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Metallization on plastic has become a handy and popular technique mainly for bringing out the merits of metals to the respective polymer substrate. In the present work, copper electroless metallization is performed, and the effect of deposition temperatures, deposition times, and etching times are examined on additive manufactured specimens. To investigate the effect of etching time, weight measurement of etched samples (5, 15, and 20 min) is performed. The deposition of copper under different conditions is compared as per the Taguchi methodology with the electrical performance and microscopic images. It can be observed from the electrical resistance measurements that conductivity increases and electrical resistance decrease with a higher deposition temperature of 70°C when etched for 20 min and at a lower deposition time of 10 min. The weight measurement results confirm that higher etching time leads to better removal of butadiene due to the creation of more binding sites for metal atoms resulting in better copper metallization. Additionally, at higher deposition temperatures, more metal atoms are trapped in the polymer substrate, thereby increasing the extent of metallization. The results confirm with the microscopic images that metallization at higher deposition temperature, higher etching time, and lower deposition time exhibits better copper deposition. [ABSTRACT FROM AUTHOR]

Purpose: The thermal behavior at the interfaces (of the deposited strands) during fused filament fabrication (FFF) technique strongly influences bond formation and it is a time- and temperature-dependent process. The processing parameters affect the thermal behavior at the interfaces and the purpose of the paper is to simulate using temperature-dependent (nonlinear) thermal properties rather than constant properties. Design/methodology/approach: Nonlinear temperature-dependent thermal properties are used to simulate the FFF process in a simulation software. The finite-element model is first established by comparing the simulation results with that of analytical and experimental results of acrylonitrile butadiene styrene and polylactic acid. Strand temperature and time duration to reach critical sintering temperature for the bond formation are estimated for one of the deposition sequences. Findings: Temperatures are estimated at an interface and are then compared with the experimental results, which shows a close match. The results of the average time duration (time to reach the critical sintering temperature) of strands with the defined deposition sequences show that the first interface has the highest average time duration. Varying processing parameters show that higher temperatures of the extruder and envelope along with higher extruder diameter and lower convective heat transfer coefficient will have more time available for bonding between the strands. Originality/value: A novel numerical model is developed using temperature-dependent (nonlinear) thermal properties to simulate FFF processes. The model estimates the temperature evolution at the strand interfaces. It helps to evaluate the time duration to reach critical sintering temperature (temperature above which the bond formation occurs) as it cools from extrusion temperature. [ABSTRACT FROM AUTHOR]

The present work investigates, by both mathematical modelling and experiment, the contribution of bonding between the filaments to the strength of the parts manufactured by fused deposition modelling (FDM). A mathematical model for neck growth between cylindrical filaments is derived based on viscous sintering for cylindrical filaments. Theoretical ultimate tensile load is determined from the layer thickness information and predicted average final neck size between filaments. The experimental ultimate tensile load is obtained by conducting a simple tension test with two different build directions. Agreement between theoretical and experimental ultimate tensile load and scanning electron microscope (SEM) photomicrographs of the fracture surface indicate that the strength of the FDM part is primarily due to intra-layer bonding, inter-layer bonding and neck growth between filaments. It also indicates that the total time and heat available to the filaments are just sufficient to grow necks but not enough to fully coalesce. [ABSTRACT FROM AUTHOR]

In the present work, the relationships between two important quality objectives, namely, strength and volumetric shrinkage of fused deposition modelling (FDM) parts and selected process parameters, namely the build interior, the horizontal build direction and the vertical build have been determined through a minimum number of experiments based on face centred central composite design. Specimens have been manufactured on an FDM machine and tests have been conducted to evaluate strength and volumetric shrinkage. The relationship for each of these two response variables in terms of the three process parameters has been constructed using analysis of variance. The resulting two objective functions are optimised simultaneously using the non-dominated sorting genetic algorithm. In order to validate the Pareto optimal solution, three randomly chosen experimental runs at intermediate parameter values (other than design of experiments levels) were repeated and good correlation was found between these results and the Pareto optimal. [ABSTRACT FROM PUBLISHER]