Automotive, aviation and aerospace industries

Production of composite materials

The modern method of obtaining a composite part is vacuum infusion molding. Dry or slightly impregnated material is laid out according to a certain scheme and then packed hermetically under a vacuum film, and at the same time air is pumped out and the binder is pumped. Then the part is molded in an oven.
Unlike metal, polymer composite is not subject to corrosion, very resistant to aggressive chemical and mechanical influences, difficult climatic conditions.

Vacuum fixation during machining of parts on CNC machines

To provide vacuum for CNC machines, CVU systems are equipped with a filter and a separator for lubricating and cooling liquids (COOLANT). This protects the vacuum pumps from mechanical impurities, and also cleans the coolant and returns it to the storage unit for reuse if necessary.

Vacuum furnaces

Vacuum heat-treating furnaces are essential in the production of aluminum alloys used in the structure of aircrafts and jet engine blade coatings. Because aircrafts need to function at optimum levels dependent on the environmental conditions, a plane’s life relies on the structure of its alloy that is produced in the vacuum furnace. In the aerospace industry, heat treatment is performed to improve the overall life and functionality of components and enhance their resistance to wear and corrosion. The vacuum furnace is used to heat metals to extremely high temperatures while achieving high consistency and low contamination of gases, blocking oxygen and reducing rapid oxidation.

Production of brake pads

Utilized on commercial and military aircraft, brake pads are essential to function and need to be able to sustain the high temperatures that come from the conversion of the plane’s kinetic energy into heat. Carbon brake pad production begins with carbon fiber that goes through a carbonization process at high temperatures in an inert gas atmosphere to eliminate excess gases. The fibers are then placed in a vacuum furnace using chemical vapor disposition and chemical vapor infiltration to repair any voids and add density to the material. Vacuum systems are essential in this process because of their ability to handle the various hydrocarbons, carbon dusts, and tar carryover that results.

Leak testing of systems

One of the unheralded but very necessary applications for vacuum pumps is the pre-evacuation and leak testing of hydraulic brake systems in new cars.
Before filling with brake fluid, the volume of the brake master cylinder and connecting brake lines (hoses and tubing) to the wheel brakes (including calipers of disc brakes and wheel cylinders of drum brakes) must be evacuated to remove air and moisture. The total volume being evacuated is normally less than a liter and the target pressure is normally 1 to 2 mm Hg Abs as measured at the master cylinder. The pressure can translate to less than 5 mm Hg at the rear brakes due to conductance limitations of the connecting hoses and the limited pumping time available. Two types of leak tests are normally conducted to insure leak tightness. One is normally referred to as the dynamic leak test which simply uses diagnostic equipment to monitor the pump-down pressure versus time during evacuation and compare to a typical pump-down curve to catch any large discrepancy in the pressure being too high. This could be the result of the vacuum quick disconnect leaking or blockage in the brake hoses that can interfere with a successful evacuation. The system would halt the test to save time, alarm, and identify the high-pressure problem before back-filling ever occurred.

The second type of leak test is referred to as the static leak test where after attaining the target pressure of 1 to 2 mm Hg Abs the vacuum pump is valved off from the brake volume and the rate of rise of pressure due to inleakage and outgassing versus time is measured and must be below a specified level based upon past qualification testing.

After the brake volume has been evacuated to the target pressure and met, the leak integrity tests the braking system volume is filled with pre-evacuated brake fluid that has been pumped on to deaerate it of gas bubbles which can cause spongy brake pedal action and lead to braking problems and/ or failure. In the past when the brake systems were composed of all metal, filling pressures of up to 400 to 500 psig were used to quickly backfill the systems. With the introduction of plastic master brake cylinders filling pressures of 100 to 150 psig are used. Most brake fluids (DOT 3, 4, and 5.1) are composed of a glycol-ether compound with corrosion inhibitor additives although silicone-based (DOT 5) and castor oil-based (DOT 2) are available. The brake fluid selected needs to meet certain quality standards to perform correctly such as a high dry boiling point (free of water) of 200 to 260°C and a wet boiling point (containing a prescribed amount of water) of 140 to 180°C depending upon the DOT requirement to avoid vaporizing during operation at elevated temperatures which could lead to spongy brakes due to too much vapor in the system. The brake fluid should have a low level of compressibility with varying temperatures, a high viscosity index to limit the change in viscosity with temperature, and be noncorrosive to common metals whether dry or wetted with water. Since most of the brake fluids are based upon a glycol-ether base they are completely miscible with water and are hygroscopic and will absorb water from the humidity in the air so that exposure should be limited. The brake fluid used for the fill is pre-evacuated to avoid air bubbles and moisture from entering the brake system. Since it is completely miscible with water any brake fluid spills can be easily cleaned up with water. Contact of the brake fluid with painted surfaces should be avoided since it will remove paint.

Fuel supply

Refueling complexes are located near airports and are equipped with fuel filtration units (FFU). Before dispensing fuel into the central filling station system, it must be cleaned not only of mechanical impurities, but also of water.
Such great attention to water is not accidental. Water has a higher density than aviation kerosene and, moreover, these liquids are immiscible. If water ends up in the aircraft's fuel tanks, it will occupy a lower position relative to the kerosene. At sub-zero temperatures, it will freeze and turn into ice, which can easily clog the aircraft's fuel system filters and cause engine malfunctions. In addition, water causes corrosion. That is why any water content in fuel is unacceptable.
Self-priming pumps of the HZS series are capable of overcoming geodetic heights and are guaranteed to perform the tasks of receiving fuel from railway and road tankers, pumping inside warehouses and dispensing fuel to centralized aircraft refueling systems.
In most cases, airfield tankers with a tank larger than 40 m³ are also equipped with HZS Dickow pumps, which can be seen on the side of the vehicle.
The key advantage that explains the popularity of HZS pumps for tanker applications is the self-priming ability of the pumps. In other words, the pump is not afraid of airing in the pipeline. The vortex stage integrated on the pump shaft ensures the pump's suction capacity even when there is no fuel in the hose or pipeline.
Among other things, the HZS 1272 and HZS 1273 pumps have a capacity of up to 165 m³/hour and provide a head of up to 100 meters of liquid column. These pump models are installed on the TZA-60 and are capable of refueling the largest airliners as quickly as possible.

Automotive, aviation and aerospace industries

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