Roller Coating Machine for Wood Finishing

Roller coating machine is the finishing machine that uses roller to apply the finishing material to the surface. The 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 it gives 98% efficiency in the finishing material. If the UV coating is used, then the material can be set with 100% solid content that makes higher efficiency with no solvent and no thinner. 

The roller machine now also has been improved a lot. There are many models, and variations of the machine have been developed to meet the current needs from the finishing process. There are two important tools in the roller coating machine: the roller and the oven. In the flat finishing line, the UV oven lamp is 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 needs a heat oven to facilitate its drying. So in the first roller, the sponge roller is used to apply the stain, followed by the heat oven. Then, at the next step, the rubber roller and the UV lamp oven are used to apply the UV finishing material (UV filler, UV sealer, or UV top coat). In the line, there could be some brush sanders or wide belt sanders 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 works to apply the coating to the surface. When the machine runs, the roller is wet by the paint and rotating automatically with constant speed, while the wood panels are inserted to be layered with the paint. The panel will be layered with the material in a 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 the 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 uneven surface. But for the flat surface, it will produce a coating layer with more roller marks.

• Rubber roller

The rubber roller is the most widely used roller to apply the UV coating. UV sealer, UV filler, putty, and UV top coat are usually applied with a rubber roller. Rubber rollers have some hardness sizes that are described with the rubber shore. The application of UV sealer, UV filler, and UV putty is 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 of the UV laser coat. The UV laser roller may superimpose the finishing materials with higher thickness in one application. The UV laser coating is designed to produce a better flow coating layer than 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. A steel roller is mounted after the rubber roller or sponge rollers before the UV lamp oven. A steel roller serves to press the filler or putty into the pores and grain while simultaneously reducing the excess wood filler on the surface.

2. Oven 

The oven is the component to heat and dry the coating on the surface. The oven is installed directly after the roller. There are two types of ovens that are used in the roller coater: the heat oven and the UV lamp oven.

• Heat oven

It is the oven that produces hot air to heat the finishing layer. The oven apparatus can be an infrared lamp or hot air that flows 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 works to accelerate the water evaporation from the finishing layer. 

• UV lamp oven

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

The UV light radiation is dangerous; it causes cancer if it irradiates the human skin. The UV oven lamp is always placed in the close box. Since the UV oven lamp only accepts 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 needs 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's a rotation belt that can be adjusted in speed and height. The adjustment of the conveyor is needed to adjust the thickness of the coating layer on 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 materials that naturally need a long time to dry and don't damage the roller. The solvent-based material is rarely applied with roller coaters since the material tends to dry fast and potentially damage the roll. The roller coater is the flat-line finishing machine that gives high efficiency in the finishing process. This machine is the best equipment to process the finishing in the woodworking modern; he can do the finishing process with high speed, full machinery process, and high efficiency. 

But this machine only works for flat products. It is the good machine to finish the wood flooring panel, door panel, wall panel, wood panels, the knockdown cabinet or table, and other flat objects.