation has been simplified and adopted in re presented in the article [28] from four to two last sequences due to the m measuring system quality. The R&R test was performed under shop flo (temp.…”

“…The implementation of a closed-loop process is possible provided that the probing system can be used for in-process and post-process measurements of parts on the machining level [28]. Hence, it is necessary submit to control determining the variability of a measurement process across the Measuring System Analysis (MSA) statistical methods such as Repeatability and Reproducibility (R&R) [28,29].…”

“…Bomba et al [28] tested a probing system based on the R&R method and statistical process control (SPC) of straight probes while carrying out an evaluation based on continuously collected data. A high R&R level was achieved and the SPC parameters of the analyzed system in relation to the manufacturing application were good.…”