Papers by Author: Syed H. Masood

Abstract: The Selective Laser Melting (SLM) process has been proved as the most effective method among Additive Manufacturing (AM) technologies to produce hard, dense and strong metallic structures with intricate shapes and profiles from wide range of metallic alloys. The SLM generated structures from 17-4PH stainless steel high strength alloys involve layer by layer building up through laser melting of successively deposited powder layers. Therefore, the mechanical properties of such structures need to be thoroughly checked and investigated before putting these materials to practical applications. This research mainly investigates the cryogenic impact properties of SLM generated 17-4PH specimen. These characteristics are very important in applications requiring high strength customized structures that could maintain their mechanical properties at sub-zero temperatures. The experimental analysis proves that SLM is a very reliable technology to produce high strength metallic structures and these specimens can function efficiently in extreme conditions.

Abstract: The Pallet Loading Problem (PLP) in packaging industry usually deals with generating optimal pallet patterns of placing boxes on a rectangular pallet. For a given pattern, the boxes can be placed in different set of sequences each affecting efficiency and productivity of robotic palletisation. Therefore, getting an optimal pallet pattern does not guarantee an optimal pattern placement strategy. Therefore, there is a need to develop a methodology that considers the palletisers physical characteristics and limitations in robotic palletising systems. This paper presents development of a methodology to determine the placement sequence in robotic pallet pattern formation with the aim of improving the operational efficiency in robotic palletisation.

Abstract: In an injection moulded part, warpage is the distortion caused by non-uniform shrinkage within the plastic part. When looking critically at the causes of warpage, it is found that several key parameters of the moulding process have some effect on the warpage. However, the two major categories that contribute to warpage include the part design and the mould design. In mould design, the gate location, runner/gate system and cooling system design are the major factors affecting not only the warpage and part quality but also the injection moulding cycle time. This paper presents an investigation of using different cooling system configuration on warpage and shrinkage of an industrial plastic part with the aim of determining which cooling configuration will provide minimum warpage and cycle time. As conventional injection mould cooling design is based on straight drilling, it limits the geometric complexity of the cooling design, especially curved shape cooling channels. Nowadays, new technology of advanced rapid tooling based on solid freeform fabrications can be been used to provide conformal cooling channels in injection moulds. In this paper, several type of cooling channels are analysed to compare the performance in terms of warpage and shrinkage and to determine which configuration is suitable for minimizing warpage. Autodesk Moldflow Insight (AMI) simulation software is applied to examine the results of the cooling performances and warpage analysis.

Abstract: Cold spray technology has the potential to be utilised in broader industrial applications especially for oxygen-sensitive materials such as titanium. In this paper, the effect of titanium cold spray coating on residual strain after deposition is evaluated. Ring-shaped sample of 16.5 mm diameter was directly fabricated from titanium powder by cold spray. Using an X-ray diffractometer (XRD) and finite element analysis (FEA), the coating surface was analysed and compared. The XRD measurements revealed that residual strain at the sample surface (εXRD) was around 0.140. There was also some X-ray peak broadening of steel, which may be related to presence of porosity in unpolished samples. In addition, a good correlation was found (εFEA ≈ 0.169) when the residual strain results obtained from FEA were compared with the conducting test outcomes. Therefore, finite element method can be considered as a cost effective tool in quantification of strain in cold spray titanium structure.

Abstract: This paper presents an investigation on the microstructure and surface hardness of the parts fabricated by laser assisted Direct Metal Deposition (DMD) technology. A series of engineering metallic alloy powders were used in the DMD process to produce simple 3D geometric structures. The alloy powders investigated include: 316L stainless steel, 420 Stainless Steel, Stellite(R) 6, tool steel (H13), Cholmoloy (Ni Based alloy), and Aluminium Bronze. These were chosen due to their frequent application in engineering parts and components. The microstructure and hardness values have been compared to those of the wrought products (as annealed) as reported in the SAE standards, Heat treater’s guide to metals ASM international, and material data sheets supplied by the materials manufacturers. A significant difference is reported in both hardness and microstructure of the laser deposited samples compared to those of the wrought form.

Abstract: Knowledge of the mechanical properties of parts processed by Fused Deposition Modelling (FDM) rapid prototyping process is essential for engineering applications of such parts as the mechanical strength of parts depends heavily on the FDM process parameters selected during part fabrication. Little knowledge is available for the Polycarbonate (PC) material used in the FDM systems. This paper presents results of the experimental work on the effect of the FDM process parameters such as air gap, raster width, and raster angle on the tensile properties of PC. Results show that FDM made parts have tensile strength in the range of 70 to 75 % of the moulded and extruded PC parts. The results will be valuable for different functional applications of FDM produced parts and assemblies.

Abstract: This paper presents an investigation on rheological properties of a new ABS (acrylonitrile-butadiene-styrene)-Iron composite for application in Fused Deposition Modelling rapid prototyping process. Test samples of ABS-Iron composites have been made by controlled centrifugal mixing and thermal compounding through a single-screw extruder and compression moulding. Rheological characterization was conducted using a capillary rheometer by measuring pressure drop at the die while varying the extrusion speed. Apparent shear rate and shear stress as well as viscosity of the melts were calculated. Modulated differential-scanning calorimetry (MDSC) techniques were used in order to characterize viscoelastic properties of these newly developed composites materials. Non-Newtonian behaviour of the composite melt has shown to follow a cross model of shear thinning characteristics.

Abstract: One of the most important aspects of mould design in injection moulding is the provision of suitable and adequate cooling arrangements. Proper cooling channel design in the mould is an important aspect as it affects cycle time and quality of the injection moulded plastic part. A new cooling channel design with copper tube insert can reduce cycle time by optimal and uniform heat transfer in the mould. In this research work a comprehensive FEA transient thermal-structural analysis has been performed with ANSYS simulation software to understand robustness and longevity of an industrial plastic part mould with these cooling channels and compared with conventional straight cooling channels. Autodesk Moldflow Insight (AMI) also has been used to get essential process parameter values for analysis. Result shows that by inserting copper tube in the cooling channels, a mould can increase cooling efficiency and can last for higher number of cycles before fatigue failure, thus increasing production rate.

Abstract: In cold spray process, the simulation of coating deposition and the arising residual stress analysis are critical for an optimisation of process conditions. However, there are not many published literatures on the role of residual stresses in a cold sprayed coating. In addition, the multi-particles deposition behavior is also not well known, especially when coating of pure titanium powder is considered. This paper considers the development of an explicit finite element model of a cold spray process with defined initial and boundary environment. The explicit finite element model is then used to determine the optimum operating parameters to deposit titanium particles. It is also used to predict the residual stress developed in the coating by examining a fluid/structure interaction. The measured velocity and temperature from Computational Fluid Dynamics model are then use as initial input parameters to the explicit dynamic simulation. The predicted results reveal that Finite Element Method can be used to study the development of residual stress in a cold-sprayed coating as well as to find the optimum operating conditions to deposit coating of titanium particles before doing a real time fabrication.

Abstract: High pressure die casting (HPDC) is widely used for manufacturing aluminum parts in automotive industry. In high pressure die casting mold, chill vents are used to allow residual air and gases to exhaust out from the mold cavity. The objective of this paper is to design and develop a bi- metallic chill vent for high pressure die casting using copper alloy material having high thermal conductivity, coated with steel layer on the surface. Transient thermal analysis was carried out using ANSYS software, and temperature distribution was compared with bimetallic and tool steel chill vents. The results show a faster extraction of heat in bi-metallic chill vent than that with steel. This paper also presents the effect of varying internal diameter of cooling channel in chill vent cooling.