There are two basic types of small vibratory finishers, the small vibratory tub type finisher, which is a rectangular tank with a rounded bottom, and the bowl finishers, which are shaped like doughnuts. The small vibratory tub finisher is more aggressive than the bowl finishers, but the tubs are usually more expensive to build and are not as popular due to high prices.
Vibratory Bowl Drive Designs
There are two drive designs available in the bowl machines. The most common finishing equipment design has a single weight mounted on a motor that is fastened under the bowl. As the weight spins, it causes the bowl to wobble at a high speed. The other drive available has a two-weight system where the second weight is on the top of the motor in the cone center hub. The single-weight system produces a nice rolling action from the outer edge to the center, but very little spiral action. The two-weight finishing equipment system, which is usually more expensive, produces both the rolling action and the spiral movement around the bowl, which is the same action achieved in the large machines. The spiral action keeps the parts spread out around the bowl.
Using a Small Vibratory Finisher
Since things are scaled down, water flow must be carefully regulated, as too much water can bring the cutting action to a halt. Machines with a drain in the bowl will allow a constant flow of solution to flush the parts clean. Use the least amount of water that will still keep the parts clean. Bowls that do not have a drain will require a compromise between cutting time and clean parts. If you can, add a drain to the bowl.
Always be very careful when measuring compounds for use in small vibrators. A few extra drops of cleaner could cause excessive sudsing, which will slow down the action. Follow the compound manufacturer’s recommendation for usage.
Small machines will work better if the load is at least 3/4 full. Not enough of a load causes poor circulation of the parts as well as ‘ding’ marks.
If small media must be used for a job, it should be mixed with a large media to push it around. Small media by itself tends to cling together due to the surface tension of the water. By adding some large media to the load, the small media will circulate much better. The best ratio is one part large media to 2-3 parts small media.
The cutting action in a small machine can also be aided by using a mildly acidic compound when possible. The acidic compound lowers the surface tension of the solution and reduces the lubricating properties of the water.
With small vibrators, careful measuring can produce a big difference in the results.
Note: All rules and advice here are aimed at vibratory finishing systems that have over one cubic foot capacity and are driven by at least a 1/2 HP motor. When working with less powerful motors, generally less than 1/4 HP or one cubic foot, the system is less forgiving of mistakes. Since there is less power per cubic foot in these small systems, an error in the setup could cause extremely long cycles or ‘ding’ marks on the parts.