Italix Co.

Photo Tooling

In order to transfer the image of the required cutting lines onto the photo resist some form of masking has to be produced. This mask consists of a sheet of clear acetate with black lines where the photo resist is to be masked from the ultra violet source (refer to image creation). As the metal is covered and etched on both faces 2 films are required, these films are known as a phototool.

Photo Tool Production

Prodcution of Phototools (Light Plotted) Modern technology now allows an image of the profile of the flat component to be transferred directly to the photographic film that is to be used as the phototool by way of a light pen plotter. These plotters operate in exactly the same way as a pen and paper plotter except that photographic film is substituted for paper and light for ink. Upon receipt of a drawing a 2D CAD image is created, which may involve calculating bend allowances and inclusion of half etch detail where required. To allow for the etching process an etching compensation factor has to be added. This involves drawing the outside profile larger than the finished component size and holes and slots smaller. The amount of adjustment is directly proportional to the thickness of the metal being processed. In general terms, for metal gauges including and above 0.3mm the width of the cutting line should be to the thickness of material being processed. The etch rate, or processing speed, is proportional to the width of cutting lines. Consequently where the component profile allows, metal gauges below 0.3mm should be processed using phototools with cutting lines plotted at 0.3mm wide. After the adjusted profile has been drawn the image is repeated to gain maximum utilization of the sheet area, taking into consideration the metal grain direction if applicable. It is at this stage that tabs to hold the component into the sheet are drawn on the profile if required, together with identification of the tool. Because 2 films are necessary to transfer the require image, it is possible to vary the detail of each film. Any cut line or text detail present on one film only will be duplicated on just one face of the metal, this detail will only be etched from one side, penetration will be at approximately 60% by the time detail on both faces of the film have pierced the sheets.