One of Horner’s customers is a major supplier of automotive grade aluminum for major manufacturers of car and truck bodies.
After the aluminum passes through a set of rolling mills to reduce the material thickness, the sheet passes through an annealing furnace to reduce material stresses from the rolling process. The annealing furnaces have fans circulating the furnace hot air to evenly distribute the heat to prevent hot spots. This particular fan assembly from one of the annealing furnaces had experienced a bearing failure.
The shaft was initially sent to Horner Washington St to evaluate the damage to the main shaft. After an initial evaluation of the shaft damage at Washington St., it was sent to Thermal Coatings for their evaluation. Thermal Coatings was able to repair the damaged bearing & seal fits with Inconel 718.
Upon further discussion, the Customer wanted a complete assembly – ready for installation to be returned. Horner’s procurement department was successful in locating a pillow block bearing housing, it was however, located in England. They were able to locate and secure seals for the shaft that were located in Tennessee. The lock nuts that hold the bearing in place were not available anywhere in the world! Faced with that challenge, Mike Butler sent the only lock nut in the world, that was in Horner’s possession to one of our top precision CNC machine shop vendors. They were able to make a drawing of the unit, and manufactured replacement lock nuts that matched the original specification. This lock nut is different from all others because it has 3 set screws to keep the lock nut in place. They are made from 4140 material, black oxide heat treated to 50/55 Rockwell on a “C” scale. That is pretty hard so the faces of the nut have to be ground smooth and parallel to each other after heat treating. We can now provide these locknuts on future shaft repairs as they come in without having to search the world for them.
The set screws do not screw into the shaft threads as the original manufacturer did not want to cause thread damage. During the manufacturing of the lock nut, a metal plug is assembled in each of the 3 set screw holes. The plugs are threaded when the lock nut bore is threaded. When the set screws are tightened, the threaded plug grips the shaft threads preventing thread damage from set screws.
Less than one week was required to manufacture 5 lock nuts for the shaft. The spare assembly was returned to the customer to be installed in the fan. Horner’s customer was very thankful for the attention to detail and the investigative work it took to find the pillow block and lock washers.