Search results

The paper aims to analyze chip formation during machining process since it can be a very important indicator for the quality of the machining process, as some chip forms can be undesirable.

It is essential to determine the sensitivity of the chip formation on the basis of different machining parameters. The main goal of the study was to analyze the sensitivity of the chip formation during the machining process by using adaptive neuro-fuzzy inference system (ANFIS).

According to the results, the chip formation is the most sensitive to feed rate.

Different cutting tests were performed to monitor the chip formation on the basis of the cutting forces and the cutting displacement. ANFIS was used to estimate the sensitivity of the chip formation during the cutting process on the basis of different parameters.

The paper aims to investigate tool wear mechanism and tool geometry optimization of drilling PCB fixture hole.

An experimental study was carried out to investigate the chip formation and tool wear mechanism of drilling PCB fixture holes. Two types of drill with different types of chip-split groove were used in this study. The performances of these two types of drill bots were evaluated by tool wear and the shapes of chips.

The chips of drilling fixture holes contain aluminum chips from the cover board, copper chips from the copper foil, discontinuous glass fiber and resin from the CFRP. Feed rate and drilling speed have a great influence on the chip morphology. Abrasive wear of the drill lip is the main reason of the fixture drill bit in drilling PCB, and micro-chipping is observed on the tool nose and chisel edge. The influence of distance between the chip-split groove and drill point center on the axial force and torque is not obvious.

In this paper, hole wall roughness and drilling temperature were not analyzed in the optimization of drilling parameters. The future research work should consider them.

This paper investigated the mechanism of burr formation and tool wear in drilling of PCB fixture holes. Tool geometry was optimized by adding chip-split grooves.

Developing countries are now fully aware of the importance of the manufacturing sector as a key factor of growth and transformation of their economy. Improved technology and method of manufacturing have produced quality products at reduced cost and this has advanced development. The study uses experimental methods based on orthogonal cutting process to measure the cutting forces using a dynamometer while machining the test specimen with a diamond cutting tool at 5° rake angle. The machining forces for the dry cutting are higher than the wet cutting in the range of 31.2‐44.31, 32.09‐40.67, 29.10‐35.62, 29.21‐45.03 and 29.94‐38.74 percent for “as received”, normalized, tempered, annealed and hardened specimen, respectively. For annealed and hardened test specimen, the cutting speed of 245 rpm is ideal for machining when it gives a fine surface finish. Also for precision machining, dry turning is by far a better cost saver and cleaner option than wet turning. This is because though wet machining is relatively more expensive, it is hazardous to health. Normalized and annealed specimens require lower cutting forces and chip formation is slow. Tempering and annealing medium carbon steel facilitated rapid machining and chip formation is rapid. It is therefore an advantage to temper or anneal medium carbon steel before processing into component parts in the manufacturing industry as it saves cost and gives fine component surface finish. The paper aims to address these issues.

Tensile samples are prepared from medium carbon steel. These prepared samples were later subjected to heat‐treatment operations (normalizing, hardening, tempering and annealing). Tensile test were carried out to obtain the materials' sensitive properties used in the modeling equations. An experimental method based on orthogonal cutting is adopted to measure the machining forces using techquipment dynamometer.

It is observed that as t_u increases, F_c increases for all conditions, i.e. as t_u increases, tool‐chip contact area increases and increasing frictional force, also volume of metal removal increase resulting in increasing energy input. F_c values is highest for the normalized followed by that of the annealed. They are less for hardened and tempered. This is because of the mode of chip formation whereby ductile structures give continuous chips as against discontinuous structure for the hardened and quenched structures. Input energy is high for the former and low for the later. This is confirmed by the m values and observed chips.

There is no limitation, except for the instrumentation. On availability of the appropriate equipment, like the Kystler dynamometer for the correct reading of the experimental results.

The implication is limited to the workshop hazard during the experiment.

The research work is original.

Many bumping techniques for flip‐chip interconnections have been developed based on sputtering and electrolytic plating processes. In order to allow bumping on single chips, a new approach is adopted. Suitable metallisation layers are obtained by chemical plating techniques; bump formation is achieved by wire bonding of lead base wires or reflow melting of atomised spherical powders (solder balls). Flip‐chip modules on silicon substrate are created after reflow soldering in vacuum or in vapour phase. The quality and reliability of the interconnections are characterised by scanning electron microscopy, shear testing, microhardness measurement, non‐destructive testing, temperature and power cycling. It is found that high strength, high quality flip‐chip interconnections can be achieved. The present method is also economically competitive in comparison with sputtering techniques for the formation of metallisation layers.

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.

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.

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.

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.

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.

This study aims to investigate the effect of microtextured tools on the geometric morphology of serrated chips, and further improve the cutting performance of polycrystalline cubic boron nitride (PCBN) tool and extend the tool life and the surface quality of the machined surface.

A three-dimensional finite element cutting model of hardened steel AISI D2 with microtextured PCBN tools were established using the finite element software Abaqus, and cutting tests were carried out. Furthermore, the stress distribution in the primary deformation zone was investigated based on the triaxiality of stress, and the influence of microtexture on the geometric morphology of serrated chips and crack development was researched.

The results show that compared with nontexture tools, elliptical pits and wavy grooves microtexture tools have lower serrated degree Gs, higher serrated frequency f per unit length and more miniature serrated step Pc. The serrated phenomenon is intensified because the tensile stress zone of chips generated by nontextured tools is longer than that of elliptic pits and wavy grooves microtexture tools. Simultaneously, the maximum value of triaxiality in the tensile stress zone achieved by nontexture tools is larger than that of the two microtexture tools, and chips obtained by nontextured tools are more susceptible to propagation fractures.

This paper mainly studies the effect of microtexture on chip microgeometry, which is relatively little studied at present. At the same time, this paper has a certain engineering significance for PCBN tool turning hardening steel.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2023-0149/

The main aim of the study was to measure the cutting forces and chip shapes based on different machining parameters.

To get the best optimal machining conditions, it is essential to use the best combination of machining parameters. Although some machining parameters are not important for the process, there are machining parameters which are very important for the machining process.

It is essential to determine which machining parameters are the most dominant to make the optimal machining conditions.

Six different chip shapes are obtained according to ISO standardization. It was determined that the different cutting forces occurred for the different chip shapes.

This study aims to detect the temperature distribution in the cutting zone during the machining process. Furthermore, temperature influence in the cutting zone on the forms of chip shapes during the turning of Steel 30CrNiMo8 was evaluated. It is very important to use optimal machining parameters to get the best production results or for high control of the machining process.

Temperature distribution in the cutting zone during the machining process could affect the forms of chip shapes. Forms of chip shapes could be considered as the most important indicator for the quality of the machining process.

Therefore, in this study, the forms of chip shapes based on the temperature distribution in the cutting zone were examined.

It was found that the snarled chip type and the loose chip type have the highest temperature variation during the machining process.

This paper presents the results of mean unit weight of chips and their time to ignition measured on a test stand specially designed for this purpose. In addition, the temperature of chips in the cutting area and the morphology of chips produced in HSM milling (as a temperature indicator in the cutting area) are investigated. Also, different fractions of chips produced in the dry milling of Mg alloys AZ31 and AZ91HP by a PCD end mill are examined. Finally, the paper presents conclusions and recommendations with regard to safety and efficiency of dry milling processes for the aforementioned magnesium alloys.

Milling can be used as a finishing operation, particularly when using PCD end mills. The application of this mill type isparticularly important when producing different machine and device components, especially in the aircraft industry. What can occur in dry machining operations is self-ignition. It is therefore justified to investigate chip temperature in the cutting zone, to classify produced chip fractions and to determine their mass. Safe ranges of technological parameters can be additionally determined based on metallographic analysis of chip edge partial-melting.

The experimental results helped determine the effect of technological parameters of milling on chip temperature in the cutting zone, chip mass and fragmentation and chip morphology images.

The results reported in this work are innovative in both cognitive and practical aspect. The authors are convinced that this work can contribute to overcoming the mistrust of industrial practitioners toward dry milling of Mg alloys, and also with respect to the application of relatively higher cutting speeds in dry milling of these alloys than it is common practice in industry today. The study investigates the problem of safety in dry milling of Mg alloys. The study was motivated by the milling process itself and the formation of broken chip, which causes a significant change in the character of heat transfer.

The paper presents a method for multi-criteria safety assessment in dry milling operations. Safe and effective parameter ranges are defined with respect to chip temperature in the cutting zone, fraction number and chip mass.

The objective of this research is focused on the design of a new hybrid composite as well as to analyse the optimum turning conditions to minimise the surface roughness and work piece surface temperature, thereby increasing the productivity.

Mechanical properties such as hardness and tensile strength of Al-Si10Mg alloy reinforced with 3, 6 and 9 wt.% of alumina along with 3 wt.% of graphite prepared by stir casting method have been evaluated. The present study addresses the machinability parameter optimisation of Al alloy-9 per cent alumina-3 per centgraphite. Experiments were conducted based on the Taguchi parameter design by varying the feed (0.1, 0.15 and 0.2 mm/rev), cutting speed (200, 250 and 300 m/min) and depth of cut (0.5, 1.0 and 1.5 mm). The results were then analysed using analysis of variance (ANOVA).

Mechanical properties of the hybrid composite increases with reinforcement content. The surface roughness decreases with increasing cutting speed and conversely increases with increasing feed and depth of cut. The work piece surface temperature increases as cutting speed, feed and depth of cut increases. The ANOVA result reveals that feed plays a major role in minimising both surface roughness and surface temperature of work piece. The cutting speed and depth of cut follow feed in the order of importance, respectively.

The vibration of the machine tool is a factor which may contribute to poor quality characteristics. This factor has not taken been into account in this analysis since major vibrations in the machine are induced due to the machining process.

Design and development of new hybrid metal matrix composites (HMMCs) with a detailed analysis on machining conditions. The findings could help in the production of composite with a higher degree of surface finish. This will enable the adoption of HMMCs as industrial product for mass scale production.

Good quality characteristics were achieved using optimum machining conditions arrived using a statistical modelling.