Jana Petrů

A new method for the prediction of laser cut surface topography

Abstract The submitted contribution focuses on the clarification of a laser beam cutting technology especially from the point of view of created surface topography. It provides a new view on a deformation process caused by laser beam action and on possibilities of using the surface topography. The measurement and characterisation of surface topography was performed in depth traces using a contact profilometer Surftest SJ 401 and by and an optical-contact profilometer Talysurf CLI 2000 (measured from the top edge of the sample). Thanks to this procedure, it was possible to observe and to measure a development of the numerical values of the surface (profile) roughness parameter Ra. Based on the measurement of the surface topography, there were analyzed and interpreted data with a purpose to theoretically describe surface topography and to develop an analytical solution for the profile topographical function. By using the profile topographical function, it is possible to solve the practical problems the most engineers and users face in laser beam cutting technology (LBC) process, as well as to maximize LBC manufacturing system performance and to determine the values of the process parameters that will reach the desired product quality.

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.

Rationalization of manufacturing of plastic injection moulds by abrasive waterjet

The article deals with a proposal and a theoretical solution for the rationalization of manufacturing of parts of plastic injection moulds by abrasive waterjet cutting. On the basis of experimental tests and by the application of advanced abrasive waterjet technology to the process of manufacturing of plastic injection moulds, it has been found that there is a possibility of considerable time saving, i.e. a marked shortage in time period from product ordering to dispatching. In such a way it is possible to increase the competitiveness of a company and to ensure its stable position on the market even in the time of global crisis.

Mechanisms of cutting blade wear and their influence on cutting ability of the tool during machining of special alloys

With increased requirements for quality and shelf life of machined parts there is also a higher share of the use of material with specific properties that are identified by the term “superalloys”. These materials differ from common steels by mechanical and physical properties that cause their worse machinability. During machining of “superalloys” worse machinability has negative influence primarily on the amount of cutting edge wear, which shortens durability of the cutting tool. The goal of experimental activity shown in this contribution is to determine individual mechanisms of the cutting edge wear and their effects on the cutting ability during high speed machining of nickel superalloy. A specific exchangeable cutting insert made from cubic boric nitride was used for machining of the 625 material according to ASM 5666F. The criteria to evaluate cutting ability and durability of the cutting tool became selected parameters of surface integrity and quality of the machined surface.

Impact of cutting tool geometry on the dynamic load of system in the machining process of nickel Alloy 625

The article is focussed on comparing and determining the impact of the cutting geometry of the cutting tool due to dynamic load on system and microgeometry machined surface. For longitudinal turning nickel alloy Alloy 625 (W. Nr. 2.4856) rounded indexable cutting insert was used (RCMT 10T3M0 – F2) and its equivalent squared indexable cutting insert (SNMG 120412 – MR3) coated with fine-grained PVD (Ti, Al) N + TiN. Experimental testing of nickel Alloy 625 was under predetermined cutting conditions. In the selected depth of the removed material of 0.5 mm and 1.5 mm was measured in the course of machining the size of the individual components of cutting forces.

INFLUENCE OF FOCUSING TUBE WEAR ON VIBRATIONS AND SURFACE ROUGHNESS

Original scientific article The paper deals with the study of the focusing tube wear influence on surface quality and vibrations produced by abrasive waterjet by means of experiments design. The experiments deal with evaluation of the influence of focusing tube wear on surface quality and parameters of vibration generated by abrasive waterjet cutting. The main task of the first experiment was to study the significance of four selected factors of independent variables (focusing tube wear, traverse rate, abrasive mass flow rate and pressure) by full factorial analysis at two levels. The aim of the second experiment was to study the influence of focusing tube wear on the vibration parameters. It has been observed that focusing tube wear has a significant negative influence on surface quality and parameters of vibration.

Comparison of Hardness of Surface 316L Stainless Steel Made by Additive Technology and Cold Rolling

The paper deals with the comparison of surface hardness and porosity of stainless steel 316L (1.4404) produced by additive technology (SLM) and cold rolled steel. The subject of the paper is a comparison of two sets of samples where the first set of samples was made on a Renishaw AM400 with a laser output of 200 W and 400 W. In each set of samples, were the samples without heat-treated and heat-treated by annealing. Measurement of porosity and surface hardness were performed on all samples. The surface hardness of the material was evaluated by a static test according to Brinell CSN EN 10003-1. The porosity measurement was performed by the optical method. The measured values were compared with the reference material, which was cold-rolled steel, in which both the porosity and the hardness of the surface were measured.

The Application of Grinding of Ceramic Materials

An application of hard engineering materials depends especially on their specific properties, included mechanical properties and their machinability. Technical ceramics belongs to such materials. Nowadays, due to its properties, it is a process of grinding that is applied in machining. Because the technical ceramics has high hardness and brittleness it is important to pay attention to the whole process of machining. In this case of the grinding, there is need to pay attention to the process from disc engagement to grind off the desired layer. The paper deals with an implementation of grinding of ceramic materials in context of determining of elements of cutting forces and the surface roughness evaluation. These are important aspects for determining the suitability of the cutting conditions and the possibility of their use in the production process.

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.

The effect of feed rate on durability and wear of exchangeable cutting inserts during cutting Ni-625

Rad se bavi postupkom rezanja super legure nikla i odabirom odgovarajucih parametara rezanja za njezino lako i ucinkovito rezanja. U eksperimentalnom dijelu predlažu se tri izmjenljive plocice i određuje ucinak parametra posmaka tijekom obrade na trajnost i trosenje reznog alata. Ovisno o izboru posmaka rezanja i kolicini trosenja tih izmjenljivih plocica, procijenjena je kvaliteta tokarene povrsine i određeni parametri visine hrapavosti. U zavrsnom dijelu iznosimo opažanja do kojih smo dosli tijekom obrade Inconel 625, određujemo ucinak posmaka na trajnost i trosenje plocica, procjenjujemo i preporucujemo prakticne korake, opisujemo mehanizme trosenja reznog klina, određujemo trajnost alata i hrapavost tokarene povrsine.