Roller coating machine for wood finishing

Roller coating machine is the finishing machine that uses roller to apply the finishing material to the surface. Roller coater machine is the best machine to apply the UV coating. The water base coating is the other material that also can be applied by roller coater. The roller application is the most efficient to apply the finishing material. With roller application there is no dust spray and no overspray and give 98% efficiency in the finishing material. If the UV coating is used then the material can be set with 100% solid content that make higher efficiency with no solvent and no thinner is used. 

The roller machine now also has been improved lot. There are many models and variation of the machine has been developed to meet the current needs from the finishing process. There two important tool in the roller coating machine, the roller and the oven. In the flat finishing line the UV oven lamp are always installed after the roller. The UV oven lamp is used to cure the UV coating that was applied by the roller. In the UV coating finishing process, the water based stain is mostly used as the first step. The water based stain need heat oven to facilitate its drying. So in the first  roller, the sponge roller is used to apply the stain then followed with the heat oven. Then at the next step the rubber roller and the UV lamp oven is used to apply the UV finishing material (UV filler, UV sealer or UV top coat ). In the line there could be some brush sander or wide belt sander are mounted to do the sanding process if necessary.

roller coater

The components of the roller coater

1. Roller

The roller is the most important component of this machine. It is part that work to apply the coating to the surface. When the machine run, the roller is wet by the paint and rotating automatically with constant speed, while the wood panel are inserted to be layered with the paint. The panel will be layered with the material in certain thickness. The thickness layer of the finishing material is controlled by the speed rotation, the type of the roller and the installation of the roller. 

There are several types of rollers that can be used in a roller coater machine; sponge roller, rubber roller, steel roller and laser roller.

•  Sponge roller

The sponge roller is the roller with the highest flexibility. Sponge roller is widely used to apply the water based coating. In the UV finish, the sponge roller is used to apply the water based stain at the first step in UV finishing system. Sponge roller is also used to layer the UV sealer on the uneven surface panels such as the hand scraped (distressed) wood flooring panels. The sponge roller has high flexibility so it can accept the slightly bumpy and the uneven surface. But for the flat surface it will produce coating layer with more roller mark.

• Rubber roller

Rubber roller is the most widely roller to apply the UV coating. UV sealer, UV filler, putty and UV top coat are usually applied with rubber roller. Rubber rollers has some hardness sizes that is described with the rubber shore. The application of UV sealer, UV filler and UV putty are usually done by the softer rubber roller (20-40 shore). While the UV top coat is applied with the harder rubber roller (40-50 shore).

• UV laser roller

It  is a special roller for application the UV laser coat. The UV laser roller may superimposing the finishing materials with higher thickness in one application. UV laser coating is designed to produce better flow coating layer better then the conventional UV coating. The UV laser coater is needed at the final coat to apply the UV laser coat to produce more flat and smooth coating film.

• Steel roller.

The steel roller is only used in the application of filler and putty. Steel roller is mounted after the rubber roller or sponge rollers before the UV lamp oven. Steel roller serves to press the filler or putty  into the pores and grain and simultaneously reducing the excess wood filler on the surface.

2. Oven 

Oven is the component to heat and drying the coating on the surface. The oven is installed direct after the roller . There are two types of oven that used in the roller coater the heat oven and the UV lamp oven.

• Heat oven

It is the oven produce hot air to heat the finishing layer. The oven apparatus can be infra red lamp or hot air that flowed into the room. If the IR lamp is used, then a fan is needed to blow the hot air into the room. The heat oven is used when the water based material is used in the machine. The oven work to accelerates the water evaporation from the finishing layer. 

• UV lamp oven

It is the oven that uses UV lamp. It used when UV coating is used in the finishing process. The UV lamp work to send UV light with certain intensity to trigger the chemical reaction in the UV coating material to dry the coating. There are 2 type of UV cured lamp. The Hg lamp and the Ga lamp. The Hg lamp is the most used, it is relatively less expensive and work for most UV coating. The Ga lamp is used when the coating layer is thick or the white paint. It will help to better curing since it can deep penetrate into the coating better than the Hg lamp. It is used for some cases when the UV coating need better curing, for example the UV white base coat, or UV coating with thick film coating. 

The UV light radiation is danger, it  causes cancer if irradiate the human skin. The UV oven lamp is always placed in the close box. Since that the UV oven lamp only accept the flat panel form, the UV oven  to the big and curved form stuff will be very expensive. It is the main reason why the UV coating is only used for the flat panel. 

3. Sanding machine 

• Wide belt sander or brush sander

Wide belt sander is usually installed in a series of flat line roller machine to do the sanding process. The UV sealer need to be sanded and it should be done automatically by the wide belt sander in the machine line. Sometimes the  wide belt sander is replaced with the brush sander. The brush sander is required to do the scuff sanding. Brush sander is used when the uneven flat surface is finished such as in the hands scrapped (distressed finish)

4. Conveyor

Conveyor is transportation toll that functions to carry the product to undergo the finishing process. It a rotation belt that can be adjusted in speed and height. The adjustment oof the conveyor is needed to adjust the thickness of the coating layer in the surface. 

The uses of the roller coater

The roller coater machine is the main machine to apply the UV coating and the water based coating. Both are the water base material that naturally need long time to dry and don't damage the roller. The solvent based material is rarely applied with roller coater since the material tend to dry fast that potentially damage the roll. Roller coater is the flat line finishing machine that give high efficiency in finishing process. This machine is the the best equipment to process the finishing in the woodworking modern, he can finishing process with high speed, full machinery process, high efficiency. 

But this machine only work for flat product. It is the good machine to finish the wood flooring panel, door panel, wall panel, wood panels, the knock down cabinet or table and other flat object.