The following procedure should be used to check the tuning of any 60 or 120 HZ base drive unit:
With the variable speed controller on and the proper level of parts in the bowl, set the dial at 35% to 40% of the in-put voltage. Some parts movement should be detected at this point. If the feed rate is too slow, increase the controller setting slowly until the desired feed rate is attained. When 80% of the in-put voltage has been used without reaching the desired amplitude or there is excessive or violent vibration, check for interference points where something may be contacting the bowl or base drive unit, then follow these tuning techniques to achieve maximum efficiency:
- Loosen a bolt on any one of the spring clamp blocks (preferably a lower bolt), very gradually, until the unit either speeds up or slows down. If the unit speeds up, it is oversprung. If the unit is over-sprung, the thinnest spring from two opposing hangers must be removed. When replacing the springs they must be torque as specified on page 6 of our “Troubleshooting Manual”.
- If after this change, there is an under-sprung reading (if unit slows down when a bolt is loosened), thinner springs must be added back to the two opposing hangers. IMPORTANT! To maintain consistent, even feed motion, the number of springs in opposing spring packs must be equal.
- The base unit should be slightly under-tuned, but the degree of under tuning must be established.
- Springs tend to work-harden on the base drive unit that has been in operation for a period of time, causing it to be over-tuned. The same procedure as described in (1.) should be used to determine if this condition exists. 5. If a unit indicates that it is still under-sprung after a spring has been added, check for a spring that may be cracked or broken. This usually happens on the bottom portion of the spring, at the top of the spring clamp hanger. In some cases, the crack cannot be seen because of paint or because it may not be all the way through to the point where it is easily visible. The springs then should be removed and struck on a hard surface. If cracked, they will then break.
- When looking for a broken spring, check the thickest spring first.
- Make sure the bolts are long enough to fasten the springs to the spring hangers. For example, if a 5/16″ thick spring has been added, there will be 5/16″ less of the threads to hold the springs. When tightened, the threads may strip and the unit will give a false tuning reading. The same also applies to the bolts holding the armature or the bowl clamp nuts. The holes for these bolts are blind, therefore if a long bolt is used that bottoms out, it will seem to be tight when it actually is not. It is very difficult to check the tuning of a unit until this factor has either been ruled out or remedied.
- Another factor that affects tuning is the stretching of the bolts that fasten the springs. We us grade “5” bolts, which are specially hardened for durability to prevent this from occurring.
- The tuning of a base drive unit is affected when a weld is either broken or cracked in:
- The mounting flange of the bowl.
- The track or skirts
- The bottom of the return pan
- The braces, pan wall, discharge area (as a general rule, these condition will create a foreign noise and be easily detected.)
- Another condition, that occasionally develops and is very difficult to detect, is when the bolts that hold the rubber feet onto the base drive are not properly tightened and back out. causing solid contact between the drive unit and mounting surface. This can cause the tuning to be mis-read. The way to check for this condition is to disassemble the unit from the common base plate, lift the unit up so that the feet are exposed and tighten the mounting screws.
- It is very important that the clamp nuts that hold the bowl to the base drive are tight. When remounting or relocating a bowl on a base drive unit, use a 12″ to 15″ pipe on 9″ to 15″ units and one 36″ to 48″ long for 18″ to 36″ units. This give the necessarily leverage to really tighten the bolts. (For the best results, use a torque wrench.) 12.Also, never pull a bowl out, even slightly, from the clamp nuts to line it up with an existing track. Instead, level the drive unit itself. If the bowl is not level, parts may fall off or drift from the track prior to entering a selector causing track jams, mis-oriented parts and/or a loss of feed rate. A feeder must be level in order to maintain proper feed motion.
- Another problem can result by omitting the thin shim (spring spacer) between the springs when springs are changed or added. These spacer shims are very important. If one is omitted, it has the same effect on a base drive’s operation as adding springs, thus tuning cannot be checked properly. If a shim is not available, one should be made and installed. Don’t take the easy way out and try to get by without it. This will only cause more problems later.
- The feed rate will be affected if the base drive unit has been installed on a machine and all bolts that attach the rubber feet to the mounting plate are not securely located. These bolts are to prevent the unit from rotating on the plate4. When the drive unit is securely mounted to the plate, optimum feed motion will be transferred to the vibratory bowl. Also, make sure that the holes are drilled on center and that the rubber feet are not stretched when tightened. This will prevent tuning problems.
- If the gravity or inline track is connected to the vibratory feeder to obtain vibration the feed motion of the bowl will be adversely effected. The solution is to use an independent inline base drive on the track to move either parts.
- If a feeder bowl has “dead spots” most often, the problem can be found by looking 180 degrees from the location of these “dead spots”. As a general rule, mass had been added without counter-balancing the bowl, the gap in the coil has been improperly set, there is a broken weld, broken spring; or a loose spring ;bolt. Any of these conditions may contribute to the problem.