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Steel drum painting knowledge Sep 06, 2018

1. What is the high pressure airless spray method? The high-pressure airless spraying method is to spray the coating through a small orifice (0.2-Imm) under the action of a high pressure of 10-20 MPa. After the high pressure coating leaves the nozzle, it immediately expands into a very fine streamline in the atmosphere. Due to the surface tension, the paint streamlines become very fine particles that are sprayed onto the surface of the workpiece. Its main feature is that there is no rebound of paint particles and a large amount of flying paint that occurs during normal air spraying. The advantage of this coating method in coating quality is that the coating has a high application viscosity, a high solid content, and a thick coating at one shot. It eliminates coating film defects caused by impurities such as moisture, oil, and dust in compressed air. The adhesion of the coating film is good, and a good coating film can be formed even in the form of slits and corners.

2, what should be noted when high pressure airless spraying? When applying high-pressure airless spray, check that the intake pipe joint, air supply joint and high-pressure pump joint should be firm and airtight before operation. Always pay attention to the suction amount of the suction device, and regularly check and clean the filter inside the suction device to ensure that the filter is not blocked. The accumulator filter can be cleaned with the unit after use. The rotary coupling of the high pressure spray gun should be firmly connected to the high pressure hose. The gun body and the gun mouth are cleaned after use. Do not drop dust, impurities, etc. in the paint bucket. After use, the accumulated paint in the pipe should be blown off with a blow gun. After spraying, the whole machine can be cleaned with matching solvent.

3. What is the kinematic viscosity and relative viscosity of the coating? How are they represented? (1) Kinematic viscosity The ratio of absolute viscosity to density, called this kinematic viscosity. The reason is that the liquid density is large, and the gravity is also large. As a result, the measured kinematic viscosity is small, and the formula is: V = η / ρ where V - kinematic viscosity; η - absolute viscosity; ρ - density. The expression of kinematic viscosity is in the legal unit of measurement m/s. (2) Relative Viscosity The viscosity measured by the coating-4 viscometer and the coating-1 viscometer which are often used during the coating operation are all such. The time taken for the quantitative volume of the liquid coating at a certain temperature in the specified structural container to flow through the small hole in the bottom of the container. Expressed by s.

4. How to determine the relative viscosity of a coating using a Tu- 4 viscometer? Structure of the Coating-4 Viscometer The material is made of stainless steel and has a cylindrical shape at the top and a conical shape at the lower portion. The bottom of the cone has a small hole of φ4±0.2mm, the volume is 100 + ImL, the inner diameter of the cylinder is 49.5±0.2mm, and the height is 72.5mm. Method of operation Prepare the container and the paint to be tested (already blended and filtered), viscometer bracket, stopwatch, etc. At the beginning of the operation, the 涂-4 viscometer was placed vertically on the carrier and placed under the viscometer. Before pouring the paint, use your fingers to first block the small hole under the viscometer until the paint is filled to the top of the inner cylinder of the viscometer. Open the stopwatch at the same time as the hole is released, until the stopwatch is closed, and the stopwatch pointer reads the viscosity of the paint in s.