M.Y. Noordin

Application of response surface methodology in describing the performance of coated carbide tools when turning AISI 1045 steel

The performance of a multilayer tungsten carbide tool was described using response surface methodology (RSM) when turning AISI 1045 steel. Cutting tests were performed with constant depth of cut and under dry cutting conditions. The factors investigated were cutting speed, feed and the side cutting edge angle (SCEA) of the cutting edge. The main cutting force, i.e. the tangential force and surface roughness were the response variables investigated. The experimental plan was based on the face centred, central composite design (CCD). The experimental results indicate that the proposed mathematical models suggested could adequately describe the performance indicators within the limits of the factors that are being investigated. The feed is the most significant factor that influences the surface roughness and the tangential force. However, there are other factors that provide secondary contributions to the performance indicators. In the case of surface roughness, the SCEA2 and the interaction of feed and SCEA provides these contributions whilst for tangential force, the SCEA2, the interaction of feed and SCEA; and the cutting speed provides them.

Optimization of cellulose acetate hollow fiber reverse osmosis membrane production using Taguchi method

Cellulose acetate hollow fiber membranes for reverse osmosis (RO) were spun using a forced convection technique. In this study, a systematic experimental design based on Taguchis method (which is a fractional factorial method) has been employed for discussing the relationship between the rejection rate coefficient, permeation rate and the dry-wet spinning conditions for making cellulose acetate hollow fibers for RO. The factors considered in the experimental design included the polymer contents (PCs), the ratio of the solvent (acetone) to swelling agents (formamide) in the dope solution, the dope extrusion rate (DER), the type of bore fluid (BF), the residence time (RT) and the nitrogen gas flushing rate (GR). The results indicate that the BF and the DER are the two most important factors in determining the performance of the RO membranes.

Performance evaluation of cemented carbide tools in turning AISI 1010 steel

In this paper, the performance of three cemented carbide cutting tools, two coated tungsten based cemented carbide — one with Al2O3 (black) outer layer and the other with TiN (golden), and an uncoated titanium based (silver grey) cemented carbide tool, with 80° — diamond insert shape were investigated during finish turning of AISI 1010 steel. The PCBNR tool holder, giving a side cutting edge angle of +15°, was used. Cutting tests were performed with constant depth of cut and at various cutting speeds and feed rates to investigate the performance of the tools under dry cutting conditions. Cutting forces and surface roughness were measured. The chips produced by the three type of tools during experimental trials were examined to determine the secondary shear zone, chip thickness and the angle of maximum crystal elongation. The tool which had the CVD with TiCN/TiC and PVD with TiN coating layer sequence performs best under the conditions tested, as lower forces with little variation were encountered, very good surface finish could be obtained and chips with minimum SSZ thickness could be produced, that contributed to low chip strain and therefore to low residual stresses on the workpiece surface.

Study of shear rate influence on the performance of cellulose acetate reverse osmosis hollow fiber membranes

The effect of shear rate on the separation performance of reverse osmosis hollow fiber membrane is discussed. Experiments involving six different dope extrusion rates (DERs) (ranging 2.5-5 ml/min) are performed with the other process factors set at the optimum conditions determined by the Taguchi analysis. This will enable an assessment to be made on the relationship between the DER and the rejection rate. The regression method is used to analyse the experimental results and an empirical model has been developed. Simultaneously, it is found that there is a fairly strong correlation between extrusion shear rate and the rejection rate of the membranes, whereby as the shear rate increases, the rejection rate increases until a critical level of shear is achieved, beyond which reverse osmosis membrane performance deteriorates, suggesting that there exists an optimum shear rate which yields optimal membrane morphology for reverse osmosis hollow fiber membranes.

Hard turning of stainless steel using wiper coated carbide tool

In recent years, tool manufacturers provide wiper geometry on cutting tools for turning applications with the purpose of increasing productivity and improving surface finish. Despite the potential added values, the use and study on wiper inserts are still lacking in quantity. This current study focuses on the performance of wiper coated carbide insert in hard turning with respect to tool life and surface finish. AISI 420 stainless steel hardened to 47?48 HRC was hard turned at various speeds and feeds ranging in finish turning parameters. Results showed that the maximum tool life of 18 min was achieved and the tool life decreased at higher cutting speeds and feeds. Wear occurred at both the rake and flank faces with crater formation exposing the carbide substrate indicating more severe wear on the rake face. The wiper coated carbide tool resulted in very fine surface finish, much better than the theoretical values.

The use of TiAlN coated carbide tool when finish machining hardened stainless steel

The introduction of hard turning has provided an alternative to the conventional processing technology used to manufacture parts made from hardened steels. Shorter product development time along with being more environmentally friendly are among the benefits offered by hard turning, which potentially results in lower manufacturing cost per part. However, common tool materials for hard turning applications are expensive. Due to the continuous developments in cutting tool materials and coating technology, inexpensive coated carbide cutting tools are being investigated to determine the potential of using them for use in extreme conditions as in hard turning. TiAlN coated carbide tool was selected to finish machine hardened steel. Performing hard turning dry at various cutting conditions, that is, cutting speed and feed rate, revealed that satisfactory tool life values and surface finish values that meet the strict range of finish machining were obtained when finish machining hardened steel of 47-48 HRC hardness.

Machining parameters effect in dry turning of AISI 316L stainless steel using coated carbide tools

Austenitic stainless steel AISI 316L is used in many applications, including chemical industry, nuclear power plants, and medical devices, because of its high mechanical properties and corrosion resistance. Machinability study on the stainless steel is of interest. Toward sustainable manufacturing, this study also includes the power consumption during machining along with other machining responses of cutting force, surface roughness, and tool life. Turning on the stainless steel was performed using coated carbide tool without using cutting fluid. The turning was performed at various cutting speeds (90, 150, and 210 m/min) and feeds (0.10, 0.16, and 0.22 mm/rev). Response surface methodology was adopted in designing the experiments to quantify the effect of cutting speed and feed on the machining responses. It was found that cutting speed was proportional to power consumption and was inversely proportional to tool life, and showed no significant effect on the cutting force and the surface roughness. Feed was proportional to cutting force, power consumption, and surface roughness and was inversely proportional to tool life. Empirical equations developed from the results for all machining responses were shown to be useful in determining the optimum cutting parameters range.

The effect of multiple pass cutting on surface integrity when hard turning of AISI D2 cold work tool steel

A judicious choice of insert material, tool geometry and cutting conditions can make hard turning produce better surfaces than grinding. AISI D2 is the most extensively used cold work tool steel in the tool and die industry. This steel of 60 HRC hardness was turned with PVD TiN coated ceramic tools (Al2O3/TiCN). Intragranular cracks were observed with single pass turning, while transgranular cracks occurred with multiple pass turning that was also accompanied by an increase in compressive stresses. In both passes, the white layer was observed, but in single pass, there was no subsurface deformed grain orientation, whereas in multiple passes, there was a distinct orientation.

A review of evolution of electrospun tissue engineering scaffold: From two dimensions to three dimensions:

The potential of electrospinning process to fabricate ultrafine fibers as building blocks for tissue engineering scaffolds is well recognized. The scaffold construct produced by electrospinning process depends on the quality of the fibers. In electrospinning, material selection and parameter setting are among many factors that contribute to the quality of the ultrafine fibers, which eventually determine the performance of the tissue engineering scaffolds. The major challenge of conventional electrospun scaffolds is the nature of electrospinning process which can only produce two-dimensional electrospun mats, hence limiting their applications. Researchers have started to focus on overcoming this limitation by combining electrospinning with other techniques to fabricate three-dimensional scaffold constructs. This article reviews various polymeric materials and their composites/blends that have been successfully electrospun for tissue engineering scaffolds, their mechanical properties, and the various parameters settings that influence the fiber morphology. This review also highlights the secondary processes to electrospinning that have been used to develop three-dimensional tissue engineering scaffolds as well as the steps undertaken to overcome electrospinning limitations.

The Effect of Cutting Parameters on Power Consumption during Turning Nickel Based Alloy

Machining process should also consider environmental aspect, with power consumption as one of the criteria. Cutting parameters can be optimized to minimize power consumption. This paper takes a study on turning of nickel-based hastelloy under dry condition (no cutting fluid) which varies cutting speed (150, 200, and 250 m/min) and depth of cut (0.5, 1.0, and 1.5 mm). Power consumption of particular machining process at various cutting parameters was derived and calculated. It was found that minimum power consumption was shown when the turning process was performed at the lowest cutting speed and depth of cut.