Design Guidelines for Direct Metal Laser Melting (DMLM)
Although additive manufacturing (AM) removes many constraints of conventional manufacturing, it imposes some new constraints of its own. Always bear in mind that design for metal AM part is even tricky than plastic AM part.
Before sending your part to be manufactured by metal AM, always determine whether metal AM is a good fit for your project. In general, if a part can be manufactured on a CNC machine, it may not be commercially viable or advantageous to use metal AM.
For DMLM parts, always design with build orientation in mind. It is one of the most important key factors that will determine your part quality, surface finish and also the amount of supports needed for your part. Always avoid too much supports generation for your part, it will not only affect the surface quality but also will increase time and cost to your projects.
Below are the general design tips for DMLM part:
Minimum Feature Thickness
Many fine features such as walls and posts will lose resolution when reach the machine limitation.
Design the minimum wall thickness and post diameter of 0.5mm. It is needed to ensure walls and posts are printed accurately and no warping or distortion during printing. Unsupported wall and pin accuracy will decrease with height.
Finer structures are possible, but are dependent on build orientation, part geometry and material.
Hole Diameter
The minimum hole diameter is 0.5mm, but dependent on material, build orientation and part size.
For holes that required tight tolerances or will be threaded, it is recommended that they are printed undersize and then machined after printing.
Gap
Ensure a minimum gap of 0.5mm. Any gaps less than 0.5mm will be merged together.
Overhang
Ensure the maximum length of an overhang surface that is printed without support is 0.5mm. Any overhangs more than 0.5mm will need supports, otherwise the down-facing surface of overhang will collapse.
Bridge
The minimum allowable bridge distance for DMLM is 2mm. Bridges that more than 2mm will have poor surface quality on the downward facing surfaces and will collapse without support material.
Self Supported Angles
The rule of thumb for self supported angle is above 45 deg from the horizontal. Any angles less than 45 deg will need supports.
It’s dependent on machine process parameter and material.
Lattice Structure
Hollowing up or replacing the inner solid areas by lattice structures design can reduce the part weight. A variety of lattice structure designs can be performed by most of the advanced software that emerged in market nowadays by understanding and calculating how much the part weight reduction needed in your project.