In the semiconductor workshop, the ageing of a dry screw vacuum pump seal was not detected in time for the whole series of crystal circles to come to an end. This oil-free dry-pump structure appears to be simple, with much more pits of repair and repair than the oil-capture pump, and many plants are still stepping on。
Why can't the high-end make a dry screw pump
Semiconductor optical carving, new energy photovoltaic plating, biomedicine dry cleaning, and thermal vacuum testing of aerospace meta-vehicle units require system vacuum stabilization at 10-3 to 10-5 pa. The oil-covered mechanical pump exhausts oil mist, which contaminates the crystal circle and thin membrane layer, the dry screw pump pump cavity without lubricating oil and the exhausting fog becomes the default choice for clean scenes。
It can also run for 10,000 consecutive hours without refuelling, with a maintenance cycle that is significantly longer than the back-up pump. For the 24-hour line of production, the plant can clear its own account by cutting off a series of good rate fluctuations, saving the cost of the stop and loss of scrap。
What does the core structure look like
The pump air tank contains two finely processed double-heavy rotors, which rotate in reverse synchronous but without contact with each other, with only a few micrometers in the gap. The internal vehicle of the cast iron or stainless steel pump becomes a cylindrical flowway matching the contours of the rotor, and the gas can only move in a one-way direction along the axis of the screw, significantly reducing the return flow and ensuring continuous stability of the vacuum。
The driver's end is synchronized gear boxes, with an internal pair of high-precision gears controlling the exact reverse rotation of the two rotors and constant interactivity. Both-end bearings mostly use angular contact ball bearings or cylindrical roll bearings to withstand high-speed rotation in the direction and axis. The axle seals are mechanically sealed or maze structures, and the dry-run seals do not touch the fluids and have a significantly longer life than the oil immersion。
Inhalation, compressed exhaust, four paces
The variable frequency powerer drives the reverse rotation of the two rotors through the synchronous gears and gradually increases the volume of the inhaling end to form a local low pressure zone. External gases are inhaled into the pump body under pressure differentials and enter a separate cavity of the rotor and pump cavity. As the rotor continues to rotate, the cavity moves along the axis towards the exhaust end, the rotor is closely integrated and the gas is not easily recoiled and is transported continuously。
The spiral structure of the rotor of the screw reduces the volume of the cavity from the inhaling to the exhausting end, and the gas is gradually compressed and the pressure continues to rise. Dry pumps do not rely on fluid dissipation, and compressed raw heat requires co-operation with the pump body cooling water or the wind cooling system. The gas compressed to target pressure reaches the exhaust end and is discharged through the vent and removed from the silencer or tail gas treatment unit。
Three rotor teeth for different jobs. Plus
Rectangular rotor gear rules, spiral angles are fixed, processing is less difficult, inexpensive, easy to maintain, and operating stability is good, suitable for conditions such as vacuum drying, vacuum impregnation, common chemical gas extraction, etc., which require a low limit vacuum. Spiral rotors employ continuous streaming gears, more flattening, high speed, good vacuum, low noise, low energy consumption, which is the largest type of industrial dry screw pump load。
The spinal rotor is a special contour contour, with higher condensation accuracy, greater compression than the first two, a greater limit vacuum and lower vibration and noise. In situations such as semiconductor optical carvings, space meta-ware testing, and high-end scientific laboratories, where the requirement for vacuums is extremely stringent, the use of wiring rotor programmes is largely earmarked and the cost of equipment is more expensive。
Status of application in several industries
The domestic photovoltaic hjt and topcon battery production lines were centralized around 2025, with a single line pvd and cvd processes containing over a dozen dry screw pumps as a vacuum. Biomedicine dry-purification links, the purity of the pump cavity directly determine the purity of the fluid, and the absence of oil drying is a hard indicator. The coating and solid drying of new energy lithium batteries is also accelerating the replacement of older oil-capture pumps。
In the aerospace field, the metaware thermal vacuum test is expected to stabilize for a long period at 10-5 pa, with a dry screw pump combined with a molecular pump as the front stage, and a large number of replacements are being made for the old oil proliferation pump. The semiconductor sealing chain is also gradually replacing the oil sealing machine pump with a dry screw pump, with the core concern that once the oil vapour is transported into the test cavity, the chip has a direct pull。
What's the point of repair and maintenance
The dry pump does not have a gas route system, but the rotor gap is only micrometer, and the alien, once entered, will die and even break. Inhalation vents shall be fitted with metal or sinter filters, and the vents shall be subjected to a monthly distillor to check for metal scrap. The bearings usually run between 8,000 and 10,000 hours, and the gear tank oil is checked semi-annually for viscosity and granularity。
Seals are the maximum loss, and mechanically sealed springs and graphite rings run long enough to grind their hair hard, and when a leaking vacuum falls fast. Daily inspections focus on three points: exhaust temperature, shell vibration values, and abnormal noise, all of which at the same time are subject to prejudicing failure almost one week in advance. Mobs do not last long enough to turn speeds, with a 10 per cent reduction in operation lasting hundreds of hours。
What kind of rotors do you use for the dry screw pump in your workshop? How many hours did the last seal change? Talk in the comment area and send a welcome message to your peers。
