Final Finishing Process Research Articles

Glassy phase influence on the optical finishing of sintered silicon carbide with Al2O3 and Y2O3

Developing low-roughness silicon carbide (SiC) mirror surfaces for aerospace applications is challenging due to their extreme hardness and brittle nature. In this work, liquid phase sintered silicon carbide (LPS-SiC) substrates were machined at different feed rates. The influence of the glassy phase on the final finishing process was evaluated. An innovative thermo-chemical etching was proposed to evince the glassy phase. X-ray diffraction (XRD) analysis revealed the change of crystal structure from β-SiC to α-SiC in addition to the presence of YAP and YAG phases, constituents of the glassy phase. Vickers microhardness and scratch tests simulating the action of a single diamond grain on the surface of the substrates with and without the glassy phase showed that the hardness of the SiC grain and its fracture resistance exceeded the values obtained for the substrate with the glassy phase by 110% and 170% respectively. Reducing the feed rate decreased the damage to the surface of the substrate with the glassy phase by 25% and to the SiC matrix by 90%.

TRIKOTAJ MATOLARIGA YUMSHOQLIK BERISH TEXNOLOGIYASI

Perforation of a fabric during sewing of garments made from knitted fabrics is one of the problematic issues. This defect occurs when threads on the knitted fabric break. In textile materials, thread breakage is characterized by complete or partial breakage of individual threads in the fabric during sewing. The porosity of fabrics can be divided into visible and invisible types, which can be eliminated by processing using different compositions. This paper explores application of soft cationic surfactants, amino modified silicone oil – 350, amino modified silicone oil – 200, DMC amino modified silicone oil – 350 and silicone-based softeners to knitted fabrics. Based on findings from experiments on the effects of variable process factors on perforation of knitted fabrics in sewing processes, it has been recommended to use imported silicone-based softener and local amino-modified silicone oil-350. The experiment findings helped to develop a technological sequence and composition of the final finishing process of «softening» of knitted fabrics using selected softeners. The experiment showed that it is expedient to heat-treat a fabric soaked in a softener solution for 5 minutes at a temperature of 140 0 C.

Integrated ANN-GA Approach For Predictive Modeling And Optimization Of Grinding Parameters With Surface Roughness As The Response

Grinding, the commonly used final finishing process across various industries for preparation of surfaces, uses an abrasive cutting wheel. Surface finish is the most commonly used index of final product quality in terms of aesthetics, corrosion resistance and others. The final surface finish of the grounded components depends on the cutting conditions of the grinding wheel and the machining parameters. Grinding wheel loading and wheel wear are the significant factors that determine the cutting conditions of the grinding wheel. Grinding wheel dressing is usually carried out to restore the original cutting conditions of the wheel. Speed, feed and depth of cut are the various machining parameters that affect the final surface finish. This paper aims to develop a predictive as well as optimization model by integrating Artificial Neural Network (ANN) with Genetic Algorithm (GA). Experiments were conducted on cylindrical grinding machine with Silicon Carbide grinding wheel. Speed, feed and depth of cut were selected as the three machining parameters with three different levels. Multilayer Normal Feed Forward ANN model of type 3-5-1 was considered for the prediction of surface roughness. Predicted values using the ANN model showed good agreement with the experimental values of surface roughness. Using ANN model alone could have the drawback that local minima based on initial parameters/training can be mistaken for the global optimum. Integrating Genetic Algorithm (GA) with ANN model overcomes this to a great extent. Such a hybrid technique can result in global optimal point of the machining parameters thereby leading to minimum surface roughness. The experimental results show the feasibility of the proposed method in the predictive modeling and optimization of grinding parameters.

Numerical analysis on effect of surface asperity of piston skirt on lubrication performance

Tooling marks usually remain as grooves on the surface of piston of internal combustion engine, due to the final finishing process by machining. In this paper, therefore, the influence of the grooves fabricated by machining process on the surface of the piston skirt on the lubrication performance was elucidated by applying the Taguchi method. The effect of shape and alignment of the grooves on the oil film thickness and the friction coefficient was calculated using Elastic Hydrodynamic Lubrication theory. From results, it was suggested the control of the groove shape in the width direction may be useful for reducing the friction coefficient.

Effect of Wet Processing Operations on Functional Properties Imparted to PET Fabrics Loaded with Different Metal Oxides Nanoparticles Part I: Effect of Finishing on Properties Imparted to Bleached PET Fabrics loaded with TiO2, ZnO and SnO2 NPs

The present article investigates the effect of finishing wet operations on functional properties imparted to bleached and partially hydrolyzed PET fabrics by loading with TiO2, ZnO and SnO2 nanoparticles. Different trials have been carried out to clarify the effect of the sequences of finishing wet process on the properties of loaded with nanoparticles PET fabrics. Characterization of the so finished fabrics was carried out through SEM, EDX and FT-IR. EDX and FT-IR have confirmed that, interaction has actually taken place between carboxylic groups created on PET fabrics and each of the applied nanoparticles. Moreover, the obtained data revealed that, the finishing wet operation has no effect on the abovementioned interaction. The effect of finishing wet operation on the functional performances of PET fabrics was evaluated by analyzing its antimicrobial activity and ultraviolet protection properties. The antimicrobial activity was tested against B. mycoides, E. coli and C. albicans. It has been found that, loading PET fabrics with TiO2 and ZnO during or after carrying final finishing process using pad-dry-cure method paves the way for imparting outstanding antimicrobial activity even after five washing cycles. Also the obtained results revealed that, the sequence of loading the applied NPs before or during or after carrying finishing wet operation highly affect the UPF values.

An Intelligent Prediction of Surface Roughness on Precision Grinding

Precision grinding is generally used as the final finishing process, and it determines the surface quality of the machined component. It’s very difficult to achieve on-line measurement of the surface roughness. The purpose of this research was to study the surface roughness prediction and avoid the defect happening in the grinding process. A surface roughness prediction model was proposed in this paper, which presented the relationship between surface roughness and the wear condition of grinding wheel and grinding parameters. An AE sensor was used to collect the grinding signals during the grinding process to obtain the grinding wheel wear condition. Besides, a fuzzy neural network was used to obtain the prediction surface roughness. Grinding trials were performed on a high precision CNC cylindrical grinder (MGK1420) to evaluate the surface roughness prediction model. Experiment verified that the developed prediction system was feasible and had high prediction accuracy.

Abrasive fine-finishing technology

Abrasive fine-finishing technology is often applied as a final finishing process, and the selection of the right technology is crucial to obtaining the desired performance of functions such as fatigue life. This paper begins with classifications of the technology along with fundamentals and brief histories of the individual methods. The material removal mechanisms, specific energies, and finishing characteristics of the various technologies are summarized giving assessments of the surfaces created by them. Guidelines developed for selecting the appropriate methods, and case studies illustrate the effectiveness of various methods. This paper ends with a discussion of the future prospects of the technology.

Temperature assessment in surface grinding of tool steels

Surface grinding being the final finishing process has to be performed and evaluated with care as the surface being machined could get damaged due to high temperatures being generated. This is evaluated with the help of mathematical modelling of the temperature generated is compared with experimental results obtained during surface grinding of the selected tool steel workpieces in both dry as well as wet environment and further compared with a simulation performed using ANSYS 14 software. The results are found to be correlating and satisfactory and are in tandem with the ones found from experimentation. The usage of production type grinding wheel reduces the temperature being generated during grinding. The dressing depth also plays an important role of reducing the temperatures during surface grinding.

Investigation of Heat Treated Electrodeposited CoNiFe on Microstructure and Hardness

In this research, heat treatment is the final finishing process applied on nanocrystalline CoNiFe to improve microstructure for good hardness property. Nanocrystalline CoNiFe has been synthesized using the electrodeposition method. This study investigated the effect of heat treatment at 500°C, 600°C, 700°C and 800°C on electrodeposited nanocrystalline CoNiFe. The heat treatment process was performed in the tube furnace with flowing Argon gas. By changing the heat treatment temperature, physical properties such as phase and crystallographic structure, surface morphology, grain size and hardness of nanocrystalline CoNiFe was studied. The nanocrystalline CoNiFe phase revealed the Face Centered Cubic (FCC) and Body Centered Cubic (BCC) crystal structure. FESEM micrographs showed that the grain sizes of the coatings were in the range of 78.76 nm to 132 nm. Dendrite shape was found in the microstructure of nanocrystalline CoNiFe. The nanocrystalline CoNiFe prepared in heat treatment temperature of 700°C, achieved the highest hardness of 449 HVN. The surface roughness of nanocrystalline CoNiFe heated at 700°C was found to be smaller than other temperatures.

Novel Force Modelling Technique for Grinding

AbstractGrinding occupies a place in the machining arena as the final finishing process, which tends to exist in all machining environments. The grinding process generates forces that have to be countered by the robustness of the machine tool and a methodology to compute the forces that might be generated by it for deciding the type of tool and depth of cut to be used for a given variety of workpiece. Prior computation of the forces being the primary concern can be a handful of help to the industrial personnel and managements to decide on the variety of machine tool and accessories to be bought for the kind of grinding to be done. Comparison of the proposed model with the available literature shows good agreement.

Experimental investigation and analytical modelling of the effects of process parameters on material removal rate for bonnet polishing of cobalt chrome alloy

Abstract Cobalt chrome alloys are the most extensively used material in the field of total hip and total knee implants, both of which need highly accurate form and low surface roughness for longevity in vivo. In order to achieve the desired form, it is extremely important to understand how process parameters of the final finishing process affect the material removal rate. This paper reports a modified Preston equation model combining process parameters to allow prediction of the material removal rate during bonnet polishing of a medical grade cobalt chrome alloy. The model created is based on experiments which were carried out on a bonnet polishing machine to investigate the effects of process parameters, including precess angle, head speed, tool offset and tool pressure, on material removal rate. The characteristic of material removal is termed influence function and assessed in terms of width, maximal depth and material removal rate. Experimental results show that the width of the influence function increases significantly with the increase of the precess angle and the tool offset; the depth of the influence function increases with the increase of the head speed, increases first and then decrease with the increase of the tool offset; the material removal rate increases with the increase of the precess angle non-linearly, with the increase of the head speed linearly, and increases first then decreases with the increase of the tool offset because of the bonnet distortion; the tool pressure has a slight effect on the influence function. The proposed model has been verified experimentally by using different Preston coefficients from literature. The close values of the experimental data and predicted data indicate that the model is viable when applied to the prediction of the material removal rate in bonnet polishing.

Development of Measurement Device for Thermal Displacement in Cylindrical Grinding Machines (Study on Measurement Method for Thermal Displacement with Rotation of Wheel Spindle)

Cylindrical grinding machines are typical machine tools for the final finishing process which produce high accurate and value-added products. However the universal method of measurement and evaluation for their thermal displacement has not been established. Therefore, in this study, we propose a measurement and evaluation method for the thermal displacement of the cylindrical grinding machines with rotation of the wheel spindle and make a device on an experimental basis based on the proposition and examine their validity. As the result of this study, it is made clear that the method proposed by us can measure and evaluate effectively and simultaneously 5 thermal displacements of the cylindrical grinding machines, that is, 3 translational deviations and 2 angular deviations.

Mathematical modeling for finishing tooth surfaces of spiral bevel gears using pulse electrochemical dissolution

Gears with a complex curve tooth, such as spiral bevel and hypoid gears, lack an ideal technique for the final finishing process. Pulse electrochemical finishing (PECF) is considered a promising method for surface finishing due to its micro-removal characteristics. A PECF system for spiral bevel gear (SBG) is established according to the generation of SBG tooth surfaces. An SBG (module, 12 mm; number of teeth, 38) is selected as the processing test piece, and mathematical models are developed for analyzing the characteristics of PECF. The influence of the experimental variables, including applied voltage, interelectrode gap, and finishing time, on the total removal thickness and surface roughness is discussed. The calculated values are found to be approximately consistent with the experimental values. The other parameters, including the concentration of electrolyte, tool rotational speed, flow rate of electrolyte, and pulse period, are also studied. Results show that the roughness of the SBG tooth surface is reduced from Rz 7.13 to 4.32 μm. The precision of the SBG is also improved.

Recent Development of the Aero-Engine Impeller and Blade Surface Polishing Technology

The air compressing efficiency and heat conductance of aero-engine is markedly influenced by the surface micro-morphology and surface roughness of the impeller and blades, which will further affect the thrust weight ratio of plane. To achieve low flow losses, the roughness values of the impeller and blade surface must be below certain limits. Some polishing techniques as final finishing process of the impeller and blades are reviewed and their recent developments are shown in the paper. Further more a new kind of point-by-point NC polishing principle for aero-engine impeller surface, in which surface roughness will gradually change from the inlet to the outlet, are presented.

全自動巻取包装機の現状

The wrapping process, which is the final finishing process for rolls (products), must meet the needs of a larger wrapping volume and a larger variety of wrapping specifications than ever before. As production control in the entire plant becomes computerized, roll wrapping machines also receive wrapping data on-line, paving the way for automatic wrapping to process a large volume and a large variety of specifications. Now we have developed a roll wrapping machine that can process rolls produced by several paper machines, by increasing its wrapping capacity as well as enabling it to follow a large variety of wrapping specifications.This machine consists of a bar code reader, inkjet printer, wrapping machine, and labeler. Operation data for each part can be set or changed easily through a touch panel. The operator training will be completed in a relatively short time.This machine has demonstrated high reliability as equipment that plays an important role in the final finishing process for rolls.

Parameter optimization by Taguchi methods for finishing advanced ceramic balls using a novel eccentric lapping machine

The final finishing process of advanced ceramic balls used in hybrid precision bearings constitutes two-thirds of the total manufacturing cost, and hence effective and economic finishing methods and processes are critical to their widespread application. A novel eccentric lapping machine is designed and manufactured. Hot isostatically pressed silicon nitride ball blanks (diameter 13.25mm) are used to investigate the feasibility of accelerating the ball finishing process while maintaining high surface quality. Taguchi methods are used during the first step of finishing to optimize lapping parameters; the L9 (34) four-parameter, three-level orthogonal array is used to design the experiment. Experimental results reveal that this novel eccentric lapping method is very promising; a material removal rate of 40 μm/h is achievable. The optimum lapping condition is found to be high speed, high load and high paste concentration with 60 μm diamond particles. The analysis of variance shows that the most significant lapping parameter is lapping load, which accounts for 50 per cent of the total, followed by lapping speed (31 per cent); the particle size and paste concentration only account for 12 per cent and 7 per cent respectively. A comparison with previous lapping experiments and the mechanism of material removal are also discussed briefly.

A NEW CONCEPT FOR DECOUPLING THE CUTTING FORCES DUE TO TOOL FLANK WEAR AND CHIP FORMATION IN HARD TURNING

Determining the temperature field in metal cutting when the tool flank is progressively worn requires the knowledge of the forces due to tool flank wear and that due to chip formation. In the past, these forces have been computed from data experimentally measured with a dynamometer, under the assumption that the chip formation configuration remained unaltered when the tool flank is progressively worn. This approach has been used in the literature even though there has been evidence that it is not correct. The error introduced by this doubtful assumption in computing the maximum surface temperature in the work-piece can be significant. Of late there has been considerable interest in employing hard turning as the final finishing process in place of grinding and superfinishing. Consequently, the ability to accurately predict the maximum surface temperature and its distribution in the workpiece is now most desirable, for avoiding thermal damage to the machined surface. This paper discusses a new method based on the thickness of the microstructural change in chips to decouple the tool-flank forces for predicting the maximum surface temperature and its distribution in the workpiece.

Cotton Protective Apparel for the Space Shuttle

All the materials for use either in a manned space flight or in a flight experiment, including materials of the spacecraft, crew provision, and equipment, must be evaluated and meet certain performance criteria as established during the Mercury, Gemini, Apollo, and Skylab programs. In addition to testing for the primary requirements of flame-resistance, odor, offgassing products, flash- and fire-point temperatures, cotton textile items were also considered as candidate space-shuttle, in-flight apparel on the basis of skin sensitivity, comfort, electrieal resistivity, colorfastness, and general protective features exhibited under certain conditions of flame and heat exposure. Chemically-treated flame-resistant cotton fabries that have been approved for space-shuttle apparel include a two-ply sateen (244 g/m2), a filling sateen (153 g/m2), and a two-ply, mercerized, single-knit jersey (187 g/m2). These fabrics are being used to fabricate the total flight ensemble from underwear to coverall and outer jacket. Fabrics for the outer garments were dyed to NASA-specified shades of blue with stable vat dyestuffs, compatible with the flame resistant treatment. These cotton fabrics were treated first with commerciat phosphonium salts and subsequently cured with gaseous ammonia. The process is more commonly referred to as the tetrakis(hydroxymethyl)phosphonium hydroxide/ammonia (THPOH/NH3) method. A second finishing application was required in order for the finished textile items to meet the slightly oxygen-enriched environment of the spacecraft crew bay area. The final finishing process comprised adding on diammonium phosphate (DAP)/urea, drying, curing (90 s @177°C), and afterwashing. DAP is a more efficient flame inhibitant than the phosphonium polymer, thus the combination treatment served to impart higher resistance to ignition and sustained combustion, as required by NASA test standards.

A Novel and Comprehensive Final Finishing Process for Worsted and Related Fabrics

In conventional processing, handle, thickness, lustre, dimensional stability, etc., are largely determined by the three final finishing processes known as pressing (hydraulic or rotary), blowing and high‐temperature decatising (the last being essentially a ‘setting’ process). The significant changes in fabric properties which are brought about in these three industrial procedures are briefly mentioned, and emphasis is given to the results that can be achieved in respect of fabric compression and subsequent recovery. There are serious limitations to the extent to which a high degree of compression can be permanently ‘set’ into fabric when it is in roll form, and also to the permanence of finish that can be achieved by continuous blowing or pressing.The principles underlying the proposed new process are then described. Data are given for the compression and recovery characteristics obtained with this process, and these are compared with the results of conventional methods.The paper consists of an account of the development of a machine for industrial production, indicating some of the problems that have had to be solved, and ends with an assessment of its anticipated commercial advantages.