Introduction to Powder Sintering
Powder sintering is the translation of the English name Selective Laser Sintering, whose acronym is SLS. With this powder sintering or laser sintering technology , plastic powder particles are agglomerated by heat and the presence of a laser. Indeed, the manufacturing chamber of the parts is heated up, a laser is then used to sinter the polyamide powder arranged in a thin layer. The part is manufactured in successive layers of 0.10 mm when the process is repeated.
The SLS process produces functional plastic parts with isotropic mechanical properties that can be used for detailed prototyping or low volume production of functional parts.
The printing dimensions of our largest machine allow us to print parts up to 350 x 300 x 420 mm.
The benefits of this 3D printing technology
- Powder sintering technology does not require support structures. The printed parts are held together by the powder that surrounds them.
- The lasers have a high scanning speed and are extremely accurate (which is different from material deposition printing such as FDM). They allow to print parts with a high precision and a good productivity.
- SLS 3D printing works with a wide range of materials: metal, polymer, glass, ceramic or composite material.
These advantages make it an ideal technology for:
- functional mock-ups ;
- Aerodynamic validation ;
- Dimensional, mechanical, thermal validation… ;
- Production of mini series up to a few hundred pieces.
Materials and finishes of the SLS
At Axis, we use the following materials:
- PA 650 (PA 12 – Polyamide) ;
- PA 615 Loaded Glass (PA 12 GF) ;
- PP (Polypropylene);
- TPU 70 shores A.
And at the level of the finishes we propose you :
- Manual cleaning of all surfaces;
- Epoxy impregnation and polishing ;
- Moisture recovery;
- Paint finish ;
- We carry out and validate the assembly of your sub-assemblies.
You want to know more about stereolithography? You can consult our material sheets.
Deadlines and part design tips
For the Powder Sintering process, it takes 2 to 6 business days depending on the size and finish of your project. For your mini series (up to a few hundred pieces, please contact us to obtain the deadline).
Regarding the design of your parts, plan for a minimum wall thickness of 0.8 mm.
The Powder Sintering in pictures
How does it work?
- Preparation :
- First of all it is essential to have a 3D file thanks to 3D design software in .STEP or .STL format;
- This file is then processed and cut by us into thin slices of 0.10 mm;
- Construction :
- This information is transmitted to the production machine. This sintering machine is composed of a pilot computer, 2 powder tanks, a platform, a lens and a laser. The construction of the part starts with the platform in the upper position, flush with the construction surface of the machine;
- A thickness of powder is deposited on the platform with a roller or an arm depending on the machine used;
- Once the machine is closed, it heats up to reach a certain temperature in the construction cabin;
- Once this temperature is reached, the laser is activated, passes through the lens and follows the trajectory calculated by the pilot computer to trace the contours of the part;
- On contact with the laser, the powder becomes compact and welded because the heat is increased at this precise point to reach the melting point and sinter the material;
- The platform is lowered by 0.10 mm, then a new layer of powder is deposited on top;
- The different steps follow one another: the laser taps on the powder to harden it, the platform descends, the roller or the arm deposits a uniform layer of powder, etc. ;
- Once all the successive layers have been produced, the temperature in the passenger compartment drops, the entire production can be accessed.
- Finishing :
- The “cake” of manufacture then resembles a cube of powder;
- It is then placed on a sieve and cooled so that its core is not too hot to avoid any risk of deformation of the parts;
- Like archaeological excavations, with the help of brushes and tools we come to seek the prototypes produced in the middle of the powder;
- The parts are then dewaxed, sandblasted, … to remove any excess powder still present.