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The main operations of the powder-coating process are staggered along a closed-loop conveyor. Given the volatile market demands, using a fixed level of staffing may result in significant productivity losses. The present study aims to capture stochastic behavior and optimize operator assignment problems in a practical powder-coating process. By using the proposed methodology, when demand changes, the optimal operator assignment configuration can be provided, ensuring high labor productivity.

The powder-coating process is an important industrial application and is often a labor-intensive system. The present study adopts a practical case to optimize its staffing level. Because of its operational complexity, the problem is solved by a proposed simulation-optimization approach. The results are promising, and the proposed methodology is shown to be an effective approach.

The proposed methodology was tested for various demand levels. The optimized operator assignment configuration always improves on the performance of other staffing levels. Given the same daily throughput, the optimized operator assignment configuration can improve performance by as much as 19%. In scenarios where there is increased demand, the resulting reduction in overtime work improves performance by between 20.33% and 56.72%. In scenarios where there is reduced demand, the optimized staffing level produces improvements between 3.13% and 50%. Compared with the fixed staffing policy of the case company, the flexible staffing policy of the proposed methodology can maintain high labor productivity across demand variations. The results are consistent with the Shojinka philosophy of the Toyota Production System.

This study proposes a solution to the operator assignment decision in a labor-intensive manufacturing system – a powder-coating processing system. Powder coating provides a solid powder coating without any solvent. Because of its excellent application performance and environmental protection, it is widely used in the field of metal coating, especially appliances for offices and homes. Most of the existing literature has solved the problem by making unrealistic assumptions. The present study proposes a simulation-optimization method to solve a practical problem in powder-coating processing. The effectiveness of the proposed methodology is illustrated by a practical application. According to the experimental results, five operators can be saved for the same daily throughput. An average of 35 and 19 min of overtimes can be saved when demand increases by 10% and 20% with one less operator; between 2 and 16 operators can be saved when demand falls by 10%–60%.

In recent years, selective laser sintering (SLS) has been used in the biomedical field, including building small‐scaled biomedical devices such as tissue engineering scaffolds and drug delivery devices. A compact adaptation system for the SLS is needed to obtain a more effective and efficient way of sintering small‐scale prototypes so as to reduce powder wastage. Limitations of available smaller‐scale adaptation devices include the need of additional electrical supplies for the device. The purpose of this paper is to report the development of such a system to be mounted at the SLS part bed without any additional energy supply.

The compact adaptation device works on the concept of transferring the motion of the SLS part bed onto the part bed of the compact adaptation device. The device is an integrated attachment that is fixed onto the building platform of the SLS. The gear system of the device lifts the powder supply bed at both sides of the device simultaneously when the part bed at the center of the device is lowered. To further increase powder saving, an improved powder delivery system named alternative supply mechanism (ASM) is mounted on top of the roller to be coupled together with the compact adaptation device.

Powder saving up to 6.5 times compared to using full build version of the Sinterstation 2500 has been achieved by using the compact adaptation device. Furthermore, powder wastage has been reduced by 84 percent when using the ASM compared to the compact adaptation device alone.

The paper demonstrates the development and viability of adaptation devices for SLS to significantly reduce powder consumption by using solely mechanical means to build small parts without using external power supply.

More than two decades after their frist start the thermosetting powder coatings became in 1985 a technically viable product and a commercial success. Powder coatings are 100% dry paints that contain no solvents. They are generally applied to metal substrates by means of electrostatic spray equipment that provides each powder particle with a small electric charge, which in turn makes it stick to the substrate. The coated objects then go into a high temperature oven (usualy 150 to 200°C), where the powder coating melts and reacts chemically while sintering together to a continuous smooth finish of a thermoset film.

A comparison of selective laser sintering (SLS) and selective laser cladding (SLC) methods is presented. Loose single‐component, Ni‐alloy powder was used in this study. The powder feeding system formed the flow of powder particles directed into the zone of laser spot. The particles were deposited directly onto a substrate or onto the top of a pedestal. The powders were treated with a CW‐ Nd:YAG laser (λ=1.06 μm). The beam was motionless relative to the powder bed. As a result, the samples of sintered or remelted powders were built up as the vertical rods. The geometrical characteristics, structure and mechanical properties of samples were investigated.

The title of this article would indicate that it's going to knock powder, or try to talk you out of using powder or even investigating powder. On the contrary, it is intended to help you investigate powder for your application by guiding your interest to certain areas where powder may be troublesome or unsuitable if misapplied.

In recent years aluminium has become a very widely used material in the construction industry. Light weight, good corrosion resistance and ease of fabrication lends itself to a whole variety of end uses. Although the tendency for aluminium to oxidise in the atmosphere is itself a form of chemical “protection”, improvements in weather and chemical resistance can be gained from the use of a variety of surface coatings. These coating technologies are typically of the following types: polyvinylidine difluoride, water‐borne electro‐paint, conventional solvent‐based paints, powder coatings and anodising. The two most popular technologies in use today are: TGIC (Triglycidyl isocyanurate)/polyester powder coatings and polyvinylidine difluoride (PVDF) solvent‐based coatings. Coated aluminium has the added competition in the window frame and door frame market from uPVC. Only coated aluminium will be discussed in this paper.

The reliable performance of critical components working under extreme conditions is paramount to the safe operation of aircraft, and material selection is critical. Copper alloys are an obvious choice for such applications whenever a combination of transport, mechanical and tribological properties is required. However, low strength and hardness issues require development of new copper alloys and composites to improve service life and reliability. This study aims to investigate the effect of carbon nanotubes as reinforcement phase in copper-matrix composites.

The development of novel copper-based composites refined to the nanoscale was envisaged through mechanical milling of mixtures containing copper and carbon nanotubes (2 Wt.%). Milling took place in a planetary ball mill for times varying between 1 h and 16 h at 400 rpm. A ball-to-powder ratio of 20:1 and alumina vial and copper spheres were used under dry conditions or with addition of isopropyl alcohol. Scanning electron microscopy/energy dispersive spectroscopy, size distribution, Raman spectroscopy and X-ray diffraction were used to study the produced powders.

Attained results show that mechanical milling of the studied system produces nanostructured powders containing second-phase carbon nanotubes homogeneously distributed in the metallic matrix, together with severe copper grain refinement. This should correspond to increased residual microstresses, envisaging significant improvement of mechanical properties of the produced copper composites.

The novelty of the work resides in the use of carbon nanotubes for the reinforcement of copper, and on the systematic microstructural characterisation of the produced composites.

Current commercial rapid prototyping systems can be used for fabricating layered models for subsequent creation of fully‐dense metal parts using investment casting. Due to increased demand for shortened product development cycles however, there exists a demand to rapidly fabricate functional fully‐dense metal parts without hard tooling. A possible solution to this problem is direct layered rapid manufacturing of such parts, for example, via laser‐beam fusion of the metal powder. The rapid manufacturing process discussed herein is based on this approach. It involves selective laser‐beam scanning of a predeposited metal‐powder layer, forming fully‐dense claddings as the basic building block of individual layers. This paper specifically addresses only one of the fundamental issues of the rapid manufacturing process under investigation at the University of Toronto, namely the fabrication of single claddings. Our theoretical investigation of the influence of the process parameters on cladding’s geometrical properties employed thermal modeling and computer process simulation. Numerous experiments, involving fabrication of single claddings, were also carried out with varying process parameters. Comparisons of the process simulations and experimental results showed good agreement in terms of overall trends.

This paper aims to study numerically the influence of the applied laser energy density and the porosity of the powder bed on the thermal behavior of the melt and the resultant instability of the liquid track.

A three-dimensional model was proposed to predict local powder melting process. The model accounts for heat transfer, melting, solidification and evaporation in granular system at particle scale. The proposed model has been proved to be a good approach for the simulation of the laser melting process.

The results shows that the applied laser energy density has a significantly influence on the shape of the molten pool and the local thermal properties. The relative low or high input laser energy density has the main negative impact on the stability of the scan track. Decreasing the porosity of the powder bed lowers the heat dissipation in the downward direction, resulting in a shallower melt pool, whereas pushing results in improvement in liquid track quality.

The randomly packed powder bed is calculated using discrete element method. The powder particle information including particle size distribution and packing density is taken into account in placement of individual particles. The effect of volumetric shrinkage and evaporation is considered in numerical model.

The purpose of this paper is to review the state of the art of laser powder deposition (LPD), a solid freeform fabrication technique capable of fabricating fully dense functional items from a wide range of common engineering materials, such as aluminum alloys, steels, titanium alloys, nickel superalloys and refractory materials.

The main R&D efforts and the major issues related to LPD are revisited.

During recent years, a worldwide series of R&D efforts have been undertaken to develop and explore the capabilities of LPD and to tap into the possible cost and time savings and many potential applications that this technology offers.

These R&D efforts have produced a wealth of knowledge, the main points of which are highlighted herein.