Before getting started, here is a guide of on what to consider with a tube laser.
By Garrett Peterson, Senior Applications Engineer at Mazak Optonics Corp.
Tubes and pipes have found a growth in applications with continued advancements in tube technology. Tube lasers continued to get faster while also processing an increased range of materials types and shapes. While fabrication often focuses on flat sheeting material processing, tube and pipes fabrication is also a major player. Here is a quick start guide for what to think about with tube and pipe laser-cutting.
First, you need to decide what your tube and pipe size demands are. Tube laser-cutting machines are based off the what sizes the machines can process. Depending on what the size and shape you are fabricating, will determine what time of tube laser you are going to need. What is the maximum and minimum diameter tube you will processing? How much power will you need to cut these tubes and pipes? Are they thin or thick wall? You will also need to know what the length of your raw material sticks and your finished parts. These requirements will determine the type of tube-laser needed.
Depending on your applications you may need a true 3D cutting head. Many tube lasers had a torch that tilts but having a fully capable 3D torch allows for expanded application opportunities. If your application requires bevels or countersinks, a complete 3D torch is a must for your tube laser. The 3D head also allows fabricators to cut any desired angle to improve weld prep and simplify assembly fit-ups.
The final prerequisite to determining the type of tube laser you need, should be how the tube is supported during the cutting processes. It is essential for tube cutting quality and accuracy, especially with longer and heavier tubes, that the material is held and rotated properly. Having the ability to support the tube on both sides of cutting is important which is why the Mazak FABRI GEAR and FG series machines have a four-chuck system. If the tube is hanging while being cut and is not braced while cutting, it could lead to inaccuracies. Another advantage to having a four-chuck system is while chuck one and two are supporting and cutting raw material, chuck three and four can be utilized to move and unload finished parts which increases throughput.
Depending on your application, there may be other aspects of tube and pipe processing you may need to consider, but that will be address in considerations and expectations.
Tube and Pipe Cutting Basics
While flat sheet and tubes are made of similar material, there are major differences with the cutting process. When cutting flat sheet material, the laser sparks, debris and slug go onto the table or into the chip buckets below, but with tubes those items fall inside of the tubing. Having the sparks and hot metal inside of the tube also means an opportunity for thermal expansion. This means that machine operators need to be cognizant to the inside and the other side of the tube.
But dealing with scarp and sparks is not a major issue. There are strategies fabricators can use. One solution is to precoat the inside of the tube with antispatter to help prevent dross from sticking to the inside of the tube. Another method fabricators can use is to have a sacrificial tube on the inside to absorb the laser beam to prevent heat buildup and damage to the other side of the part.
Tube cutting as compared to flat sheet cutting, requires a supreme finished cut in order for the machine to move on to the next part. In sheet metal cutting, the machine can easily move from one part to the end with no complication regardless of cut quality. This is not the case for tube and pipe cutting. Since the raw material will cut multiple parts, the last cut of the part must fully separate from the unprocessed stick. If the finished part is not separated by that final cut, it could create complications for starting the next part.
Another aspect of tube cutting that needs to be examined is the straightness of the tubes themselves. If the material is not straight, you will need to determine if the machine has the capability to correct for it. This is essential to take into account from both the operator’s and the program’s viewpoint. Both must take into account how well the drawing matches up to the material being used and the accuracy of the cutting process. If the print and the material are not the same, the end result may not be as expected. Luckily, many machines include compensations for feature overrides like a corner radius to ensure the part can still be cut correctly. The FABRI GEAR and FG series machines also has self-centering of the opening and closing of the chucked tube supports to keep the material in line and machine functions to find the center of the material before cutting, this helps to make very precise parts.
Considerations and Expectations
Tube laser-cutting machines are a major investment. So much so, that some fabricators would rather not invest in a tube laser just for cutting raw stick which could be processed faster on a band saw but it also is less accurate and requires secondary processing such as grinding. But tube lasers do have their place. They can be used to cut shapes and features that cannot be done with other methods. Having these capabilities expand a fabricator’s range to take on additional jobs. The more features on a part, the faster the return on investment a fabricator will get from a tube laser.
Some tube lasers, like the FABRI GEAR and FG series machines, offer a done-in-one solution. These machines can perform a number of different processes including: material handling, cutting, machining, drilling, tapping in punching. Having all of these processes performed on one machine eliminates the need to have an operator work through these multiple steps moving the part from machine to machine.
There are additional components like automatic loading and unloading systems, seam detection and spatter extraction that can increase a machine efficient for producing parts.
This blog post is a variation of “A guide to laser tube cutting” article published in the November issue of Canadian Fabricating and Welding. Read the original article here.