Pic. 1 Laser C.B.Ferrari
The main reason for the purchase was to free up capacity on the Hermle 5-axis machining centres and to lower our dependency on logistically very complex cooperations in the field of cutting sheet metals.
The laser is placed in the building known as the greenhouse (skleník) where connection to the gases required by this technology (nitrogen, arcal, argon and oxygen) is possible.
The workplace operates in 2-shift mode, and operation is split between Petr Dvořák and Martin Uhlíř, who are sharing their experience with us.
Pic. 2 Martin Ulhíř and Petr Dvořák
How does laser machining work?
The material is removed by a thin laser beam with a high energy density. The removed material is melted and blown-off, it burns and sublimates. The cut is very clean so no further machining, cleaning, or degreasing of the product is required. This is contactless machining so no tools are worn out during the operation.
What’s it like working with the equipment? What are its benefits and drawbacks?
The laser has two independent sources, one for drilling and cutting, and the second one for drilling and welding. Currently, we are mainly using the cutting and drilling. The welding is in the testing and result evaluation phase and we will be doing further testing.
This technology is great mainly because of the machining speed and also thanks to the fact that no tools are worn-out and the quality of the output is always constant. Another benefit is the fairly simple maintenance and also the fact the end product doesn’t need to be cleaned, for example, from cooling fluid as with traditional machining.
Although it has its specifics, in particular, the need to constantly check a larger number of parameters which lengthen the preparation operation.
The main drawbacks are mainly the need to continuously inspect a larger number parameters, which lengthens the preparation operation. Some conductive materials are harder to machine (for example, aluminium, copper, brass, etc.), we are limited by the size of the workspace for planar work (850 x 520 mm) and we’ve detected an increase in dust.
Pic. 3 Combustion chambers of the APUs and jet engines
What parts do you machine with the laser and which materials do you work with?
We primarily use the laser to cut rings and other components of the combustion chambers of engines and APUs. We are also trying to carry out multiple operations on the parts that were previously handled by external cooperation, for example, cutting sheet metals.
Concerning materials, we’re working with all types of stainless steels, for example with Hastelloy, aluminium, copper, brass, and other materials. We have also tested a rubberised sheet, rubber, hardened paper, sheets with various surface treatments, for example, zinc-coating for the purpose of testing the damage to the surface.
Most tests turned out very well so the spectrum of materials is fairly wide despite the fact that some tests were connected with some side effects, for example, titanium sparks significantly and rubber smells a lot.
It is necessary to add, however, that some materials are more suited to this technology than others. For example, copper, brass, and aluminium are more conductive which lowers the laser’s effectiveness. Aluminium contains a lot of silicon which reflects parts of the beam and the operation itself takes longer.
Can you compare the specifics of working with traditional machining centres to the laser?
With the laser, it is more complex to prepare the operation. I’ll give you a practical example: a traditional machining centre travels to the part thanks to sensors, the laser travels manually thanks to a camera, which is more time-consuming. Many factors must be monitored throughout the entire preparation. On the other hand, once the operation is prepared, the machining itself is problem-free and it is also substantially faster than with traditional chip machining. Machining one part with the laser takes about 1/3 of the time compared to a traditional machining centre. Machining rings on one combustion chamber, therefore, only takes about 12 minutes. The preparation time, however, is about 1.5 hours. It would be ideal for us if we could produce the largest possible series which would make working with the laser more effective.
Is there something that would make working with the laser easier?
Yes, air conditioning would definitely be a benefit for us, it would lower the temperature of the workplace. The temperature is not only increased by the power supply of the laser and the operation itself, but also the neighbouring vacuum ovens. Often, the temperature rises above 35 °C, which may negatively affect some of the laser’s functions.