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Interesting Use for Castings

Posted by Gavin Mason

An Unexpected Use for Metal Castings

234525654676gfbhdfWho doesn't enjoy going to the movies now and then? Popcorn, candy, a big comfy seat, and a screen the size of your house.. what's not to like? Well ok, maybe the price of a movie these days, but that's not the point. The point is, without castings you may have never been able to see your favorite movie in high definition on the big screen. One of the largest manufacturers of high definition projectors is Christie Digital Systems and they have been using castings in their projectors for years. 

In all, there are more than 75 different castings used by Christie in their wide line of products which equates to more than 20,000 castings per year. The most common casting used at Christie is for the base plates of each projector, which supports much of the weight and provides rigidity. Casting the base plates vs. machining them from stock or fabricating them by welding, greatly reduces overall costs while also providing improved mechanical and physical properties. The base plates are produced using the sand casting method, which is a balance between accuracy and cost. Because the base plate does not require tight tolerances, sand casting can be used to produce the raw casting, then machining as required to meet the desired tolerances.

There are other castings that the projectors rely on, for example: the cast lens mount is one of the most important pieces within a HD projector and even the slightest error could produce a myriad of technical problems. The lens mount must align perfectly with the lens to produce the HD picture that is desired, which is why they chose to cast the part. Die casting is used for the lens mount because you can cast thinner walls while simultaneously producing tighter tolerances when compared to sand casting. But the lens mount demands exact specifications to perform as intended, so a combination of die casting and CNC Machining is used to meet the exact standards needed. 

Even companies with years of experience purchasing and using castings, such as Christie Digital Systems, are always looking to improve their production process to reduce costs and improve productivity. Recently Christie started to experience problems with a magnesium casting (pictured above) and were eventually forced to reexamine the supplier. The supplier of the magnesium casting was located in Asia, which made things difficult when it came to communication and time critical projects. When the casting designed was examined by other casting suppliers, it was suggested that the casting should be cast as one piece, rather than the two piece casting they currently used. The single casting would eventually reduce part count ratios, improve physical and mechanical properties, simplify inventory management, and minimize machining operations/time... not to mention is also helped decrease shipping, tooling, and machining costs while reducing the components weight by 8%!

To read the full article in Modern Casting Magazine Click Here.

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*Image courtesey of Modern Casting Magazine Feb. 2015 issue. 

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