Robert Čep

Surface Roughness after Machining and Influence of Feed Rate on Process

The aim of the work is find out influence of feed rate on the quality for the machined surface, especially surface roughness. The experiment was carried out by cutting tool HURCO VMXt30 with respect to the following cutting parameter: cutting speed 250; 350; 450; 550 and 850 m.min-1, feed 0,1; 0,5 and 1,0 mm/tooth. For testing was used two most common materials in the steel grade 1.1191 (12 050) and 1.2343 (19 552), and we chose two ordinary parameters of surface roughness; Ra - arithmetical mean roughness deviation and Rz - the largest inequalities height profile in the transverse direction and the longitudinal direction of machining. The structural equations will be the result which can describe the character depending on the cut surface parameters.

Surface Quality Control of Materials Being Cut by Laser with Respect to Corrosion Resistance

In the field of laser cutting, the research area is oriented mainly to understanding of the mechanism of removal, as well as to the combination of factors entering the process. This process of disintegration of materials presents a problem of analytical approximation, elaboration, and description [1 - . Compared with previous approach to a solution, we have chosen our own way and we focus on mechanical respectively stress-strain parameters of the material being cut and the mechanical balance system: material properties tool properties deformation properties. We shall present here the basic forms of prediction equations for calculating the roughness of cutting walls, as well as other equations which were derived by modifying the basic equations for different application purposes, especially to calculate the optimum traverse speed vpopt, optimal laser performance Wlasopt and technologically important ratio INDvpwopt = vpopt/Wlasopt. These contain easily available input variables for substitution. The basic forms, including the modified forms are aimed at predicting the quality of cut with its depth limits. The paper presents the method of optimization of the ratio between the traverse speed vpand laser power Wlas which minimizes the final surface roughness after cutting with a direct impact on corrosion resistance of materials.

Research of the Technological Parameters Importance for Plasma Arc Thermal Cutting

Many clients and plasma arc thermal cutting devices providers deal with the question which technological factor in adjustment process of cutting has the greatest influence on the final product quality. Many researchers and teachers deal with this issue during lecturing these knowledges for university students. The article presents the design and evaluation of plasma arc cutting technological process. Influence of technological factors on roughness parameters Ra of the steel surface ISO Fe510 have been evaluated using planned experiments. Using factor experiment, the significance of the four process factors: plasma burner feed speed, plasma gas pressure, nozzle diameter, distance between nozzle mouth and material have been observed. Regression models obtained by multiple linear regression indicates the quality level as observed factors function.

Properties and comparison of PVD coatings

Razvoj i primjena novih materijala u strojarskoj praksi dovode do mnostva pitanja u odnosu na njihovu tehnolosku primjenu. Ovaj je rad usmjeren na istraživanje problema povezanih s cementiranim karbidom premazanim primjenom PVD (Physical Vapour Deposition) metode. U teorijskom dijelu rada upoznaje se PVD tehnologija nanosenja sloja i detaljnije opisuje metoda isparavanja luka. Opisuju se također materijali i vrste slojeva, njihova svojstva, moguce primjene i na kraju objasnjavaju nacela eksperimentalnih metoda primijenjenih u ispitivanju slojeva. U eksperimentalnom dijelu rada opisuju se postupci mjerenja i ispitivanja te daju rezultati ispitivanja. Adhezija i trajnost slojeva uspoređeni su na izrezanim umetcima s razlicitim PVD – premazi s nanostrukturom i nanoslojem. Ispitivanja su provedena glodanjem ugljicnog celika 1.1191 (C45) buduci da se taj celik uvelike rabi u mnogim industrijskim primjenama, a također i kao referentni material. Na kraju se ocjenjuju rezultati ispitivanja na temelju dobivenih podataka.

Short-Term Testing of Cutting Materials Using the Method of Interrupted Cut

Purpose of this paper is to compare the characteristics of cutting of materials of different structures for testing intermittent cutting. Materials comparisons in the machining of steel strips samples C45 (12 050) are: cutting ceramics and cemented carbides. These materials have different characteristics of the cutting properties. Intensive development in the form of improved cutting properties passed in recent year’s just cutting ceramics. This is what resulted in its use not only for machining a continuous section, but its application was extended to the intermittent cutting machining.

Study on Edgetrimming of Holes in the Thick Steel Plates by Metal Plastic Forming Technology

In this paper the results of investigations carried out in the field of hole-flanging in thick steel sheets were presented. All experiments were performed in the Division of Metal Working of the Institute of Materials Technology at the Poznan University of Technology. An experiments of hole-flanging were carried out using cylindrical, spherical and conical punches. The blanks made of BW11, 34GHA and 15HGMV steels were investigated using different holes diameters. The holes were prepared using boring and laser techniques. The influence of the method of holes preparation on the quality and dimensions of obtained flanges were discussed.

Surface Integrity at Reaming by Reamer MT3 Head

Abstract The article is focused on surface integrity at reaming with high-productive reaming MT3 head made by HAM-FINAL Company. The term surface integrity is the surface condition of a workpiece after being modified by a manufacturing process. A machining process produces a surface characterized by the shape, metallurgy and mechanical properties. These surface aspects clearly indicate that a machined surface is very complex. Obviously, a high-energy input increases the likelihood of metallurgical damage and therefore results in a poor surface integrity which has effect on final product. Taking into account different types of created energy transferred to the tested surface and subsurface layer, the basic factors influencing surface integrity are temperatures, residual stresses, metallurgical transformations and also surface plastic deformation. The aim of experimental part is surface integrity tested on holes by reaming MT3 head during manufacturing process and last aim is find out MT3 head tool-life with their evaluation.

Evaluation of residual stresses after irregular interrupted machining

Residual stress occurs in many machined components and parts. Over time, several methods have been developed for the investigation of residual stress in the material – destructive and non-destructive. This article deals with the evaluation and comparison of residual stress in the material when machining steel C45 and 11CrMo910, when the tool enters into the cut and stands out in conditions of an interrupted cut. A non-destructive method, based on X-Ray diffraction, was applied to evaluate the residual stress. The points were measured on the last machined slat by using interrupted cut simulator. An irregular interrupted cut was achieved by gradually machining 4, 3, 2 and 1 slat. The experiments were realized in co-operation with the Faculty of Mechanical Engineering, VSB – Technical University of Ostrava, Czech Republic and the Faculty of Mechanical Engineering, the University of Žilina, Slovakia.

Measurement System Analyses – Gauge Repeatability and Reproducibility Methods

Abstract The submitted article focuses on a detailed explanation of the average and range method (Automotive Industry Action Group, Measurement System Analysis approach) and of the honest Gauge Repeatability and Reproducibility method (Evaluating the Measurement Process approach). The measured data (thickness of plastic parts) were evaluated by both methods and their results were compared on the basis of numerical evaluation. Both methods were additionally compared and their advantages and disadvantages were discussed. One difference between both methods is the calculation of variation components. The AIAG method calculates the variation components based on standard deviation (then a sum of variation components does not give 100 %) and the honest GRR study calculates the variation components based on variance, where the sum of all variation components (part to part variation, EV & AV) gives the total variation of 100 %. Acceptance of both methods among the professional society, future use, and acceptance by manufacturing industry were also discussed. Nowadays, the AIAG is the leading method in the industry.

SURFACE MICROHARDENING STUDIES ON STEELS AFTER HIGH FEED MILLING

The paper deals with the impact of high-speed machining production methods on the integrity of component surfaces. One has to point out that cutting conditions during machining have a significant impact on the final properties of surface and subsurface layers of the workpiece. The conclusion summarizes and analyzes the achieved results of experimental activities on stainless austenitic steel 1.4301, hardened tool steel 1.2343 and high-speed steel 1. 3344 (ASP 2023). The results of the work experimental parts demonstrate the influence of cutting parameters on selected surface integrity ones, specifically strengthening the surface and subsurface layers. The performed experiments show that microhardness of a surface layer of the machined material can be influenced by suitable cutting conditions and other cutting process parameters.