Delivering Minimum Quantities of Lubricant At High Frequencies

A common goal in surface lubrication is to lubricate the component with the correct amount of lubricant while keeping the surrounding environment dry. SKF's VOGEL® Vectolub system is a clean alternative for applying lubricant to surfaces. The minimal quantity lubrication (MQL) systems can optimize lubrication efficiency, reduce consumption of the lubricant and preserve the safety and cleanliness of work areas in a wide range of applications. These systems are ideally suited to externally lubricate machine tools, assembly equipment, conveyer chains and countless other applications.

How Does It Work?
A pneumatically actuated, positive-displacement micropump delivers a small amount of lubricant through the inner capillaries of a coaxial tube into a spray nozzle.

The low-pressure carrier air is swirled in the nozzle. As a result, the metered quantity of oil is broken down into microdroplets that travel (along with the carrier air) to the lube point. No mist is formed and the microdroplets produce a properly sealed layer of lubricant.

Some advantages of minimal quantity lubrication include:

• Exact delivery rate adjustments

• Greater safety and environmental hygiene in the workplace (no mist, clean breathing air)

• Simple and reliable, easy to adjust

• Compact unit, to be installed as close as possible to the application

Figure 1

System Components
The Vectolub system consists of the following:

• Oil/air components
  
• Spray nozzles
  
• The VTEC unit for fluid metering and delivery
  
• The VE1B unit for fluid metering and delivery

Oil/air Components
The oil/air components are pneumatically or electrically actuated valves designed to control the unit. The components contain individually regulated pneumatic pumps to meter the lubricant. They also consist of an electrically actuated pulse generator to control the pump, control devices (pressure gauges and switches for the carrier air), control equipment and a lubricant reservoir with lubricant level check.

These components are installed in a unit or in correspondingly prepared housings to maintain the number of outlet ports required (one to 24), the control requirements, the required volume pump ranges, and in keeping with the ambient conditions.

Spray Nozzle
The purpose of the spray nozzle is to generate tiny droplets of lubricant in the desired size and direct them to the lube surface with the help of carrier air. The shape and size of the lubrication pattern are determined by the shape and dimensions of the individual nozzle openings. The "no oil mist" is produced by the internal shape of the nozzles. They are designed to assure that appropriate flow velocities and trouble-free outflow are produced.

In other words, the exactly metered quantity of oil is converted into microdroplets in the nozzle and delivered to the contact surface with pinpoint accuracy, which keeps oil mist from forming. The unit parameters are adjustable, and various nozzles can be chosen to fit the size and shape of the contact surface.

Users can choose from three types of nozzles:

• Circular jet nozzle - 20 mm diameter sprayed surface at a distance of 50 mm

• Wide jet nozzle - 20 × 40 mm sprayed surface at a distance of 50 mm

• Annular jet nozzle - sprayed surface of H=15 mm with a diameter of 50 mm

Each nozzle also contains two coaxial inlet ports for oil and air.

VTEC
The standard Vectolub system product line includes VTEC and VE1B units. The VTEC is a full modular MQL system in which the user can create his own standards according to specific needs. The system can also be retrofitted at anytime. The VTEC system can be directly mounted on the machine frame by the use of standard fixing rail, or installed in a protective housing when the environmental conditions are not ideal.

The VTEC system is equipped with up to eight outlets, features modular construction to adapt or expand any application, and provides the capability to simultaneously lubricate several independent applications.

The main technical data of the VTEC system includes: lubricant inlet pressure of a minimum of 0.1 bar and a maximum of 0.5 bar; delivery rate of three to 90 mm³/stroke; lubricant viscosity of 10 to 400 mm²/s; and operating temperatures of 10°C to 50°C. The unit is made of a synthetic, polyethylene terephthalate (PETP) material that is light and nonsensitive to oxidation.

VE1B
The VE1B units of the Vectolub product family are compact, easy-to-use and economical MQL systems. They can accommodate up to four outlets because they are comprised of one to four volumetric pneumatic micropumps, each feeding one lubrication point. The lubricant is delivered through the inner capillary tube of the coaxial line into a bi-fluid projection nozzle.

The working frequency of all micropumps can be adjusted with a pneumatic pulse generator or a solenoid valve, which is directly mounted on the unit. Every outlet contains a regulating valve to adjust the pressure of the carrier air.

The unit can stay moveable with a magnet foot or may be installed near the application. The unit is therefore installed closer to the lubrication points in an area protected from projections.

A Smart Alternative
The Vectolub MQL system is a clean and economical alternative for lubricant projection in minimal quantity. It works with volumetric pumps that deliver small quantities of lubricant (starting at three mm³) at a high frequency to the friction point by the use of a projection nozzle. The system can be used for machining, drawing, sawing, lubricant coating, conveyer lubrication and lubricant metering.

About the Company

SKF is a registered trademark of SKF USA Inc. and VOGEL is a company of the SKF Group. SKF is the world's largest manufacturer of rolling bearings and accessories. SKF USA Inc. has approximately 5,000 employees in the U.S., nine manufacturing locations and nearly 1,500 authorized distributor branch locations. The product line is sold to more than 130 nations worldwide.

Machinery Lubrication (3/2007)