Metal 3D printing is still one of the most desirable of additive technologies. While for the vast majority of people, 3D printers are no longer something special, they mostly they bring them to popular and most common FDM / FFF method. Additive manufacturing with the use of metal is still something abstract and hardly anyone realizes how it works – and therefore, what can it really be used for? In this article, we will briefly outline what 3D printing from metal is, but first of all we will try to make people who have little (or no…) contact with this technique aware of what to use it for, and what is it completely unsuitable for?
Every week, many people contact us with a request for a quote for a 3D metal print – unfortunately, in 4 out of 5 cases we do not even reach the stage of preparing the official price offer… After a telephone conversation or a quick exchange of e-mails, it turns out that the person / company would like to make a detail that is completely unsuitable for 3D printing from metal. Customers expectations regarding the price are completely out of touch with reality, which is simply due to the lack of basic information and knowledge on the subject of 3D printers for metal and the specifics of the manufacturing process itself.
The basic problem is always the same – no idea what to use this technology for? Usually, the motivation for sending an inquiry is the hope that 3D printing will be cheaper than CNC milling – it is possible, but only if the milling is either terribly expensive or is at the limit of technological feasibility. The second problem is stereotypes about 3D printing acquired on the basis of experiences with cheap, desktop 3D printers printing from plastic – if they are so cheap to operate, how much more expensive can 3D printing from metal be …?
The thing to understand is that FDM / FFF plastic 3D printing is something completely different from metal 3D printing. These are two completely different production methods, the only common denominator of which is that they produce details in an incremental manner – layer by layer. This means that if someone has mastered the secrets of 3D printing from filaments on a desktop 3D printer and feels really strong in this area, it does not matter when it comes to 3D printing from metal and translates into effects – his knowledge and experience are worthless, he must everything. to learn from the beginning.
What is metal 3D printing technology?
Metal 3D printing is a powder technology. Although, in principle, it works in a similar way to the SLS method (3D printing from powdered polyamides) it differs in a whole lot of technological nuances. From the point of view of a person who wants to order 3D printed parts, the most important difference is that in SLS technology you do not need to use support structures, in the case of 3D printing from metal it is necessary. Therefore, the printouts cannot be stacked in the working chamber, and when designing details, one should take into account the need to use supports, which must be removable after 3D printing.
During the 3D printing process on the surface of the bed an even layer of powdered metal is spread, which is selectively melted with a laser beam. When one layer is melted down, the bed is lowered by the height of the given layer, another layer of powder is spread and the laser melts it again, sintering with the previous layer.
After the process is finished, we clean it of unmelted powder, then cut it off the bed and remove the supports. Additional heat treatment is necessary for certain types of metal alloys.
Why is metal 3D printing so expensive?
In all respects, metal 3D printing technology is the most expensive of all additive methods – 3D printers, materials and widely understood operating costs, as well as 3D prints themselves are expensive. Where it comes from?
- 3D printers are expensive because they use very expensive components (laser heads and precise control systems, ventilation systems creating a vacuum inside the working chamber and pumping technical gas into it, massive and tight structure), and their production and assembly are complicated
- the materials are powdered metal alloys; in order to produce them, the raw material must first be transformed into wire and then atomized to a given granularity, which in itself is an extremely complicated and expensive process; the cost of a kilogram of powdered stainless steel is a multiple of a kilogram of raw material used in CNC
- operating costs are mainly technical gas and maintenance of all infrastructure necessary for post-processing
- 3D printing is the result of all of the above, where the most expensive variable is always the cost of the material.
When to use metal 3D printing and when to avoid it and choose another manufacturing technique?
The most common mistake in thinking about metal 3D printing is equating it with CNC milling. If something can be milled relatively easily, there is no point in manufacturing it on a 3D printer – the cost of 3D printing will always be higher. This is especially important for high volume / heavy parts. The more material we use for 3D printing, the more expensive it will be.
When does metal 3D printing make sense?
- when CNC milling or any other machining is impossible
- when CNC is very complicated
- when thin-walled elements (less than 1 mm thick) are to be produced – depending on the geometry, a metal 3D printer can make walls with a thickness of up to 0.2 – 0.3 mm
- when small and precise elements are to be produced, with dimensions of 1-5 cm in XYZ axes
- when there are elements to be made empty inside or having a lattice internal structure.
3D printing is also applicable where we can make one complex detail, instead of assembling it from several or a dozen independent parts (e.g. three body elements + a set of bolts, washers and nuts to put them together).