GSI Group - Laser Division
JK300HP/JK300P/JK125P
Issue 2.0
Pre-installation and User Manual
Part No: 1EA300E01
Page
165 of 172
Increased focused spot size increases the width of cut.
Cutting performance is normally presented in the form of material thickness versus cutting
speed graphs.
10.10 Cutting in Modulation Mode
When cutting, the square wave pulsed output of the Laser is used to improve the piercing
speed. When starting a cut, square wave also improves the cut quality for thick materials. It
also improves cut quality when cutting at an angle to the surface of the part.
Pulsing improves the cutting of high heat conductivity metals such as Aluminium, by using
the peak intensities to overcome energy lost to conductivity and reflectivity.
Modulation also improves the edge quality of the cuts where intricate features are to be
trepanned and Laser power reduced while maintaining a high intensity focus.
10.11 Cutting Fixtures
Control of the material position relative to the Laser beam is achieved using Jigs and
Fixtures. Good position control is essential if good quality, consistent results are to be
achieved.
If flat sheet materials are to be processed, the simplest form of control is by clamping the
material in a fixed plane relative to the Laser beam. Refer to Figure 36 that shows two
simple arrangements, clamping from above or below.
Experience has shown that the clamping method used should ensure that the parts to be
welded are held with the joint ±0.5mm relative to the Laser beam focus position.
10.12 Cutting Assist Gas
The co-axial assist gas used in Laser cutting facilitates removal of molten material from the
cut.
Both Air and Oxygen are used in Laser cutting and contribute additional heat during the
cutting of steels. This is due to an exothermic reaction that occurs between the Oxygen in
the assist gas and the Iron in the steel. This additional heat increases both cutting depth and
cutting speed.
Oxygen bearing assist gas pressure is required to be optimised to achieve best results.
Excessive pressure can produce uncontrolled burning of the cut edge. This may result in a
cut of varying width.
Insufficient pressure may lead to failure to cut through the material and possible nozzle
blockage or optic damage.
A good starting pressure for cutting with Air or Oxygen assist gas is 3-5 bar (measured close
to the nozzle).
Gases with high Oxygen purity can offer an increase in performance of between 10 and
20%; however the benefits of increased performance must be balanced against the
corresponding increase in the cost of the gas.
10.13 Inert Assist Gases
Inert gases such as Argon or Nitrogen can be used as assist gases during cutting. Unlike
Oxygen-bearing gases, they do not contribute additional heat to the process. Their use is
primarily to assist in the removal of molten material and prevent oxidation of the cut faces.
This is important for applications where the cut faces are to be welded subsequently without
the need for further edge preparation and cleaning.
Petitioners Canadian Solar Inc. and Canadian Solar (USA) Inc.
Ex. 1025, p. 165
