• RAPID PROTOTYPING TECHNIQUE
    SLS | LASER SINTERING
    For employed throughout the cycles of product development.
SLS laser sintering is a rapid prototyping technique that can be employed throughout the cycles of product development, up to the final functional prototype, from the creation of one-shot models, to the production of parts for functional tests, and the production of limited series of products. With laser sintering, in fact, bulk quantities of components (series with more than 100 pieces) can be produced.

  • Why is Selective Laser Sintering a good choice?

This technology can accelerate the development of a business, since it remarkably reduces the initial project phase, thus allowing assessment of the project, even before it is completed. Today, many projects involve SLS based designs and, in fact, all evaluations related to shape, applications, dimensions and functions of a product can be performed before it is produced.

  • These are some good reasons for choosing laser sintering:

  • it is fast and cost-effective;
  • it can build durable and functional parts;
  • it can build big and complex pieces;
  • it allows direct production of reduced volume projects;
  • it ensures maximum freedom in design (no supports are needed);
  • it allows various finishes;
  • it builds parts that can be air tight sealed.


  • How it works

The parts built with laser sintering are made of layers. The basic material is a plastic powder (PA) whose particles have a 50 mw dimension. Each powder layer is applied on top of the previous one. When all layers are placed, a CO2 laser beam, connected to a PC, scans the surface and selectively bounds the powder particles in the diagonal section corresponding to the product. In other words, the laser beam works like a pen reproducing on the powder, layer after layer, what the PC is viewing.

During laser exposition, the excited powder goes beyond the glass transition point and adjacent particles fuse to each other till solidification. This process is called sintering.


SLS layout

  • Recommended for

  • Complete production of functional prototypes whose mechanical properties are comparable with the PA12 injection molded parts;
  • Serial production of small components, as a cheap alternative to injection molding;
  • Production of functional parts of big and complex dimensions up to 700x380x580 mm in a single piece;
  • Production of customized details, complex details and customized designs, traditionally built. Also, production of a single product, in small quantities.

  • Technical features

  • Standard accuracy: ± 0.3% (with a ± 0.3 mm lower limit);
  • Minimum thickness of the wall: 1 mm, with possible 03 mm edges;
  • Maximum dimensions of the piece: unlimited. Details can be made of various sub-parts. The maximum working area of the equipment is 700x380x580mm;
  • urface structure: the parts usually have a grained surface, but different levels of finishing can be applied in order to obtain a smooth and pleasant-looking surface;
  • Possible finishing treatments are: sandblast, dyeing (soaked), painting, coating, etc.

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  • Materials

eported below, a list of selected materials that can be employed with this technology.
They are all different materials that can lead to different results and meet any requirements.

  • Polyamide (PA)

Being a solid material, powder is self-sufficient and it does not involve the use of supports, usually required for stereolithography.
The polyamide parts have an excellent long-term stability; they resist against most chemical products and can also be air-tight by impregnation. This is the reason why this material is recommended for functional prototypes with high thermal and mechanical resistance.

Also, polyamide is a bio-compatible certified material and it does not damage health or environment.

  • Datasheet

Units ASTM# Range
Tensile modulus Mpa DIN EN ISO 527 1650 +/- 150
Tensile strength Mpa DIN EN ISO 527 48 +/- 3
Elongation at break % DIN EN ISO 527 20 +/- 5
Flexural modulus N/mm2 DIN EN ISO 178 1500 +/- 130
Charpy – impact strength Mpa IN EN ISO 179 53 +/- 3.8
Charpy – notched impact strength Mpa IN EN ISO 179 4.8 +/- 0.3
Izod – impact strength Kj/m2 DIN EN ISO 180 32.8 +/- 3.4
Izod – notched impact strength Kj/m2 DIN EN ISO 180 4.4 +/- 0.4
Ball indentation hardness DIN EN ISO 2039 77.6 +/- 2
Shore D/A-hardness DIN 53505 D 75 +/- 2
Heat deflection t° °C ASTM D648 86
Vicat softering temperature B/50 °C DIN EN ISO 306 163
Vicat softering temperature A/50 °C DIN EN ISO 306 181
Density g/cm3 0.95 +/- 0.03
Actual values may vary with build conditions.

  • Glass fiber reinforced polyamide (PA-GF)

If compared to PA-CS, this material ensured better features due to its higher module of traction and bending.
The roughness of the product is approximately 1μm, and the melting point is about 180° C. For many applications like, for example, coverings, closing devices, connectors, cooling/heating fans, structural components, sport functional prototypes, rigid parts for packaging and other applications in naval and aerospace industries this material is more recommended than others.

  • Datasheet

Units ASTM# Range
Tensile strength Mpa DIN EN ISO 527-1 51,9
Tensile modulus Mpa DIN EN ISO 527-1 5505
Elongation at break % DIN EN ISO 527-1 2,1
Flexural strength Mpa DIN EN ISO 14125 83,5
Flexural modulus Mpa DIN EN ISO 14125 4963
Impact stength (23 °C charpy unnotched) Kj/m2 ASTM D256 16,59
Impact stength (23 °C charpy notched) Kj/m2 ASTM D256 4,63
Melting point °C ASTM D3418 180
HDT, 1.82 Mpa °C ASTM D648 173,4
Vicat 10N °C ASTM D1252 175,5
Surface finish after SLS Process Ra µm 7,4
Surface finish after finishing Ra µm 1
UTS per density unit Mpa g/cm3 39,65
Tensile modulus per density unit Mpa g/cm3 4205,5
Density (20 °C) g/cm3 1,309
Actual values may vary with build conditions.

  • Alumide

Alumide is a mixture of powder and polyamide which conveys a metallic look to the product and allows the building of non-porous components, easy to manipulate and resistant to high temperatures.
Alumide is typically employed in the production of rigid, metal looking parts for the car sector as, for example, wind tunnel testing and for other parts, not relevant in terms of security. Alumide can also be used in the production of parts in limited series.

  • Datasheet

Units ASTM# Range
Tensile modulus Mpa DIN EN ISO 527 3800 +/- 150
Tensile strength Mpa DIN EN ISO 527 48 +/- 3
Elongation at break % DIN EN ISO 527 3.5 +/- 1
Flexural modulus N/mm2 DIN EN ISO 178 3600 +/- 150
Charpy – impact strength Mpa DIN EN ISO 179 29 +/- 2
Charpy – notched impact strength Mpa DIN EN ISO 179 4.6 +/- 0.3
Shore D/A-hardness DIN 53505 D 76 +/- 2
Heat deflection t° °C ASTM D648 (1.82 Mpa) 130
Vicat softering temperature B/50 °C DIN EN ISO 306 169
Density g/cm3 1.36 +/- 0.05
Actual values may vary with build conditions.

  • TPU 92A-1

TPU 92A-1 is appropriate for building details requiring flexibility and resistance, thus keeping their functionality.
TPU 92A-1 is the only material used in rapid prototyping that combines important features all together.
Namely:
  • durable elasticity;
  • high resistance against tear;
  • high resistance against dynamic charge;
  • high abrasive resistance;
  • snappy answer;
  • good temperature range (-20 °C a 80 °C).

  • Datasheet

Units ASTM# Range
Tensile strength Mpa DIN EN ISO 527 27
Elongation at break % DIN EN ISO 527 400
Flexural modulus N/mm2 DIN EN ISO 178 9
Shore D/A-hardness DIN 53505 A 92
Abrasion resistance mm3 ASTM D648 (1.82 Mpa) 130
Vicat softering temperature A/50 °C DIN EN ISO 306 90
Density g/cm3 1,2
Actual values may vary with build conditions.
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