Perforated plastic sheets are usually used for perforated spacer mats in autoclave cages and retort cages in food and beverage processing industry. The perforated spacer mats can be either in plastic sheet such as polypropylene(PP) sheet and HDPE sheet or in aluminum sheet, however the selection of the most suitable spacer mats needs time because they have an influence on the loading and unloading, the capacity depending on method also on the sterilization process. The thickness varies from 3mm to 5mm or even thicker. The perforated PP sheet can withstand the high temperature of 140-150 centigrade. The other material is perforated HDPE sheet, compared with perforated PP mats, it is a little softer with lower temp. There are usually two perforation designs for the spacer mats, the design depends on the working situation. One design is full perforation with solid borders,which spares only the mat edge. However, if the spacer mats are to be used automatically, they need suction surfaces for the arms of the robot. Depending on the size of the autoclave cage,these are usually 4-6 perforation-free areas. The perforated hole design depends on customer's design, the popular design is staggered rows perforation with hole diameter varying from 5-20mm.