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AM Design Rules SLS

The AM Design Guide for SLS contains a brief description of the most important elements of the parts designed for production through SLS additive technology.

Bounding box

Attention: Building chamber = Part + Scaling!

The possible part size is depending on the scaling factor.

Scaling of 3.2% means a possible part size of 193.6 mm in X axis.

It is not possible to build a 330 x 250 × 200 mm part for EOS Formiga P110.


  • To avoid steps on your surface, the angle of the plane should be 0° or >20° to the X-Y plane
  • Visibility and size depending on layer thickness


  • Gaps (A) for Hinges:
    • x/y: 0.3 mm – 0.5 mm
    • z: 0.5 mm – 0.6 mm
  • Variables:
    • gap between bush and bolt (A)
    • length of the hinge (B)
    • diameter of the bolt (C)
    • thickness of the surrounding bushing (D)
    • building direction
  • With advance geometries smaller gaps are possible


  • Minimum font size 14 suitable for every direction
  • Smaller fonts possible but it depends on:
    • building direction
    • inside / depth of font
    • outside / height of font
  • Sans serif font is recommended

Tolerances in Parts

  • Depending on the fact that we build exact the same part as in the cad-system designed it is necessary to change your measurements to a symmetric tolerance zone.
  • The bad example has a unsymmetrical Tolerance zone, the good one a symmetric.
  • In the AM process it is only possible to build with symmetric tolerances.

Lose Connection

  • Use 0.1 mm distance for lose connection
  • A male and female part without a gap have a press fit
  • Only for parts not built together! else see

Minimal Wall and Pin Sizes

  • Walls
    • X/Y
      • min possible wall thickness = 0.45 mm for FORMIGA P 110
      • min wall thickness for reproducible measurements and mechanical properties = 1.5 mm
    • Z
  • Pins
    • min pin thickness = 0.8 mm
    • min pin thickness for reproducible measurement and mechanicals properties = 1.8 mm


The min size of a gap depends on the wall thickness of the part


Possible min hole diameter depends on the thickness of the wall

Powder Removable Design

  • Powder must be removable
    • Problems in small long pipes
    • Very complex parts with inside structure
    • The example is easy to produce but in the long hollow pipe inside it is impossible to remove the whole powder (pic2 grey). With compressed air is it possible to clean one or two windings but the rest remains inside.
  • If the powder is removable very simple your post processing time is shorter
Example part
Example part (transparent)

Data Format

  • The interchange format for RP technologies is STL
  • The file describes a surface by triangles
  • The file size and detail resolution are depending on the number of triangles
  • Square-cut surfaces are easy to describe exact pic1. For freeform or round shaped parts, you need a lot of triangles pic 2+3
  • A guide value for plastic parts is:
    • deviation tolerance: 0.01 mm
    • angle tolerance: 2°

Rough triangulation | fine triangulation


BG 6000 Stara Zagora, Industrial Zone South


+359 (0) 42 661 333

+359 (0) 883 551 333


+359 (0) 42 661 333