An experimental study of PMMA precision cryogenic micro-milling

Polymethyl methacrylate (PMMA) has been used more and more widely in the fields of microfluidic devices and high-precision optical components due to its excellent mechanical and optical properties. Micro-milling is one of the methods that has been used in the machining of polymer materials. The machinability of PMMA is highly dependent on temperature, and the cryogenic method is also applied to control the processing temperature. In this work, the PMMA was milled with different processing parameters at the temperature of -55℃ and 25℃. The influence of each milling parameter on the surface quality under different temperature conditions were investigated. According to the results, the cutting depth is the dominant factor that influenced the surface roughness. The shape accuracy of the rectangular microgroove processed under low-temperature conditions is better. The material removal mechanism under different temperatures was also discussed, and the material is cut in a brittle way under low temperatures.

Investigation of the Processing of Biological Sediments by the Cryogenic Method

The study of the processes of intensification of sludge dewatering at sludge sites of sewage treatment plants (WWTP) is presented. The parameters that determine the water yielding capacity of the compacted and excess activated sludge have been clarified. The process of cascadecyclic freezing – thawing of biological sediments has been investigated. The degree of influence of cryogenesis on the specific resistance of the sediment filtration and its water yielding has been determined. Dependences of the resistivity of precipitation on the content of ashless substance and freezing temperature have been established.