Analiza sila rezanja kod čeonog glodanja uporabom rotacijskog, centralno kompozicijskog plana pokusa i Taguchijeve metode

This paper presents a study of the influence of cutting conditions on the cutting force components during face milling of steel 42CrMo4. Two experimental plans, rotatable central composite design and the Taguchi method with orthogonal arrays and signal-to-noise ratio, have been designed and performed on controlled machining with corresponding cutting conditions. Equations for the cutting force components, as a functions of cutting parameters, have been obtained by means of regression analysis. The Taguchi method has been used to analyse impact of cutting parameters on the cutting force components and to find optimal level of the cutting parameters. The comparison of results obtained by means of the rotatable central composite design and the Taguchi method was performed.U radu je istražen utjecaj parametara obrade na komponente sile rezanja pri čeonom glodanju čelika 42CrMo4. Eksperimenti su provedeni prema odabranim planovima pokusa, a to su rotacijski, centralno kompozicijski plan pokusa i Taguchijeva metoda s ortogonalnim nizovima te omjerom signala i šuma. Regresijskom analizom dobivene su jednadžbe komponenata sile rezanja u zavisnosti od parametara obrade. Analiza utjecaja parametara obrade na komponente sile rezanja te određivanje optimalnih parametara obrade za minimalne komponente sile rezanja provedeni su uporabom Taguchijeve metode. Na kraju su uspoređeni rezultati primjenom rotacijskog, centralno kompozicijskog plana pokusa i Taguchijeve metode

EXPERIMENTAL ANALYSIS AND OPTIMIZATION OF THE CONTROLLABLE PARAMETERS IN TURNING OF EN AW-2011 ALLOY; DRY MACHINING AND ALTERNATIVE COOLING TECHNIQUES

The latest trends in machining research show that great efforts are being made to understand the impact of different cooling and lubrication techniques as well as cutting parameters on machining performances. This paper presents the investigation results of different cutting parameters and different cutting environments such as dry machining, minimum quantity lubrication (MQL) and minimum quantity lubrication with compressed cold air (MQL+CCA) on average surface roughness, cutting force and material removal rate. The experiments were designed based on three input parameters and three different cutting environments when turning of EN AW-2011 alloy. Taguchi-based grey relational analysis was used to identify the optimal process parameters by which minimum values of surface roughness, minimum value of cutting force and maximum value of material removal rate will be achieved. The results showed that minimum quantity lubrication in the stream of compressed cold air, in comparison to dry and minimum quantity lubrication machining, gives the best machining performances. Therefore, the use of MQL + CCA method, which reduces the amount of lubricant may represent in the described extent of turning operations an alternative to turning processes most often carried out by wet method that causes considerable costs for purchasing, maintaining and using cutting fluids

Surface roughness modelling in super duplex stainless steel turning

Super duplex stainless steels are alloys that have good corrosion resistance properties and are intended for applications in corrosive environments. Due to their chemical composition and microstructure providing high strength and thermal resistance as well as high ductility, the machinability of these alloys is difficult, resulting in longer production cycles and higher costs in terms of more frequent replacement of tools. In this paper, the machinability of the super duplex EN 1.4410 was investigated under environmentally friendly machining process by using cold compressed air as a coolant. Experimental data were generated using the range of selected input parameters and correspondingly analysed surface roughness as output data. Predictive models were developed in order to make a comparison of their prediction performance. In addition, this paper also describes the methodology for optimised development of a particular predictive model. Finally, comparative analysis of the accuracy of predictive models was performed in order to define which model represents the best fit for the analysed experimental data, and also to show validity of the optimisation process

EXPERIMENTAL INVESTIGATION OF FACE MILLING ALUMINUM ALLOY EN AW – 2011 T6 USING VARIOUS COOLING TECHNIQUES

The main goal of this paper is to determine the influence of cooling technique on surface roughness during up and down face milling of aluminum alloy EN AW – 2011 T6. Along with dry machining, three cooling techniques were observed: cutting fluid (CF), minimum quantity lubricant (MQL) and cold compressed air (CCA). Thirteen experiments were conducted for each technique. Following the defined plan of the experiment, cutting speed and feed per tooth were varied. An optical profilometer was used to analyze arithmetic deviation of the profile (Ra) and arithmetic mean of the absolute height (Sa). Down milling produced up to 24 % lower Ra and Sa values in comparison to up milling. Increasing feed per tooth greatly increased surface roughness while increasing cutting speed led to a 12 % to 14 % decrease in surface roughness. Using the same cutting parameters, CCA produced the lowest, while CF produced the highest Ra and Sa values. Using the test results and regression analysis, mathematical models were generated allowing for precise Ra and Sa predictions. Optimization of the regression models was carried out with the goal of achieving the lowest surface roughness for each milling strategy and applied cooling technique

A New Mathematical Model for Flank Wear Prediction Using Functional Data Analysis Methodology

This paper presents a new approach improving the reliability of flank wear prediction during the end milling process. In the present work, prediction of flank wear has been achieved by using cutting parameters and force signals as the sensitive carriers of information about the machining process. A series of experiments were conducted to establish the relationship between flank wear and cutting force components as well as the cutting parameters such as cutting speed, feed per tooth, and radial depth of cut. In order to be able to predict flank wear a new linear regression mathematical model has been developed by utilizing functional data analysis methodology. Regression coefficients of the model are in the form of time dependent functions that have been determined through the use of functional data analysis methodology. The mathematical model has been developed by means of applied cutting parameters and measured cutting forces components during the end milling of workpiece made of 42CrMo4 steel. The efficiency and flexibility of the developed model have been verified by comparing it with the separate experimental data set

Contribution to the assessment of economic viability of hard milling process

Tvrdo glodanje je postupak obrade materijala tvrdoće iznad 45 HRc. Kao tehnologija u razvoju, tvrdo glodanje predstavlja alternativu postupku obrade koji uključuje glodanje i završne operacije kao što su brušenje ili elektroerozijska obrada. U radu se na temelju eksperimentalnih podataka analizira istosmjerno i protusmjerno glodanje te istosmjerno i protusmjerno tvrdo glodanje. Na osnovi optimalnih parametara promatranih procesa, provedena je procjena ekonomske i kvalitativne održivosti tvrdog glodanja u odnosu na uobičajeni postupak obrade otvrdnutog čelika. Za procjenu optimalnih vrijednosti parametara obrade, kojima će se osigurati minimalno vrijeme obrade i minimalni troškovi obrade, korišteni su genetski algoritmi. Optimalne vrijednosti dobivene genetskim algoritmima, uspoređene su s vrijednostima dobivenim metodom simuliranog žarenja. Rezultati istraživanja pokazuju da su troškovi istosmjernog tvrdog glodanja 14 % viši od troškova istosmjernog glodanja, a troškovi protusmjernog tvrdog glodanja za 4,48 % viši nego troškovi protusmjernog glodanja. Ovo predstavlja polazni podatak u detaljnoj usporedbi standardne obrade tvrdih materijala i postupka tvrdog glodanja.Hard milling is milling of the parts with hardness of above 45 HRc. As a technology in the development, hard milling has a potential to replace the procedure which includes milling and finishing operations like grinding or electrical-discharge machining. The process parameters and machining performance considered in this work deal with the real experimental data in the down and up milling as well as down and up hard milling process. Based on the optimal parameters of observed processes, the estimation of economical and quality sustainability of hard milling process, regarding the conventional milling process of hardened steel, has been carried out. Genetic algorithms are used to estimate optimal values of cutting parameters that lead to a minimum unit machining time and a minimum unit production costs. Optimal values, obtained by means of genetic algorithms, have been compared with the results obtained by using simulated annealing optimization. The results of this study showed that down hard milling costs are 14 % higher than the costs of down milling while the costs of up hard milling are 4,48 % higher than the costs of up milling. This is a source data for a detailed comparison of standard procedure of machining parts increased hardness and hard milling procedure

Evaluation of 3D tool wear in machining by successive stereo-photogrammetry and point cloud processing

Procjena trošenja alata ima značajan utjecaj na kvalitetu proizvoda, kao i na učinkovitost proizvodnog procesa. Primijenjena je procjena trošenja alata temeljena na iskustvu i ukupnom vremenu trajanja obrade. Taktilni mehanički uređaji i optički mikroskop su također primijenjeni. Predlaže se i primjenjuje inovativna optička metoda mjerenja trošenja alata koja se zasniva na 3D skeniranju uporabom stereo-fotogrametrije i triangulacije. Metodom je moguće točno izmjeriti trodimenzionalne devijacije na ukupnoj površini rezne pločice, jer je trodimenzionalni vektor odstupanja oblika dobiven pomoću milijun točaka. Trodimenzionalnu funkciju svekupnog istrošenja alata moguće je dobiti i bez uklanjanja alata s alatnog stroja. Određivanje istrošenja alata kao trodimenzionalne funkcije nudi mnoštvo informacija prema kojima je moguće dovesti u vezu pojedinačne oblike trošenja alata s mogućim uzorcima trošenja.The tool wear evaluation has a very strong impact on the product quality as well as efficiency of the manufacturing process. Experience-based assessment of tool wear and total cumulative time of operation has been applied. Tactile mechanical sensing devices and optical microscopes have been applied as well. This paper proposes and applies an inovative optical tool wear measurement method. It is based on 3D optical sensing using stereo-photogrammetry and triangulation. It offers high accuracy 3D dimensional deviation measurement spanning over the total tool surface, hence 3D deviation vectors from some reference shape are obtained simultaneously for millions of points. The overall tool wear shape function in 3D is generated, in many cases even without disassembly of the tool. Capturing the tool wear as a 3D shape function potentially offers abundant information towards diagnostics in terms of correlating the particular tool wear shape function with respective potential causes

ANALYSIS OF PRODUCTION METHOD AND STABILIZING AGENT ON STRUCTURE OF ALUMINUM METAL FOAMS

Aluminum alloy foams are a form of porous metal whose structure resembles the shape of natural materials such as coral, bone, sponge, etc. Due to their structure, these materials retain good mechanical properties of the base material while being significantly lighter than non-porous metal. Metal foams can be used as energy and vibration absorbers, heat exchangers, insulators, and filters. The main disadvantage of this type of material is its high production cost. To reduce production costs, aluminum alloy chips are used as base material. Foams are made of A360 and AA 7075 aluminum alloys. To produce a porous structure, CaCO3 is used as a foaming agent while Zn and CaO were added as stabilizing agents. The main goal of the paper was to investigate the difference in the shape of pores and relative density after foaming with different stabilizing agents

THE INFLUENCE OF TEMPERATURE AND pH VALUES ON SEED GERMINATION AND SEEDLING TRAITS OF RED CLOVER CULTIVARS

Istraživanje utjecaja temperature (10 i 20ºC) i pH vrijednosti vodene otopine (pH 4, 5, 6 i 7) na klijavost sjemena i svojstva klijanaca (dužina radikule, hipokotila i klijanaca) provedeno je u klima komori sa sjemenom dva kultivara crvene djeteline (danski Rajah i poljski Viola). Naklijavanje sjemena izvršeno je metodom rolanog filter papira tijekom 10 dana. Dobiven je značajan utjecaj (p=0,01) temperature i pH vrijednosti za sva ispitivana svojstva. Razlike između kulitvara bile su također značajne (p=0,01) za sva svojstva osim za dužinu radikule. Veće prosječne vrijednosti ispitivanih svojstava dobivene su na višoj temperaturi. S obzirom na pH vrijednost, u prosjeku najveća klijavost utvrđena je na pH 4 i 6, a najmanja na pH 5. Prosječna dužina radikule je bila najveća na pH 4, a najmanja na pH 7. Vrijednosti prosječne dužine hipokotila i ukupne dužine klijanaca su bile najveće na pH 4, a najmanje na pH 5. Kultivar Rajah je imao veću prosječnu klijavost, dužinu hipokotila, kao i ukupnu dužinu klijanaca.Investigation of temperature (10 and 20ºC) and pH values of water solution (pH 4, 5, 6 and 7) influence on seed germination and seedling traits (radicle, hypocotyls and seedling length) of two red clover cultivars (Danish Rajah and Polish Viola) seeds was carried out in growth chamber. Seed was germinated by the rolled filter paper method during 10 days. Significant influence (p=0.01) of temperature and pH values on all investigated traits was found. Differences between cultivars were also significant (p=0.01) for all traits with exception of radicle length. Higher average values of investigated traits were obtained at higher temperature. Regarding pH values, the highest average germination was found at pH 4 and 6, and the lowest at pH 5. The average radicle length was highest at 4 and the lowest at pH 7. Values of average hypocotyls and seedling length were highest at pH 4 and the lowest at pH 5. Cultivar Rajah obtained higher average germination, hypocotyls and total seedling length