" " wisno wood furniture finishing: Compressor and its calculation for furniture finishing

Friday, February 19, 2010

Compressor and its calculation for furniture finishing

Compressor is the important equipment in the finishing room. Compressor as the machine to provide the compressed air is a basic equipment in the finishing room. The compressed air is the main power in the finishing processes; for atomization in the spray gun, and power supply for mechanic equipment to handle finishing materials such as: pump and agitator. The mechanical equipment such as: sanding machines, screw drivers, drill, should also powered with the compressed air, when the equipment is used in the finishing room. Therefore, the compressor is standard equipment which must be available in a modern finishing room.
When we start to build a finishing room and decide to buy a compressor we must consider the budget we must prepare. Compressor is a big device and requires big money to purchase. Therefore the selection of compressor must be done carefully so that it could really be useful and appropriate for our needs. There are many brands and types of compressors which are usually equipped with a technical service that can assist us in determining the choice of a type of compressor most suitable for us. But after all we must know the basic knowledge of the compressor so we can make better decision in choosing a compressor. 

Compressor types 
According to the air compression, there are 2 types of compressors: screw compressor and piston compressor. Piston compressor is the compressor which is using a piston that moves forward and backward for compress the air to achieve the desired air pressure. This compressor is more suited to support the work which require small quantities volume of compressed air. The piston compressor price is relatively cheap compared with screw compressor. But if the big volume and continuous compressed air is needed, this compressor is not suitable since his efficiency and durability is relatively low.
The second type is a screw compressor. This compressor uses a screw to pressure the air inlet to produce a certain pressure of compressed air. This compressor has better endurance and efficiency than the piston compressor, but it is more expensive. The screw compressor is not much available in small sizes. Screw compressors are normally used in a furniture factory, especially for big furniture factories that need a continuous compressed air pressure in large amount. 
The compressor capacity. 
To choosing the right compressor, we must calculate compressed air requirement needed. The air pressure needed is calculated based to the volume of compressed air needed by each tools and equipments in the finishing room. The volume compressed air needed from every tool can be seen from the specifications of tool used.  When we buy an air powered device, there are specifications written in there, including the compressed air volume and air pressure needed to make the device can function properly. From the tools used for the finishing process and the specifications of each devices, the total requirement of compressed air can be calculated and then from here we can determine the compressor capacity we need.
When we buy a compressor, we must know that the capacity of compressed air needed is the capacity of compressed air outlet from the compressor, not the capacity of the inlet capacity. The definition of inlet capacity compressor is the amount of inlet air entering and sucked by the compressor, while the outlet capacity is the amount of compressed air generated by the compressor when compressor is working. Outlet capacity is the inlet capacity of the compressor time by the compressor efficiency. So the outlet capacity is the real volume of compressed air generated by the compressor when he operates, and that's what we need from the compressor.

Here is the consumption of compressed air for some equipments in the finishing room:
EquipmentVolume air pressure needAir pressure
Air gun200-300 liter/minute4-6 bar
Air spray gun100-250 liter/minute3-4 bar
HVLP spray gun250-600 liter/minute2-3 bar
Diaphragm pump50-100 liter/minute3-4 bar
Pail agitator500-600 liter/minute4-6 bar
Drum agitator600-800 liter/minute4-6 bar
Airless pump20-50 liter/minute4-6 bar

conversion factor:
1 cfm. = 28,3 liter/minute
1 bar = 14.7 psi
The consumption of air pressure and the air pressure needed in the table above is just for guide. The exact amount is depend on the specification of every equipment that depend on the type, size and brand of the equipment and condition of the machine.


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