Technological Aspects in Manufacturing of Non-Circular Gears

The construction and manufacture of non-circular gears is one of the most difficult issues in machine technology. Due to the limited technological capabilities of traditional machines and tools, past manufacturing methods were unable to calculate the assumed shape of the tooth line and its profile. Modern manufacturing methods using computer numerical control allow for the generation of non-circular gears with free-form tooth profiles and curvilinear teeth in their lengthwise direction. These methods are also used to manufacture internal gears. This article provides a review of the methods of machining non-circular gears and presents the results of the research on the Fellows method using a shaper cutter, as well as the wire electrical discharge machining method

Statistical Process Control Using Control Charts with Variable Parameters

An extremely important issue in quality management is monitoring and diagnosing processes, and, subsequently, supervising them using so-called control charts. In typical production processes, charts with constant parameters are commonly used, such as x-R, x-s, CUSUM, EWMA and others, which, in most cases, are effective tools for process stability evaluation. Charts considered untypical (in statistical process control) are those with variable sample sizes, variable sampling intervals and/or variable control limits. Such charts are used when process analysis based on standard, well-known charts may lead to serious errors. Modern control charts are a response to the requirements of Industry 4.0 and are an excellent tool for supervising production processes. Their use together with Cp and Cpk indices and other process capability indices is a starting point for process improvement. The methodology of nonstandard charts is inadequately recognized and rarely used in practice. The theory of their design and examples of their use will be presented and characterized in this paper

Spindle Error Movements and Their Measurement

The spindle of a machine tool is an important component of the machine. Its condition affects not only operation of the machine tool but also, above all, the quality of the workpiece. This paper explains the terminology and describes the research methods used to measure the spindle error movements of cutting machine tools. This article explains the impact of spindle motion inaccuracies on the quality of workpieces, quotes the requirements of European and American standards, and describes the current state and directions of development of the presented methods. Our own research work in this field is also presented

Feasibility of Cobalt-Free Nanostructured WC Cutting Inserts for Machining of a TiC/Fe Composite

The paper presents results of investigations on the binderless nanostructured tungsten carbide (WC) cutting tools fabrication and performance. The scientific novelty includes the description of some regularities of the powder consolidation under electric current and the subsequent possibility to utilize them for practical use in the fabrication of cutting tools. The sintering process of WC nanopowder was performed with the electroconsolidation method, which is a modification of spark plasma sintering (SPS). Its advantages include low temperatures and short sintering time which allows retaining nanosize grains of ca. 70 nm, close to the original particle size of the starting powder. In respect to the application of the cutting tools, pure WC nanostructure resulted in a smaller cutting edge radius providing a higher quality of TiC/Fe machined surface. In the range of cutting speeds, vc = 15–40 m/min the durability of the inserts was 75% of that achieved by cubic boron nitride ones, and more than two times better than that of WC-Co cutting tools. In additional tests of machining 13CrMo4 material at an elevated cutting speed of vc = 100 m/min, binderless nWC inserts worked almost three times longer than WC-Co composites