Machining of Wood as a Natural Composite Material

In the paper, the wood as natural fibre-layered composite is used to study the principles of effect in machining of such composites and provide the suggestion how to eliminate the unwanted effects in composite material cutting. The suggestion is not in special tool geometry, cutting tool material, toolpath strategy etc. but is based on basically different principle of machining. The actual research in cutting of composites is focused on orthogonal cutting as 2D process. We have to take into account the 3D behaviour of chip forming, as the workpiece material is non-homogeneous and directionally oriented. Thus, we studied the idea of so-called free cutting or cutting by straight cutting edge. The principles of such cutting were tested on wood as natural fibre - layered composite and the results are presented in the paper

Abrasive waterjet (AWJ) titanium tangential turning evaluation

The paper deals with abrasive waterjet titanium tangential turning. Titanium grade 3 with a diameter of 55 mm was used as an experimental material. Technological conditions of turning tests were the same by gradually changing value of traverse speed (vf = 1,5; 3; 4,5; 6; 7,5 mm·min-1). Experiment tests were performed by using continuous abrasive waterjet of pressure p = 400MPa, by rotation n = 60 rpm of workpiece. The abrasive particles (Barton Garnet) were fed to the waterjet in the amount of 0,4 kg·min-1. It was determined that acceleration of traverse speed did not increase the surface profile parameters.Web of Science53454053

Nové analytické vyjadrenie základných závislostí v obrábaní

Doterajšia teória obrábania kovov bola založená na stave vývoja rezných materiálov v priebehu 20. storočia. Najmä zdokonaľovanie rezných materiálov, ako aj nových štruktúr obrábaných materiálov, snaha o zvyšovanie rezných rýchlostí si žiada prehodnotenie doterajších definícií. Pri aplikácii v minulosti definovaných vzťahov medzi reznými podmienkami a výsledkami obrábania sa objavujú nepresnosti, ktoré môžu viesť k nesprávnej voľbe rezných podmienok v konkrétnych podmienkach obrábania strojárskych súčiastok. Pokúsime sa analyzovať doterajšie rovnice, používané v praxi a na základe rozsiahlej experimentálnej analýzy optimalizovať ich tvar. Týka sa to posudzovania všetkých fyzikálnych a technologických parametrov, ako stlačenie triesky, mikrogeometria obrobeného povrchu, rezné síly, opotrebenie a a trvanlivosť rezných nástrojov

Reduction in Total Production Cycle Time by the Tool Holder for the Automated Cutting Insert Quick Exchange and by the Double Cutting Tool Holder

The time taken to exchange a cutting tool and the actual machining time are the components in a total production cycle time for a part, that affects productivity. Automated plate exchange systems strive for the simplest possible principles to achieve the shortest possible tool exchange time with sufficient accuracy. The tool holder in the presented article is based on the principle of a combination of translational, rotational movement, and stop surfaces by using a single pull–push rod for simple control. The article provides alternative tool holder designs and turning results of such holders using Rz-f dependence. The results of the time reduction are satisfactory and give a prerequisite for using a tool holder for the automated exchange of triangular cutting inserts. Moreover, the article provides the approach to reduce the mentioned total production cycle time by a reduction in the actual machining time for a part by use of tooltip radii, not by increasing the cutting speed. The triangular cutting insert can have three tooltips of three different tooltip radii for roughing and finishing. In addition, for reduction of the actual machining time, the double cutting tool with both the small tooltip radius for rouging and the large tooltip radius for finishing is presented. The double tool holders showed a 2.4-times reduction in the actual machining time for a part with Rz = 20 µm

Analysis of wide-range dependence of cutting parameters and the coating impact in deformation zone

254-260This paper deals with analysis of wide-range dependence of cutting parameters and describes and interprets physical-mechanical-thermal changes in such range. The paper experimentally evaluates the coating impact on cutting and deformation process, on shape and structure of the chip, nature of the tool wear and tool life and surface roughness. Moreover, the paper analyses and evaluates the advantages of the selected monolayer and multilayer coatings in terms of roughness of the work-piece and tool wear. Influence of coating thickness and temperature in coated and uncoated cutting tool is evaluated by numerical simulation

The mould for production of plastic spout cap with internal thread by injection moulding

The main aim of this article is the mould design for production of plastic spout cap with inner thread by injection moulding technology. There are described the basic steps of whole design process with respect to fulfil all technology and functionality requirements. The application of hot runner system as well as hybrid ejection system based on rotary cores and stripper plate can be considered as the main innovative features of the designed mould. The mould flow analysis was carried out for the functionality demonstration

Development and Applications of a Free Cutting by Nonconventional Tools

In publications concerning unconventional schemes can be seen working draft of different designs of rotation turning tools and tools with linear cutting edge. Sporadically, this tools has appeared in the specialized publications. So far its operational characteristics, mainly its considerable influence on machined surface quality, exceptional durability and possibility to be used to turn hard machinable and other materials. Some of its priorities are verified in this paper

SURFACE INTEGRITY EVALUATION OF TURNING WITH AUTO-ROTATING TOOL

The technical practice requirements comes to have increased demands on higher productivity, speed and quality of the machining process of various materials. Hard to machine materials, whose machining led to the development of turning with rotating cutting edge are not an exception. The machining process of auto-rotating tool is more complicated than the conventional process of turning, especially for the process of reshaping cutting layers into chips. There is a significant load in the system, that may affect the life of the cutting edge of the tool as well as the whole system and also in the final extent of the qualitative parameters of the workpiece (product / product). The article specifies the knowledge and findings of measurement in machining material 100Cr6 with an auto-rotating tool. The measurements were conducted to evaluate the integrity of the surface (roughness) of the workpiece to the impacts of cutting conditions, in particular the feed and the cutting edge inclination. It also analyzes the presence (size, character, action) of residual stresses concentrated in the surface layers of the workpiece by changing the cutting conditions