Off-Line Programming for Spraying and Laser Cladding of Three-Dimensional Surfaces

Abstract The economic efficiency of spraying a frequently changing spectrum of parts is strongly dependent on the costs of planning the spray process. In many cases, the robot program for coating a three-dimensional surface is generated directly on the control unit computer. Programming results in costly downtime. At IWS, a technology for off-line programming of robots and CNC systems for thermal spraying (TS) and laser cladding (LC) was developed. Coating programs are developed using CAD data from a workpiece and checked with simulation software. All steps are accomplished off-line without influencing ongoing production. Off-line programming of spray processes for three-dimensional surfaces enables substantial time savings to be realized, more so with increasing part complexity. These programs enable a constant spray distance and traverse speed as well as a permanent spray angle of 90° to the substrate to be achieved.</jats:p

Multifunctional silk-heparin biomaterials for vascular tissue engineering applications

Over the past 30 years, silk has been proposed for numerous biomedical applications that go beyond its traditional use as a suture material. Silk sutures are well tolerated in humans, but the use of silk for vascular engineering applications still requires extensive biocompatibility testing. Some studies have indicated a need to modify silk to yield a hemocompatible surface. This study examined the potential of low molecular weight heparin as a material for refining silk properties by acting as a carrier for vascular endothelial growth factor (VEGF) and improving silk hemocompatibility. Heparinized silk showed a controlled VEGF release over 6 days; the released VEGF was bioactive and supported the growth of human endothelial cells. Silk samples were then assessed using a humanized hemocompatibility system that employs whole blood and endothelial cells. The overall thrombogenic response for silk was very low and similar to the clinical reference material polytetrafluoroethylene. Despite an initial inflammatory response to silk, apparent as complement and leukocyte activation, the endothelium was maintained in a resting, anticoagulant state. The low thrombogenic response and the ability to control VEGF release support the further development of silk for vascular applications