Design guidelines are show minimum dimensions, or necessary constraints in design in order for the design to be manufactured and also for post processing .
Every manufacturing / designing process has a set of guidelines which are expected to be followed to ensure product quality , customer satisfaction and manufacturability.
In Additive manufacturing too, we have design guidelines that the designers follow in order to prevent failure in models and ensure the customers get a product According to their desire.
The design guidelines are made taking a lot of factors into consideration , such that when we start to manufacture the part we will have a seemless experience.
Design guidelines apply to :
- Minimum wall Thickness
- Overhang Angle
- Support Structures
- Finishing And Post processing Operations
FDM Design Guidelines
Fused Deposition Modelling is a Additive Manufacturing technique where molten material is deposited over each subsequent layer to form the shape of the final product that is required. Most cases FDM uses thermoplastics as the working material since they can be easily melted and Solidified.
Because FDM produces parts with specific characteristics and capabilities different from those of other prototyping processes, the systems have become increasingly used as a tool for producing manufactured products.
Let us have a closer look into what these guidelines are and how you can apply these to have a perfect 3D printing experience.
Design Considerations For Great Printing
1. Wall Thickness
Minimum wall thickness for FDM parts varies depending upon the slice thickness that will be used to build the part.
Supported wall: 0.8 mm
Unsupported wall: 0.8mm
In FDM method generally holes are made fractionally smaller , and in times of tight tolerancing , its better to manufacture the part without a hole and later drill the hole into it .
Ideal Hole Diameter : 2mm
When designing built-in threads, avoid sharp edges and include a radius on the root. Sharp edges can be stress concentrators in plastic parts and lead to failure. Therefore care must be taken in such cases.
Threads made using FDM methods are not recommended
Must be used to decrease stress concentration between surfaces so that failure is reduced.
In case there are Sharp corners and edges in the part design , the chances of the part failing at these regions is higher since stress concentration in these areas will be high.
TO avoid such mishaps , it is advised to have filleted edges and corners in the design.
FDM can print fillets with radius as low as 1mm
5.Bosses & Ribs
It is not necessary to reduce wall thickness of a boss, rib, or gusset in FDM parts.
Generally bosses can be the same size as the part thickness or up to 0.5 mm less. It is also essential to use gussets or ribs to support the bosses in parts printed using FDM. This will increase the amount of stress the feature can withstand .
Since FDM uses heated environment much care need not be given in this aspect , but while designing thin walls , ribs are to be provided to give structural intergrity and avoid warping of surfaces.
Maximum Unsupported Inclination : 45 Degrees
For Extrusions which are at an angle greater than 45 degrees it is necessary to have support structures .
Care must be taken for support to be provided in the design , otherwise , it will result in print failure.
8 . Maximum Tolerance
Tolerance range for FDM ranges from: -0.5mm to +0.5mm
9. Post Processing
Parts manufactured by Additive Manufacturing methods can be subjected to various machine operations like drilling , milling , shaping etc.
The heat produced can melt the part so care must be taken to keep the part cool by supplying coolant .
Other post processing operations may include smoothing, burnishing, sealing, joining, bonding, and plating.
10. Emossed & Engraved Details
0.6mm wide, 2mm high
Designing will be much easier and printing will be hassle free , if the above mentioned guidelines are followed .