Design Guidelines

Stereolithography (SLA):

Accuracy:

• SLA accuracy is approximately ±0.2 mm. Accuracy will vary, depending on build parameters, part geometry and size, part orientation and post-processing method.

Dimensions:

• Maximum build size is 1498 x 762 x 558 mm (59 x 30 x 22 in)
• The layer resolution ranges from 25 to 100 microns, depending on the settings specified.  Unless otherwise specified, we will print all SLA parts at (HD) 50 microns.
• Minimum wall thickness should be at least 1 mm (0.039 inches) for unsupported walls, and 0.7 mm (0.024 inches) for supported walls.
• Embossed details must be raised at least 0.1 mm (0.004 inches)
• Debossed details should have a width, depth, and height of at least 0.4mm (0.0157 inches).
• When designing parts that fit together, keep in mind that surfaces may grow by ±0.127 mm (0.005 inches).
• Holes should be at least 0.5 mm in diameter (0.02 inches)
• Clearance for moving parts, hinges, joints, etc, is 0.3mm on all sides.

Support:

• Hollow sections will be automatically be filled with support material – a drain hole of at least 1 inch (25.4mm) in size must be included to avoid damage to the part as uncured resin expands. If it’s not possible to put a hole that large into the enclosure, multiple smaller holes must be placed (one to allow the material out, one to allow the air in).

Powder Bed Fusion (Includes SLS & MJF)

Accuracy:

• Accuracy is approximately ±0.25%, with a lower limit of ±0.25 mm.
• Orientation and placement can greatly affect part tolerances.

Dimensions:

• Maximum build size is 650 x 300 x 560 mm (25.6 x 11.8 x 22 inches)
• (Minimum wall thickness is 1 mm (0.039 inches)
• Embossed or debossed details should have a depth, width and height of at least 0.7 mm (0.028)
• Holes should be at least 1.5 mm (0.059 inches) in diameter
• Clearance for moving parts, hinges, joints, etc, is 0.5mm on all sides.

Support:

• Hollow sections will be automatically be filled with support material – drain holes of at least 25.4 mm (1 inch) in size must be included to allow powder to drain

Surface Finish

• Parts are bead blasted to remove all powder, which leaves a consistent overall texture.

Direct Metal Laser Sintering (DMLS)

Overview

Direct Metal Laser Sintering (DMLS) is an additive manufacturing process which selectively scans a cross section of a CAD model and fuses fine metal powder layer by layer with a high powered laser. Typically metal parts are subtracted from a solid metal block with a CNC machine to create a designed part, whereas DSLM has the ability to create very complex geometries such as long and narrow channels, custom internal contours, fastening features, etc that would be difficult to achieve with a CNC machine. Items and geometries which require strict flatness are not a good fit for this process.

• Maximum Build Volume: 250 x 250 x 300 mm
• Layer Height: 30 microns

Accuracy & Tolerance:

• Forge Labs will manufacture the product from the model to the specifications listed. If your parts require specific tolerances, please include an engineering drawing along with the part. Metal parts can be supplied 'as-built' or finished using various post processing and finishing techniques. Depending on the material used, there are various forms of finishing available.
• Accuracy is approximately ±0.3%, with a lower limit of ±0.3 mm. This is geometry dependant and my not be possible to achieve for all parts. Orientation and placement can greatly affect part tolerances. If part tolerances are critical, please inquire.

Wall Thickness:

• Supported walls connected to two or more sides and thick enough to support the model require a minimum thickness of 1 mm. We recommend a thickness of at least 1.5mm for downfacing surfaces that require support.

Pins:

• Minimum Diameter: 1.5mm

Minimum Detail size:

• Engraved details are much less legible, so be sure to compensate with larger thickness and depth than would be acceptable for protruding letters. Forge Labs recommends using a 3-5 degree draft when extruding text as the extra taper from the draft can help in preserving delicate details.
• Embossed details are raised features on your model. We require a  thickness of 1 mm & depth of 0.5 mm
• Fonts should have at least 0.7mm line thickness and 0.5mm depth. A minimum font size of 14 is suitable for every direction. Bold Sans serif font is recommended.

Part Clearances:

• Clearance is the distance between two moving parts on a model. We require a minimum of 0.5mm

Hinges:

• Hinges, similar to clearances, is the minimum allowed gap between a bush and a bolt. While the minimum recommended distance for hinges is 0.3mm, we recommend that parts have a minimum distance of 0.5-0.6mm to ensure there is no bonding of the hinge parts.

Threads:

• Threads can be sintered directly into parts spending on the size of the thread and print orientation. Threaded sections will be printed vertically and should have sufficient clearance to allow a tap or die to be used. Smaller threads should be left to be Drilled and tapped rather than CAD designed.

Holes:

• Depending on print orientation, hole diameters between 6mm - 10mm can be printed without supports, while in the horizontal orientation, holes greater than 10mm require support structures.
• Holes with a diameter between 0.5mm - 6mm can be printed without support.
• Holes printed on a vertical plane larger than 10mm diameter require support. 
• Minimum hole size is 1mm

Gaps:

• A maximum gap depth of 0.2" or 5mm is preferred, especially If support material is required for removal. Generally you can request certain gaps oriented along the xy-plane to ensure resolution is maintained on those features.

Escape Holes:

• Hollow walls and enclosures will be filled with support material, and must be designed with escape holes so that the support can be dissolved and removed during cleaning. A diameter of 4mm is required.

Support Structures:

DMLS 3D printed parts use both a bed of metal powder for support but also physical supports. These physical support structures are required for: 

1. 1. Anchoring the part to the build plate
   2. Reducing or eliminating warping
   3. Supporting overhanging geometry 

• Overhanging Surfaces - The minimum angle where support material is not required on an overhanging surface is 45º relative to the horizontal in most cases. 
• Unsupported Edges - The maximum length of a cantilever-style overhanging surface is 0.5 mm. An overhanging horizontal surface supported on both ends can be 1 mm long. These rules will apply to embossed and engraved features with unsupported surfaces as well.

Fillets:

• To avoid support material on overhanging geometries, design fillets or chamfers on corners and features to make them self-supporting.
• Fillets can be used to reduce stress concentrations and increase the strength of your part. When designing fillet features, try to design the outer radius equal to the inner radius + the wall thickness to maintain part accuracy.

Surface Finish

• Roughness values of 200 to 400 µin Ra, depending on material and resolution.

PolyJet Matrix Technology:

Accuracy:

• PolyJet accuracy is approximately ± 0.127 mm (± 0.005 in.), or ± 0.0015 mm/mm (± 0.002 in/in), whichever is greater. The larger the part is the looser the tolerance – if you need a specific tolerance on a part, please ask

Dimensions

• Maximum build size is 490 x 389 x  200 mm (19.3 x 15.35 x 7.9 inches).
• The layer resolution ranges from 16 to 28 microns, depending on the settings specified. Standard layer height is 28 microns unless otherwise stated.
• Minimum recommended wall thickness is 1 mm (0.039 inches). Thicknesses that are achievable in the real world depend on the design of the part, and walls built to the minimum thickness may be fragile when cleaned and finished.
• Embossed or debossed details should have a depth, height, and width of at least 0.5 mm (0.02 inches).
• Extruded text should have a draft of 5 degrees, to minimize breakages during cleaning
• Pins and holes have a minimum size of 1mm diameter (0.039 inches). Deep holes are harder to clean and may have support residue remaining after cleaning. Pins that are longer than they are wide are still fragile and may break during cleaning
• Clearance for moving parts, hinges, joints, etc, is 0.3mm – 0.4mm on all sides.

Support:

• PolyJet parts are printed with a support material that is mechanically removed with a high pressure water jet after printing.  Hollow sections will be automatically be filled with support material – large holes must be included in the 3D model to allow this is to be removed.

Surface finish:

• There are two surface finishes available – glossy and matte.  By default, surfaces in contact with support material will print matte, whereas any surface facing upwards can print either matte or glossy.  Additional smoothing can be achieved through manual finishing.
• VeroClear prints translucent, but it can be made optically clear by polishing after printing. The matte finish is recommended to prevent yellowing. Small features and detailed internal cavities that can’t be polished by hand may appear cloudy and translucent, rather than completely clear.

• Other guidelines:
  • 3D models cannot have overlapping geometry, incorrectly oriented normals, or ‘holes’ in the surface – they must be water-tight.