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Centrifuge Scroll Balancing Case Study
Journal-less Balancing Component
Centrifuge scroll. Used in separating liquid from sludge. This is the internal component that spins just slightly less than an outer shell about 3450 rpm. There are roller bearing internal. There are no outside Journals. This customer sent this from a New Jersey equipment repair facility. No other balancing shop in the Jersey New York area had a solution. At HI-TEK we complete challenging unusual tasks like this on a regular basis.
Setup Challenge
The rotor is supported by the inside races of the internal ball bearings. Square tubing are slid into the inner race to cradle the bearing. The rolling elements become anti friction surfaces. The square tubing is simply welded to a piece of flat bar and the flat bar is clamped to the Balancing Machine. Balancing Machines generally don’t respond well to these odd setups, especially hard bearing machines. Twisting motion cause by asymmetric loading of the measuring stands creates lots of error in fixed calibration machines. Rigid bearing below resonance balancing machines can be calibrated to deal with odd situations like this. This Balancing Machine was designed and built at HI-TEK. It is instrumented with an IRD 236 electronic.
Driving this rotor with a belt provides challenges too. The outside diameter left nowhere to run a drive belt. We simply wrapped aluminum sheet around the scroll to provide a smooth surface.
Results
We were very satisfied with the results. The resolution could detect displacements less than .0002 inches. The rotor was trim balanced to less than 20 gram inches, or better than ISO g 6.3 required.