Contact angle measuring instrument, mainly used to measure the liquid on the solid contact angle, that is, liquid on the solid wetting. The instrument can measure the contact angle of various liquids to various materials. The instrument for oil, printing and dyeing, medicine, spraying, mineral processing and other industries have a very important role in scientific research and production. The contact angle can be measured with a protractor fitted in a low magnification microscope, or by measuring the droplet image with the protractor. This method can not avoid the error of the tangent. The instrument is the computer through the intake of the image analysis, reducing the human error. And can save historical data and images for access and calculation. There are video and playback functions.

Contact angle There are two commonly used test methods: one is the outline image analysis method; the second is the weighing method, which is commonly referred to as wetting balance or infiltration method of contact angle meter, but the most widely used, Direct and accurate or contour image analysis methods.
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The principle of the contour image analysis method is to drop the droplet on the surface of the solid sample, obtain the shape image of the droplet through the microscope lens and the camera, and then use the digital image processing and some algorithms to calculate the contact angle of the droplet in the image.

The method of calculating the contact angle is usually based on a specific mathematical model such as droplets that can be considered as part of a sphere or a vertebral body and then calculate the contact angle by measuring the specific parameters such as width / height or by direct fitting. The Young-Laplace equation describes the relationship between the inner and outer pressure differences of a closed interface and the interface's curvature and interfacial tension, which can be used to accurately describe the contour of an axisymmetric droplet to calculate its contact angle.

Also mechanical often refers to the bearing contact angle:

In the ball bearings, the ball and the inner and outer ring channel contact, generally for each point. The contact point connects along the channel normal and passes through the center of the ball. The external load is along the straight line, from one ring to another, so it is called the bearing pressure line and the diagonal angle between the pressure line and the radial plane is called the pressure angle.