The surface finishing section of the paper machine is processed in multiple steps to obtain good surface quality. Most paper is calendered by a mechanical calender after the paper machine, so that the paper surface is flat and consistent. The mechanical calender is made of several cold cast iron rolls, and the paper surface is flattened by the weight of each roll or another pressure. If higher surface smoothness is required, it should be calendered with a super calender. It generally consists of a paper pulp roll and a cold cast iron roll arranged alternately. According to different application requirements, some varieties need surface sizing to improve surface quality; others need surface coating to improve appearance quality or printing quality. Surface sizing and coating can be processed outside the paper machine using a paper sizing machine and a coating machine, or the size machine and coating equipment can be combined in the paper machine for in-machine processing.