Thermalspray inspector eyesight testing

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Thermal spray production facilities invariably have three levels of inspection, namely incoming, inprocess and final. Thermal spray inspection techniques generally fall into two categories namely visual and dimensional. Incoming inspection to check for starting dimensional points and visual inspection for dents and other damage, while seeming to be mundane and not glorious forms the basis for subsequent inspection and processing levels. Inprocess inspection in thermal spray operations usually entails verification of proper masking lines and non-maksing areas as well as proper grit blast surface by way of visual inspection as well as prevention of masking failure. For example by over grit blasting, if the thermal spray masking tape gets deteriorated to the point of getting frazzled, then proper masking is not going to be achieved in subsequent flame spray operations. In process inspection also involves dimensional checks at the thermal spray booth as parts get coated to observe any significant deviations from mean dimensions, as well as visual inspection of coating quality. There are many specialized thermal spray applications with hard coatings such as tungsten carbide-cobalt coated using specialized parameters that produce super hard coatings but are also prone to cracking. In-process inspection using quick fluorescent penetrant methods at the flame spray booth on parts as they come out is critical to ensure that crack propensity is observed and corrected immediately. Then of course final inspection covers almost all aspects of inspection from visual inspection to ensure proper coverage, proper masking lines, proper demasking and deburring of the coated areas, dimensional checks as well as testing for cracks and other defects. While the necessary instrumentation must be made available to the inspectors and all the applicable training provided, the key to this post is the observation I have made in many thermal spray coatings facilities about conducting eyesight testing for quality control inspectors. Again seems rather mundane and non-glorious, but think for a minute. If the inspector who basically accepts hardware, critical hardware sometimes that end up in aircraft engines and medical devices, does not have accurate vision, then how much weight can you put on his inspection report? Was he able to accurately determine crack free surfaces or accurate cut off points on masking criteria? Well, many thermal spray companies require a mandatory physical testing of new hires from a health stand-point that includes eyesight, hearing and respiratory testing but this is mostly performed for liability reasons from a workmen's compensation stand-point rather than from an quality assurance stand-point. What needs to be done ( and by the way this IS done in some thermal spray facilities ) is that past the initial testing, every thermal spray inspector regardless of incoming, in-process or final, should be sent out for eyesight testing every six months and proper eyesight correction procedures must be performed and actually the company should pay for this procedure. If there is a fighting contest as to who will pay, then frankly that shows that quality control is not taken seriously.