Choose orientation, wall construction and fasteners together. Design filament parts around the real loads, assembly fit and surfaces your customer will see.
The useful unit is not simply “a layer.” The printer controls a heated flow of model material, and often a separate support material, while temperature and path planning determine how adjacent roads join.
Prepare
Build software converts the model into layers, perimeter and infill paths, support regions and machine-specific settings.
Deposit
Drive wheels feed filament into a heated liquefier and nozzle. The head lays softened thermoplastic along each XY toolpath.
Support
Breakaway or soluble material carries selected overhangs. Its contact face and removal path become part of the surface plan.
Stabilize
The deposited roads cool in the chamber. The part is released, supports are removed, and specified surfaces are finished and inspected.
This sequence follows Stratasys’ FDM process description. Tip, chamber, support system and toolpath vary by machine, so the mechanism does not create one universal property set.
FDM deposits thermoplastic roads in layers. Their connections, the chamber conditions and toolpath affect strength as well as surface quality.
A layer-built part is weakest where a load pulls layers apart (the Z direction). Orient the part so the main load runs along the layers, or design to the Z data of the material.
Every face that overhangs the plate needs supports and comes out rougher underneath. Turning the part removes the supports but changes footprint, build height and which faces sit on the plate.
Schematic illustrations; not to scale. Confirm the design for the chosen material, process and final use.
Load
Show the force direction and critical snap arms. A fixed percentage reduction across layers is not valid for every material, printer and toolpath.
Surface
Supports can leave a different texture. Specify visible faces, sealing surfaces and fitted bores before choosing the orientation.
Fit
Layer height describes a build increment, not the tolerance of every Z dimension. Holes, shrinkage and warpage still need review.
Extrusion width, layer height, perimeter count and infill work together. A nozzle diameter alone does not set all feature limits.
| Feature | Starting point | Design implication |
|---|---|---|
| Industrial FDM walls | 0.72 mm at 0.18 mm layersStratasys Direct design-guide example | The same guide lists 1.00 mm at 0.25 mm layers. These are process examples, not structural ratings for all filaments. |
| Desktop-style 0.4 mm extrusion | 0.8 mm = two nominal roads | This is a geometric illustration. Actual road width can differ from the nozzle; inspect the sliced path. |
| Non-multiple wall widths | Check variable-width and gap-fill behaviour | Modern slicers may fill widths that are not exact nozzle multiples; a 1.0 mm wall does not automatically contain a void. |
| Load-bearing shell | Specify walls and local reinforcement | Infill percentage alone cannot describe strength. A well-placed perimeter or rib may matter more than filling the entire interior. |
| Hole or pin | Review size, depth and orientation | Small horizontal holes may need support or a revised roof. Machine a critical bore to its finished fit. |
| Bridge or overhang | Trial the material and cooling settings | A 45° chamfer is a useful design candidate, not a universal support-free guarantee. |
| Small text | Make strokes resolvable in the toolpath | Put labels away from support scars and check legibility after the final finish. |
Increasing nozzle size or choosing a different tip changes the toolpath; it does not automatically double every feature minimum.
Only the inside of an FDM part is optional. The skin is always solid: perimeter roads around every wall and several solid layers top and bottom. Infill is the pattern printed between them.
| Level | Interior | Use it for |
|---|---|---|
| Default (≤20%) | Sparse diagonal lines that change direction each layer | Form, fit and handling prototypes where strength is not the question. Lightest, fastest and lowest cost. Desktop PLA prints at 20%. |
| Medium (20–50%) | A grid in every layer | Stiffer parts with some weight saving. Avoid on large volumes that see wet finishing: liquid can stay trapped in the cells and leak later. |
| Solid (50–80%) | Dense alternating roads pressed together | Strength-led parts. Behaves like a solid part, but small voids remain between roads, so FDM is not watertight as printed. |
The percentage describes the interior pattern, not the density of the whole part. A thin plate can be fully dense at Default because its solid top and bottom layers meet; a large block at Default is mostly hollow.
Select a product grade using the properties that matter in service. Heat deflection temperature is a test result, not a continuous-use temperature.
| Family | Useful starting application | Check before using |
|---|---|---|
| PLA | Form studies and display models | Heat, impact and creep in the actual environment; a stiff room-temperature model may still deform in service. |
| PETG | General enclosures and handled prototypes | Required stiffness, sustained loading, surface quality and chemical exposure. |
| ABS / ASA | Housings; ASA for weather-exposure candidates | Chamber control, distortion and the product’s weathering evidence; outdoor lifetime is not defined by the family name. |
| PA / filled PA | Tooling, wear parts and brackets | Moisture conditioning and build direction. Added fibres can increase stiffness while changing ductility and interlayer behaviour. |
| PC / PC blends | Impact- or heat-sensitive prototypes | The exact blend, printed orientation and long-term load; there is no single strongest common filament. |
| TPU | Grips, cushions and flexible features | Shore hardness, section thickness, compression set and the geometry of any lattice. |
| PEEK / PEI / PEKK | Specialist thermal or chemical requirements | Machine/material qualification and the applicable test evidence. A high-performance resin does not itself certify a printed component. |
A polymer family is the start of selection. Named products reveal printer compatibility, support route, test orientation and conditioning that a generic “ABS” or “nylon” label hides.
| Material family | Product examples | Selection direction | Performance evidence to compare |
|---|---|---|---|
| General-purpose thermoplastics | ABS-M30 ASA | Fit checks, housings and visual/handling prototypes. | Compare XY and upright tensile data, impact method, heat-deflection test load, colour and compatible support. |
| Engineering blends | PC PC-ABS | Impact-, stiffness- or heat-led functional prototypes. | Use the named blend and printed orientation; include creep, chemical exposure and the final wall geometry in the test plan. |
| Reinforced nylon | FDM Nylon 12CF | Stiff tools, brackets and fixtures where fibre direction is understood. | Review direction-specific modulus, strength and elongation. Higher stiffness does not establish better impact or layer-opening performance. |
| High-performance PEI / PEKK | ULTEM 9085 resin Antero 800NA | Qualified thermal, chemical or transportation workflows. | Match the exact printer, grade, traceability level, orientation and applicable qualification. Resin identity alone does not qualify a part. |
These are manufacturer portfolio examples, not a FabDigit stock list. Confirm the available machine/material/support combination and the evidence that ships with the order.
Use the live library to move from a thermoplastic family to its grade page and manufacturer products. These pages support comparison; the quote confirms the available machine and material combination.
20 material grades 0 manufacturer products
Explore the indexed grade and product pages here. A quote confirms the material, machine, finish and sourcing available for a specific order.
For repeated assembly, an insert or captured nut often gives a more serviceable joint than a fine thread printed directly in plastic.
Choose the insert or fastener first. Its geometry and installation method set the pilot hole, boss wall and edge distance.
Heat-set, ultrasonic, press-fit and bonded inserts are different processes. Do not apply a thermoplastic heat-set rule to cured thermoset resin.
Schematic illustrations; not to scale. Confirm the design for the chosen material, process and final use.
| Joint | Design decision | Check |
|---|---|---|
| Heat-set insert | Use the insert supplier’s pilot and boss dimensions | Add sufficient surrounding material and tool access; verify installation, pull-out and torque in the printed grade. |
| Captured nut | Provide insertion access and anti-rotation geometry | The pocket needs tolerance and load-bearing area, not a universal +0.2 mm offset. |
| Thread-forming screw | Use the screw-specific pilot recommendation | Test assembly torque and retention. Repeated disassembly may require a different joint. |
| Printed thread | Choose a coarse, accessible profile | Feasibility depends on pitch, orientation and resolution; there is no universal M10 lower limit. |
| Snap | Reduce root strain and avoid layer-opening load | Validate retention after cycling and conditioning; greater stiffness is not always better for a flexure. |
| Press fit | Test a fit coupon or machine the interface | A single interference value can split one printed material and be loose in another. |
A smaller layer step may improve appearance without solving shrinkage, hole size or flatness. Match the remedy to the feature.
Primary
Breakaway support is cut or peeled; compatible soluble support is washed out. Internal access and trapped solution matter as much as the visible overhang.
Confirm: support type, removal access, thin edges and the surface allowed to carry witness marks.
Texture
Abrasive finishing can reduce layer texture and support scars. It also rounds edges and can change text, holes and thin walls.
Confirm: media, masking, edge retention and dimensions after the complete operation.
Surface
Chemical or vapour smoothing is polymer-specific. It can close surface texture while changing gloss, edge definition and local dimensions.
Confirm: named material, validated solvent route, cavity drainage and final fit or leak testing.
Colour
Primer and paint add a film rather than colouring the full section. Adhesion depends on cleaning, surface preparation and the polymer.
Confirm: colour reference, coating build, masking, environmental exposure and acceptance sample.
It depends on tip or nozzle, layer height, extrusion width, material and span. Stratasys Direct gives 0.72 mm at 0.18 mm layers and 1.00 mm at 0.25 mm layers as industrial FDM examples; load-bearing walls need separate evaluation.
No. The actual extrusion width can differ from the nozzle, and variable-width or gap-fill toolpaths can handle other wall sizes. Check the sliced result for continuous walls rather than assuming every non-multiple contains a gap.
Default (up to 20%) unless you choose Medium (20–50%) or Solid (50–80%) in the quote. The walls and the top and bottom layers are solid at every level; infill only changes the interior.
Not exactly. Solid infill presses neighbouring roads together so the part behaves as solid, but small voids remain where roads meet. FDM parts are not watertight as printed; specify sealing if the part must hold liquid or pressure.
The difference depends on material, temperature, toolpath and test method. Use orientation-specific data for the chosen process instead of applying a universal 30–50% reduction.
The answer depends on angle, length, material and cooling. A 45° chamfer can be a useful starting geometry, but confirm support needs on the sliced part and the required underside quality.
Use a hardware-specific heat-set insert or captured nut for repeated assembly where appropriate. Direct printed threads and forming screws need a geometry and load trial; a universal pilot-hole offset is unreliable.
Confirm dimensional limits for the exact material, size, orientation and final finish. Layer height is not a tolerance; critical bores or mounting faces may need machining or a different process.
Upload your model with material, quantity, critical dimensions and visible surfaces. Confirm orientation, finishing and delivery with the quote.
