Which Metal Cutting Method is Best? Laser, Water Jet, or Plasma?

Metal fabricators across many industries need to create a wide range of parts and components. Such a varied product mix means no cutting tool can fully meet every challenge that fabricators will face. When it comes to light industrial applications, there are three major types of processing method to evaluate:

  • Laser Cutters

  • Water Jet Cutters

  • Plasma Cutters

Each has their own strengths and weaknesses, but one technology may suit a specific style of cutting job better than the others. Let's take a closer look at what sets these CNC machines apart and which is best for your project.

Laser cutting electrical components from thin sheet metal
Precision, speed, and cleanliness are the strengths of laser cutting machines

LASER CUTTING


There are two main types of laser, fiber and CO2. Each has its own strengths, but both lasers excel at cutting thin sheet metal and complex or fine geometries.


Although they use heat to cut metal, lasers cause minimal warping due to using nitrogen and compressed air to assist in the cutting process. These assist gases help reduce heat distortion by cooling the immediate area around the slit or cutting profile. This helps lasers keep parts within tighter tolerances (+/-.005) than plasma which can experience major warping issues that can challenge the integrity of part profiles.


Laser cutting is also the cleanest cutting method. By using nitrogen and air to blast slag and contaminants out of the cutting slit, lasers provide parts that are ready to fabricate without intermediate processes. The dry cutting process also mitigates the chance of rust or water related issues that can appear with water jet parts that aren't cleaned or packed effectively. This gives fabricators parts with clean edges that don't require grinding or cleaning operations prior to welding, drastically reducing downstream assembly costs.


Processing speed is the third major benefit of using a laser cutter. Precise computer controlled programming allows lasers to cut intricate parts from thin metals at speeds much faster than water jet or plasma. This lowers lead times when planning production schedules as well as significantly lowers costs as a result of higher throughput.


Laser cutting is well suited for architectural metal and light industrial applications like car panels, electrical boxes, HVAC, appliances, and other thin gauge components.



Water Jet cutting thick metal
Water jets are best used for non-metal materials or thick plate metal


WATER JET CUTTING


Water jets use high pressure water (of course) and an abrasive grit made from garnet to to cut through hard materials. Unlike lasers, water jet isn't limited to only cutting metal.


Thicker materials including granite, polymers, and ceramic are best cut on a water jet due to penetration depth of the abrasive water, which can be up to 12 inches for some materials. While they offer deep cutting capabilities, the abrasive jet is unable to apply consistent cutting at high speeds like the light based cutting methods can.


Lower cutting speeds mean lower throughput. For jobs cutting thick material, this isn't the worst outcome since you are often limited to using a water jet regardless. For thin materials though, the speed of water jet can be prohibitive, especially when cutting high quantities. This means large production runs can see higher prices and longer lead times in comparison to laser or plasma.


When evaluating the precision of water jet, the conversation once again revolves around material thickness. Thinner materials can be problematic on a water jet because small or thin parts may not fare well under the high pressure and force exerted by the jet while cutting. Lasers perform on thin material or complex geometries much better than water jet will. But for thick steel plate, the water jet is the clear winner with significantly better edge quality and precision than a plasma cutter.


Water jet is a good fit for aerospace applications that may require a part without any form of heat affected zone (HAZ) as well as non-metal materials like ceramics, glass, rubber, granite, and plastics.



Plasma cutting brackets from thick carbon steel plate
Plasma quality can be rough, but they shine in heavier industrial applications


PLASMA CUTTING


Plasma tables are one of the most well known cutting machines, found everywhere from hobbyist's garage shops to production floors.


Plasma cutting is the least precise cutting method by far, but it works well for parts that don't require tight tolerances. Warping and heat affected zones are byproducts of the plasma cutting process which cross thin metal and complex geometries off the list. Plasma is intended for parts that are often simple in design, and don't require strict adherence to quality standards.


Plasma is limited to metals, similar to laser, but doesn't provide a clean cut. Parts require additional processes like grinding or sanding due to slag buildup, especially if powder coating or welding are planned downstream. While money can be saved on the front end for the cutting service, that is often insignificant in comparison to labor costs if secondary processes are needed between cutting and final use of the parts.


Where plasma excels though, is in cutting thicker steel or metal plate when precision isn't necessary. Heavier industrial applications without strict part finish specifications will find plasma to be an excellent option.


PRIMARY CONSIDERATIONS


When you are evaluating cutting methods for your project, make sure to take all factors into account, beyond price. You need to make sure you're using the right tool for the job at hand.


The key elements to consider are:

  • Material Type

Do you need to cut metal or non-metal? If you aren't cutting metal, then water jet is going to be the best tooling option.

  • Material Thickness

Do you need to cut metal 1/4" or thinner? Thin material is best processed on a laser and takes advantage of its fast cutting speeds. Lasers were historically limited to cutting non-reflective metals like carbon steel, but new fiber technology has widened the range of possibilities. If you're wondering what can be cut by a fiber laser, take a look at our materials. If you don't see your metal listed, contact us and we would be happy to test samples for you.

  • Level of Precision Required

Do you need your dimensions to be correct? Should holes be the size they were drawn? If measurements are important, then laser is the most precise, but water jet can provide decent tolerance adherence as well. Plasma will not be the best choice for these types of projects.

  • Part Intricacy - How detailed is the geometry of your part?

How detailed is your part? Lots of holes, close geometries, or tiny slit sizes? Laser is the best bet for intricate designs or small slot and hole sizes.

  • Edge Quality

Do you need a finished edge that is ready for secondary processes or assembly? Laser and water jet are able to cut parts with fabrication ready quality.


SO WHICH CUTTING METHOD IS BEST?


It depends, but taking all of our primary considerations into account, we can create the following guidelines for project planning:


  1. Laser: Metals 1/4" and thinner, especially if high in quantity or requiring secondary processes like welding or powder coating

  2. Water Jet: Metals 1/4" and thicker with decent precision that require welding or powder coating, non-metals

  3. Plasma: Metals for parts that don't require dimensional accuracy or secondary processes like welding or powder coating

We hope this guide helps you evaluate the proper CNC machine for your parts. If you have any questions about laser capabilities, contact us, we would be happy to discuss your project!