Water Cutting and Laser Cutting of titanium sheet
Titanium sheet, as well as titanium plate, are great raw materials for applications that require high strength but lightweight components.
Titanium is similar to steel in when it comes to strength, but it can be around 40% lighter. And it has many other properties that make it the preferred choice for different manufacturers.
However, there are some issues that need to be taken into account when working with titanium sheet and titanium plate. Especially if you are thinking of milling these materials. The main considerations are:
- Possible problems with chip formation and accumulation that may lead to tool failure.
- Work hardening which can result in abrasions.
- Surface finish may not be the required for the application.
- It may produce slow cutting problems.
The best solution to the issues above when working with titanium sheet or titanium plate is using alternatives such as water cutting or laser cutting.
What are the differences between water and laser cutting?
To better understand what are the differences between water and laser cutting, let’s take a look at the basic definitions of each method.
Water cutting, also known as water jet cutting, is a process that uses water at high pressure together with an abrasive element that is capable to cut through the metal. Common abrasive media include:
- Aluminium oxide
- Silicon carbide
- Garnet for silica sand
Laser cutting can be defined as a cutting method with no direct contact to the material which uses energy concentration in the form of a beam of light to cut through the metal. The light beam is focused through a nozzle and melts the metal until eventually vaporizing it. Most common laser cutting machines used to cut titanium sheet are CO2 machines with nitrogen or oxygen as supporting gases.
So, the main differences between water and laser cutting can be summarized as follows:
- Different cutting media.
- Water cutting has direct contact with the material opposed to laser cutting.
- Laser cutting requires more energy.
When to use water cutting and when to use laser cutting for cutting titanium metal sheets?
Both water cutting and laser cutting work well on titanium sheet and titanium plate. However, there may be reasons to choose one over the other.
For example, water cutting for titanium sheet and titanium plate makes more sense when cutting simple shapes, since it will be a more cost-effective and efficient approach.
However, while water cutting can achieve results when cutting a titanium sheet or titanium plate in a more complex shape, the process will take very long. In this case, laser cutting is a better option. Initial costs may be higher for laser cutting, but a reduction in operational costs will compensate that initial investment.
On the other hand, thanks to the high-precision that can be achieved with laser cutting, laser cutting will be a better idea when cutting very small holes on a titanium sheet or titanium plate. It is not that water cutting will not achieve it, but it will be harder and might not meet tight tolerances.
What are the advantages and disadvantages of water cutting and laser cutting?
When cutting titanium sheet and titanium plate to manufacture parts, water cutting and laser cutting are usually the best options. Of course, they have their own advantages and disadvantages. These are the most relevant.
Advantages of water cutting
- Speed. While it is true that cutting a thick titanium plate may take too long with water cutting, cutting a thin titanium sheet and getting the end part can be done in one pass while keeping tolerances in the range of +/- 0.12 mm according to some manufacturers.
- No contamination. Water cutting is a very clean process without toxic fumes and dust to worry about.
- Easy to cut different patterns. Water cutting does not require a very skillful operator to achieve the required patterns from the titanium sheet to obtain the end product.
- No thermal damage. Water works both as a lubricant and as a coolant during the process, so thermal reactions are not a problem when water cutting a titanium sheet or titanium plate.
- High thickness. Some waterjet cutting machines claim their machines can handle up to 300 mm.
Disadvantages of water cutting
- Limited surface finish.
- Possible failure due to low quality orifice.
- High starting costs when compared to other cutting processes. Moreover, there are operational costs associated to the process such as the cost of water, the cost of the abrasive, power consumption, among others.
Advantages of laser cutting
- High accuracy. Laser cutting usually creates an end part that meets very tight tolerances and does not require further processing.
- Convenience. Once it is set up, the laser cutter can perform different cuts without the need of changing tools or creating a new set up as long as the thickness is uniform.
- High repeatability. This is a very important advantage for mass production. Some manufacturers claim achieving +/- 0.05 mm.
- No contact. There is no tool-piece mechanical contact, so no wear to worry about.
- More than cutting. Laser cutting can be used to cut, but also to mark or engrave a titanium sheet or titanium plate.
Disadvantages of laser cutting
- It requires a skillful operator to use the full potential.
- High thickness is not a possibility. It usually works better with thickness values up to 20 mm.
- Fumes control required. Some potentially toxic fumes can be generated by laser cutting a titanium sheet.
- Initial cost. Similar to water cutting, laser cutting can be expensive when compared to similar cutting alternatives, including being more expensive than laser cutting. Some experts claim initial costs of up to £1,000,000. However, this could be compensated in the long term.
What are the standards covering water and laser cutting?
Water cutting and laser cutting are two titanium sheet and titanium plate processing methods which have grown in popularity in recent years. Therefore, there are a couple of international standards which cover the best practices for these two processes.
The most relevant standards include:
- ASTM E1575 – Standard Practice for Pressure Water Cleaning and Cutting.
- ISO/TC 44 N 1770 – Standard for Water Jet Cutting – Geometrical Product Specification and Quality.
- BS EN ISO 11553-1-2:2008 Safety of Machinery – Laser Processing Machines.
- BS EN (IEC) 60825-1:2007 Safety of Laser Products – Equipment classification, requirements.
- BS EN ISO 9013:2002 Thermal cutting – Classification of thermal cuts – Geometrical product specification and quality tolerances.
- NF EN 22768-1 Class m – Standard Tolerances for Laser Cutting.
Water cutting and laser cutting of titanium sheet. Which is best?
As you can see, both water cutting and laser cutting work well for cutting a titanium sheet or a titanium plate.
However, the answer to which is best out of the two options is that it will depend on the application in hand and the resources available. Also, the need for complex geometries plays an important role.
Nevertheless, whenever in doubt, the best thing to do is to ask an expert before investing in water cutting or laser cutting of titanium sheet.