Microlubrication which is also named minimum quantity lubrication (MQL) is a means to bring accurate quantity of liquid in a process.

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Microlubrication principles

• Difference between microlubrication and spraying
• Microlubrication system components
• Management of micropumps
  • Adjustment of capacities
  • Management of microlubrication
• Nozzles
• Differences between microlubrication systems

Difference between microlubrication and spraying

These two technologies are able to spray liquids. Means to adjust the liquid flow are different:

	Microlubrication systems			Spray systems: liquids are sprayed by a gas		Spray systems: liquids are sprayed without a gas
	with coaxial tubes		with single tubes	a pump feeds the nozzles with liquid	nozzles suck the liquid up
Liquid flow production	Each nozzle is fed by a micropump			A pump feeds all nozzles.	Nozzles suck the liquid up with a gas.	Each nozzle is fitted with a pump
Flow adjustment	by changing capacities of micropumps by changing working rates of micropumps			by adjustable jets		With nozzles: by changing capacities of integrated pumps by changing working rates of integrated pumps
Nozzles are fed with	liquid gas		a mist made up near the micropump	liquid gas	a gas which sucks the liquid up from another intake.	something from which the pump sucks the liquid up
Spraying thinness	is adjustable by: the nozzles the gas flow		Nozzles throw a mist	is adjustable by: the nozzles the gas flow	Nozzles generate mist	is adjustable by: the flow the pressure
Advantages	It is easy to manage each thinness and each little flows.		A micropump can feed several nozzles.	It is easy to manage the thinness.	It is cheap.	It does not require gas. The strength of the jet
Drawbacks	Each nozzle requires a micropump.		the mist the distribution between the nozzles fed by a micropump the management of liquid flows	the cost	the mist the management of liquid flows	Results when the liquid flow is low
Devices	Instantaneous lubrication systems	Continuous lubrication systems		Spray nozzles		(top)
	without a cabinet	without a cabinet
	in a cabinet	in a cabinet

Some nozzles may be used with microlubrication systems or spray system.

Microlubrication system components

	Essential components		Optional components
for all systems		a tank	a cabinet
			an attachment magnet under the system
	one or several	micropump	attachment magnet for nozzle
		single or coaxial tube	quick coupling
		nozzle or connector
for continuous systems		a sequencer	a tap
			a solenoid valve
for instantaneous systems		a solenoid valve

When a system is fitted with several micropumps, switches may be provided to select working micropumps.

Management of micropumps

Adjustement of capacities

Most micropumps are fitted with a device to adjust their capacities. It may be a screw or spacers.

The driving

As microlubrication micropumps are volumetric using a piston, they push an amount of liquid each time they are activated. So it is necessary to distinguish two cases:

The need	one amount of liquid	a continuous flow
Constraint	The capacities of micropumps must suit the need. The operating cycle must allow a correct functioning.	It is necessary: to run regularly micropumps to smooth the flow
System type	Instantaneous microlubrication system	Continuous microlubrication system (top)
Devices	without a cabinet	without a cabinet
	in a cabinet	in a cabinet

Nozzles

There are several kinds of nozzles:

• nozzles which spray the liquid on a circular area
• nozzles which focus the liquid
• nozzles which produce a flat jet
• nozzles for specific processes. (top)

Differences between microlubrication systems

Two microlubrication systems with same characteristics may not give same results because:

• there are differences between micropumps
• each manufacturer produces its nozzles
• the cabinets are different
• and so on.

These differences involve that:

• nozzles do not focus or spray liquid with the same efficiency
• the liquid flow regularity is not the same
• all microlubrication systems cannot process all liquids. (top)