3D printing service for prototypes and small series

Functional prototypes, pre-series and small runs through additive manufacturing.

Professional 3D printing

Professional 3D printing is the ideal way to turn a CAD file quickly into a physical component, functional and ready for testing, validation or small production runs. Through additive technologies such as FDM, SLA, DLP and HP Multi Jet Fusion it is possible to make complex geometries, technical prototypes, cosmetic components and strong parts without the lead times and set-up costs of traditional moulds. Marca Eng. combines the speed of digital prototyping with an industrial production approach: from the choice of technology and material through to the final quality check, every stage is designed to obtain parts that are reliable, repeatable and consistent with the application requirements of the project.
3D printing is particularly suited to functional prototypes, fit tests, pre-series runs, jigs, light tooling and small customised batches, with functional validation at every step of the product.

MJF 3D printing

Technology overview — MJF 3D printing

MJF (Multi Jet Fusion) 3D printing builds the part by fusing a bed of polyamide powder layer by layer: the printheads deposit a fusing agent where the part must solidify and a detailing agent along the edges, then infrared lamps fuse the treated powder. The unfused powder supports the parts during the build, avoiding dedicated supports. Cavities and channels must allow the powder to be removed. After cooling and depowdering, the components go through the planned finishing and inspection. Build volume 380 × 284 × 380 mm, 80 µm layers, tolerances declared by HP for each material, after bead blasting, in the table below. The tolerances achievable on a given part also depend on size, geometry and orientation, and are confirmed when the project is reviewed. It is the technology for functional prototypes, small and medium batches, and parts that have to work, not just be looked at.

Tolerances declared by HP, in mm, after bead blasting, Cpk 1.33
Material	0–30 mm		30–50 mm		50–80 mm
Material	XY	Z	XY	Z	XY	Z
PA12 S and PA12 Black	±0.25	±0.42	±0.30	±0.50	±0.37	±0.60
PA12	±0.25	±0.42	±0.30	±0.50	±0.37	±0.60
PA12 W	±0.20	±0.42	±0.25	±0.50	±0.30	±0.67
PA11	±0.27	±0.45	±0.33	±0.60	±0.40	±0.99
PA12 FR	±0.20	±0.42	±0.25	±0.50	±0.30	±0.60
PA12 Glass Beads	±0.31	±0.43	±0.35	±0.71	±0.39	±1.16
PP	±0.45	±0.90	±0.50	±1.30	±0.60	±1.40

PA12 Glass Beads and PP are printed on HP Jet Fusion 5200, the others on HP Jet Fusion 5600.

FDM 3D printing

Technology overview — FDM 3D printing

Large-format industrial FDM 3D printing is ideal for functional prototypes, technical parts, assembly jigs, production fixtures and large custom pieces. High-performance thermoplastics make parts robust enough for real use, cutting time and cost compared with moulds or conventional machining. Build volume up to 914 × 610 × 914 mm in industrial FDM.

SLA 3D printing

Technology overview — SLA 3D printing

Stereolithography builds the part by curing a liquid resin with an ultraviolet laser that traces the perimeter and fills the sections. It suits fine detail and high-quality surfaces; the result depends on machine, resin, orientation and finishing. Build volume up to 600 × 600 × 500 mm.

Resins available: a versatile one for aesthetic and functional prototypes, a transparent one with a glass-like look, and a tough one for when mechanical strength and thermoplastic-like behaviour are needed.

What holds for DLP holds here too: these are photopolymer resins, not thermoplastics. The part grows on supports that leave a mark to be finished off, it has to be post-cured to reach its stated properties, and it must be protected from ultraviolet light if it stays outdoors. The advantage of SLA is the surface: when how the part looks and feels is what matters, this is the right route.

DLP / LCD 3D printing

Technology overview — DLP / LCD 3D printing

Whole-layer photopolymerisation (DLP / LCD) cures a photopolymer resin by exposing the entire layer to light at once, either with a projector (DLP) or through an LCD mask. That is the difference from stereolithography, where a laser traces the outline point by point: exposing the entire layer, build time depends on the height of the part and not on how much area it takes up. The result is fine detail and a surface finish that filament and powder technologies do not reach. Build volume up to 330 × 185 × 400 mm, in-plane resolution down to 43 µm, adjustable layer thickness. Minimum walls, holes and details depend on resin, geometry and orientation, and are checked against the project.

Resins available: an elastomer, a general-purpose one, a tough one, one for high temperatures, a dissipative one, one with documented biological testing, a structural one, a ceramic-filled one and a silicone. The figures in the panel below are those declared by the material manufacturers.

A photopolymer resin is not a thermoplastic. Some imitate its mechanical behaviour closely — stiffness, impact resistance, elongation — but they age differently and must be protected from ultraviolet light if the part is meant for outdoor use. DLP can also produce end-use components, using a resin qualified for the application. If the specific thermoplastic grade intended for injection moulding has to be validated, a compatible tooling route is assessed. An MJF component allows geometric and functional checks, but does not automatically reproduce the material and behaviour of an injection-moulded part.

What to keep in mind. DLP works within contained build volumes: it is the technology for small and medium parts where detail and finish matter, not for bulky ones. The part grows hanging from supports that have to be removed, and the attachment point leaves a mark to be finished off. After printing a post-cure is needed: that is what brings the resin to its stated properties, and a part that has not been post-cured does not have them. For sustained loads, high temperatures or outdoor exposure the right resin has to be chosen — and in some cases it is better to change technology.