TechArchive

Original article date: March 2000

So, what’s been happening in the field of bowls and feeding systems? Tommy Miller has been asking some of the leading suppliers

Machine builders have to respond to the demands of their customers, and bowl feeder suppliers are no different. So while machine builders are having to design and build machines that assemble or test products at ever-higher rates, bowl feeder suppliers have had to develop feeding systems that will feed components at correspondingly higher rates. This has not been a sudden change over the last year, but a gradual trend that has continued.

Alphamation has addressed this problem by developing a new type of bowl feeder and driver that is believed to be unique among UK-manufactured systems. Whereas UK bowls have traditionally operated at 50Hz using a half-wave vibration source, the new system uses a 100Hz full-wave system. This gives a higher feed rate, but its other main advantage is that the feed is smoother, which is beneficial for difficult or delicate parts.

Linear feed rates of up to 30m/min can be achieved with the new system, and it can be applied to bowls manufactured from mild steel, stainless steel and cast aluminium.

Clearly this is a major development for the feeding and orientation of parts, but Alphamation was quick to remind us that high speed centrifugal (ie non-vibratory) feeders are still an excellent option when high feed rates are required.

Another company that emphasised the higher feed rates that are being demanded by machine builders was Accomplished Automation. The company says that it is often necessary to use multiple-lane external tooling on the bowl to feed and orientate the components, and then to integrate the lanes into one to achieve the desired feed rates.

Accomplished Automation also highlighted that bowl feeders are increasingly being specified with quick-change tooling so that different components can be fed with the same bowl, but with minimal changeover time.

More often now, bowl feeder suppliers are being asked to incorporate inspection within the feeding and orientation process so that only good components are supplied to the assembly station. Inspection can be achieved in a variety of ways, depending upon the budget and the importance of rejecting bad parts. For example, simple (but effective) gauging heads can be incorporated within the bowl tooling so that mis-shapen or tangled parts can be quickly ejected outside the bowl.

A more costly solution, but one which is sometimes necessary, is to use a vision inspection system. This certainly has more sophistication and is potentially more effective.

Alphamation says that it often incorporates vision systems so that parts are 100% inspected, but it sometimes also uses vision systems as a means of increasing the overall feed rate. If, for example, a part feeds 50% ‘right way’ and 50% ‘wrong way’, a vision system can be used to identify the ‘wrong way’ parts so that they can be re-orientated by a pick-and-place unit. The alternative would be to have the parts rejected back to the bowl, which would have the effect of halving the feed rate. Thanks to recent advances in vision system technology, both the cost and ease-of-use have improved to a level that makes this approach feasible.

There are few hard-and-fast rules that can be applied to bowl feeders, and this question of orientating parts after they have been fed from the bowl is no exception. For high feed rates, it is often true that rejecting parts back to the bowl and allowing them to be orientated by the tooling is faster overall than any pick-and-place unit could ever be.

The answer, as is so often the case, is to talk to several alternative suppliers and see what they recommend for any particular project.

• Accomplis hed Automation
• Alphamation

March 2000