Józef Kuczmaszewski

Comparative Analysis of Energetic Properties of Ti6Al4V Titanium and EN-AW-2017A(PA6) Aluminum Alloy Surface Layers for an Adhesive Bonding Application

The purpose of this article is to present energetic properties of surface Ti6Al4V titanium as well as surface EN-AW-2017A(PA6) aluminum alloy layers. Values of surface free energy after selected mechanical operations and ozonation were compared. In addition, the influence of different values of ozone concentration on surface layer energetic activation was analyzed. Dispersive and polar components of surface free energy were of particular concern. Comparative evaluation of shearing strength of Ti6Al4V titanium and EN-AW-2017A(PA6) aluminum alloy single-lap adhesive bonded joints were presented. Results can be used as pro-ecological methods of titanium and aluminum alloys preparing for applications where adhesive phenomenon is important.

Investigation of ignition temperature, time to ignition and chip morphology after the high-speed dry milling of magnesium alloys

Purpose The purpose of this paper is to determine time-to-ignition of magnesium alloy chips and the ignition-preceding stages as well as to examine chip morphology. The tests were conducted according to the following pattern: directly after a milling operation, after ignition using a special test stand located outside the machine tool and after intensive oxidation which prevented ignition. Design/methodology/approach Milling is a machining process widely used in the manufacturing of various parts that are applied, e.g. in the aircraft industry. Milling is used for both roughing and finishing machining. In the dry machining of magnesium alloys, spontaneous ignition can occur; therefore, the analysis of chip temperature in the cutting area is of great significance. Additionally, time-to-ignition and chip morphology are crucial when considering the safety of magnesium alloy machining processes. Findings The experimental results demonstrate the effect of parameters of the milling process on time-to-ignition of chips made of magnesium alloys AZ31 and AZ91HP. The experiments also involved examining the morphology of a selection of chips produced at the maximum cutting velocity vc and feed per tooth fz. In addition, we analysed the morphology of both ignition products and chips subjected to high temperature where ignition did not occur. Practical Implications Based on the time-to-ignition and chip morphology results, it is possible to indicate both safety levels in machining and the efficient range of parameters in the milling of aircraft parts made of magnesium alloys. Originality/value The paper presents a new approach to assessing safety in milling operations. The results of the tests of chip flammability (time-to-ignition) which were run at a special test stand placed outside the machine tool enabled determination of both safety and efficiency range of the milling process.

THE STUDY OF CUTTING FORCES AND THEIR AMPLITUDES DURING HIGH-SPEED DRY MILLING MAGNESIUM ALLOYS

This paper presents the state of knowledge on cutting forces values during milling of different magnesium alloy types. Additionally, the results of own research on cutting forces and their amplitudes after milling magnesium alloys used for manufacturing elements applied in the aerospace industry are included. The subject of the analysis was the influence of technological parameters and the tool type on cutting forces and their amplitudes. The analysis is important due to the correlation between cutting forces and temperature in the cutting area, and, consequently, the safety of machining and strain of the workpiece.

Effect of a Notch on Impact Resistance of the Epidian 57/Z1 Epoxy Material after "Thermal Shock"

Adhesive bonding is increasingly being applied as structural joining technique in highly reliable machines and appliances operating in the circumstances of variable thermomechanical loads.The manufactured specimens of the Epidian 57/Z-1 epoxy material had been subjected to cyclic thermal loading, with respect to a defined program, in a thermal shock chamber within a temperature range of ‑40°C to +60°C for 200 cycles. The accepted temperature range was typical for machinery maintenance, including the aircraft.The aim of the research was first of all determination of thermal load (fatigue), as well as the presence of notch effect on the resistance to fracture.A significant measure of the adhesive bonds quality is the repeatability of the strength examination results, both in the summary and long lasting tests. It is often more important criterion for the adhesive joint selection than higher strength of the joints using the particular adhesive.The obtained results of the conducted research have been elaborated statistically with respect to the appropriate scientific standards.

Impact of depth of cut on chip formation in az91hp magnesium alloy milling with tools of varying cutting edge geometry

Safety of Mg milling processes can be expressed by means of the form and the number of fractions of chips formed during milling. This paper presents the state of the art of magnesium alloys milling technology in the aspect of chip fragmentation. Furthermore, the impact of the depth of cut ap and the rake angle γ on the number of chip fractions was analysed in the study. These were conducted on AZ91HP magnesium cast alloy and milling was performed with carbide tools of varying rake angle values (γ = 5o and γ = 30o). It was observed that less intense chip fragmentation occurs with decreasing depth of cut ap. The number of chip fractions was lower at the tool rake angle of γ = 30o. The test results were formulated as technological recommendations according to the number of generated chip fractions.

SURFACE ROUGHNESS OF THIN-WALLED COMPONENTS MADE OF ALUMINIUM ALLOY EN AW-2024 FOLLOWING DIFFERENT MILLING STRATEGIES

The paper presents an analysis of surface roughness following milling of thin-walled components made of aluminium alloy EN AW-2024, taking into account the three different machining strategies and rolling direction of semi-finished product in the form of a plate combined with the milling feed. The aims of the study were to compare the results of machining using various technologies and show the best of them, providing the smallest roughness of the component following milling, as well as to determine the impact of rolling direction of the plate on the quality of the end surface. Measurement results of surface roughness parameters were provided information about the progress of the machining process.

STUDY OF CHIP IGNITION AND CHIP MORPHOLOGY AFTER MILLING OF MAGNESIUM ALLOYS

The paper analyses the impact of specified technological parameters of milling (vc, fz, ap) on time to ignition. Stages leading to chip ignition were analysed. Metallographic images of magnesium chip were presented. No significant difference was observed in time to ignition in different chip fractions. Moreover, the surface of chips was free of products of ignition and signs of strong oxidation.

Assessment of the Accuracy of High-Speed Machining of Thin-Walled EN AW-2024 Aluminium Alloy Elements Using Carbide Milling Cutter and with PCD Blades

The paper presents an assessment of the accuracy of high-speed machining of thin-walled elements made of the EN AW-2024 aluminium alloy using two different tools: a milling cutter with carbide blades and a milling cutter with PCD blades. Additionally, the impact of so-called technological history effect on machining accuracy is also analysed. In the studied case, the rolling direction of the semi-finished product, longitudinal or transversal, is taken into account. The degree of post-machining deformations and the quality of sample surface after HSM are adopted as indicators describing machining accuracy. Based on the obtained results, it can be stated that depending on the adopted accuracy assessment criteria, i.e. shape error or machined surface quality, it is recommended to use carbide tools or tools with PCD blades.

A Comparative Analysis of the Impact of CNC Miller Programming on Machining Effects

Abstract This paper presents a comparison of the impact of the programming methods of a CNC miller on the machining effects. As a part of the study, the test samples were made of the EN AW-2024 aluminium alloy. The CNC machining programs compared were developed with two programming methods: by inputting the CNC machining program directly from the CNC millers control panel (machine level programming) and in a CAM software environment (CAM programming). The machining effect indicators adopted included: machining time, surface quality, and dimensional deviation of specific geometrical features. A measurement of the machining times revealed than the CAM programming reduced the machining time up to 20% from the machining time of the machine level programming. A conclusion stands valid that CNC machining programs developed in the CAM software environment are more efficient than CNC programming directly with the CNC miller control panel, most likely due to the machining path optimisation in CAM. In addition, given the experimental test results, it was found that smaller machined errors were also obtained for CAM programming. To conclude, the comparative analysis revealed that CAM programming provided better machining results than the machine level programming.

Carbide Milling Cutter Blades Durability during Machining of AL-SI Casting Alloy

Abstract The paper presents results of wear measurements of carbide shank milling cutters during machining of AlSi10Mg casting alloy. The comparison was made between blades wear of milling cutters without protective coating, with TiB2 coating, and with TiAlCN coating. All cutters had identical geometry dedicated to milling of materials of ISO N group. To assess blades wear degree, measurement of two direct indicators, i.e. VBC and VBBmax, and one indirect indicator, i.e. machined surfaces roughness, were used. Received results allowed to determine usefulness of using selected protective coatings in machining of aluminium alloys, especially Al-Si casting alloys.