A dry screw pump in the semiconductor workshop was suddenly shut down and the production line was shut down for a day, with less than a few dozen to millions of material losses. The root is often not the pump itself, but rather the routine maintenance and operating protocols are not correct and minor problems are causing major problems。
How did the oil-free compression work out
Dry screw vacuum pump(c) the reverse rotation of the completion cycle under the synchronized gear drive by a pair of reverse screws. The volume of the inhaling end teeth is gradually increasing, and the gas is pumped into the pump cavity via the vent; the rotor continues to move and the gas is enclosed in the gears along the axis to the exhaust end. The congested line keeps the volume of gas in transport decreasing, equal to one internal compression completed and saves the additional compression level。
Only a few to a dozen micrometres are left between rotors and between rotors and the walls of the pumps, which operate without contact by means of high-precision synchronized gears, and no lubricating oil at all in the pump cavity. That's the essence of dry. In 2024, china central international, the waoxin semiconductor, etc., converted the oil seal pump into a dry screw pump in bulk. The central claim was to eliminate the secondary contamination of the crystal surface by oil vapour。
The rotors and seals determine how long the pump will last
The rotor end-line is the technological lifeline. Pyramid lines are mature, compressively limited, and suitable for a rough vacuum segment; a wider range of convoluted threads can have a maximum vacuum of less than 1 pa, but the grinding cost is two to three times higher. It is now common for mainstream domestic producers to follow a screw-spacing route, with rotor surfaces made of hard nitrogen or pvd aluminium plating, with a grinding lifetime of over 80,000 hours。
Seals are divided into three layers by location: the axle seals are heavily covered by carbon graphite or metal bellows to prevent process gas leaks; the rotor lines are co-ordinated by gear synchronisation, usually contained between 20 and 50 micrometres; and the pump body and end caps are covered by a fluoride rubber or perfluorinated ether o circle. Distortion of sealed materials under corrosive conditions was the number one reason for the leak alarm in the first six months of operation。
Refrigeration and preservation are not auxiliaries
The fluids in the pump cavity carry no heat and are dispersed by the shell water colds or wind cold wings. When the ambient temperature is above 35°c in the summer, if the cooling water intake temperature is above 30°c, the exhaust temperature will exceed the design ceiling and accelerate the ageing of the seal and the emulsion of lubricating oil. The project recommends cooling water temperature pressure within 25°c, with traffic remaining at 1. 5 times the mark value。
Chemical and pharmaceutical lines often draw mixed gases containing hf acid fog, isopropanol or nmp solvent vapour. The shell is coated with at least 316 l stainless steel, and the inner wall is sprayed with tfron; the cooling channel is isolated with titanium or pph tubes. In early 2025, a cro laboratory treated solvent-containing exhausts without preservatives and less than three months after the pump had suffered from intensive erosion of the wall and had to stop early to replace the pump。
Turning on the heat is destroying the pump
The cold-state direct load, the temperature difference within the pump is easily pulled to above 60°c, the rotor and shell heat swells are not synchronized, the design gap is squeezed to zero or even negative, and the teeth are scraped directly. Low-temperature lubricating oils are as sticky as honey, and gears and bearings are not filmed at all and are in a state of semi-dry friction. The preheating goal is to lift the temperature of the pump body to the point of exposure to the pump。
The correct approach is an air-borne low-speed heater, with an eye on the electric current curve and then the normal turn-off, which usually takes 15 to 30 minutes. Common error zones: people who feel that they can burn empty for five minutes and actually expect to read the exhaust temperature table to be in place, and people who jump quickly in summer, don't jump in winter, and have a summer failure rate more than double that of winter。
Gas blowing is more than cooling
The blowing gas usually follows dry nitrogen gas or process accommodations, cutting in from the vent and bringing out the condensable vapours, solvents left in the pump cavity and the back and back pipes. Refrigerated without blowing, condensed condensed into liquid membranes in low-temperature areas, with liquids rushing directly into the pump cavity at the next cold start, while light is stuck in the rotor, and heavy is bursting the axle, with maintenance costs running at tens of thousands。
Do not fill the flow, usually at 5 to 10 per cent of the pump's rated speed. To give the general assembly an effective velocity, the vacuum is simply not up; to blow too little and the residue continues to corrupt the inner walls. In 2024, a six-inch crystal circle plant managed to reduce the blowing air from dry nitrogen gas to compressed air with moisture, and in six months, four pump axes were completely corroded。
Choosing and routine maintenance pits
The selected type first locks out the pumping speed range and the maximum vacuum, then checks the corrosivity and dust content of the pumped medium. A 200-cubic pump can cover 90% of small and medium work, but the corrosive tail gas containing hf acid fog must be sealed with titanium alloy rotor plus perfluoride, and light is insufficient for the parameter table. (b) vegetative rhythm: two weeks of cooling water glucose, monthly axle sealing with a leak detector, quarterly change of gear case lubricating。
Many of the protections are based only on the flow of the pump, and not on the trend in exhaust temperature and current fluctuations in the electric power. Early axial wear and sealing aging augurs for 350 hours in advance of the current curve. It is recommended that a four-gauge check-sheet be made to record the vent temperature, vibration band values, current values, blow-outs, and that any drift exceeding 10 per cent be scheduled for dismantling。
The dry screw pump in your factory, the most disturbing thing at this point is to speed down from one year to the next, or to seal the axle? For a chat in the comment area, if you find it useful, send it to your workshop colleagues。
