In most of the cases, it is better to have feeder bowls coated. Coatings can be either polyurethane spray coating, pasting of sheets on the bowl surface, teflon coating etc. The advantages and disadvantages of each of these are given below –
Polyurethane Spray Coating – The advantages are firstly, in case of metallic components, the noise level can be drastically reduced by eliminating the metal to metal contact between the metallic bowl surface and the components. Another major problem faced by customers is of feeding oily components. Oily components reduce / eliminate the friction between the components and the bowl track. As vibratory feeders work on the principle of friction, this results in the components slipping and hence they are not able to feed properly. Proper type of coating can eliminate this. It is better to have a rough coating in case of oily components while in case of dry components, it is beneficial to have smooth coating. This improves the friction between the components and bowl, resulting in better movement of parts forward. In case of polyurethane spray coating, smooth as per as rough finish is possible, depending upon type of parts (oily or clean) which are to be fed in that bowl. Further FDA approved polyurethane coatings are also available.
Pasted Coating – In this type, synthetic or polyurethane sheets are pasted to the bowl surface to act as lining. However, these have many disadvantages. First and foremost, in case the adhesion is not proper at any place, air bubbles get created and the whole sheet gets removed. Even if any adhesive is used, it gets removed in cases where there is oily residue on the components. This coating is applied as a bonded sheet. As a bowl lining, it is used primarily to reduce marking of plastic parts. It also provides impact protection from heavy parts.
Teflon Coating – This can be pretty long lasting for certain parts however, they keep getting removed and the bowl will have to be recoated after some ime. This coating is sprayed on primed metal and baked at 800 degrees Fahrenheit. As a bowl lining, Teflon is used primarily to reduce friction of sticky parts and assist the feed characteristics. Teflon also very non-reactive and can be used where reactive or corrosive chemicals are present. In chemistry, polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene which finds numerous applications.
Rubber coating – In this type, the bowl is coated with galvanized rubber. This is a very crude type of coating. It does not last long and is very rough, resulting in the parts not being fed properly.
In conclusion, the best solution is to go with polyurethane spray coatings which can give you either a rough or smooth finish and also are very long lasting.