Kennedy Valve, a McWane Inc. division in Elmira, NY, is an old-line manufacturer of cast-iron fire hydrants and valves of all types, for water distribution. Though it's been producing since 1877, today it is a fully integrated metalcasting and machining operation, everything down to final assembly and painting of the finished products.
The foundry consists of a green-sand molding line producing approximately 10 tons/hour of different types of castings, ranging in weight from 2 lb up to 600 lb apiece. After shakeout in vibratory drums, the castings are shot blasted, and then proceed to various machining centers. After final assembly and painting, the finished products are shipped.
As recently as two years ago, Kennedy Valve was using three large steel-flighted tumblast machines — two Wheelabrators and a Pangborn — each with a capacity of 34 ft3. When these machines needed replacement, Kennedy Valve started looking for different solutions.
Arne Feyling, assistant general manager, recalls: "Our steelflighted blast machines required a high degree of maintenance, and we were tired of having to spend literally hundreds of thousands of dollars for maintenance and spare parts every year. He also explains that unloading the machines was difficult, so that the operators frequently had to "rake the last parts out of the tumbling mill."
Kennedy Valve was looking for alternatives, including continuous blasting systems like rocker barrel operations and continuous tumblast machines.
In the end, Kennedy Valve chose the multi tumbler concept offered by Rösler USA (www.roslerusa.com), purchasing three MT 34 machines. They were impressed by the tumbling action in the rotary barrel; by the blast cleaning results; and by the simplicity and robustness of the design. According to Rösler, the design means that the MT 34 can significantly reduce the maintenance costs for Kennedy Valve's shot blast operations.
The installation consists of:
- Three MT 34 multi tumbler machines, each one with a working volume of approximately 34 ft3 (1,000 liters). Each machine operates with a 75-HP (55 kW) blast wheel.
- A vibratory loading hopper equipped with weighing cells.
- An unloading conveyor for finished, shot-blasted parts. Because many of Kennedy Valve's castings are very bulky, batch sizes are limited to 1,300 lb (600 kg). The operators use S 550 steel shot for blast cleaning, and due to the amount of sand still on the castings the MT 34s are equipped with a magnetic separator and a double cascade air-wash separator.
Since their installation, the Rösler MT 34s have been running very well, according to Feyling, with uptime over 95%. "The choice for the MT 34 multi tumbler equipment was a calculated risk," he says, "but to date we have not been disappointed. We are pleased with the high productivity, the high uptime and, especially, the low maintenance cost so far."