Other Materials
Selective Laser Sintering (SLS):
Alumide
Alumide (by EOS) is a mixture of PA12 and aluminum powder. It is characterized by it’s stiffness and metallic appearance. While the mechanic and thermic properties are improved, the material shares more characteristics with PA12 than with aluminum. The addition of aluminum to PA12 causes a cut break effect in the sintered material. This makes it easier to machine and post process, but decreases abrasion resistance of the parts.
Overview
Technology
Lasersintering (SLS)
Colors
Metallic-grey or dyed
Max. Size
300 x 200 × 180 mm
Cost
$$$
(medium)
Lead Time
10 – 12 business days
Accuracy
± 0.3% with a lower limit of 0.3 mm
Material-Details
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Functional Prototypes
Parts made of Alumide are stiffer and easier to machine than PA12 parts. The material is typically used, where PA12 is too flexible, e.g., in wind tunnel tests or parts requiring high dimensional stability. Furthermore, the heat resistance is higher than in PA12 which makes it a great material to ue in high-temperature environments.
Due to the lower abrasion resistance, the material should not be used for moving parts or parts exposed to any form of abrasion.
Visual Prototypes
The metallic appearance makes Alumide a very popular material for visual prototypes. It is significantly less expensive than 3D-printed metal, and theretofore a cost-efficient alternative for visual models of metal parts. Furthermore, the material has a very distinct look when dyed black, blue, or red and is used for models that attract attention, like merchandise articles or fair models. The material can be polished and has a better surface quality than PA12.
The price for Alumide is based on two factors:
- Material consumption: The material used for producing the part itsself.
- Machine Space: The more space the part uses, the longer it takes to print it. Furthermore, not-sintered material cannot be reused – the more space the part takes, the more material must be discarded after printing. Unlike laser-sintered PA12, where half of the unused material can be reused, pricing of Alumide is determined mainly by machine space.
The average approximate price of a laser-sintered Alumide model are around EUR 1.00 – 2.00 (excl. 19% VAT, or ~EUR 1.19 – 2.38 incl. 19% VAT) per cm³ Material volume.
Look & Feel
- The surface is rough, but can be polished quite well.
- The color has a metallic appearance.
- The weight is significantly higher than PA12.
Characteristics
- More rigid than PA12
- Better heat resistance compared with PA12
- Low abrasion resistance
Tensile
Strength
48 MPa
Elongation at break
4 %
Modulus of Elasticity
3,600 MPa
Flexural
Strength
72 MPa
Vicat A
175 °C
Shore
hardness
76D
Minimum Wall Thickness
The minimum wall thickness should not be less than 1 mm. For long structures or structures that face mechanical stress, the wall thickness should be increased.
Cavities
Hollow parts can be printed, as long as they contain escape holes with a diameter of 5 mm or more, which allow to remove excess material. For larger cavities leave two or more escape holes.
The material is compacted during the printing process and therefore challenging to remove. Hence, thin tubes in the part might contain excess material which cannot be removed.
Clearance Gap
In case your file contains several shells, make sure to keep a clearance gap of min. 0,5 mm between the shells, otherwise they could be fused together.
Resolution
The minimal details size should not be smaller than 0,5 mm.
Interlocking parts
Interlocking parts can be printed, please allow a distance of min. 0,5 mm between the objects. Make sure that the area can be access to remove excess powder.
Bounding box
The maximum size of the part cannot exceed 300 x 200 × 180 mm.
Standard-Finishing
- Cleaning parts from excess material
Optional Finishing
- Manual polishing
- Machine polishing (tumbling)
- Dyeing (black, red, blue)
Details about the process can be found in our Laser Sintering: Technology Overview.
A thin layer of powder is spread on a retractable built platform. In this powder layer the cross-section of the desired part is drawn by a laser – sintering the powder in those areas. Sintering means that the material is heated to just below the melting point, fusing the powder together. This is in contrast to the laser melting method (also called direct metal 3D printing), in which metal powder is heated with a laser beyond the melting point during the printing process.
After successfuly sintering of the first layer, a new layer of powder is spread over the previous one and the process is repeated. The sintered component is fully surrounded by powder thus providing support. Therefore – unlike SLA or Polyjet, support structures are not needed.
Laser sintering takes a comparatively long time. In a completely filled machine space, the printing cycle can last up to 2 or even 3 days.
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SLS process schematic. Source: Youtube, 3D Systems