Metal Cutting Fibre Lasers

LASER is simply an acronym for: Light Amplification by Stimulated Emission of Radiation

A Laser can be defined as a device that generates a Coherent beam of high intensity monochromatic light,

The Laser Beam itself is not made up of matter, but of Photons, which have no mass, so an actual Laser Beam cannot have temperature.

A Fibre Laser Beam has a single direction, its direction is fixed and its Beam Diameter is small and constant, this concentration of light, Photons, is what allows Lasers to have high power output, vaporizing metal at the Laser Beams focus spot.

A Laser Beam is always Monochromatic, Collimated and Coherent.

Before the Fibre Beam reaches the Laser cutting head, the Photon Light beams are scattered, the Collimating lens turns these scattered Photon light rays, into a beam of light with a high number of parallel rays, with a low beam divergence.

The Fibre Laser Beam is Coherent, meaning that all the light beams, photons, are all synchronised.

With a Fibre Laser, the Gain Medium is an optical fibre doped with a rare- earth element, such as Ytterbium the important feature of a Gain Medium is that it emits light. Ytterbium is a soft metallic element of the rare-earth group atomic number 70

The Energy Source is what causes the Gain Medium to emit light, often the energy source is a bank of Diodes that transform electricity in light, Photons.

Assuming you have decided the preferred model type, i.e., exchange pallet, or the smaller pull out cutting table type, the maximum size of sheet or plate to be cut, therefore you know the required size of the Fibre Laser downdraft cutting bed, plus the required Kw of the Laser, i.e., you have consulted the Fibre Laser manufacturers cutting charts.

Then ongoing consideration should be directed to these points:

i) The TOTAL power required for the installation (Kva) for:
The Laser Unit itself, the machines requirements being: axis drives, lighting, cameras, down draught cutting bed extraction fan, then take into consideration power requirements for the: ancillary equipment, voltage transformer, power stabilizer unit.

ii) The TOTAL Floor area required for:
The machine frame, its steel enclosure, the parked exchange table, or the pull out cutting table, when its cutting table is in cut piece loading / unloading position The Laser Unit, voltage transformer, power stabilizer unit. Plus if using bottled gas sufficient room for the 12/16 palletized gas bottles

iii) Which Laser Source manufacturer you prefer:
The ‘options’ generally are : IPG manufactured in Germany & Russia, MAX Photonics, manufactured in China, Raycus manufactured in China, n Light manufactured in USA, Finland, China

iv) Which cutting head manufacturer you prefer:
The ‘options’ generally are PRECITEC manufactured in Germany, SWISS TAYLOR, manufactured in China, LT ULTRA manufactured in Germany

v) The specification of the dust extraction unit:
Cutting most steels produces carcinogenic dust particles, what maximum / minimum particle size do you want to filter down to?, does your company accept the filtered dust to be expelled out into the workshop?, if exhausted into the workshop do you want a HEPA filter fitted to the extraction unit?. or do you intend to duct the downdraft cutting table to a dust to an extraction unit placed outside the workshop, but please be cautious, generally the size (HP) of the fan fitted to a downdraft cutting table anticipates a ducting length of no more than 2000 mm from the downdraft cutting table to the dust extraction unit.

Explosion risk, when cutting a mixture of carbon steel & aluminium, there is a risk of an Exothermic reaction causing fire and explosion within the ducting and dust extraction unit, do you wish to consider a spark arrests unit, explosion panels ?

vi) Warranty, and reliable back up – requires serious consideration

OK so you have now worked your way thru the above, the final bit of the jigsaw who can you rely on for Warranty, and reliable back up, plenty suppliers promise this, but do they actually have a UK team?

5 considerations:

1. A sales team with Knowledge of the Fibre Laser technology
2. Availability of technical support, spare parts availability
3. A  supplier with a team of engineers for ongoing support
4. Machinery delivery, installation, commissioning, training experience
5. Affordability

CARBON STEEL
STAINLESS STEEL
ALUMINIUM
BRASS
COPPER
WEATHERING STEEL, often referred to as Corten Steel Being  an Atmospheric Corrosion Resistant Steel

Plus the NOBLE materials the 8 Noble metals  ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), osmium (Os), iridium (Ir), platinum (Pt), and gold (Ag).

Laser 
Defined as a device that generates a Coherent beam of high intensity monochromatic light, with a low light beam divergence.

Single Module CW Fibre Lasers
CW Fiber lasers are a specific subset of DPSS lasers.
However, instead of a crystal, they utilize a doped fiber optic cable as the gain medium. Typically, they utilize rare-earth elements like erbium, ytterbium, and neodymium as the doping agent.

Multi Module Fibre Laser
High-power fibre lasers are made of multi-module beams, that is, the output of multiple laser modules coupled into a single fibre output, when compared to the output fibre core of a single laser module, the output fibre core diameter of multiple modules when combined combined produce a larger cable diameter

DPSSL  Fibre Laser
A Diode-Pumped Solid-State Laser (DPSSL) is a solid-state laser made by pumping a solid gain medium, for example, a Ruby or a Neodymium

Pumped Diode
A Diode, Ruby or Neodymium, pumped directly with electrical current creates a photonic monochromatic light beam.

Photons
Are simply light particles.

Collimating Lens
Before the fibre monochromatic light beam reaches the the Laser head, the photonic light beam will be refracted and scattered, it is therefore necessary to pass the photonic light beam through the Collimating lens to turn the scattered photon light beams into a parallel beam of light.

Refraction
Deflection from a straight path undergone by a beam of light. The change in direction of a wave passing from one medium to another caused by its change in speed.

Coherent light 
Coherence is defined as consistency, meaning that all the light beams, photons, are all synchronised.

Matter
The three most familiar forms of matter are solid, liquid, gas. A Laser beam is not made of  matter, but photons, which have no mass, therefore the Laser beam itself has no temperature

Photons
Are simply light particles

Irradiates
To effect by radiant energy, power density (irradiance) in the cutting zone and the width of the produced kerf.

Ytterbium
A soft metallic element of the rare earth group –  Ytterbium with symbol Yb and atomic number 70. Ytterbium is added, as a Doped medium, to the glass Fibre core for it’s high brightness, reflective properties.

Doped Gain Medium
A Laser gain medium is a medium which can amplify the power of light, a photonic light beam

Attenuation
The loss of signal strength

Diode
An electrical component that allows a flow of current in one direction.  Emits light when stimulated by an electrical current

Gain Medium
Is a material that posses quantum properties that allow it to amplify a photon monochromatic light beam by means of a stimulated emission

Attenuation
The Loss of signal strength

Coaxial
Down the centre of the Beam

Diffuse 
Its the action of spreading light

Diffusion
Movement of a substance from an area of high concentration to an area of lower concentration

Kerf
Is simply the width of the cut, its derived from a Middle English woodworking term, where the width of a saw blade was known as the 'Kerf'

Exothermic Reaction
A chemical reaction of oxygen burning iron, a reaction between a metal and oxygen, is a chemical reaction that releases energy by light or heat.

Voltage Stabilizer
An electrical appliance designed to deliver a constant voltage, regardless of changes in the incoming supply voltage.

Quadrilateral
A quadrilateral is a polygon having four sides, four angles, and four verticals. The word ‘quadrilateral’ is  from the Latin words ‘quadri,’ which means four, and ‘latus’, which means side.

Polygon
A Polygon is a flat , two-dimensional closed shape, bounded with straight sides. a Polygon has no curved sides. The sides of a polygon are also called its edges. The points where two sides meet are the vertices or corners.

Noble Metals
A noble metal is any of several metallic chemical elements that have outstanding resistance to oxidation, even at high temperatures. the 8 Noble metals  ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), osmium (Os), iridium (Ir), platinum (Pt), and gold (Ag).

Element
A substance that contains only one type of atom

Linear Interpolation
A common type of motion for multi axis machine systems, coordinating motion between axis so that 2-3 axis reach the same point, at the same time

It is difficult to make a Fibre Laser Cutting Head absolutely dust, pollution free, but some measures will reduce the degree of dust, pollution, improving the service life of the Fibre Laser Cutting Head, reducing down time and maintenance, repair costs.

Cause of the problem of dust, pollution within the cutting head:-

After the Laser metal cutting stops and the Fiber Laser is turned off at shift end, then with a Non pressurised Fibre Laser Cutting head, the internal temperature of the cutting head drops to ambient temperature, the internal air pressure reduces to the ambient air pressure, the ambient external air contains dust, the dust,  the ambient air will slowly transfer into a Non pressurised cutting head until the internal and external air pressures are balanced, at which point the cutting head becomes contaminated

Solution
Keep the air pressure inside the cutting head always pressurised/positive i.e., internal cutting head pressure greater than the ambient air pressure, so as to isolate the dust, pollution, that is within the environment  air.

Always feed clean, dry and oil-free gas into the Laser cutting head (nitrogen is recommended, 0.15 bars pressure <0.3bar);

Use reliable quality Fibre Laser Cutting Head replacement parts, such as protective glasses and O-rings, this will help to seal the Fibre Laser cutting head.

Through the application of the above pollution prevention method, i.e., a pressurised cutting head, then the dust/pollution condition of the optical lens in the optical fiber cutting head is greatly improved.

Mode refers to a Pumped Diode
Single Mode Fibre Cable

The advantage of the Single Mode is that its PHOTON Monochromatic light spot is smaller than a Multi Mode PHOTON Monochromatic light spot,  making it very suitable for cutting thin sheet.

A  Single Mode Laser Fibre core diameter is small (14um), the energy is Gaussian distribution, the focal spot is small, with a high energy density, under the  same Laser Kw power, the energy density is more than 4-10 times that of the Multi Mode spot, and the heat-affected zone (HAZ) is small, especially for the high-reactive alloy's (aluminum, copper)

For 3/6/12kw machine, the Single Mode technology is well proven.

Multi Mode Fibre

A Multi Mode Fibre is a Fibre supporting propagation of Multiple Mode's.

A Multi-Mode Fibre cable has a fairly large core diameter that enables multiple PHOTON light modes to be propagated, and limits the maximum length of a transmission link because of modal dispersion

A Multi Mode Fiber is is about 10 times larger than a Single Mode cable, the Fibre cable has a core diameter of 50-100 microns, however It causes more PHOTONIC light distortion and gives less bandwidth than a Single Mode (Monomode) Fibre Cable

The advantage of Multi Mode is that when one Mode is damaged, the other Modes can keep the Fibre Laser machine working.

A Multi Mode Fibre cable is used to combine the Photonic Monochromatic light from more than one PUMPED solid gain medium,  the spot quality is not as good as that of Single Mode Fibre cable, therefore, the Multi Mode is more suitable for machines above 12kw that are generally cutting thicker materials where spot size definition may not be so critical.

Supporting Notes :

A DIODE-pumped solid-state laser (DPSSL) is a solid-state laser made by pumping a solid gain medium, for example, a ruby or a neodymium-doped YAG crystal.

The Laser light propagates in the Yb-doped center core due to total internal reflection at the boundary of inner cladding and center core,As the DIODE pumped light propagates through the Yb-doped center core, the Yb ions are excited.

Yb= Ytterbium | ytterbium is a bright and shiny metal that is both ductile and malleable and is more reactive than the other lanthanide metals Lanthanide is a chemical element in the periodic table

Continuous Wave Fibre Laser (CW) simply means that a continuous, uninterrupted Coherent beam of high intensity monochromatic light is released and remains on continuously until stopped, which is ideal for applications such as Fibre Laser cutting of metals.

The phrase continuous-wave refers to the coherent beam of monochromatic light emitted by the gain medium

Standard: DIN EN 207:2017, DIN EN 208:2009, DIN EN 12254:2010

The Optical Density (OD) or absorbance of a light beam is a logarithmic intensity ratio of the Coherent beam of high intensity monochromatic light, (the Laser Beam) falling upon the material  (the view panels), to the light transmitted through the material, i.e., the (the view panels)

Verify an Optical Density (OD): Fibre Laser metal cutting view panels  are marked with an (OD) rating for each wavelength range, the higher the (OD) rating, the greater protection. Generally, an (OD) of 5 or higher is recommended for powerful Fibre metal cutting Lasers.

A high Optical Density (OD) number for a view panel  indicates low monochromatic light transmission through the view panel. Optical Densities (OD) of 6.0 or greater than (OD ≥ 6.0) are used for extreme blocking needs.

What does it mean when a Laser view panels has a high Optical Density (OD) value?. Optical Density (OD) is a measure of the attenuation of energy passing through a filter (a view panel).
The higher the OD value, the higher the attenuation and the greater the protection level, In other words, (OD) is a measure of the Fibre Laser beam energy that will pass through a filter (a view panel).

attenuation, a lessening in amount, force, magnitude, or value 

To calculate the weight of a metal plate, you can use the formula:

Weight=Volume×Density

Weight=Volume×Density

where:

• Volume is the product of the plate's dimensions.
• Density is the density of the metal, typically measured in kilograms per cubic meter (kg/m³) or pounds per cubic inch (lb/in³).

Steps to Calculate the Weight:

1. Determine the dimensions of the plate:
   • Length (L): Measure in meters (or inches).
   • Width (W): Measure in meters (or inches).
   • Thickness (T): Measure in meters (or inches).
2. Calculate the volume:Volume=Length×Width×ThicknessVolume=Length×Width×Thickness
   • If you use meters for dimensions, the volume will be in cubic meters (m³).
   • If you use inches, the volume will be in cubic inches (in³).
3. Look up the density of the metal:
   • Common densities:
     • Steel: ~7850 kg/m³ (0.284 lb/in³)
     • Aluminum: ~2700 kg/m³ (0.0975 lb/in³)
     • Copper: ~8960 kg/m³ (0.324 lb/in³)
4. Calculate the weight:Weight=Volume×DensityWeight=Volume×Density
   • If you use SI units (meters and kg/m³), the weight will be in kilograms (kg).
   • If you use imperial units (inches and lb/in³), the weight will be in pounds (lb).