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1

Experimental investigation and machining analysis of Mg/TiC composites during EDM

Dash Dharmeswar, Devarajaiah Devarasiddappa, Dash Santosh Kumar, Samanta Sutanu, Rai Ram Naresh

Composites Theory and Practice

|

2024

|

R. 24, nr 1

9--16

EN

Electrical discharge machining (EDM) is one of the prominent non-conventional machining processes used to machine metal matrix composites. Mg/TiC composites are found in many industrial applications and conventional machining of the same is highly challenging. This paper aims to study the machinability analysis of Mg/TiC composites using EDM with pulseon time (Ton), pulse-off time (Toff) and input current (I) as the process variables with the material removal rate (MRR) and surface roughness (SR) as the performance measures. Stir cast Mg-alloy reinforced with TiC (0, 5, 10, 15 and 20) by weight was used as the workpiece. The EDM experiments were conducted as per L25 orthogonal array (OA) and the results were analyzed to study the effect of the process variables on MRR and SR. The parametric study showed that SR increases linearly with Ton and is attributed to larger craters produced at a higher pulse energy. MRR was also observed to grows with the rise in Ton as more material melts due to high-intensity pulses. As per the ANOVA results, Ton was found to be the most influential process variable affecting SR and MRR with a 79% and 34% contribution, respectively. Surface morphology investigations using SEM micrographs revealed the presence of globules and sphere-shaped metal deposits and were found responsible for increased SR.

2

Influence of EDM process parameters of novel Al7010/B4C/BN hybrid metal matrix nanocomposite

Dirisenapu Gopichand, Salavaravu Laxmanaraju, Dumpala Lingaraju

Composites Theory and Practice

|

2023

|

R. 23, nr 4

191--196

EN

In this present research work, the electrical discharge machining (EDM) characteristics of an Al7010/2%B4C/2%BN (the reinforcement particles are taken as wt.%) hybrid metal matrix nanocomposite (HMMNC) are discussed. The effect of the EDM process variables like the discharge current (I), pulse on time (Pon), pulse off time (Poff) and gap voltage (Vg) on the response characteristics like the material removal rate (MRR), tool wear rate (TWR), and surface roughness (SR) are presented. The results revealed that the MRR, TWR, and SR grew with an increase in Ip and Pon. MRR, TWR, and SR increased with a rise in Poff up to 25 μs then declined. MRR, TWR, and SR decreased with an increment in gap voltage. The highest MRR was observed for a discharge current of 8 A, Pon of 60 μs, Poff of 25 μs and Vg of 30 V. SR and TWR were the smallest at Ip of 2 A, Pon of 15 μs, Poff of 55 μs and Vg of 60 V. The scanning electron microscope (SEM) micrographs of the machined surfaces revealed voids, craters and micro cracks.

3

Study on Near-Dry EDM Performance Characteristics of MSGNP/Al-7075 Using Air, Argon, Nitrogen, and Freon Dielectric Medium

Abd Haneen Lateef, Ali Saad Mahmood

Advances in Science and Technology. Research Journal

|

2023

|

Vol. 17, no 6

254--273

EN

The primary aim of the current study is to investigate the influence of input parameters of near dry electric discharge machine (ND-EDM) upon the output performances including the MRR, EWR, SR and WLT for the fabricated new metal matrix composite (MMCs) of aluminum A7075 matrix nanocomposites by adding 8% of Microscopic Slide Glass Nanoparticles (MSGNPs) as reinforcements to improve the metallurgical and mechanical properties of Al-7075/MSGNP composites using stir-casting method. In (ND-EDM), the dielectric medium plays a significant role in the procedure responses. In the current work, the vegetable oil with gases, such as air, Ar, mix (Ar+N2), and Freon were used as a dielectric media. The obtained results show that the highest MRR achieved when using the vegetable oil + Freon gas, reached 29.425 mm3/min, and then 26.943 mm3/min when using the vegetable oil + Air as a dielectric. The lowest EWR achieved when employing the vegetable oil + Argon gas, reached 0.120 mm3/min, and then 0.175 mm3/min. The lowest SR values obtained for all the designed experiments reached 3.287 µm when using Ip (10 A), Ton (1600 µsec), and Ar additive gas, followed by 4.567 µm when adding Freon gases to the dielectric. In the ND-EDM, the average of recast white layer thickness in the case of vegetable oil + air, vegetable oil + Ar, vegetable oil + mix (Ar-N2), and vegetable oil + Freon was 1.505, 1.180, 0.456, and 0 μm, respectively. These unique results can be used to increase the service and fatigue life of parts and machines that are exposed to sudden dynamic mechanical or thermal loads, without the need for additional operations to remove this brittle layer, which causes the failure of these parts with a short service life. The created mathematical models displayed a higher value of R-Square and the adjusted R-square, which manifest a better fit. Normal probability plots of the residuals for MRR, EWR, and SR elucidated an obvious pattern (i.e., the points were stabilized in a straight line) which indicates that every factor affects the mentioned responses and the outcomes of these responses from the regression model (predicted value by factorial) and the true values (from the experiments).

4

Assessing Machinability and Surface Characteristics of a Shape Memory Alloy (SMA) Processed through Wire Electro Spark Erosion Method

Ebenezer George, Khan Adam M., Chellaganesh Duraipandi, Winowlin Jappes J. T., Haider Julfikar

Archives of Metallurgy and Materials

|

2022

|

Vol. 67, iss. 3

921--930

EN

In this paper, a study was carried out to investigate the surface roughness and material removal rate of low carbon NiTi shape memory alloy (SMA) machined by Wire Electro Spark Erosion (WESE) technique. Experiments are designed considering three parameters viz, spark ON time (SON), spark OFF time (SOFF), and voltage (V) at three levels each. The surface roughness increased from 2.1686 μm to 2.6869 μm with an increase in both SON time, SOFF time and a decrease in voltage. The material removal rate increased from 1.272 mm3/min to 1.616 mm3/min with an increase in SON time but a varying effect was observed the SOFF time and voltage were varied. The analysis revealed that the intensity and duration of the spark had an unswerving relation with the concentration of the microcracks and micropores. More microcracks and micropores were seen in the combination of SON = 120 μs, voltage = 30 V. The concentration of the microcracks and micropores could be minimised by using an appropriate parameter setting. Therefore, considering the surface analysis and material removal, the low carbon NiTi alloy is recommended to machine with 110 μs - 55 μs - 30 V (SON - SOFF - V respectively), to achieve better surface roughness with minimal surface damage.

5

Path Interval and Its Relevance to Cutting Force in Ball and Filleted End Milling

Sekine Tsutomu

Advances in Science and Technology. Research Journal

|

2022

|

Vol. 16, no 1

85--94

EN

Computerized milling process is widely used in product manufacturing. Although manufacturing has gradually become highly-automated, the selection of machining conditions still remains an ever-present challenge in the process. To provide some findings contributable for the process planning, this study focuses on ball and filleted end milling. After brief explanations were given to the path interval determinations in both milling processes, the experiments were conducted to verify and characterize each procedure. The results of computational procedures showed good agreement with the experimental ones. Then, material removal rate and cutting force were analytically proposed for effective selection of machining conditions. The following findings were obtained from the demonstrations with discussion. Ball end milling required relatively large cutting force in the first tool path even though the material removal rate was comparatively small. On the contrary, filleted end mill enabled us to maintain a moderate cutting force in the first tool path even if the material removal rate expanded with increasing tool radius.

6

Process parameter optimization and anisotropy sensitivity study for abrasive belt grinding of nickel-based single-crystal superalloy

Wang Chao, Yan Xufeng, Liao Hongzhong, Chai Linjiang, Zou Lai, Huang Yun

Archives of Civil and Mechanical Engineering

|

2021

|

Vol. 21, no. 4

584--602

EN

Nickel-based single-crystal superalloys (SXs) are used as materials for aero- and industrial gas turbine blades due to their superior high-temperature strength. However, SXs have low thermal conductivity, high hardness, and high working hardening, which significantly increase the machining difficulty. Improving machining performance has been a critical aspect that influences functional performance, including the fatigue life of the blades. In this study, preliminary comparative tests were performed for abrasive belt grinding of SXs to obtain better performance in terms of surface roughness (Ra), material removal rate (MRR) and abrasive belt wear rate (Bw). Two empirical models of the process parameters of abrasive belt grinding were established using response surface methodology (RSM), and the influences of belt speed (Vs), feed speed (Vw), and normal grinding force (Fn) on Ra and MRR were analysed. The Ra and MRR were optimized with multiple responses to balance the grinding quality and efficiency based on the desirability function method. Both the percentage error of the experiments and model prediction error are within a reasonable range of 5%. In particular, three typical crystal planes ((001), (110), and (111)) were prepared and used to study the grinding performance from the perspective of anisotropy sensitivity.

7

Investigation on machining characteristics of banana fiber and silicon carbide reinforced polymer matrix composites

Gopalan Venkatachalam, Pragasam Vignesh, Narayanaswamy Hitesh Byatarayanapura, Balasubramanian Gokula Krishnan, Chinnaiyan Pandivelan

Engineering Transactions

|

2020

|

Vol. 68, iss. 3

297--313

EN

In this study, machining characteristics of polymer composite consisting of banana fiber and silicon carbide (SiC) as reinforcements and epoxy resin as matrix are investigated. Reinforcement phases consist of raw banana fiber powder sieved to 100 microns size of 1% (w/w) and SiC powder of 1% (w/w). The conventional machining process is carried out on the fabricated composite samples by considering the depth of cut, feed rate and speed as influential parameters. The central composite design (CCD) is used to design the experiment based on response surface methodology (RSM). The analysis of variance (ANOVA) is used to study the influences of the depth of cut, feed rate and the speed on the material removal rate (MRR) and surface roughness. The results reveal that the feed rate is the most influential parameter for minimizing surface roughness and maximizing MRR. It is observed that the feed rate plays an important role in determining the surface roughness and MRR followed by the depth of cut and speed. The optimized parameters for maximum MRR and minimum surface roughness are also obtained.

8

Machining of microholes in Ti-6Al-4V by hybrid micro electrical discharge machining to improve process parameters and flushing properties

Mugilan T., Aezhisai Vallavi M. S., Santhosh S., Sugumar D., Christopher Ezhil Singh S.

Bulletin of the Polish Academy of Sciences. Technical Sciences

|

2020

|

Vol. 68, nr 3

565--573

EN

In this research work, the Ti-6Al-4V material was used for the investigation of machining parameters by means of hybrid micro electrical discharge machining to improve the machining process and reduce the negative effects of debris accumulation in the drilled hole. L9 orthogonal array was used in the Taguchi based grey relational analysis to optimize the parameters such as material removal rate and diametrical accuracy of the machining process for Ti-6Al-4V. This work encompasses the design, development, and calibration of the work piece vibration platform and experimental analysis of the process parameters by means of the hybrid micro electrical discharge machining process. The maximum material removal rate and minimum surface roughness was observed at the current value of 2.5 A, pulse on time is 2 μs and pulse off time is 14.5 μs. The maximum material removal rate was observed for the increase in pulse on time with 14.4 μs and 4 A current level. The diametrical accuracy of the microholes was increased while increasing the pulse off time and decreasing the pulse on time. The fluid flow simulation has been conducted to find out the pressure drop and to know the velocity of the flow inside the hole for the effective flushing of the debris during machining.

9

Investigation of surface roughness and material removal rate on machining of TiB2 reinforced aluminum 6063 composites: A Taguchi's approach

Emmanual L., Karthikeyan T.

Mechanics and Mechanical Engineering

|

2018

|

Vol. 22, nr 4

1319--1327

EN

The utilization of TiB2 particles reinforced aluminum (Al6063) metal matrix composite materials in many different engineering fields has undergone a tremendous increase. Accordingly, the need of accurate machining of composites has increased enormously; an attempt has been made to assess the factors influencing surface roughness and material removal rate on machining the composite. The orthogonal array, the signal-to-noise ratio, and analysis of variance were employed to study the performance characteristics in turning operations of 5 and 10 wt. % TiB2 particles reinforced aluminum (Al6063) metal matrix composites. Taguchi method was used to find the optimal cutting factors for surface roughness (Ra) and material removal rate (MRR). Three cutting factors namely speed; feed and depth of cut were optimized with considerations of Ra and MRR. The experimental plan and analysis was based on the Taguchi L27 orthogonal array with three cutting factors using carbide tool (K20). The optimal parametric combination for K20 carbide insert was found to be feed, speed and depth of cut. The analysis of variance (ANOVA) result shows that feed the most significant process parameter on surface roughness followed by speed. For MRR result show that the speed and the feed are the significant parameters followed by the composition of composite material.

10

Electrical discharge machining of difficult to cut materials

Świercz R., Oniszczuk-Świercz D., Dąbrowski L.

Archive of Mechanical Engineering

|

2018

|

Vol. LXV, nr 4

461--476

EN

The development of industry is determined by the use of modern materials in the production of parts and equipment. In recent years, there has been a significant increase in the use of nickel-based superalloys in the aerospace, energy and space industries. Due to their properties, these alloys belong to the group of materials hard-to-machine with conventional methods. One of the non-conventional manufacturing technologies that allow the machining of geometrically complex parts from nickel-based superalloys is electrical discharge machining. The article presents the results of experimental investigations of the impact of EDM parameters on the surfaces roughness and the material removal rate. Based on the results of empirical research, mathematical models of the EDM process were developed, which allow for the selection of the most favourable processing parameters for the expected values of the surface roughness Sa and the material removal rate.

11

Modyfikacja struktury przestrzennej czynnej powierzchni ściernicy (CPS)

Świercz R., Zawora J., Dąbrowski L., Marciniak M.

Mechanik

|

2017

|

R. 90, nr 10

900--902

PL

Przeprowadzono badania skutków modyfikacji struktury CPS w zakresie intensyfikacji wydajności procesu szlifowania, z jednoczesnym spełnieniem standardowych wymagań odnośnie do chropowatości powierzchni. Elementami modyfikacji są modelowo określone udziały 2 granulacji ziaren SiC oraz 2 granulacji ziaren CrA w ściernicach trzpieniowych ze spoiwem ceramicznym do szlifowania czołowego.

EN

The investigation has been carried out into the effect of modifying the active wheel surface structure in view of enhancing productivity of the grinding process. This undertaking should be consistent with standard surface roughness requirements. This modification involves the model-based shares of the two SiC grain grit sizes and two CrA grit sizes in the grinding pins with ceramic bond for the face grinding process.

12

Experimental investigation and optimization of material removal rate and surface roughness in centerless grinding of magnesium alloy using Grey Relational Analysis

Dinesh S., Mahadevan G., Senthil Kumar T.

Mechanics and Mechanical Engineering

|

2017

|

Vol. 21, nr 1

17--28

EN

Modern enterprises concentrate on higher production rates with reduced time and admired quality. The surface integrity defines the quality of the product. Several processes like grinding, polishing and buffing have been used to improve the surface texture of the machined products. The most prominent challenge that is faced by an engineer is to manufacture a component with better surface integrity at reduced time, leading to increased production rate and improved profit. It is important to select proper combination of the machining parameters for obtaining the best results. The process called through feed centerless grinding helps in obtaining better surface texture. The main aim of this work is to examine the influence of various machining parameters such as regulating wheel angle, regulating wheel speed and depth of cut over surface roughness and machining time in machining magnesium alloy using silicon carbide grinding wheel. Grey relational analysis method is used for investigating the results. The optimal machining parameters were found with regulating wheel speed, regulating wheel angle and depth of cut being 46 rpm, 2 degree and 0.2 mm.

13

EDM of aluminum alloy 6061 using graphite electrode using paraffin oil and distilled water as dielectric medium

Imran M., Rahmanshah S. M., Mehmood S., Arshad R.

Advances in Science and Technology. Research Journal

|

2017

|

Vol. 11, no 3

72--79

EN

EDM machining of Al 6061 was performed under varying conditions of pulse current and pulse duration. Graphite was used as an electrode material with distilled water and paraffin oil as two different dielectric mediums. The aim is to characterize the surface integrity produced as a result of EDM machining under both varying electrical and non-electrical parameters as it is important in determining the service life of EDM machined components. The vertical, horizontal and corner surfaces are studied independently for each single set of conditions. The average white layer thickness (AWLT) and surface roughness was found to be dependent on pulse current values and pulse duration. The dielectric medium also has an influence on the thickness and nature of white layer. It was found that the thickness and nature of the white layer formed from distilled water is different from that of paraffin oil. New methods of AWLT and surface roughness measurement through an optical microscope are described. The surface roughness method developed was calibrated against an identical surface roughness tester. Finally, material removal rate, tool wear rate, the presence of micro cracks, voids and globules were compared for different conditions and conclusions were drawn according to the actual physical conditions during machining.

14

Wpływ parametrów obróbki elektroerozyjnej na właściwości użytkowe stali o wysokiej przewodności cieplnej

Świercz R., Oniszczuk-Świercz D.

Mechanik

|

2015

|

R. 88, nr 1CD

29--34

PL

W artykule przedstawiono wpływ podstawowych parametrów obróbki EDM (tj. czasu impulsu wyładowania ton i natężenia prądu I w impulsie) na wydajność procesu usuwania materiału, oraz wybrane parametry profilu chropowatości. Obróbce poddano materiał o wysokiej przewodności cieplnej elektrodami cienkościennymi.

EN

The paper presents experimental investigation of EDM parameters (current I and discharge time ton) on material removal rate and parameters of roughness profile. In experiment processed material with high thermal conductivity with thin walled electrodes.

15

Analiza statystyczna wpływu warunków obróbki na proces EDM

Świercz R., Oniszczuk D.

Mechanik

|

2014

|

R. 87, nr 12CD

13--15

PL

W artykule przedstawiono wyniki badań doświadczalnych wpływu wybranych parametrów obróbki elektroerozyjnej na jej wskaźniki. Przedstawiono zastosowaną metodykę budowy statystycznych modeli matematycznych w analizowanym procesie wytwarzania.

EN

The article presents the results of experimental studies influence of selected parameters on the indicators of EDM process. The paper presents the methodology of construction statistical mathematical models.

16

Steel C45 elements lapping

Molenda J., Charchalis A.

Journal of KONES

|

2014

|

Vol. 21, No. 1

169-174

EN

Lapping is a process by which material is precisely removed from a workpiece to produce a desired dimension, surface finish or shape. It also removes subsurface damage caused by sawing or grinding. According to the classification surface to be generated, type of surface, kinematics of the cutting process, and tool shape (profile), many process variants can be distinguished. Among them face lapping are the most widespread lapping processes. They are used to produce a smooth, flat, unpolished surface. The process of lapping materials has been applied to a wide range of materials and applications, ranging from metals, glasses, optics, semiconductors and ceramics. Workpiece material properties and structure determine kind of material removal. Material removal by cutting, microfusion processes and material removal by microdeformation or by the induction of microcracks are to be underline. C45 is a medium carbon steel used when greater strength and hardness is desired than in the "rolled" condition, especially in mechanical engineering and automotive components. To minimize wear in high-speed applications requires extreme size accuracy, straightness and concentricity. To meet those high demands turning, grinding, lapping and polishing processes are used. This work presents results of steel C45 elements lapping. The experiments were conducted during flat lapping with use of ABRALAP 380 lapping machine. The lapping machine executory system consists of three conditioning rings. The process results were surface roughness Ra and material removal rate.

17

Measurements of lapping plate temperature

Molenda J, Charchalis A.

Journal of KONES

|

2014

|

Vol. 21, No. 3

245--250

EN

Lapping process is commonly used for ultra-precision machining of various materials. An essential role during lapping plays flatness of the wheel-working surface because workpiece surface takes mirror image of it. Due to its applications requiring extreme size accuracy, straightness and concentricity, it is very important that working surface remains flat in the course of machining. Getting out of flatness can be caused by uneven wear or heating. To prevent nonuniform wear of lapping plate surface, conditioning rings should be suited appropriate. Lapping machines producers and researchers make recommendations about proper rings position during machining. To provide constant temperature of the wheel, cooling systems are applied in modern machines, but not in all of them. Therefore, wheel temperature problem is significant one, and it should be known. This paper presents results of authors work on choosing proper measurement method of lapping plate temperature. During lapping process wheel is rotating. Maximum velocity value for ABRALAP 380 lapping machine is 65 rev/min. Mainly for this reason, contactless infrared method was selected. Because getting an accurate temperature of an object using this method is difficult, during experiments temperature rise not exact value were analysed. There were also presented results of experiments which goal was to find lap plate emissivity.

18

Electro-discharge machining of type H13 tool steel titanium carbide composites

Duszczyk J., Biało D., Perończyk J., Daniels R.

Composites Theory and Practice

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2014

|

R. 14, nr 1

8--12

EN

One of the most popular steels which have been used for tools in the hot metal extrusion process is AISI type H13 hotwork tool steel. Although this steel has relatively good properties - wear resistance and hot toughness - it is no longer completely satisfactory because new extrusion materials place higher demands on extrusion tooling, and H13 type steel in its current form is not optimal. The paper presents the proposition of improving the properties of H13 type steel by introducing hardceramic particles as reinforcement to the structure. Such composites consist of a modified H13 steel matrix and TiC particles of 0, 10, 20 and 30 volume percent. The composites were manufactured by the powder metallurgy method. The atomized matrix powder was mixed with a TiC powder using a Tubular mixer for 60 min. The mixed materials were consolidated by Hot Isostatic Pressing (HIP). Prior to the HIP process, the powder materials were placed in a steel can. The conditions of hot isostatic pressing for the modified H13 tool steel matrix composites were: temperature 1150°C, time 4 hours and pressure 100 MPa. Particle reinforced metal matrix composites are difficult to machine using conventional manufacturing processes due to high tool wear caused by the hard reinforcement, even those tools which are made of cemented carbides. One of the best methods of machining of composite dies is sink electro-discharge machining EDM or wire electro-discharge machining WEDM. This work concerns the investigation into the machinability of Titanium Carbide (TiC) particle reinforced modified H13 steel using wire electro discharge machining (WEDM). WEDM cutting was conducted using a machine equipped with a RC type relaxation generator. The dielectric used in this experiment was deionized water. As the tool material, brass wire with a diameter of 0.25 mm was used. To compare, wrought H13 steel was also machined. The machining parameters such as pulse time and load voltage were varied in order to optimize the metal removal rate and surface integrity. The obtained results indicate that MMCs can be machined using WEDM although the metal removal rates are lower compared to conventional machining processes. It is shown that the surface roughness increases with higher discharge energy and decreases with the volume fraction of the reinforcement. The optimum machining rate considering the roughness and cutting rate, was when the pulse on-time is at 1.5 μs, pulse off-time at 10 μs and load voltage at 122 V.

PL

W procesie wyciskania na gorąco jedną z najczęściej stosowanych stali na matryce jest stal narzędziowa do pracy na gorąco typu H13 (wg AISI). Ta stal charakteryzuje się stosunkowo dobrymi własnościami: odpornością na zużycie i odpornością na pękanie na gorąco. Jednak wobec stale rosnących wymagań odnośnie do podwyższonych parametrów wyciskania i większej wydajności procesu jej własności pozostają nie w pełni zadowalające. W artykule przedstawiono propozycję podwyższenia jej własności przez wprowadzenie do struktury twardych ceramicznych cząstek. Jako fazę zbrojącą zastosowano cząstki TiC w ilości 10, 20, 30% obj. Do wytworzenia kompozytów zastosowano proces metalurgii proszków, w którym proszki osnowy i proszki fazy zbrojącej mieszano, a następnie prasowano metodą izostatyczną na gorąco HIP. Warunki prasowania: temperatura 1150ºC, czas 4 godziny i ciśnienie 100 MPa. Jak wiadomo, kompozyty metalowe są trudne w obróbce mechanicznej z uwagi na obecność w osnowie twardych cząstek zbrojących, które powodują intensywne zużywanie ścierne ostrzy narzędzi. Jedną najbardziej obiecujących metod obróbki kompozytowych matryc do wyciskania jest obróbka elektroerozyjna w obu znanych odmianach: drążenia wgłębnego EDM i wycinania drutowego WEDM. W prezentowanej pracy do obróbki kompozytów zastosowano wycinanie WEDM. Użyto wycinarki elektroerozyjnej zaopatrzonej w generator typy RC. Narzędzie obróbcze stanowił drut mosiężny o średnicy 0,25 mm. Obróbkę prowadzono w wodzie dejonizowanej. Przebieg obróbki kompozytów porównywano z przebiegiem obróbki stali handlowej H13 i spiekanej (MH13). Jako podstawowe parametry obróbki przyjęto czas trwania wyładowań (impulsu) i napięcie w impulsie. W funkcji tych wielkości optymalizowano wydajność obróbki i chropowatość uzyskanych powierzchni. Badania wykazały, że obróbka kompozytów jest mniej wydajna niż w procesie obróbki mechanicznej. Chropowatość powierzchni rośnie wraz ze wzrostem energii pojedynczych impulsów i ulega obniżeniu dla kompozytów z największą zawartością TiC. Określono najkorzystniejsze warunki obróbki WEDM badanych kompozytów: czas trwania impulsu 1,5 µs, czas przerwy pomiędzy impulsami 10 µs i napięcie robocze 122 V.

19

Influence of lapping velocity, pressure and time on ceramic elements machining results

Molenda J.

Zeszyty Naukowe Akademii Morskiej w Gdyni

|

2013

|

nr 81

85--92

EN

Ceramics in recent years have been sought in many applications due to their improved properties like low density, high fracture toughness, high hardness and wear resistance, good high temperature strength and others. On the negative side, they are far less ductile than metals and tend to fracture immediately when any attempt is made to deform them by mechanical work. This is why machining of ceramic materials is a big challenge and quite expensive affair. Primarily they are finished by abrasive machining processes such as grinding, lapping and polishing. Lapping is used for achieving ultra-high finishes and close tolerances between mating pieces. It has been found very useful in the manufacture of optical mirrors and lenses, ceramics, hard disk drive, semiconductor wafers, valve seats, ball bearings, and many more parts. Lapping process on ceramics usually produces the surface finish as about 1÷0.01 µm of Ra. Aluminium oxide is one of the hardest materials known. Its high hardness promotes a series of applications in mechanical engineering, such as bearings and seals. During research Al₂O₃ sealing elements were lapping. The main goal was to check the results of machining for different process parameters. The experiments were conduct during flat lapping with use of ABRALAP 380 lapping machine. The lapping machine executory system consists of three conditioning rings. The process results were surface roughness Ra and material removal rate.

PL

Zakres zastosowań ceramiki technicznej obejmuje współcześnie prawie wszystkie dziedziny techniki. Tak szerokie wykorzystywanie wynika z jej licznych zalet, jak korzystny stosunek masy do objętości, wysoka twardość, odporność na ścieranie, odporność na korozję, mechaniczną wytrzymałość w wysokiej temperaturze, trwałość kształtu i inne. Istotną cechą prawie wszystkich materiałów ceramicznych jest ponadto ich kruchość. Te szczególne cechy ceramiki, w połączeniu z wysokimi wymaganiami pod względem jakości powierzchni obrobionej oraz dokładności wymiarowokształtowej wyrobu, sprawiają, że należy ona do grupy najtrudniej obrabianych materiałów konstrukcyjnych i należy przywiązywać szczególną uwagę do wyboru metody obróbki i doboru jej parametrów. Zastosowanie znajdują tylko niektóre metody wytwarzania. Szeroko wykorzystywane są przede wszystkim szlifowanie, docieranie i polerowanie. Docieranie stosuje się najczęściej wtedy, gdy wymagana jest jednocześnie wysoka dokładność kształtu, dokładność wymiarowa oraz określona mikrostereometria powierzchni obrobionej. Jako rodzaj obróbki wykończeniowej docieranie ma obecnie wiele zastosowań, między innymi w przemyśle kosmicznym, samochodowym, narzędziowym, medycznym, elektrooptyce, wytwarzaniu elementów urządzeń do archiwizacji danych, elementów pomp i zaworów. Pozwala ono na uzyskanie chropowatości powierzchni elementów ceramicznych Ra = 1–0.01 µm. Tlenek glinu jest jednym z najtwardszych materiałów konstrukcyjnych, co umożliwia jego szerokie zastosowanie w budowie maszyn, między innymi na elementy łożysk i uszczelnień. W pracy przedstawiono wyniki docierania elementów wykonanych z tego materiału. Głównym celem było sprawdzenie efektów obróbki przy zastosowaniu różnych parametrów procesu. Badania prowadzono w czasie docierania jednotarczowego na docierarce ABRALAP 380 o podstawowym układzie wykonawczym, składającym się z trzech pierścieni prowadzących. Analizowano chropowatość powierzchni opisaną parametrem Ra i ubytek materiałowy, liniowy i masowy.

20

Wpływ warunków wycinania elektroerozyjnego na cechy geometryczne przedmiotów i wydajność procesu

Oniszczuk D.

Mechanik

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2013

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R. 86, nr 10

872--876

PL

Proces wycinania elektroerozyjnego (WEDM) to zaawansowana technologia coraz szerzej stosowana w przemyśle maszynowym, szczególnie w sektorach: przetwórstwa tworzyw sztucznych (produkcja form wtryskowych), odlewniczym (kokile), obróbki plastycznej (stemple, wykrojniki), do wykonywania precyzyjnych części lotniczych itp. Podstawowym czynnikiem determinującym proces obróbki elektroerozyjnej jest energia wyładowania elektrycznego. Opracowano stanowisko do wyznaczania rzeczywistych przebiegów natężenia i napięcia elektrycznego. Na tej podstawie przeprowadzono badania doświadczalne, których rezultatem jest opracowanie statystycznych modeli matematycznych pozwalających przewidzieć wpływ parametrów energetycznych obróbki na: chropowatość powierzchni, błędy kształtu oraz wydajność powierzchniową wycinania elektroerozyjnego.

EN

The wire electrical discharge process (WEDM), refers to the state of art technique widely spreading recently in the engineering industry, particularly in the plastics processing industry (in production of injection molds), metal casting (permanent molds), metal working (punches, blanking dies) or production of precision aircraft parts. The primary factor in the treatment process is energy of the electrical discharge. Therefore, a measuring system was developed first to determine the real current – voltage characteristics. With a so predetermined set of electrical parameters experimental studies were carried out and relevant statistical and mathematical models were obtained for predicting the effect of electrical parameters on surface roughness, shape errors and material removal rate.