Inside Metal Additive Manufacturing
  • About
  • Blog
  • Contact

High-resolution digitalisation for components’ shape accuracy

16/1/2015

 
Designing (or scanning) and converting the component’s CAD model into a universal STL file is the first step towards Selective Laser Melting (SLM) of metal components. AM machines universally read STL files. To accurately reflect the geometry and complexity of the specimen without artifacts such as faceting, the conversion from CAD to STL files must be carried out with suitable resolution for a fine balance between parts' shape accuracy and convenient digital processing time.
Picture
The STL file (Standard Tessellation Standard) converts the original CAD file into a mesh of tiny triangles laid over the surfaces defined by the CAD model. The STL file simplifies the complex mathematical description of the solid surface geometry into a form that is easily and universally readable by SLM machines. The surface geometry is broken down (tessellated) into a series of logically small triangles known as facets. Each facet is described by the triangle and its perpendicular direction.
The size and number of facets (triangles) determine the accuracy of the surfaces. A mesh with large triangles will create a small STL file and produce a prototype with visible facets. A mesh with triangles the size of the material layer thickness (~20/80um range) will produce an accurate prototype. A smaller triangular mesh will increase the STL file size and require longer digital processing times (subsequent repairs, slicing,…)  without added prototype accuracy.
Picture
Picture
A triangle is by definition flat and planar. When original 3D models exhibit curvatures or apertures, error and/or deviations from the initial geometry occur. The deviation can be reduced by using small triangles (down to a practical limit). If the triangles are too small, the file size increases in line with the number of facets (triangles) required. Most CAD software offer suitable settings to output STL files displaying a balance between file size and part resolution and accuracy. However, it is worth not to rely on the default parameters in order to avoid cleaning (post-machining) the facets.
In SolidWorks, the option to refine these resolution settings is accessible when the file is saved as an STL dataset.
Picture
Picture
Picture
When saving the file as an STL extension, go into 'option' to optimise the resolution and size of your output file.

Comments are closed.
    We provide practical and actionable info dedicated to additive manufacturing of high-value metal components

    I want to know more about metal AM

    * indicates required

    Categories

    All
    Applications
    Background
    Certification
    Design
    Heat Treatment
    Laser Direct Deposition
    Materials
    Modelling
    NDE
    Parameters
    Post Processing
    Powder
    Production
    R&D
    Review
    SLM
    Surface Roughness
    Surface Treatment
    Technology

© Copyright 2014-2018 InsideMetalAdditiveManufacturing.com - All rights reserved | Privacy Policy | Terms of Service | Powered by TMS