" " wisno wood furniture finishing: Electrostatic spraying equipment

Monday, April 12, 2010

Electrostatic spraying equipment

Electrostatic spray gun is one of the developments of the spray gun as the equipment for the application of modern finishing materials in the wood furniture finishing industry. The spray application of the finishing materials can indeed produce a very good coating result, but the transfer efficiency is very low. The transfer efficiency of material  by  spray equipment is around 20%-60%  depends on the equipment, operator skill and the shape of the object  (see my article the spraying equipment type). The efficiency is lower if the spray is carried out for the working objects with small surface area like a posh, table legs, chairs, rattan furniture, etc. It is easy to be understand since for the small surface area, more the spray finishing materials will be meet the empty space and wasted in the air. The spray width of spray gun has a limitation to be adjusted  to follow the surface area.  For the wide surface area, the spray can easily be adjusted to get better efficiency. From my experience and calculation that I've ever done, for objects with small surface area such as leg, posh, chair,  the finishing materials consumed could reach 3x compare with the material for objects with large surface area such as cabinets, top table, dresser, etc.

This situation makes people then think further to create a device or system that could improve the material efficiency of a spray system for the small surface subject. One tool developed to improve the efficiency of spraying system for small object is electrostatic spray. The basic principle of electrostatic spray is to use electric force to improve the placing of material on the surface of the object based on the rule of Farady. The Farady law says that a negative electrically charged objects attract other objects which will be electrically charged positive. An electrical charge is put to the paint causing the particle to behave as though they are magnetized within the electrostatic field which is the spraying device serves as the point passes one terminal, while the object to be coated is placed in the opposite of terminal charged or pole. The electrically charged paint particles attracted to the object area, to wrap and paint all side exposes areas.
The electrostatic spraying achieves significantly higher efficiency in applying material for small surface objects.  This equipment is really worked in applying to finish the small object. This tool is particularly successful and work better for finishing process for objects of metal. It very reasonable because metal is a material that has good conductivity better than wood. Electrostatic coating was developed and has found uses for the metal finishing products. For wooden objects the result is not as good as the objects of metal. The moisture content in the wood is help the wood to become an  electrically conducting material. For finishing small objects such as small chair, crib or rattan, this equipment is helpful for improving reduce the material usage. The electrostatic spraying equipment now is becoming an important part in some of the furniture finishing industry operation.

This equipment is more suitable for the factories which have products that are consistent in size and shape with a high volume of jobs. In this factory the finishing is done by an automatic spray in an automatic finishing line. The devices to spray are spray gun, disc or bell. Because the large volume of material is used, there should be a large save for the finishing materials. This equipment usually is used for factories which has lots of small items or parts product such as factory that made: baby crib, chair, metal furniture or rattan furniture. This equipment is relatively complicated in its use and maintenance, and therefore some people do not like it to use it very much. For the production process with a lot of variation product and model especially with the  small volume then this device becomes less practical.


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