Historical Articles

February, 1953 issue of Plating

LIGHTING FOR THE FINISHING INDUSTRY

The several illustrations presented on these pages offer practical examples of the importance of lighting to metal finishing plants in their daily operations.

The views of general lighting for high and low bay areas provide a basic reference for all industry. Most of the nation’s manufacturing plants are dependent upon lighting, vitally to some degree, for all or part of their production processes. By and large, this need begins with a range of seeing tasks and the individual eyesight of a group of workers doing related jobs. A general level of illumination is sought’ which will take care of individual eyesight demands for the various ranges of tasks. To the extent this basic overhead lighting is well planned and maintained, a key factor for efficiency and safety is adequately provided. The wisdom of having general lighting of this character would seem to be self evident. Nevertheless, it is the exceptional plant that has such lighting and regularly maintains it.

Specialized seeing tasks are represented by the several examples of work that must be inspected visually. As the examples indicate in the caption descriptions the light needed for these tasks is usually at levels much higher than for general lighting. Besides the: extra quantity required, the task may demand that the lighting be directional or diffuse or of a particular spectral quality, such as the black light inspection technique.

Radiant energy has also been ‘used for several years in one aspect of metal finishing which involves no seeing. Infrared drying, now widely established, has greatly reduced the time needed for finishing painted metal surfaces. It takes a certain amount of lamps to do a specific drying job. No manufacturer using this process neglects to use the number needed. Not if he wants the full benefit of the process. All lighting problems deserve such consideration.

Another lighting application is represented by an example of a type of lamp useful for indicator service such as in circuits controlling generators, exhaust blowers and the like.

Also represented is the field of applications for ultraviolet type of lighting which is now finding a wider use industrially. Germicidal, ozone producing and sun tanning lamps fall into this classification of mercury vapor lamps which are designed so that they emit radiations of selected wave lengths of ultraviolet energy to produce the desired effect.

Since the lighting requirements of each plant do vary, there is indicated, for those who desire more detailed data, the need for reference to a recognized source of information. The American Standards Association has recently issued a revised American Standard Practice for Industrial Lighting (August 22, 1952) under the sponsorship of the Illuminating Engineering Society. The publication represents the lighting experiences of numerous organizations and, undeniably, is one that is a valuable addition to the files of metal finishing plants, both large and small.

Acknowledgment is hereby made to the General Electric Company and the Westinghouse Electric Corporation for their contributions of photographs and data in this presentation.

These two views were taken in the plant of an instrument manufacturer. Because operations involve handling of polished metal, quality illumination is especially valuable. The machine room area is 20 by 60 feet with an 8 foot ceiling. Four continuous rows of fluorescent fixtures are used to provide 60 foot candles. The units are louvered and designed to direct a portion of the light to the white ceiling. Louvered shielding softens the effect of direct lighting and minimizes annoying reflected glare from metal surfaces. The upward component of the illumination prevents sharp contrasts of light and ‘dark areas on the ceiling and adds a further diffuse effect to the balanced quality of the general illumination	The overall effect of light in the high bay area emphasizes the part played by the upward component. Three rows of fluorescent luvered units are used. About 45 foot candles average is delivered on the work
Detroit Arsenal’s Engineering Building uses J-H1 color corrected fluorescent mercury vapor lamps. Mounted at 25 feet in aluminum high bay fixtures over the machine shop, these lamps provide bright, safe working illumination for operators of sheet metal cutters, etc.	Two types of mercury vapor lamps are shown in close up, with a color-corrected J-HI fluorescent type being inserted into the fixture as a replacement for one of the A-HI type. Both lamps draw 400 watts and operate from the same type of indoor ballast. The J-HI provides 20 per cent more light with greatly improved color quality
This is representative of a technique of inspection for surface irregularities. The light is controlled so that it hits the surface at a grazing angle causing the defects to stand out. Here zinc sheet is inspected. The installation uses eight 150-watt R-40 reflector spot lamps mounted on 6-inch centers. The lamps are on an adjustable mounting so that the best angle can be set. The same general technique works well in the inspection of many surface irregularities	Chromium plate must be inspected to see if it covers completely and is well polished. This must be done by detecting differences in color and specularity. Because the material is so shiny, it is difficult to get enough light comfortably to see the defects. The problem is solved by using a unit that has a large area and uniform, fairly low brightness. Although reflections of this source are seen in the material, they are uniform and low enough in brightness so that they are not distracting. The fixture in the photograph was made by bolting two rows of three industrial units each, side by side, and covering the bottoms with tracing vellum between two pieces of glass. Each unit contains two 85-watt fluorescent lamps. This fixture provides an illumination of about 85 foot candles which enables the inspector to see the defects easily
Panels of portably mounted 250-watt infrared lamps (about 56 on either side) complete drying of enamel on water softener cases in a few minutes while the cases progress through the operation on the conveyor	A car body presents a large complex surface, but the size and area of the drying oven permits its heat to reach every spot thoroughly on the ride through. This process, much improved since it was first introduced in the middle thirties, has produced a substantial economy in the automobile industry. Techniques for a greater variety of metal finishing operations have been widely adopted.