Fused Deposition Modelling (FDM)
FDM is a great technology for producing quick turnaround prints. It is used extensively in the studios as it offers a large range of material options. Low Cost FDM is often used for initial prototyping before a higher quality print is produced either on our indistrial scale FDM machines (Fortus) or using another 3D Printing technology such as Selective Laser Sintering or Polyjet. The maximum build size using FDM technology is 406 x 355 x 406 mm however due to the high accurancy and limited warping of the parts produced using FDM, multiple parts can be bonded together to produce extremely large parts.
Low Cost Plastic - With Low cost plastic we print using one of our prosumer FDM 3D Printers. Each of our studio has a selection of these available. Typical turnaround for low cost plastic is 24-48 hours but smaller parts can be produced in as little as 3 hours.
Medium Quality Plastic - For this offering we use our high end Stratasys and Fortus equipment. The parts provided are of the highest quality available from FDM printing today
ABS - Tough and strong plastic perfectly suited to functional prototypes. ABS can be vapour smoothed and finished with automotive paints.
PLA - Biodegradable polymer made from starch, print quality is high and large parts are dimensionally stable. More brittle and temperature sensitive than ABS.
BronzeFill - Metal printing on an FDM machine! Realistic bronze finish due to the metal particles, though needs polishing to bring up the shine.
PET - Food safe, tough and dimensionally stable. This material is also available in a water clear, making it perfect for electronics and lighting projects. Also available with Carbon Fiber fill for incredibly stiff prints.
A plastic filament is unwound from a coil and supplies material to a heated extrusion nozzle, much like a hot glue gun.
This nozzle is computer controlled and moves the extruder around line by line, layer by layer to build up a completed 3D print.
FDM printing is currently the most economical printing method, however produces parts with visible layer lines and limited resolution. For higher resolution printing, SLS or Polyjet is recommended.'
Q: What are the best applications for FDM and what materials can it use?
A: Fused Deposition Modeling (FDM), a form of rapid prototyping or 3D printing, builds parts layer-by-layer with engineering-grade thermoplastics. It can build complex geometries and functional parts, including prototypes, low-volume production pieces, and manufacturing aids such as jigs and fixtures. FDM thermoplastics range from general purpose materials for prototyping and end-use production to high-performance materials for medical and aerospace applications. General-purpose thermoplastics, such as ABS, ABSi, ASA, Nylon 12, and polycarbonate, have good flexural strength and exhibit high tensile and impact properties. These general purpose thermoplastics have been further enhanced to create specialty materials. Advanced FDM thermoplastics include ABS-ESD7, a conductive material which prevents static buildup; C-ISO, a polycarbonate with biocompatible properties and certifications; and ABS-M30i, a material engineered for the food and pharmaceutical packaging industries. For aerospace applications, flame retardant and chemically resistant ULTEM 9085 has been developed to work with FDM.
Q: Do shrinkage and warping present problems with FDM parts?
A: Some FDM machines add shrink rates to parts when they are made, so shrink factors do not have to be designed in. Users can also adjust the shrink values to fit specific geometries when large production runs of similar part designs are needed. FDM systems add small amounts of molten material in a heated environment, so warping is not a common problem. However, to avoid potential warping when building thin-walled sections of a model, such as deformation of vertical walls, designers might add ribs to the walls. This is similar what would be done with standard injectionmolded parts.
Q: Can engineers design FDM parts with threads?
A: Yes they can, but there are several caveats. When designing built-in threads, avoid sharp edges and include a radius on the root. Sharp edges can be stress concentrators in plastic parts. Creating ACME threads with rounded roots and crests works well with FDM. Users should ensure parts have “dog point” heads of at least 1/32 in. (0.8 mm) to make starting the threads much easier. FDM should not be used to make small threads and cannot make holes or posts smaller than 1/16 in. (1.6 mm) in diameter. An easy alternative is to use a tap or die to thread holes or posts.
Q: What is the maximum size limitation on FDM parts? And does it matter how parts are oriented during FDM construction?
A: 3D Printing Studios can FDM parts can be as large as 406 x 355 x 406 mm. (X, Y, and Z). Designers should note that extruded plastic is strongest in the tensile mode along the X-Y plane. Layers are held together by newly deposited material across the strands (one strand cools while the other is laid on top of it), so the finished part’s lowest strength is in the Z-direction for both tensile and shear modes. Overhanging nonsupported features, such as the top of a closed box, require that support material be built, which increases the time and material needed to build a part. Therefore, orientation is usually determined by the part processor. For example, half of a box-shaped casing is built with the main exterior facing down so no internal support is needed.
Q: Can all of an assembly’s parts be made at one time on an FDM machine?
A: Yes but we need to ensure enough clearance between parts to prevent them from fusing together. The guideline for clearances on assemblies is a minimum Z clearance of the slice thickness. The X/Y clearance should be at least the default extrusion width based on a suggested minimum wall thickness.
Q: Why and how do parts get sectioned?
A: Sectioning is used to: build parts too big for the build chamber by cutting parts into sections; minimize support structures; remove overhanging features from the top of parts (in their build orientation) and build them separately; prevent fragile features from damage during post processing; and to isolate fragile features from a part and build them separately. After fragile features are removed, they can be built in orientations that result in stronger parts. There are several bonding methods to reattach features and join sectionedparts. Parts may be sectioned prior to manufacturing in CAD, in prototyping software applications or by an FDM service provider.
Q: Can FDM parts be post processed?
A: FDM uses engineering-grade thermoplastics, so parts will withstand a number of post-manufacturing processes. These include machining operations such as drilling and tapping, sawing, turning, and milling. But heat builds up quickly in plastic parts, so removing material slowly and using coolant keeps parts from distorting. Other post processing operations may include smoothing, burnishing, sealing, joining, bonding, and plating.