Comparison of Volumetric to Surface Heating for Filament-Fed Laser Heated Additive Manufacturing of Glass

This paper presents work using a laser-heated fiber-fed technique to deposit fully dense glass. A stationary laser beam is focused on the intersection of a quartz filament with the workpiece. The workpiece is articulated on a precision 4-axis stage. The laser beam continuously melts the glass filament so that its viscosity is low enough to wet and fuse the workpiece. The focus of this paper is to compare volumetric heating of the glass as opposed to surface heat flux. CO2 laser radiation (λ = 10.6 µm) strongly couples to the silica phonon mode (optical penetration depth < 5 µm). This requires printing at very slow rates in order to allow the heat to diffuse from the surface of the glass to the interface of the filament and the workpiece. CO laser radiation (λ = 5.3 µm) provides volumetric absorption because of weaker coupling (optical penetration depth of ∼500 µm for fused quartz). This produces a more uniform temperature profile in the glass filament and supports deposition at greater speeds. The maximum deposition rates for 0.5 and 1.0 mm diameter fused quartz filaments are determined by extrapolating the power required to achieve wetting using both CO2 and CO lasers. The results show that volumetric heating (CO laser) produces surface wetting with significantly lower power. The results are compared to a 1D conduction model which suggests that still greater deposition speeds are possible as the optical penetration depth approaches the filament diameter.

The Design and Weaving of Glass Filament Spacer Fabric

Glass filament reinforced composite materials have become an indispensable material in national economic construction. The main purpose of this project is to produce the spacer fabric adopting glass filament through changing weaving process. First glass filaments were treated with epoxy resin to prevent from its low bending rigidity. Second ground warps and binding warps were separately warped and double warp beams were used in the weaving. At the shed crossing point the height of heald frames was different between the top layer and down layer warps, then the drafting sequence of the top layer of warps, the down layer of warps and binding warps were adjusted. The cotton yarns were chosen as the selvage warps which have good wear resistance and uniform tension. The long and short beat–up method was used. Eventually 3cm thickness of glass filament spacer fabric is achieved. It is hoped that this work will provide meaningful help to the development of glass filament spacer fabric.

Study on the Performance of Woven Basalt Filament Diaphragm Fabric

The tensile properties of basalt filament were measured and compared with these of E-glass fiber. The plain basalt filament fabric (PBFF), twill basalt filament fabric (TBFF) and plain glass filament fabric (PGFF) that woven by the CSW-03 loom under the same fabric density were used to make diaphragm preforms. Thermoplastic acrylic resin was chosen to coat on the diaphragm preforms using Werner Mathis AG LTF97885 coating machine when the coating thickness is 0.1mm, curing time is 30min. Tensile test was carried out on the diaphragm performs and coating diaphragm by 3380Instron advanced testing machine. Effect of curing temperature (<200°C) on tensile properties of diaphragm materials was investigated. The coating PBFF and the coating TBFF were compared to analysis the effect of organization structures on the elastic modulus. The results indicated that the best elastic modulus of diaphragm materials was achieved when the curing temperature was 120°C. PBFF is more suitable for diaphragm materials than PGFF and TBFF. The proposed curing temperature for making diaphragm with different elastic modulus ranges from 100°C to 140°C.