Vacuum pumps are used in thermoforming to pull heated and softened sheet material tightly against the mould. Products are commonly divided into thick-sheet and thin-sheet categories.
Selecting a Vacuum Pump for Thermoforming
Selection should follow the actual process. The two main reference parameters are vacuum level and pumping capacity.
Vacuum level describes the degree of rarefaction and is commonly expressed in Pa, mbar or mmHg. Deeply recessed products generally require a higher vacuum level, while insufficient vacuum can lead to bubbles and forming defects.
Pumping capacity is the volume removed per unit time, commonly expressed in m³/h, L/s or L/min. Product size and sheet thickness determine how much air must be removed and therefore the required pump capacity.
Routine Maintenance
- Top up vacuum-pump oil in time and observe its colour through the sight glass. Replace oil that has become dark and viscous.
- Stop the pump if abnormal noise appears, identify the cause and prevent damage to the pump body.
- Replace the built-in oil-mist separator on schedule, typically every 2,000 operating hours, to prevent smoke caused by separator failure.