Process optimization and removal of phenol formaldehyde resin coating using mechanical erosion process

Consumption of coated abrasive discs in various automobile and pipe fitting application is increasing, due to its good surface finish. Coated abrasive disc consists of single layer of abrasive grain bonded to a fibre backing. The major portion of the disc is comprised of fibre backing. But the sustainability of the fibre backing is low and is dumped as waste after usage. The present work deals with the removal of resin coating and recovery of fibre backing from the spent coated abrasive discs using physical separation process such as sand blasting technique. Initially, the recovery experiment was carried out based on L16 orthogonal array. The factors and levels chosen for the experiments were erodent pressure (0.2, 0.4, 0.6 and 0.8 MPa), erodent size (36, 60, 80 and 120 grit), disc orientation (30, 45, 60 and 75°) and number of times flexing (5, 10, 15 and 20). The experimental result shows that erodent size and erodent pressure have a major impact on recovery of the fibre backing. The surface structure of the recovered backing was analysed using scanning electron microscopy and optical microscopy. The recovered backing was very much useful for the coated abrasive industry as the flexible backing and support material for abrasive grain coating.

Modeling and Simulation of the Surface Generation Mechanism of a Novel Low-Pressure Lapping Technology

Aluminum alloy (Al6061) is a common material used in the ultraprecision area. It can be machined with a good surface finish by single-point diamond turning (SPDT). Due to the material being relatively soft, it is difficult to apply post-processing techniques such as ultraprecision lapping and ultraprecision polishing, as they may scratch the diamond-turned surface. As a result, a novel low-pressure lapping method was developed by our team to reduce the surface roughness. In this study, a finite element model was developed to simulate the mechanism of this novel lapping technology. The simulation results were compared with the experimental results so as to gain a better understanding of the lapping mechanism.

Tribological Behavior and Analysis on Surface Roughness of CNC Milled Dual Heat Treated Al6061 Composites

Dual heat treatment (DHT) effect is analyzed using the machining of Al6061-T6 alloy, a readily available material for quickly finding the machining properties. The heat treatments are conducted twice over the specimen by the furnace heating before processing through CNC machining. The HSS and WC milling cutters are preferred for the diameter of 10 mm for the reviewed rotational speeds of 2000 rpm and 4000 rpm, and the constant depth of cut of 0.5 mm is chosen based on various reviews. Worthy roughness could be provided mostly by the influence of feed rates preferred here as 0.05 mm/rev and 0.1 mm/rev. The influencing factors are identified by the Taguchi, genetic algorithm (GA), and Artificial Neural Network (ANN) techniques and compared within it. The simulation finding also helps to clarify the relationship between influenced machining constraints and roughness outcomes of this project. The average values of heat treated and nonheat treated Al6061-T6 are compared and it is to be evaluated that 41% improvement is obtained with the lower surface roughness of 1.78975 µm and it shows good surface finish with the help of dual heat treatment process.

An Apparatus Designed for Coating and Coloration of Filaments Used in Fused Filament Fabrication (FFF) 3D Printing

Background: Three dimensional (3D) printing is emerging technology, capable of manufacturing a solid layer by layer. With the advancements of materials for 3D printing, this technology is applicable in almost every sector. But in accordance with the product requirements we need to modify the mechanical properties of material. To achieve good surface finish we require coating of filament. For this purpose an apparatus is designed for coating of material over a filament, which is capable of coating filaments uniformly and with automated process. Objective: The objective of present invention is directed to a filament feeding device for applying uniform coating on a filament in order to make 3D solid objects with good quality finishing, thereby eliminating the chances of strains and imperfect coating on the filament. Methods: The present invention relates to a filament feeding device, comprising a container equipped within the device for storing a chemical solution in a liquefied form, an inlet port fabricated on the container for inserting a filament inside the container, plurality of relief valves placed at a bottom portion of the container for controlling the leakage of the filaments during insertion of the filaments. A stepper motor in association with a blade equipped within the container to rotate the main extruder of a 3D printer, and an outlet port designed opposite to the inlet port for discharging the filament from the container for 3D printing of the filament in order to manufacture the solid object. Results: The apparatus makes it easy for coating and coloration of materials to make the reinforced composite filaments. As this apparatus provides uniform coating of material on the filaments, the product printed by filaments have good surface finish. Conclusion: The proposed method can reduce coating time and printing time. This work provides meaningful implication to researchers who are doing research in the domain of additive manufacturing.

Investigation on Precision Finishing of Helical Gears Using Newly Developed Silicon Carbide Mixed Styrene Butadiene Media and Abrasive Flow Finishing Process

The good surface finish of gears is one of the critical parameters which leads to its noise-free operation, efficient power transmission, and longer service life. However, most of the gear manufacturing processes do not produce a good surface finish. Therefore, gears need post-processing to finish their surface. Out of several methods of gear finishing like gear grinding, lapping, and honing, the abrasive flow finishing process offers more flexibility due to its self-deformable abrasive medium which can easily flow across complex internal or external geometry. The present study aims to improve the surface finish of helical gear by abrasive flow finishing (AFF) by experimentally identifying the optimum range of the potential input process parameters. An AFF set up was used for gear finishing by using a medium of styrene-butadiene and soft silicone polymer, Silicon carbide abrasive, and silicone oil as a blending agent. A special fixture was developed comprising of five parts namely spider, mandrel, upper, middle, and bottom cylinder with a circumferential hole, which allows the back and forth movement of AFF medium through the annular volume between fixture and gear. Further, an experimental investigation of process parameters like viscosity, effect of percentage of various components in medium, operating pressure, and helix angle of helical gears have been studied on percentage improvement of surface roughness (Ra) value of the gear. It is found that the concentration of abrasives in media and extrusion pressure were the two most significant parameters that have a maximum effect on the percentage reduction in surface roughness and finishing rate. Results show that the optimum combination of the extrusion pressure and abrasive weight percentage is 38 bar and 40 % that produces best results of around 76 and 69 % improvement in Ra for gear of helix angle 30 degree and 45 degree respectively.

A review of the techniques used to characterize laser sintering of polymeric powders for use and re-use in additive manufacturing

Additive manufacturing (AM), is one of the key components of the 4th industrial revolution. Polymer laser sintering (PLS) is a subset of AM that is commonly used to process polymers, and which achieves good surface finish, good mechanical properties of finished products and for which there is no need for support structures. However, the requirements for polymeric powder for PLS are strident. Moreover, PLS subjects polymeric feed powders to high temperatures that lead to degradation of their thermal, rheological, and physical properties and is thus an impediment to their recyclability. Therefore, it is imperative to investigate the degree of polymer degradation or aging before re-using the material. This paper reviews the common techniques that are employed to characterize the suitability of polymeric powders for use and re-use in the PLS process. These include, but are not limited to, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), laser diffraction analysis, gas pycnometry, scanning electron microscopy (SEM), and melt flow index (MFI) testing.

Parametric Study on In Situ Laser Powder Bed Fusion of Mo(Si1−x,Alx)2

Mo(Si1−x,Alx)2 composites were produced by a pulsed laser reactive selective laser melting of MoSi2 and 30 wt.% AlSi10Mg powder mixture. The parametric study, altering the laser power between 100 and 300 W and scan speed between 400 and 1500 mm·s−1, has been conducted to estimate the effect of processing parameters on printed coupon samples’ quality. It was shown that samples prepared at 150–200 W laser power and 400–500 mm·s−1 scan speed, as well as 250 W laser power along with 700 mm·s−1 scan speed, provide a relatively good surface finish with 6.5 ± 0.5 µm–10.3 ± 0.8 µm roughness at the top of coupons, and 9.3 ± 0.7 µm–13.2 ± 1.1 µm side surface roughness in addition to a remarkable chemical and microstructural homogeneity. An increase in the laser power and a decrease in the scan speed led to an apparent improvement in the densification behavior resulting in printed coupons of up to 99.8% relative density and hardness of ~600 HV1 or ~560 HV5. The printed parts are composed of epitaxially grown columnar dendritic melt pool cores and coarser dendrites beyond the morphological transition zone in overlapped regions. An increase in the scanning speed at a fixed laser power and a decrease in the power at a fixed scan speed prohibited the complete single displacement reaction between MoSi2 and aluminum, leading to unreacted MoSi2 and Al lean hexagonal Mo(Si1−x,Alx)2 phase.

Experimental Investigation of Electrochemical Micro Turning of Ti6Al4V With NaOH Solution

Ti6Al4V is a highly favorable material in biomedical, aerospace and many other industries. However, rapid tool wear during machining has made Ti6Al4V into a difficult-to-machine material. Electrochemical machining may be a solution to that challenge. Moreover, high chemical affinity and formation of oxide layer over the surface have limited the application electrochemical machining for Ti6Al4V. In this paper, an experimental approach of electrochemical micro turning of Ti6Al4V has been described. The electrolyte was 10% aqueous solution of NaOH and the tool was SS 310. For each and every experiment workpiece rotational speed and machining time were kept constant. Constant DC voltage was applied and the inter-electrode gap between tool and workpiece was kept constant for each experiment. Experiments were performed using two different levels of applied voltage, axial feed rate and inter-electrode gap. Their effects over MRR and surface roughness have been determined. Additionally, the optimum working condition was determined in order to maximize MRR and minimize surface roughness. For each experiment, acceptable material removal and good surface finish have been achieved. The maximum surface roughness (Ra) was found 1.128 μm in experiment 1. The utilization of NaOH solution has resulted in controlled electrolyzing current, controlled material removal and therefore, good surface finish.

Cylindrical Concentricity and Coaxiality Optimization for Boring Process by Using Taguchi Method

Machining is the process where the material on the surface of the workpiece is being removed through application of force and relative moment. Machining process involves a lot of process parameters. The utmost important thing in machining process is to achieve accurate dimensions and good surface finish where its lead to produce the high-quality product. A good surface finish is one of the factors that greatly influence manufacturing cost and also describes the geometry of the machined surface combine with the surface texture. This experimental research has been conducted in order to determine the optimum parameter involved that could affect the Concentricity and Coaxiality value by using Taguchi Method. To select the cutting parameters properly, the researcher collects the previous study to select the cutting parameters involving in Boring Operation of Computer Numerical Control (CNC) Lathe machine. Based on the collected previous study, it is shown that best cutting parameters used for the boring process are cutting speed, feed rate and depth of cut and using these cutting parameters as the controllable factor in this experiment. The researcher also uses the different type of materials which are Aluminum Alloy 6061, Mild Steel and Carbon Steel. This experiment also used only one type of cutting tools which is cemented coated carbide. Taguchi Method approach has been used to achieve the best-intended models and analyze the optimum parameter for the boring process by measure its concentricity and coaxiality of the workpiece. There are 9 workpieces been run in Conventional Lathe machine after been designed from the Computer-Aided Design (CAD). Analysis of Variance (ANOVA) and main effect plot been analyzed to find out the significant factor that affects the concentricity and coaxiality.

Effect of Process Parameters for Wirecut Electric Discharge Machining of Cladded SS304

The usage of cladded materials is grown in automobile industry. However, cutting of cladded material is considered as a challenging task because of its heterogeneous nature, therefore it is often subjected to thermal cutting like plasma arc cutting or gas cutting process. Wirecut Electric Discharge Machining (WEDM) is a competent alternate for good surface finish but this process offers relatively low level of cutting. The objective of this work is to identify the optimal values of WEDM process parameters such as pulse on time, table feed and working time and then study their effects on the surface roughness and Kerf width.