Laser Cutting

This enables customers to achieve the high quality and cost benefits of laser cutting for much thicker stainless steel plate than is possible with the laser cutting technology typically available at stainless steel service centers.

PSP Superior Laser Cutting

All laser cutting at PSP is done by a plate-laser cutting machine.

• Excellent large size sheet and plate cutting capability with dual heads, as compared to sheet lasers and as compared to Dynamic™ Waterjet cutting.
• Excellent thicker plate cutting capability, as compared to sheet lasers. Most sheet-lasers are not able to cut past the ½ to 5/8″ thickness range.

Huge selection of plate and sheet inventory, including large sizes and over 30 grades are available. By offering extensive inventory and large size plate cutting capability, Penn Stainless Products is uniquely positioned to provide cost and time savings opportunities. Penn Stainless Products has 30 years of processing experience to help customers select the most cost effective processing options that best meet their needs.

Penn Stainless Products will accept CAD files in .dxf or .dwg format, PDF renderings of CAD files, PDF scanned drawings, faxed drawings, or textual (i.e. descriptive) dimensions. PDF and CAD files are preferred over faxed drawings.

About Plate Laser Cutting

Plate-laser Cutting machines, which are designed to be large and powerful, are optimized to provide a cutting solution for larger and/or thicker work pieces.  Plate-lasers and are usually characterized by extremely large material working areas and high wattage resonators commonly in excess of 3.0 kW (3,000 watts).  They are able to cut through stainless steel plate up to 1.25” thick.  This enables customers to get the high quality and cost benefits of laser cutting for much thicker stainless steel plate than would be possible with sheet-lasers. Furthermore, plate-laser cutting is an excellent solution for cutting large size stainless steel sheet and plate, including sizes that are outside the range of waterjet cutting capabilities.

Plate-laser cutting machines are able to deliver high quality cuts across large plate sizes by delivering a consistent beam length that provides the same amount of power to all points on a work piece.  There are various ways to do this.  Penn Stainless Products utilizes a traveling resonator that moves with the cutting head assembly.  The traveling resonator delivers a consistent beam length by keeping the origin of the laser beam approximately the same distance from the cutting material at all times during the cutting process.

Overview of Penn Stainless Products Plate Laser Value Add

• High quality cuts provided by laser cutting are now available for large size sheet and plate.
• Excellent thicker plate cutting capability, as compared to sheet lasers.   Most sheet-lasers are not able to cut past the ½ to ⁵/₈” thickness range.
• Huge selection of plate and sheet inventory, including large sizes and over 30 grades are available.  By offering extensive inventory and large size plate cutting capability, Penn Stainless Products is uniquely positioned to provide cost and time savings opportunities to the end user customer as compared to other service centers.
• Penn Stainless Products has 30 years of processing experience to help customers select the most cost effective processing options that best meet their needs.

Guidance for Choosing Plate Laser to Cut Stainless Steel

Plate-Laser Benefits

• High cut quality.  Can typically produce cut-perpendicularity error less than 1°
• Low cost cutting method, particularly for parts less than 3/4” thick
• Excellent flexibility for handling thicker gauges. Can handle plate up to 1.125” thick.
• Excellent flexibility for handling large plate sizes.  Can handle plate up to 13 ft wide X 80 ft length.
• Fast
• Good tolerance on cut edge (±0.01” to 0.035”, depending on gauge.)
• Extremely versatile process enables very detailed 2D Geometry.
• Narrow cutting width  (Kerf is  0.015” to 0.030” on all thicknesses)
• Can cut small holes
• Creates much smaller HAZ area (0.010” to 0.015” is typical), as compared to plasma cutting.
• Less likely to lead to expensive secondary processing steps, as compared to plasma cutting.

Plate-Laser Limitations

• Plate-laser cutting (as does sheet-laser cutting) uses heat.
  • Creates heat affected zone (HAZ) around the cut edge (albeit, a small one)

Cost Factors to Consider when Comparing Processing Costs

In order to help customers accurately determine the true cost of cutting when comparing processing options, it is important to consider all three of the following: Cutting Costs Overall, laser cutting offers a high quality cut at a good price.  Laser cutting is typically less expensive than Dynamic Waterjet® cutting.  Laser cutting is more expensive than plasma cutting, but offers many advantages over plasma cutting.

• Laser cutting is especially cost competitive for parts less than 0.75 inch thickness.
• Laser cutting costs increase with thicker materials, but are typically still less than Dynamic Waterjet cutting costs.

Material Costs  When comparing material costs between cutting processes, it is important to consider 1) extra material that may need to be machined off in a secondary process, and 2) scrap losses as a result of the cutting process.

• In the case of laser cutting, extra material that needs to be machined off in a secondary process is typically not a significant factor, especially as compared to plasma cutting (due to the small laser HAZ area).

Extra Cost in Later Processing Steps It is always important to consider if the cutting method will lead to additional processing costs as compared to other cutting processes. Here are some important considerations:

• Grinding Costs
  • Plasma cut parts are far more likely than laser cut parts to need grinding to remove the HAZ area and/or the dross.
• Machining Costs
  • While both plasma cut parts and laser cut parts may need machining to remove the HAZ area, plasma HAZ removal is significantly more difficult than Laser HAZ removal.  Also, Plasma HAZ removal wears heavily on tool life, which can add additional cost to this processing step on plasma cut parts.
  • For parts that will be welded as is, high quality laser cuts (as well as high quality Dynamic Waterjet cuts), may save costs in two ways, as compared to plasma cutting:
    • Less downstream welding consumables are needed to fill gaps when welding parts together.
    • Facilitates the ability to robotically weld.

History and Development of Laser Cutting

History of Laser Cutting Machines for Cutting Stainless Steel Plate and Sheet
While there are many different types of lasers in existence today, the general principals used to create laser beams for all lasers evolved from theories first proposed by Albert Einstein in 1917. Albert Einstein wrote equations to back up his theories at that time, but did not develop his proposals further.  It was not until the 1940’s and 1950’s that various scientists began doing extensive work to create a practical device based on Einstein’s principals.  The first working lasers were introduced in the early 1960s.  Notable scientists that contributed to the field include Theodore Maimam, Arthur L. Schawlow, and Charles H. Townes. While the very first lasers were described by some as “a solution looking for a problem”, countless uses were quickly discovered for a wide range of applications, including medical, scientific, military, medical and commercial.  Many different types of lasers were developed in order to achieve this.  Laser types, which are typically classified by the medium that they use to create the laser beam, include Solid State, Gas, Dye, Excimer and Semiconductor.

The C0₂ laser, which is classified as a gas laser, is the standard laser technology used for cutting stainless steel plate and sheet.  It can also be used to cut other metals and materials, as well as other applications, such as welding and laser surgery.  The C0₂ laser was invented in 1964 by Kumar Patel.

Development of Laser Cutting Machines for Cutting Stainless Steel Plate and Sheet

Today’s industrial laser cutting machines typically include a C0₂ resonator, a beam delivery system, and a cutting assembly.  The resonator generates continuous single wavelength light emission by running electricity through a gas tube under appropriate artificial conditions.  This light is sent through a beam delivery system, which includes a series of reflective and partially reflective surfaces.  The beam is then delivered to a focusing lens, which brings the unfocused, larger diameter beam into a focused beam capable of cutting through stainless steel plate and sheet, as well as other materials.  This beam of light is very different from the low intensity light emitted from a standard light bulb that includes a mix of wavelengths and frequencies, and that is neither focused nor coherent.

C0₂ Laser cutting machines generate light in the infrared range and are extremely powerful.  They rely on the coherency of the directed laser beam to transfer power to the stainless steel plate or sheet work piece accurately. Laser cutting does not usually involve any mechanical contact with the surface of the material.  As soon as the light beam contacts the work piece, it heats the material such that it begins to melt and vaporize. Once the beam completely penetrates the part, the cutting process begins.   The melted material is than forced out of the cut area with a blast of gas.

Laser Cutting machines come in three basic forms concerning positioning systems; Fixed head, Hybrid and Flying Optic. In a Fixed Head positioning system, the stainless steel plate or sheet moves in both x and y axis while the laser head remains fixed. In a Hybrid system the stainless steel plate or sheet moves in one axis (x-axis) and the laser head moves in the other axis (y-axis). In a Flying Optic system the stainless steel plate or sheet remains stationary and the head moves in both x and y axes.   Most industrial machines utilize Flying Optics capability.

While early laser cutting machines had the power capability to cut through stainless steel plate and other stainless steel materials, they struggled with inconsistent beam delivery, excessive heat in the cut material, and other limitations.  Many advances have been made over time to resolve these issues, including advances in the motion system to move the cutting head assembly over the laser cutting machine bed, improved processes to pierce the cutting material prior to cutting, and the addition of computer control software to direct the output of the laser beam.