U is a unit that represents the external size of the server. It is an abbreviation for unit. The detailed size is determined by the Electronic Industries Association (EIA) as an industry group. The specified size is the width (48.26cm=19 inches) and height (multiples of 4.445cm) of the server. Because the width is 19 inches, the rack that meets this requirement is sometimes called a "19-inch rack." The basic unit of thickness is 4.445cm. 1U is 4.445cm, and 2U is 8.89cm twice as much as 1U. 4U is 17.78CM.
4U industrial computer servers are generally used in harsh environments. It needs to be resistant to extrusion, corrosion, dust, and vibration.
Therefore, the outer shell is generally made of galvanized steel sheet produced by steel mills, which has higher deformation resistance and better corrosion resistance.
In order to meet the needs of industrial environments, 4U rack network servers are generally required to have vibration resistance. The purpose is to prevent customers from malfunctioning when operating the machine on site. High-performance industrial computers are generally fanless design structures, CPU motherboards, etc., run when they are working, and emit a lot of heat. The chassis here has good heat dissipation and high resistance. If the industrial computer is used in the open air, the design of the high temperature cabinet must be considered.
For example, there are strict requirements for the working temperature of industrial computer in some areas, and some require up to -40 degrees Celsius. This requires testing the operating temperature of the 4U server when designing it, and the case also needs to have a waterproof function to protect the normal operation of the internal work.