Written by: RNA Automation
How to tool a vibratory feeder bowl? Tooling a vibratory feeder bowl has often been described as a black art. Two bowl tooling technicians working side-by-side on bowls for the same part may come up with two completely different solutions. Orientation of a component can often be predicted by how parts will behave in a vibratory feeder bowl by dropping a handful on a table and analysing their positions.
By knowing a components centre of gravity, you can get an idea of a components natural orientation, often parts dropped on a table top will give their natural orientation.
Experience is critical, it takes 4 to 5 years of on-the-job training for someone with basic welding skills to learn bowl tooling techniques.
The first step in building a bowl is to analyse the geometry of the part. The toolmaker needs to know all the potential positions the part might take in the bowl. The toolmaker also looks for dimensional features that can be used to orient the part.
A lot can be learnt about a component simply by holding it in your hand, If you can’t tell one end of the part from the other it can be difficult to orient
Can two or three parts be stacked together without interlocking? Is there a good surface for the parts to push against each other? If not, it’s going to be difficult.
Another early step is to put several parts in a generic bowl with a flat track to see how they react under vibration. The goal of this exercise is to discover the part’s natural orientation and to see how many parts accept that orientation. For example, a pen cap will likely feed with the open end trailing, because more weight is at the closed end.
“If 80% of the parts come up in a certain position–even if it’s the wrong position–you have to start with that position and look for ways to change it,”
Once the toolmaker has an idea of the features and behaviour of the component, the tooling process can begin, some parts of the bowl can be designed and simulated with CAD software; others by cutting them out with a cardboard pattern and attaching them to the bowl with masking tape. Often, the toolmaker will tool the bowl in stages, installing and testing one section of track before constructing the next one.
Subsequent sections of track are responsible for getting the part in the correct orientation. These sections have two tasks: to save parts that are slightly misaligned and to reject those that can’t be saved. To maximize the feed rate toolmakers try to save as many parts as possible.
The last section of track contains the components and feeds them to a linear feeder or a pick-and-place device. Often, this section will contain one final tooling section for misaligned parts. After, the component will be tightly confined by rails, or the section will be enclosed. Once the component part is in the correct orientation, we want to make sure that we don’t lose it.
The Devil in the Details
Vibratory feeder bowls are usually made from 304 series stainless steel, or cast aluminium. Standard bowls are made from 304 stainless, while bowls for food and medical applications are made of 316 stainless steel.
Various coatings can be applied to the bowl to protect fragile component parts, reduce noise, improve part traction, and increase the durability of the bowl. Feeder bowls get smoothed down with use, so parts have less traction. A coating will increase the life of the bowl and can be FDA approved.
RNA can supply bowl feeders from as small as 120mm to 1200mm diameter and utilise the RNA range of standard drive units and control boxes. Often a bowl feeder built at RNA will be part of a larger system such as a pick and place unit, Robot cell of vision inspection machine.
Link: RNA Bowls
Learn More About Our Vibratory Bowl Feeders >
RNA Automation Ltd
Unit C Castle Bromwich Business Park Tameside Drive, Birmingham B35 7AG, UK
T: +44 (0)121 749 2566
Fax: +44 (0)121 749 6217
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