Stanislaw Legutko

Microhardness and Surface Integrity in Turning Process of Duplex Stainless Steel (DSS) for Different Cutting Conditions

The objective of the investigation was to identify microhardness of surface integrity (SI) after turning with wedges of coated sintered carbide. SI is important in determining corrosion resistance, and also in fatigue crack initiation. The investigation included microhardness analyses in dry and wet machining of duplex stainless steel. The microhardness of SI for various cutting speeds was compared. It has been shown that wet cutting leads to the decrease of SI hardening depth, while increasing the rounded cutting edge radius of the wedge increases the maximum microhardness values and the hardening depth. An infinite focus measurement machine has been used for the rounded cutting edge radius analysis. The study has been performed within a production facility during the production of electric motor parts and deep-well pumps as well as explosively cladded sheets.Graphical Abstract

Investigation of wear and tool life of coated carbide and cubic boron nitride cutting tools in high speed milling

The objective of the investigation was analysis of the wear of milling cutters made of sintered carbide and of boron nitride. The article presents the life period of the cutting edges and describes industrial conditions of the applicability of tools made of the materials under investigation. Tests have been performed on modern toroidal and ball-end mill cutters. The study has been performed within a production facility in the technology of high speed machining of 55NiCrMoV6 and X153CrMoV12 hardened steel. The analysed cutting speed is a parameter which significantly influences the intensity of heat generated in the cutting zone. Due to the wear characteristics, two areas of applicability of the analysed tools have been distinguished. For vc  ≤ 300 m/min, sintered carbide edges are recommended; for vc  > 500 m/min, boron nitride edges. For 300 ≤ vc  ≤ 500 m/min, a transition area has been observed. It has been proved that the application of sintered carbide edges is not economically justified above certain cutting speed.

An influence of active additives on the formation of selected indicators of the condition of the X10CrNi18-8 stainless steel surface layer in MQCL conditions

The paper presents the results of the research into the impact of anti-wear added to emulsion mist on the geometrical state of the machined surface of stainless steel after turning. In the research, the following machining conditions were compared: dry machining and cooling with compressed air, emulsion mist, emulsion mist + Crodafos O4A-LQ-(MH) and emulsion mist + Crodafos EHA-LQ-(MH). In the first stage, the influence of modifiers on roughness parameters of the machined surface were established. The aim of the second stage was to submit the machined material to microroentgenospectral analysis. The presence of chemical elements on the machined material surface for the aforementioned conditions of machining was analysed. Research results indicate that the application of cooling with emulsion mist with modifiers reduces the roughness parameters of the machined material even up to 80%. Adequately selected conditions of forming emulsion mist forms border layer, beneficially influencing the cutting conditions.

Influence of cooling conditions on the machining process under MQCL and MQL conditions

Original scientific paper The paper presents the results of investigation of the influence of conditions of forming emulsion and oil mist on the chip shape and surface roughness of X10CrNi18-8 stainless steel during turning. In the tests, the following machining operations have been compared: dry machining, cooling by the MQCL (Minimal Quantity Cooling Lubricat) method, cooling by the MQL (Minimum Quantity Lubricat) method. The tests have been performed in two stages. In the first stage, the influence of the mass flow of the active medium on the chip shape and on the Ra and Rq roughness parameters of the machined surface have been determined. The purpose of stage two was to determine the influence of the MQL and MQCL method on the selected indices of the machining process as compared to dry machining as a function of variable cutting speed. It has been found that, under MQCL and MQL conditions, the area of formation of elemental chips and ones with the shape of short spirals is wider as compared to dry turning. With increased mass flow of emulsion and oil, tangled chip is formed. Cooling by the MQCL and MQL method results in reduction of the selected roughness parameter values by 2 % to 42 % as compared to dry machining.

Optimizacija toka materijala – analiza slučaja u industriji motornih vozila

Optimizacija toka materijala - analiza slucaja u industriji motornih vozila Izvorni znanstveni clanak Danas je vecina organizacija suocena s mnogim dilemama, bit kojih je određivanje nacina postizanja ili održavanja stecenog položaja u konkurentnom okruženju. Poduzeca moraju neprestano povecavati svoju ekonomiju. Jedan od nacina stjecanja nadmoci nad konkurencijom je analiza i optimizacija toka materijala, sto doprinosi smanjenju troskova. Tok materijala u proizvodnoj organizaciji govori nam mnogo o organizaciji sustava. U radu se daje analiza postojeceg stanja toka materijala u jednoj proizvodnoj organizaciji motornih vozila. Predlaže se i projekt optimizacije toka materijala; projekt se sastoji od novog programa internog prijevoza i optimizacije položaja radnih standova. U radu se opisuju postojeci problemi u internom prijevozu poduzeca i daju rjesenja tih problema. Kljucne rijeci: analiza toka materijala; industrija motornih vozila; logistika poduzeca; optimizacija; program internog prijevoza

Improving the efficiency of running-in for a bronze–stainless steel friction pair

In this paper, the possibility of the transfer of additives that are in the emulsion mist is shown by the example of the bronze CuSn7Zn4Pb6–stainless steel X10CrNi18-8 friction pair. The additive is first transferred on the processed surface of the part and through it–in the contact zone of the friction pair. It was established that the emulsion mist reduces the roughness of machined stainless steel surface more than three times, and the introduction of additives based on phosphate esters into the emulsion reduces the roughness by 4–4.5 times. Phosphate-based additive remains on the machined surface in significant quantities, even after 30 min working at heavy loads, reducing the instantaneous friction coefficient and the temperature of the friction zone. The mean width of profile elements of the assessed profile of bronze samples decreases by two times and their bearing length ratio decreases by four times. In this case, a decrease in the wear rate of bronze by more than 40% is ensured. This fact indicates the better running-in of the friction pair.

Topographic inspection as a method of weld joint diagnostic

The paper demonstrates a topographic inspection in the specific context of three kinds of inspection methods of austenitic stainless steel welds. Visual and metrological inspection was analysed during tungsten inert gas (TIG) welding tests, showing the non-destructive techniques: X-ray, computed tomography, and surface profilometry. The article is a response to the lack of information, especially in the area of non-destructive techniques suitable for wide practical application. The Paper presents advantages and drawbacks of the analysed diagnostic methods and a classification of conventional and specific welded joint flaws. The most important defect in practical applications determining reliability of a welded joint is cracks. This kind of diagnostic is based on the obtained information about anisotropic and inhomogeneous volume under consideration in the heat-affected zone of a weld.

Research on emulsion mist generation in the conditions of minimum quantity cooling lubrication (MQCL)

The paper presents the effect of emulsion mist generation parameters and the distance of the nozzle from the contact zone of the cutting wedge with the workpiece on the diameter and number of droplets supplied into the cutting zone. The conditions of emulsion mist generation, in which all the droplets supplied to the cutting zone in a given time, are evaporated in this time. An analysis of heat flow in the MQCL method was presented and it was proved that the air flow and the distance of the nozzle from the cutting zone have the most significant effect on the diameter of droplets.

Materials Flow Analysis in the Production Process - Case Study

The paper presents an analysis of the materials flow in the company on the example of the production process of the selected product. The analysis was carried out in three stages. This division has enabled to take into account many factors that have a significant impact on the internal transport during production. The first step in the analysis was to determine the current situation of the flow of materials. In the second stage, the obtained data were used to develop a detailed program of internal transport, associated with the production of the considered product, and the last stage of the analysis was to identify opportunities for rationalization actions. The rationalization concerned the machine tools spatial location, the choice of handling equipment and transport tasks.

EFFECT OF ANTI-WEAR ADDITIVE ON CUTTING TOOL AND SURFACE LAYER OF WORKPIECE STATE UNDER MQCL CONDITIONS

The work presents the results of investigation of the influence of anti-wear additive Crodafos EHA-LQ-(MH) added to the emulsion mist on the condition of machined surface of 1.4310 stainless steel after turning. The investigation included the comparison of the following cutting conditions: dry machining, cooling by the MQCL method and cooling by the MQCL method with Crodafos EHA-LQ-(MH). In the paper, the influence of the Anti-Wear (AW) additive on the roughness parameter Ra of the machined surface for various cutting speeds, vc, and mass flow of the emulsion E has been shown. It was found that the MQCL+AW method decreases the Ra parameter values by 14 % to 35 % in comparison with dry cutting and by 17 % in comparison with MQCL method.The machined material and the rake face of the cutting wedge have been subjected to micro X-ray spectroanalysis. Chemical analysis of the cutting wedge and the surface layer of the machined material has been performed. The results show that water dropletts in MQCL method are very good transport facility for active compounds of AW additive that consequently form the dry-film lubricant on the machined surface.