FDM Prototypes
Fused Deposition Modeling
Produces cost effective, strong, functional prototpyes.
ABOUT FDM PROTOTYPES
FDM (Fused Deposition Modeling) is also known as FFF or Fused Filament Fabrication. It is a material extrusion method of additive manufacturing (AM) process.
FDM produces cost effective, exceptionally strong, functional parts using production-grade thermoplastics. FDM parts are durable, dimensionally accurate and stable making them ideal for ‘form, fit, and function’ testing. FDM parts can withstand rigorous testing and won’t shrink, warp or absorb moisture.
Typical FDM uses are concept or engineering models, functional testing prototypes, manufacturing tools such as jigs or fixtures, prototypes which require secondary processes such as drilling, tapping, or threading and low volume manufacturing.
THE FDM PROCESS
An FDM printer uses a polymer-based filament fed through an extruder that heats, melts, and extrudes the plastic through a thin nozzle.
The extruder and nozzle form the print head, which moves along the build plate to draw every layer, one after another. It follows a set of instruction from a specific file which, in simple terms, contains a sliced version of a 3D model.
Each “slice” corresponds to a unique layer. The taller the object, the more slices there will be – amounting to a longer print time. As the print head deposits the filament, the plastic melts onto the previous layer and then hardens.
FDM is a less expensive process, works well with a wide variety of plastics and can incorporate carbon fiber and other composites. Materials include ABS plastic, PLA polymer plastic, nylon, TPU, HDPE and more.
FDM® is a registered trademark of Stratasys Ltd.
CATEGORIES OF FDM 3D PRINTING
FDM has two distinct categories: Prototype (desktop) FDM and Industrial FDM. These are the capabilites of both categories:
Industrial FDM:
Maximum build size: 10″ x 10″ x 12″ (254 x 254 x 305 mm)
Dimensional Accuracy:
X/Y Planes: ±0.005″ for the first inch, plus ± 0.002″ for every inch thereafter.
Z Plane: ± 0.010″ for the first inch, plus ± 0.002″ for every inch thereafter.
Layer Height: 0.010″ ( 0.254 mm) or 0.013″ (0.330 mm)
Infill: Solid
Prototyping FDM:
Maximum build size: 10″ x 10″ x 10″ (254 x 254 x 254 mm)
Dimensional accuracy: ± 0.5% with a lower limit on ± 0.012″ (± 0.3 mm)
Layer Height: 0.0031″ (0.08 mm) to 0.0079″ (0.20 mm)
Infill: Solid
FDM Prototype Specification Guidelines
Outlined below are the options which need to be specified when ordering an FDM prototype. This includes materials, resolutions, and finishing.
Industrial FDM Materials:
ABS+ (Acrylonitrile butadiene styrene)
A true production-grade thermoplastic that is durable enough to perform virtually the same as production parts.
Heat resistance - High toughness - High impact resistance - Sturdy & durable
Prototyping FDM Materials:
ASA (Acrylonitrile Styrene Acrylate)
Highly durable material that offers exceptional UV, weather, mechanical, and thermal resistance. Its unique combination of properties makes it ideal for outdoor models and structural parts that have long-term exposure to challenging outdoor conditions.
PETG (Polyethylene Terephthalate Glycol)
Superior resistance to water, UV, and temperatures. Tougher and more durable than PLA, with high temperature resistance, it the perfect choice for printing outdoor items. Additionally, it's ideal for outdoor items that require long-term exposure and the ability to withstand impacts.
PLA (Polylactic Acid)
Derived from renewable resources like corn starch, PLA is considered an environmentally friendly alternative to plastics. Decent tensile strength and impact strength make it suitable for prototypes, decorative items, and low-stress applications.
TPU - 95A (Thermoplastic Polyurethane)
TPU offers impact resistance, flexibility, and cold-temperature resilience. Exceptionally soft and flexible with extraordinary impact resistance, enabling parts to withstand impact, collision, and falling.
Material Options
Thermoplastic Resin
Industrial FDM Build Resolutions :
Standard Resolution
0.010" (0.254 mm) Layers
Low Resolution
0.013" (0.3302 mm) Layers
Prototyping FDM Build Resolutions:
Extra Fine Resolution
0.0031" (0.08 mm) Layers
Fine Resolution
0.0047" (0.12 mm) Layers
Standard Resolution
0.0063" (0.16 mm) Layers
Low Resolution
0.0079" (0.20 mm) Layers
Build Resolution Options
Industrial FDM Finishing Options
Standard
All supports are removed and part is as printed.
Primed
All supports are removed.
Stair stepping (layers lines) are NOT removed.
Primer is applied for a ready to paint surface. Unless otherwise requested, only the outer surfaces are primed.
Quick Paint
All supports are removed.
Stair stepping (layers lines) are NOT removed.
Paint is applied as per customer supplies PMS color number. If a multi-color model is required, a JPEG file or document depicting the paint scheme is preferred.
Presentation
All supports are removed.
Part is sanded to remove stair stepping (layers lines).
Paint is applied as per customer supplies PMS color number. If a multi-color model is required, a JPEG file or document depicting the paint scheme is preferred.
Prototyping FDM Finishing Option:
Standard
All supports are removed and part is as printed.
Finishing Options
FDM
Design
Considerations
When designing a part to be generated using FDM technology, build process should be considered.
FDM extrudes thin layers of molten thermoplastic layer by layer until a part is completed.
Since FDM produces parts with specific characteristics and capabilities different from those of other prototyping technologies, they have increasingly been used as a tool for producing manufactured products.
Bosses and Ribs
FDM parts can often be solid rather than a hollowed out design supported by bosses and ribs. This can reduce build time and use less support material. It is not necessary to reduce wall thickness of a boss, rib or gusset in FDM parts. This will increase the amount of stress the feature can withstand.
Draft Angle
Since FDM is an additive process, draft is not required.
Fastening Hardware
Recommend utilizing a cap screw or a flanged cap screw. The flat surface eliminates multi-directional stresses from cracking the part. Washers can also be used to spread the load over the largest possible surface area. Lock nuts, embedded nuts, or metal inserts are all stronger fastening options than adding threads to the FDM plastic.
Fillets
Although fillets are not necessary in FDM parts, they can be used to reduce stress concentrations and increase the overall strength of the part. Design fillets with an outer radius equal to the inner radius plus the wall thickness to maintain consistent thickness.
Holes
Holes (those in bosses as well) on an FDM part are generally undersized. When tight tolerances are required, holes should be drilled or reamed to ensure the diameter is accurate.
Orientation vs. Strength
Designers should note that extruded plastic has its strongest strength in the tensile mode along the x-y plane. Since the layers are held together by “hot flow” across the strands (one stand is cooling while the other is laid upont it), the lowest strength is in the Z-axis for both tensile and shear modes.
Shrinkage
The FDM process adds shrink rates to the part when processed, so shrink factors do not have to be designed into the part.
Text
Minimum suggested text size on the top or bottom build plane is 16 point boldface. Minimum suggested size on vertical walls is 10 point boldface.
Threads
When designing built-in threads, avoid sharp edges and include a radius on the root. Sharp edges can have the effect of concentrating stress in plastic parts. Creating an ACME thread design with rounded roots and crests has been found to work well when using FDM. Also, use a “dog point” head of at least 1/32 in. (0.08 mm). This dog point design makes starting the thread much easier. Small threads produced by FDM are not recommended and not possible for hole or posts smaller than a 1/16 in. (1.6 mm) diameter. An easy alternative is to use a tap or die to thread holes or posts.
Undercuts
Since FDM is an additive process, undercut for design features such as O-ring grooves are not an issue.
Wall Thickness
Minimum wall thickness for FDM parts varies depending upon the slice thickness that will be used to build the part.
Single Contour Width:
0.010″ (0.25 mm) slice thickness = 0.020″ (0.50 mm) minimum wall
0.013″ (0.33 mm) slice thickness = 0.026″ (0.66 mm) minimum wall
Note: building multiple layers while using the minimum contour width will cause the feature to be brittle. Warping may occur if there are large extents of minimum-thickness, vertical walls without support features like ribs or a support material tower.
Stratasys encourages the use of the recommended minmum wall thickness (below), which will eliminate brittleness.
General Recommendation:
0.010″ (0.25 mm) slice thickness = 0.040″ (1.02 mm) minimum wall
0.013″ (0.33 mm) slice thickness = 0.052″ (1.32 mm) minimum wall
Warp
To avoid potential warping (deformation of vertical walls) when building thin-walled sections of a model, designers might chose to add ribs to the walls (similar to what would be done with standard injection molding processes).
Secondary Operations
Since the FDM processes uses engineering-grade thermoplastics, the parts produced are capable of withstanding a number of post-manufacturing processes, including machining operations such as drilling and tapping, sawing, turning, and milling. Other post processing operations may include smoothing, burnishing, sealing, joining, bonding, and plating.
INDUSTRIAL FDM - Prototype Quote Request
You will receive an e-mail confirming receipt of your request.
Files up to 20MB may be sent via e-mail to: Sales@Versadyne.net
Prototyping FDM - Prototype Quote Request
You will receive an e-mail confirming receipt of your request.
Files up to 20MB may be sent via e-mail to: Sales@Versadyne.net
