The Engineering

During the process of formulating the chemical system it was clear that like any chemical system the spray chrome system would only be consistent if all the system's physical parameters were consistent. The specification of the chemical system called for them to be manufactured to laboratory reagent standards and it was necessary to design a spray fixture which would give control of the other physical parameters of the process. In particular it had been found that for consistent results the process was critically dependant on the temperature that the working solutions were sprayed at. In addition rates of spray and avoidance of contamination were critical to success. The fixture inherited from the US system was little more than a trolley having pressure tanks connected directly to the spray guns with no provision for material temperature regulation or system cleaning and so was disregarded.

Gamma Science then, on the clients behalf, undertook the design of a completely new spray metallization fixture. In designing the spray fixture we strove to take the guess work out of spray chroming. Using our skills in the area of man machine interface great emphasis was placed on design to prevent avoidable errors due to operator confusion. The main requirements were provision for the 4 working fluids plus the deionised water to be sprayed at the correct temperature, easy cleaning for the system before and after use to prevent as far as possible contamination for deteriorated working solutions. In addition to the above main requirements during our use of the US spray fixture for development we had noted that both the silver and tin salt solutions used in the process had a tendency to “plate out onto” the surface of the stainless steel pressure vessels used for storage of working solutions in that system, more problematic was the fact that this plating did not appear to be fully adherent to the surface and flake like particles of silver or tin could be found floating in the tanks. As a result Gamma Science specified HDPE pressure vessels which in addition to being less prone to surface plate out are also translucent so that the quantity of working solution remaining in a tank can be seen by the operator without de pressurizing and opening the tank.

Using state of the art solid modelling software Gamma Science completed the design from inception to the point of producing the files for laser cutting the metal work for machine manufacture. The completed design has many unique features including a 5 channel heat exchanger system to maintain correct solution temperature, other features built into the unit include a system of solenoid operated fluid valves to route air, water and working fluids to where they a needed, to economise with working fluids by allowing them to be drawn back to their storage tanks when spraying is completed and to make cleaning of the fluid paths simple after use. An external electronic pod providing system control and monitoring. At Gamma Science we built both the proof of concept and prototype machines in our own prototype workshop, specifying and sourcing all the parts required including many parts manufactured to our drawings. Work carried out by Gamma Science even encompassed the completed design and manufacture of the electronic control pod including the circuit design and layout of the control PCBs.

The prototype machine when delivered to the client was able to be put into full production use within 24 hours of delivery and continued to be used for many months without any failures and was in use even after production units were available.