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Baked Gearbox

With Summer’s heat approaching, it’s timely to discuss an extreme environment application. High temperature solutions are required in many industries.

A customer recently came to us with an application for operating a painting fixture. The fixture was to hold aircraft parts for the U.S. Air Force. The basic design called for an inline helical speed reducer which would drive, what amounted to, a rotisserie device that would slowly rotate the part so that all surfaces were easily accessible. While it was relatively a straight forward application, there were some critical caveats.

The first was a requirement for a cost effective, compact inline design, with an input shaft. The reducer was to be manually driven with a hand wheel. Because of the weight of the units to be painted, a high ratio of approximately 200:1 was desired to provide the necessary mechanical advantage to rotate the load.

A second requirement was for a unit with relatively low backlash. Because the parts had an uneven weight distribution, the customer didn’t want a lot of shock from gear clearance when the weight crossed the apex of the rotation and gravity took over.

To achieve these two goals, we offered our Watt Drive Series ASA parallel shaft speed reducer. Although the input and output shafts are offset, they are still in an inline orientation, which the customer needed. This provided a much shorter profile than a standard inline design. To help the length requirement even further, the unit was provided with a hollow bore for direct shaft mounting. This eliminated the need for a coupling and the length required to incorporate it.

The ASA Series is also a low backlash unit, with a value of about 8 Arc minutes in ratios above 50:1. This not only satisfied the parameters for this application, but allows the use of this design in many servo applications when provided with a servo motor adapter flange. Unfortunately, these weren’t the only requirements of the reducer. When painting of the parts was complete, the entire fixture, drive and all, was slid into a drying oven. The oven temperatures could be as high as 300 degrees Fahrenheit. So, sealing components, paint surfaces, and reducer lubrication had to withstand the high temperatures.

Had the gearbox needed to operate under the high temperatures, the solutions would have been a bit more challenging. The shaft seals were of primary concern. We selected a Viton based material that had a static capability of slightly over 300 degrees. Had the shafts been rotating, the additional friction would have lowered the ambient capacity significantly. So we were good there.

Satisfying the other elements was merely a matter of specifying high temperature compounds. Because of the slow rotations during operation, we were able to use a high temperature grease instead of the normal synthetic oil which is usually included in this reducer design.

We also were able to source a high temperature paint to meet the color spec for the assembly. To seal the housing components, we used a high temperature silicone derivitive instead of o’rings. These customized elements made the reducer virtually impervious to the heat during the drying process while allowing normal operation of the reducer in it’s intended function.

While, for us, the solution was relatively simple, most reducer manufacturers were reluctant to work on this project. According to the customer, many were concerned about the temperature. Whether they didn’t want to do the investigation for only 10 pieces, which was the required quantity for this project, or weren’t able to provide a solution, the lack of competition was good for us.

DieQua Corporation welcomes these types of design challenges. And our customers value the technical support we offer to find solutions to their unique problems. A significant percentage of the orders we receive include options or customization that our competitors either charge too much for, or simply don’t offer. That’s what makes DieQua different than the rest.

Whether you have a standard motion control or power transmission drive application, or one that requires a little something special, DieQua Corporation most likely has the product to fit the bill, along with the know how to help you apply it. Give us a call with your toughest jobs.

By | 2018-06-22T11:47:49+00:00 May 9th, 2018|Application Examples|0 Comments

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