Advantages of oil-free vacuum pumps in industrial processes

Manufacturers in various fields are always looking for ways to increase profit margins – with the aim of improving process efficiency without affecting quality and safety. This article introduces you to the dry vacuum pump technology originally used in the semiconductor industry, which has shifted to industrial and laboratory vacuum processes due to its cleanliness and efficiency in operation. The dry vacuum pump provides many benefits by making the working volume oil-free. Firstly, it enhances the reliability of the pump. Dry pumps are not as susceptible to water vapor or dust particles as oil sealed pumps, so they are more durable and require less maintenance work. Reducing oil consumption also means reducing the cost of carefully handling oil. The use of dry vacuum pumps also minimizes possible contamination, which may occur in the oil – affecting pump performance, or in certain extreme situations, such as in the final product.
To successfully replace an existing oil based vacuum pump system, the key is to find the most suitable solution for a specific application. To take a look at the different types of applications that can benefit, the following are four different industrial production processes and their main benefits of using dry vacuum pumps.
Rolling spray repair
Metal spray coating is a long-standing processing process in the rolling spraying industry, which uses thermal evaporation technology in a vacuum environment. A thin layer of metal (most commonly aluminum) adheres to paper, polyethylene (PE), or other polymer films, forming a sturdy and beautiful packaging material that is moisture-proof, dustproof, and light isolating. This is an ideal material for food applications as it keeps the product fresh and extends its shelf life. This processing process is increasingly being used to produce decorative paper, gift packaging paper, and film.
During the processing, large rolls (up to 2 meters wide) wrapped around substrate materials (paper or PE film) were used, which were safely placed in the winding chamber. These reels rotate continuously – causing the substrate material to pass through the diaphragm at high speed and enter the spray chamber (Figure 1). The spraying chamber requires a very high vacuum level, between 10-4 and 10-5mbar. The winding chamber can maintain a low vacuum level, approximately 10-2mbar. Spraying is the result of a thermal evaporation process in which the metal is heated, causing it to vaporize and then precipitate on the substrate material.
The vacuum pump system used in the field of rolling spraying applications includes several steam boosters/diffusion pumps, as well as one or multiple stages of mechanical boosters, in addition to the front stage pump (Figure 1). The front stage pumps must always meet the production capacity and pressure requirements of the system – therefore, the most important thing is that they are reliable and easy to maintain. This minimizes the loss of production time, which can affect the productivity of the equipment.
In many advanced rolling spraying companies, dry pumping technology has become an increasingly attractive alternative to the previous stage pump, replacing traditional oil sealing systems. Dry pumps are inherently clean equipment that are not easily affected by the accumulation of dust or other particles, which often occurs in the sealing liquid of wet pumps, leading to a decrease in the quality of spraying. The dry pump will not experience performance degradation between different operations, thus ensuring repeatability during the rolling spraying process.
The use of oil in the pump also brings other environmental and maintenance benefits. For example, the oil used in wet pumps is often exposed to the gas during the processing, which is pumped to the spraying chamber. Therefore, oil can be contaminated by particles during the processing. Over time, the oil will deteriorate, requiring regular and frequent oil replacement.
It must also be considered that the gas is being used. For example, if oxygen is used to generate alumina, then when oxygen is mixed with hydrocarbon oil, explosive air will be formed. Dry pumps can safely pump any concentration of oxygen, so using dry pumps as a substitute means that companies do not need to install strict production process metal control panel electronic base equipment, which requires significant cost
Effectively handling water vapor
Dry pump technology is currently widely used in metallurgical and heat treatment applications. Recently, some of the world’s largest dry pump systems have been installed for large-scale steelmaking exhaust. A slightly smaller system is used for processing refined steel and ultra heat-resistant stainless steel.
For example, Vacuum Induction Melting (VIM) is a metallurgical processing process that was originally developed to treat special 6061 alloys, but now it is increasingly used to produce other materials such as stainless steel. Typical applications for using VIM include casting aircraft engine components and refining high-purity metals and alloys.
This process uses electromagnetic induction to melt the metal under vacuum. This will induce eddy current in the metal – the induction source is an induction coil, which carries alternating current. Eddy current heats up the load and melts it.
A metallurgical process like this produces a certain amount of condensable water vapor, which contains water vapor. Oil sealed rotary piston pumps were once the most common type of pump used in these treatment processes, but with this type of pump, water vapor can mix with the lubricating oil, causing the lubricating oil to age and increasing the wear of the pumping mechanism. Dry pumps are not affected by water vapor like this because they operate at higher temperatures and there is no oil in the processing room.

Reduce maintenance costs
Vacuum is also used in brake refueling stations, which are part of the automotive production line. Car manufacturers hope to assemble as quickly as possible, and they have developed a method that uses a vacuum pump to empty and fill the brake circuit, and conducts a leak test on the brake circuit – as a result, they can now complete the entire process in 60 seconds. A certain automobile manufacturer recently replaced the original three oil sealed vacuum pumps with three BOC Edwards Drystar pumps; Each braking circuit has one pump and an additional backup pump. The main reason for doing so is that maintenance is required on the oil sealed pumps to maintain their maximum operating capacity. Unlike the replaced oil sealed pumps, the installed dry pumps now only require a major overhaul every 6 years. The dry vacuum pump system is also more cost-effective as the required consumables are also reduced. Many pumps, such as BOC Edwards’ GV series, have the same safety features as standard pumps, such as quickly closing the temperature switch and protecting the pump in case of thermal issues related to the processing.
Minimize the risk of pollution as much as possible
A mass spectrometer manufacturer recently included a dry pump in its highly anticipated mass spectrometer series of products. Mass spectrometers are used to measure and analyze molecules, and they are essential equipment for research and development tools in the industrial and academic fields. They separate gas ions based on their different masses and charges, thereby determining the chemical composition of the substance. To achieve this goal, it is necessary to ensure that when ions are generated (which occurs at the beginning of the process in the ionization chamber), they can freely travel through the machine without colliding with air molecules – thus creating a vacuum to ensure that there is no air inside the room. Making the working volume of the vacuum pump free of oil can also ensure that there are no oil molecules present.
Most users are pharmaceutical companies that require equipment for biological analysis and drug identification for clinical trials. The dry vacuum pump solution better ensures high-precision measurement, which is essential for certain institutions that must comply with regulations established by the US Food and Drug Administration (FDA) and other national departments. By using a dry vacuum pump, the danger of pollution is eliminated.
Summary: Dry pumps have been successfully used in the semiconductor production industry for many years and have become increasingly common in various industries. The above examples indicate that dry pumps are more fully prepared to meet the challenges from an increasing number of industrial applications, where traditional oil sealing technology once dominated.
The reason for their increasing application is clear, as they are reliable, wear-resistant, and easy to maintain, bringing significant benefits to the results. For example, in the rolling coating industry, the annual maintenance cost of an oil sealed vacuum pump used in this environment is approximately 40% of the cost of a new pump. Dry pumps allow for longer normal working hours and, due to their repeatability, result in higher production yields and cost savings. This technology is not only safe, but also designed to work faultlessly even in demanding working environments. Dry pumps have good investment returns and are expected to yield returns within 12 to 18 months – assuming that the processing process can be improved without reducing investment.