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What Lasers Do Well
While die cutting still remains a highly economical means to produce large runs using some materials, here are some laser advantages to consider when you are looking at your processes and system operations (See 1A)

laser advantages

One of the main advantages of lasers is the flexibility it gives companies in taking on a variety of jobs – especially small or specialty work. Lasers eliminate the need for tool and die fabrication, as well as the need to maintain and store dies. Laser control systems use digital CAD files to aid in just-in-time manufacturing. Repeat orders can be retrieved and duplicated in minutes.

RCP Rotary System with FlashLiteLasers are especially useful with applications where it is beneficial to keep the cutting tool from coming in contact with the processed material. Non-contact with the cutting surface means that materials with adhesive surfaces will not become gummed up during the cutting process. Also, a laser cut is a thermo process that can vaporize fine material; therefore, leaving less fine particulate matter in the process.

Basic Types of Lasers Used with Non-metallic Materials
Today, most Fiber and Nd:YAG type lasers are used in metals processing operations. Typically, ultra violet (UV) and Fiber lasers use diode pumped solid state (DPSS) technology. New lasers are being developed that use alternative wavelengths that will expand the capabilities of laser processing.

Lasers used in the non-metal gasket industry can generally be divided by the wavelength required. Most use CO2 gas or ultraviolet wavelengths to process materials such as polypropylene, polyesters, and polyimides.

Laser Characteristics

Laser Delivery
Depending upon the material and product used in the process, a laser beam delivery option needs to be made. Delivery of the laser beam is typically accomplished in one of the following ways:

  1. Fixed Beam – XY table moves the material
  2. Flying Optic – XY moves beam over stationary platform
  3. Galvanometer – Steered or directed beam with or without any material motion.
  4. Robotic Motion

Laser Platforms
What are galvos, XY systems, XY tables, and flying optics? These are all types of laser platforms designed to handle different types of materials. Lasers and optics are continuously improving providing the capability to process faster, cleaner and more accurate cuts.

Some platforms are designed to primary handle sheet stock materials, some web stock materials, and some both. Further, laser beam options impact the spot size on cutting speeds and power requirements. The following is a simple comparison of platform types and performance:

Platform
Position Accuracy
Relative Cost
Stepper
Low
Low
Belt Drive
Low
Low
Rack and Pinion
Medium
Medium
Ball Screw
High
High
Servo (Rotary)
High
High
Servo (Linear Motors)
High
High

Important Issues for Achieving a Quality Laser Cut

HAZ – Heat Affected Zone is typically considered undesirable because this condition can leave burrs, a ridge or even discoloration on the material. There are times however, with adhesives for example, that it can be an advantage as HAZ will cauterize the edge and not allow the adhesive to flow, thus providing better edge quality.

Kerf Width & Taper - Kerf is the amount of material the laser removes. Taper is the difference between the kerf at the top of the cut and the bottom of the cut. Ideally, most materials are processed so that the kerf is equal all the way through the material. This set up can be achieved by setting the focal point correctly.

Focal Length - A lens is used to focus the laser beam to a spot. A short focal length creates a tight spot with higher power density.

Assist Gases – Typically, when cutting nonmetals, assist gasses are not used. However, the two most commonly used gasses are compressed air and nitrogen.

Spot Size, Power Density & Impact on Cutting Speed – A fast cut requires the use of a tight spot with high power density. Another consideration is desired edge quality. For example, acrylic can be cut fast, but in order to create a fire polished edge it must be cut at a slower speed.

Special Lenses (Telecentric Lenses) - Telecentric lenses are used to help correct the angle of the beam in the entire field of view. These lenses orient the beam perpendicular to material when galvonometers are used in the process. Telecentric lenses are beneficial in minimizing taper and when cutting geometry is close to the edge of the field of view. However, telecentric lenses can only be used for small cutting areas.

Thermal Distortion – Thermal distortion is an undesirable situation where heat causes material to ripple or warp. It is similar to the condition found with HAZ.

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