Laser welding fume filtration Laser welding fume filtration for additive manufacturing methods
HYDAC – your partner for welding fume filtration in additive manufacturing, especially with SLM technology.
Laser welding fume filtration for additive manufacturing methodsHYDAC – your partner for welding fume filtration in additive manufacturing, especially with SLM technology.
Selective laser melting (SLM) is an additive manufacturing method that involves parts being manufactured in layers directly from a material in powder form.
In the SLM method, the powder material is fused directly to the processing point by the heat energy of a laser beam. To prevent the material from oxidising, the working chamber is filled with a protective gas. This causes welding fumes to develop in the machine’s working chamber which could impair the welding point of the laser. For this reason, the welding fumes need to be filtered. The dusts that are generated are combustible if they react with oxygen. Some of the dust particles are so small that they are respirable. With the current technology, filter is therefore either flooded with water or brought to an inert state with slaked lime when the filter is changed.
The disadvantages of this method:
- The disposable filter elements can sometimes have very short service lives (in some cases only lasting for one construction job)
- High filter running costs and extensive filter change workload
- Complex inertisation is needed when the filter is changed, as the entire housing needs to be removed, flushed with water and cleaned
- Frequent filter change results in a large disposal volume
- Occupational health and safety is unsatisfactory
Optimisation of the filter solution with the innovative laser welding fume filter solution from HYDAC
Our customer is a global player among machine tool manufacturers. With their solutions, they cater to the huge trend of additive manufacturing, using selective laser melting (the SLM method) in their metal 3D printers. One major challenge that this poses is the filtration of the laser welding fumes that are generated.
The existing filtration solution required very frequent filter changes, as new disposable filter elements were needed for almost every construction job. This resulted in a large and costly filter element disposal volume for the machine owner.
Another disadvantage of the complex filter change process was the inadequate occupational health and safety resulting from the fire hazard posed by the metal powder in the event of a reaction with oxygen. On top of this, the particles were very small and respirable. This meant it was necessary to flood the filter housing with water every time a filter was changed. Then the entire housing was removed, flushed out with water and elaborately cleaned. With this method, it could take up to 2 hours to change the filter.
The entire filter change process was inefficient and entailed health risks. This is why the customer came to us with the following requirements:
Improve occupational health and safety
Develop a filter system with long filter life and cost-effective operation
The high disposal costs for the end user should be eliminated
A filter that can be used universally for all types of powder material in the additive manufacturing method
With these defined goals in mind, a requirements specification was developed in collaboration with the customer. A test of the first prototype of the HYDAC filter was performed right at the customer’s premises, of course with support from our skilled filter experts. After some adjustments, the customer approved series production.
FlushPACK – the laser welding fume filter solution from HYDAC
HYDAC took up the challenge of filtering laser welding fume particles – the result is the innovative filter system, FlushPACK.
The principle of passivation
First, the particles are filtered out of the protective gas in a gas filter (1). A hydraulic accumulator (3) charged by a compressor (2) performs backflushing in the filter, causing the contamination to fall to the filter base. There, it combines with a passivation fluid, which is extracted into a separate container (4) where it is stored. The particles are now bound. As an option, a HEPA filter (5) can also be installed.
As the contamination is passivated directly inside the filter, no PPE (personal protective equipment) is needed for the filter change. At the same time, the occupational health and safety of the method is increased. Thanks to the very long filter life, the filter system can be operated cost-effectively. The change system means that the high disposal costs are eliminated – used filters can be returned to HYDAC. Because of the use of the passivation fluid, the filter system can be used for all types of powder material. The powder material can even be changed without changing the filter.
“The long service life of the filters and the simplicity of the filter change and disposal fully convinced us. We are now going to retrofit an existing machine with the FlushPACK.”