Capability
3D printing
Additive parts for fit checks, prototypes, and low volume production, where tooling would not pay for itself.
How this works
Additive processes build a part one layer at a time from a 3D model, with no tool and no fixturing. That removes the setup cost that dominates machining and the tooling cost that dominates molding, which is why printing wins decisively at low volumes and for geometry that no subtractive process can reach.
The trade-off is that layer construction makes parts anisotropic and dimensionally less predictable than machined ones. Designing around that, rather than treating a printer as a fast mill, is what separates a usable printed part from a disappointing one.
The three processes differ in how the layer is made. FDM extrudes a bead, SLA cures liquid resin with light, and SLS fuses powder with a laser. Powder supports the part in SLS, so no support structures are needed and the geometry can be almost arbitrary.
Processes compared
| Process | How it builds | Strengths | Limits |
|---|---|---|---|
| FDM / FFF | Extrudes molten thermoplastic filament layer by layer. | Cheapest, real thermoplastics, large parts, fast turnaround. | Visible layer lines, weak across layers, needs supports over 45 degrees. |
| SLA | Cures liquid photopolymer resin with a laser or projected light, then post-cures under UV to reach specified properties. | Best surface finish and fine detail, smooth and near-isotropic within a layer. | Most resins are brittle and degrade under UV. Needs supports, and an incomplete post-cure leaves the part below spec. |
| SLS | Fuses powdered polymer with a laser in a heated bed. | Tough functional nylon parts, no supports needed, complex geometry free. | Grainy matte surface, parts are porous and dye rather than paint. |
| MJF | Jets fusing agent onto powder, then fuses with infrared energy. | Similar to SLS with faster build and more consistent mechanical properties. | Same surface and porosity characteristics as SLS. |
| DMLS / SLM | Fuses metal powder with a laser. The two are often used interchangeably, but strictly DMLS sinters a powder blend at partial melt while SLM fully melts a single-alloy powder; SLM gives higher density, DMLS a wider alloy range. | Real metal parts, topology-optimized geometry, internal channels. | Expensive, needs supports and heat treatment, requires machining on critical faces. |
Materials by process
A material is only available if a process can run it, so material and process are chosen together rather than in sequence.
| Process | Materials | Notes |
|---|---|---|
| FDM | PLA, ABS, ASA, PETG, nylon, polycarbonate, carbon-filled grades | PLA is for appearance and fit only; it softens near 60 C. Use ASA rather than ABS for anything in sunlight. |
| SLA | Standard, tough, durable, high-temperature, castable, and flexible resins | Certified biocompatible resins exist, but the certification applies to that resin printed and post-cured to the maker’s validated process. |
| SLS / MJF | Nylon 11, Nylon 12, glass-filled nylon, TPU | PA12 is the workhorse. Glass fill adds stiffness; TPU gives genuinely flexible parts. |
| DMLS | Ti-6Al-4V, AlSi10Mg, stainless 316L, 17-4PH, Inconel 718 | Parts normally need stress relief, support removal, and machining on mating faces. |
Tolerances and accuracy
Printed parts do not hold tolerance the way machined parts do. Accuracy varies with process, material, part size, and orientation in the build, because polymers shrink as they cool or cure and shrinkage accumulates over length.
- Deviation usually scales with dimension rather than being a fixed value, so large parts deviate more in absolute terms.
- The Z axis, along the build direction, is generally the least accurate and the weakest.
- Holes print undersize on powder processes and normally need reaming where a fit matters.
- Thin unsupported walls warp and large flat areas parallel to the build plate curl.
- Post-processing changes dimensions. Bead blasting, dyeing, and support removal all remove or add material.
- Do not apply a machined drawing tolerance block to a printed part. Call out the few dimensions that carry a fit, and expect those to be machined or reamed after printing.
Finishes
| Finish | Applies to | Result |
|---|---|---|
| As-printed | All | Standard. Layer lines visible on FDM and SLA, matte grain on SLS and MJF. |
| Bead blasted | SLS, MJF, DMLS | Uniform matte surface, removes loose powder. |
| Dyed | SLS, MJF | Through-color, most commonly black. Batch-to-batch variation is normal. |
| Vapour smoothed | FDM, SLS, MJF | Chemically melts the surface to a smooth, sealed finish. Reduces porosity. |
| Sanded and primed | FDM, SLA | Prepares for paint. Labor intensive but gives a near-molded appearance. |
| Painted | All polymers | Color matching to a specified reference. Usually the largest post-process cost. |
| Machined faces | DMLS, SLS | Critical mating surfaces and bores cut after printing to hold real tolerance. |
Design rules
- Give every wall a real thickness. A surface with no thickness cannot be printed.
- On FDM and SLA, overhangs beyond roughly 45 degrees from vertical need support, and supports leave marks and cost time to remove.
- Powder processes need no supports, so overhangs and internal geometry cost nothing extra.
- Strength is lower across layers than along them. Orient the part so load runs in plane, or state which direction carries load.
- On powder processes, enclosed cavities trap unsintered powder. Add escape holes.
- Engraved text usually survives better than embossed, and both need adequate depth and stroke width.
- Break up large flat areas parallel to the build plate, or orient them at an angle, to control warp.
Any downward-facing surface shallower than about 45 degrees from horizontal needs support in FDM and SLA. Support costs material, adds print time and leaves witness marks that must be finished. Orienting the part to avoid it is usually cheaper than removing it afterwards.
When to print and when to mold
Printing and molding are not competitors so much as different points on a volume curve. The question is where the crossover sits for your part.
- Print for fit checks, functional prototypes, jigs and fixtures, and geometry that cannot be molded or machined.
- Print for production only where volumes stay low, or where consolidated geometry saves more than the per-part cost.
- Mold as soon as tooling pays back across the volume, which is usually somewhere in the hundreds to low thousands.
- If a printed part is a step toward a molded one, design it with draft and uniform walls from the start so the same model carries forward.
Also available
Other capabilities
Injection molding
Production molding runs from a tool you already own or one we build for you. Quotes cover the part, the tool, and the lead time separately so you can see what you are paying for.
Injection molds and tooling
Tool design, build, and sampling. The tool type follows the part and the volume, so quotes state which configuration is proposed and why.
CNC machining
Milling and turning from metal and plastic stock, for prototypes through to production quantities.
Let’s get started on your part
Send your CAD files and target volumes. We come back with a price, a lead time, and any design notes that would reduce either.