3D Printing

The process of manufacturing prototyping parts on demand, piece by piece, and in a personalized manner through 3D printing SLS and SLA service based on the 3D drawings or creative designs provided by customers.

Prototyping and small batch production, and high flexibility, and widely used in industry, medicine, art, education and other fields.

Production Processing:

Design Drawings

Clients submit design drawings, such as STL, IGS, STEP, OBJ and other file formats; and provide detailed requirements such as size, color, surface treatment requirements, etc.

Engineering review

Renjiu professional engineers evaluate the printability of the model and determine the appropriate printing technology and materials.

3D printing parts production

Renjiu can use suitable technologies such as SLA and SLS for printing, and accurately control the operating temperature, humidity, and exposure time of the equipment; Renjiu support simultaneous multi-piece parallel printing to improve efficiency.

Support removal and preliminary cleaning

Professionals will remove the support structure and use special cleaning agents for surface cleaning.

Surface Treatment

Grinding, polishing, painting, coloring, silk screen printing, UV coating, etc.

Material customization

Composite resin materials can be developed according to product characteristics, such as flame retardant, flexible, high hardness, and impact-resistant materials.

Structural design support

Assist customers to optimize design models, adjust wall thickness, chamfers, and hole structures, and improve printing success rate and strength.

Surface customization

Special surface processing can be performed, such as sandblasting, electroplating, UV, painting, silk screen printing, etc., to improve appearance and durability.

LOGO customization

Brand logos can be reserved or laser engraved on the structure to meet brand identification and traceability management.

What We Print: SLA, SLS and FDM

We run three additive processes, and the choice between them is driven by what the part has to do — not by which one is cheapest. Each has a distinct accuracy, surface and material profile.

	SLA (resin)	SLS (nylon powder)	FDM (filament)
Tolerance	±0.1 mm	±0.1 mm	±0.2 mm
Surface	Smooth, fine detail	Even, granular	Visible layer lines
Strength	Rigid, brittle	Strong, functional	Moderate, layer-weak
Min. feature	~0.2 mm	~0.5 mm	~0.5 mm
Best for	Visual models, fit checks	Functional prototypes, small batches	Large simple parts, jigs

For material selection within each process, see our 3D printing materials page.

Tolerances, Build Size and Lead Time

Additive parts are never as accurate as machined ones, and it pays to design around that. A practical summary:

Tolerance. Plan for ±0.1 mm on SLA and SLS, looser on FDM. Where a feature must be tight, model it oversize and machine it after.
Build size. Large parts are printed in sections and bonded, or moved to a different process if the joint would be a weak point.
Lead time. A one-off part can be printed within days; SLS batches scale well because the build chamber fills with parts.
Post-processing. Support removal, sanding, dyeing, sealing and painting all add time — allow for them in the plan.

Design Rules That Save Money

Keep walls uniform. A consistent wall thickness cools evenly and avoids warp.
Respect the minimum feature for the chosen process rather than modelling detail that will not survive.
Orient for strength. Layers are the weak direction; place them away from the main load.
Use self-supporting angles. Slopes gentler than about 45° need support material that must be removed later.
Leave clearance for moving fits. Printed parts need more play than machined ones; design a test fit before committing.
Combine parts. The biggest advantage of additive is part-count reduction — a single printed bracket can replace several assembled ones.

Typical Applications

Concept and appearance models for design review
Form-and-fit prototypes before cutting metal
Functional test rigs, jigs and fixtures
Small-batch production parts where tooling cannot be justified
Custom ducting, covers and brackets with organic geometry
Patterns for casting and vacuum forming

Frequently Asked Questions

Can a printed part replace a machined one?

For fit, form and light functional duty, yes. For tight tolerances, real service loads or a specific engineering material, machining remains the better choice.

How accurate will my printed part be?

Expect roughly ±0.1 mm for SLA and SLS on well-designed features. Very small holes and thin walls are the first features to drift.

Do you provide finishing after printing?

Yes — support removal, sanding, priming, painting, dyeing and light machining of critical features are all available as follow-on operations.

What file format do you need?

STEP or STL for geometry, plus a 2D drawing where any dimension is critical. Where only a drawing exists, we can model the part first.