SLS Nylon 3D Printing Guide: Design, Tolerances, Finishing and RFQ

Selective laser sintering, usually called SLS, is a powder-bed 3D printing process widely used for functional nylon prototypes and low-volume plastic parts. It can build complex geometry without conventional support structures, making it attractive for housings, ducts, brackets, snap fits, clips, mechanisms, customized products and assemblies that would be difficult or expensive to machine or mold.

However, “print it in nylon” is not a complete manufacturing specification. Material grade, wall thickness, trapped powder, feature clearance, orientation, surface finish, conditioning and inspection all influence the result. A design that looks valid in CAD may contain inaccessible powder cavities, fragile details, distorted panels or tolerances that require secondary machining.

This guide explains how SLS nylon printing works, how to design reliable parts, what affects dimensional accuracy and surface quality, which finishing options are available and what buyers should include in an RFQ.

Quick Answer: When Should You Choose SLS Nylon?

Choose SLS nylon when you need functional plastic parts with complex geometry, no dedicated mold and greater durability than many appearance-focused photopolymer prints. It is particularly useful when the design includes internal channels, integrated hinges, organic forms, nested components, short production runs or frequent revisions.

SLS may not be the best choice when you need optical transparency, a very smooth as-molded cosmetic surface, extremely tight unmachined tolerances, certified injection-molded material behavior or high-volume economics that justify production tooling.

A successful project begins by matching the process to the actual requirement rather than selecting SLS only because the CAD model is printable.

What Is SLS 3D Printing?

SLS is a polymer powder-bed fusion process. A machine spreads a thin layer of powder across a heated build area. A laser selectively fuses the cross-section of each part. The platform then moves, another powder layer is spread and the sequence repeats until the complete build is finished.

The surrounding unfused powder supports overhangs and internal geometry during printing. This is the main reason SLS can produce shapes that would need extensive supports in filament or resin printing.

A typical workflow includes:

1. Review CAD, drawing, material, quantity and finish requirements.

2. Repair or confirm a watertight 3D model.

3. Orient and nest parts within the build volume.

4. Prepare, blend and load the qualified powder.

5. Preheat the build and fuse each layer with the laser.

6. Cool the complete powder cake under controlled conditions.

7. Excavate parts and recover unfused powder.

8. Remove residual powder by brushing and blasting.

9. Apply dye, smoothing, sealing, machining or other finishing.

10. Inspect, label and package the parts.

Printing is only one stage. Cooling, depowdering, finishing and inspection can determine both lead time and final quality.

Why SLS Does Not Need Conventional Support Structures

In SLS, the powder surrounding a part acts as a temporary support. A bridge, overhang or internal passage does not normally require a separately generated support scaffold attached to the component.

This creates several design advantages:

• Fewer support-removal marks.

• Greater freedom for undercuts and organic shapes.

• Ability to nest separate parts in three dimensions.

• Potential to print moving or interlocking assemblies in one build.

• Access to internal channels that would be difficult to machine.

• Less orientation constraint than processes that attach parts to a platform.

Support-free does not mean rule-free. Heat distribution, powder removal, wall stiffness, feature size, spacing and orientation still matter. A closed cavity full of unfused powder remains full unless the design provides an escape path.

SLS, MJF, FDM and SLA: Key Differences

These processes overlap, but they should not be treated as interchangeable.

SLS and MJF both make powder-bed nylon parts and share many design rules, but their energy input, agents, thermal management, surface appearance and qualified materials differ. Do not assume a drawing approved for one process will give identical results in the other.

Common SLS Nylon Materials

PA12 Nylon

PA12 is the most widely requested SLS material. It offers a useful balance of strength, toughness, dimensional behavior, chemical resistance and process maturity. Typical applications include housings, brackets, clips, ducts, jigs, covers and end-use low-volume components.

The exact properties depend on the powder system, machine, build parameters, orientation, refresh strategy and conditioning. Ask for the supplier’s current data sheet when mechanical performance matters.

PA11 Nylon

PA11 is often selected when higher ductility, impact behavior or flexibility is desired. It can be useful for clips, protective components and parts expected to deform without brittle failure. Its behavior is not simply “better PA12”; compare the specific grade and application requirements.

Glass-Filled or Mineral-Filled Nylon

Filled nylon can increase stiffness, temperature performance or dimensional stability for selected geometries. The tradeoffs may include reduced ductility, different surface texture, greater brittleness in thin features and different finishing behavior.

Use the full material designation. “Glass-filled nylon” does not identify filler percentage, base polymer or qualified property values.

Flexible Powder Materials

Some powder-bed systems process TPU or other elastomeric materials. Flexible parts require careful definition of hardness, wall thickness, compression behavior and trapped-powder access. A thick TPU wall can feel much stiffer than a thin wall made from the same material.

Flame-Retardant and Specialty Grades

Specialty powders may offer flame, electrostatic, chemical, food-contact or other characteristics. A material family name does not prove compliance. Request the exact documentation, test standard, thickness and color that apply to the supplied grade.

Material Properties: Use Data Carefully

Published values are normally generated from standardized test specimens under defined build, orientation and conditioning conditions. A thin snap hook, lattice or hollow duct does not automatically achieve the same result.

For engineering decisions, confirm:

• Exact powder trade name and revision.

• Whether values are typical or minimum guaranteed values.

• Test-specimen orientation.

• Dry or conditioned state.

• Build and refresh conditions.

• Color and finishing influence.

• Temperature and environmental exposure.

• Whether the supplier provides lot traceability.

Nylon absorbs moisture from the environment. Moisture can change dimensions, flexibility, toughness and stiffness. Inspection and functional testing should reflect the intended service condition.

Design for the Process, Not Only the CAD Model

SLS permits geometry that is difficult for conventional production, but manufacturability still depends on load, scale and feature interaction. A robust design considers how the part will print, cool, be found in the powder cake, be depowdered, finished, measured and used.

The design review should identify:

• Critical load paths.

• Thin walls and isolated pins.

• Long flat or curved panels.

• Enclosed spaces and channels.

• Areas that trap powder or blasting media.

• Mating and moving features.

• Cosmetic faces.

• Sealing or fluid-contact surfaces.

• Threads and hardware.

• Dimensions needing secondary machining.

• Post-processing access.

Avoid applying one generic minimum feature size to the entire part. A short supported rib behaves differently from a long free-standing wall of equal thickness.

Wall Thickness Guidelines

Minimum printable wall thickness depends on material, wall height, shape, orientation and handling. A supplier may be able to build a thin coupon that is too fragile for a tall enclosure or shipping environment.

Use these principles:

• Increase thickness as wall height and unsupported span increase.

• Add curvature, ribs or flanges to stiffen large panels.

• Avoid sudden transitions from thin flexible walls to heavy rigid masses.

• Review thin edges after blasting and tumbling, which can round or weaken them.

• Consider the force needed during depowdering and assembly.

• Define functional stiffness rather than requesting the thinnest printable wall.

A thin wall may print but fail during cleaning. A thicker wall may survive handling but warp because of uneven mass. The right value is application-specific.

Solid Sections, Heavy Masses and Thermal Behavior

Very thick solid regions use more powder, retain heat differently and increase cost. They can also cool differently from surrounding thin geometry, contributing to distortion.

Where full material is not required:

• Hollow large volumes.

• Use ribs or lattice structures for stiffness.

• Maintain gradual transitions.

• Provide generous powder-escape openings.

• Avoid tiny internal passages that cannot be cleaned.

Do not hollow a load-bearing part automatically. Review compression, impact, fastening and environmental requirements. A hollow form may need internal structure and inspection access.

Hollow Parts and Powder-Escape Holes

An enclosed cavity will contain loose powder after printing. To remove it, provide openings that are large enough, correctly positioned and accessible to cleaning tools and airflow.

Consider:

• At least two openings can improve flow through a cavity.

• Place holes so gravity and compressed air can move powder out.

• Avoid dead-end pockets behind internal ribs.

• Ensure channels do not narrow below a cleanable section.

• Account for the powder’s tendency to pack in long or curved passages.

• Decide whether escape holes remain open, receive plugs or are hidden in assembly.

• Include the holes in the controlled CAD model.

A cavity may appear connected in CAD but still be impossible to clean completely. For medical, food, pneumatic, optical or contamination-sensitive applications, trapped powder risk needs special review.

Internal Channels and Ducts

SLS can produce curved internal channels that subtractive machining cannot reach. The limiting issue is often not printing but powder removal and verification.

For internal flow paths:

• Use smooth transitions rather than abrupt constrictions.

• Provide access from both ends where possible.

• Avoid long small-diameter passages with no cleaning line of sight.

• Consider sectioning a prototype to confirm internal cleanliness.

• Specify leak, pressure-drop or flow testing if relevant.

• Review whether surface roughness affects fluid performance.

• Add machining allowance at precision ports and sealing interfaces.

For regulated or high-purity systems, do not assume an enclosed SLS channel can be certified clean without a defined cleaning and validation method.

Holes, Pins and Small Features

Small holes may print undersize or retain powder. Small pins and thin blades are vulnerable to handling and finishing damage.

Improve reliability by:

• Increasing hole diameter where function permits.

• Using a teardrop or accessible shape for difficult horizontal passages when appropriate.

• Adding a machining allowance for precision bores.

• Reaming or drilling holes that control bearings, dowels or seals.

• Increasing pin diameter and adding a base fillet.

• Avoiding long unsupported slender features.

• Protecting fragile details with surrounding geometry during shipping.

State which holes may be drilled after printing. A supplier should not silently machine nominally printed features without reflecting the operation in the quotation and inspection plan.

Ribs, Bosses and Fillets

Ribs can stiffen a wall without creating a completely solid mass. Bosses support screws, inserts and alignment features.

Design guidance includes:

• Blend ribs and bosses with fillets to reduce local stress.

• Avoid extremely thin tall ribs that can chip during cleaning.

• Connect isolated bosses to nearby structure when loads are significant.

• Provide enough material around heat-set or press-fit inserts.

• Consider tool access for insert installation.

• Avoid heavy boss intersections that distort a thin cosmetic wall.

• Use gussets when load transfer matters.

Unlike injection molding, SLS ribs are not primarily governed by sink marks opposite a thick rib. Thermal mass and distortion still matter, so balanced geometry remains valuable.

Clearance for Moving and Interlocking Assemblies

SLS can build chains, hinges, ball joints and nested mechanisms in one build, but separate bodies need adequate gaps. If clearance is too small, partially fused powder can join the surfaces or prevent powder removal.

Clearance depends on:

• Length and area of facing surfaces.

• Orientation in the build.

• Powder and machine system.

• Required motion.

• Accessibility for cleaning.

• Finishing that removes or adds material.

Ask the supplier for a process-specific clearance recommendation. Increase gaps for large mating areas, deep internal joints and parts that must move freely without manual break-in.

For a critical mechanism, consider printing a clearance test coupon or separate first iteration before committing to a large batch.

Fit Between Separately Printed Parts

CAD parts with identical nominal dimensions will not create a reliable slip fit. Include functional clearance and define the fit objective.

Consider:

• Build variation on both mating parts.

• Surface texture at the interface.

• Dye, coating or smoothing thickness.

• Moisture conditioning of nylon.

• Part flexibility during assembly.

• Whether components are built together or in different batches.

Use assembly tests or gauges for important fits. If the interface must repeat tightly, machine critical faces or use inserts rather than tightening the as-printed tolerance everywhere.

Snap Fits and Flexible Features

Nylon’s toughness makes SLS useful for snap hooks and clips, but performance depends on geometry, material, orientation and conditioning.

Design a snap fit with:

• A controlled flexible beam length.

• A generous root radius.

• A lead-in face for assembly.

• A retention face suited to release or permanent locking.

• Strain consistent with the selected material.

• Clearance for the beam to deflect.

• Protection against accidental overtravel.

• A realistic number of assembly cycles.

Test the complete mating assembly. A snap that works once in a dry new print may behave differently after moisture conditioning, temperature exposure or repeated use.

Living Hinges

SLS nylon can form thin flexible hinge regions, but it should not automatically be treated like an injection-molded polypropylene living hinge. Material, layer structure, surface texture and geometry differ.

If a hinge is needed:

• Identify required cycles and bend angle.

• Use a smooth transition into the hinge.

• Avoid notches and sharp corners.

• Review hinge direction relative to the build.

• Test dry and conditioned parts.

• Consider a mechanical pin hinge for demanding service.

A prototype hinge may be useful for concept evaluation even when the production design will use another material or process.

Threads and Fasteners

Large coarse threads can sometimes be printed, but small precision threads are better tapped or formed with an insert.

Options include:

• Print a pilot hole and tap it after printing.

• Install a heat-set threaded insert.

• Use a press-in or bonded insert designed for plastic.

• Capture a nut in a printed pocket.

• Print a large service thread and verify with the mating component.

Specify thread standard, engagement length, torque, pull-out load and cycle requirement. Provide insert part numbers and installation drawings. Ensure the boss has enough wall thickness and access for the selected installation tool.

Text, Logos and Surface Detail

Raised and recessed text can be printed, but legibility depends on character size, stroke width, depth, orientation and finish.

For clear markings:

• Use a simple font with adequate stroke width.

• Increase size for recessed text on rough surfaces.

• Avoid shallow details that disappear during tumbling or coating.

• Place identification where blasting can reach it.

• Use raised cavity or part numbers when traceability matters.

• Confirm whether dye contrast is sufficient.

For very small permanent marks, laser marking, printing or an applied label may be more controllable than integral geometry.

Lattices and Topology-Optimized Geometry

Lattices can reduce weight, tune flexibility and create energy-absorbing structures. Their performance depends on cell type, strut size, connection quality and cleaning access.

Before using a lattice:

• Define the load case and failure mode.

• Confirm minimum strut size with the supplier.

• Avoid closed regions that trap powder.

• Add inspection coupons if mechanical properties are important.

• Consider how dye and blasting reach internal surfaces.

• Decide whether CAD or implicit geometry can be transferred reliably.

• Verify file size and mesh integrity before quotation.

An attractive generative design is not automatically manufacturable or inspectable. Validate representative parts under the actual loading condition.

Build Orientation and Part Nesting

Because SLS does not use attached supports, orientation is flexible, but it still affects dimensions, surface texture, thermal behavior, mechanical response and packing density.

The supplier may orient parts to balance:

• Dimensional accuracy of critical faces.

• Surface appearance.

• Warpage risk.

• Mechanical load direction.

• Powder removal.

• Build height and time.

• Number of parts per build.

• Consistency across the order.

Tell the supplier which surfaces and load directions matter. Do not prescribe an arbitrary orientation unless it has been validated; the service provider may have machine-specific data that supports a better choice.

For repeat orders, record whether orientation and build location must remain controlled.

Dimensional Accuracy and Tolerances

SLS accuracy is affected by machine calibration, powder condition, scan strategy, geometry, orientation, build position, thermal history, cooling, depowdering and moisture. A single universal tolerance cannot describe every part.

Large overall dimensions accumulate more variation than small local features. Long thin panels can warp. Holes and internal corners may not reproduce the CAD exactly. Soft or flexible geometry can also move during measurement.

Use a tolerance strategy:

1. Identify dimensions that control assembly or function.

2. Apply realistic general tolerances to noncritical geometry.

3. Define datums that can be measured repeatably.

4. Add machining stock on critical interfaces.

5. Use gauges or assembly tests for flexible features.

6. Agree on conditioning time and inspection temperature.

7. Review first articles before approving a larger batch.

Requesting tight tolerances on every dimension increases cost without necessarily improving function.

Warpage and Distortion

Warping can occur when a part cools unevenly or contains large unsupported spans, abrupt mass changes or unbalanced geometry.

Risk increases with:

• Long flat panels.

• Thin walls with heavy bosses on one side.

• Sharp thickness transitions.

• Large open frames with low stiffness.

• Asymmetric cross-sections.

• Closely packed thermal masses.

• Aggressive cooling or early excavation.

Reduce risk with curvature, ribs, balanced sections, gradual transitions and realistic flatness requirements. The service provider may adjust orientation, nesting or cooling, but design geometry remains a major factor.

If flatness is critical, add a machining or fixture plan. Mechanical straightening can create residual stress and should not be assumed without agreement.

Surface Finish of SLS Nylon

Fresh SLS nylon has a fine granular texture. Surface character varies with powder, machine, orientation and cleaning. It is not equivalent to a polished injection mold or SLA appearance.

The standard finish usually includes powder removal and bead blasting. Additional finishes can change color, texture, dimensions, sealing behavior and edge definition.

Before selecting a finish, identify the real objective:

• Uniform color.

• Lower surface roughness.

• Better cleanability.

• Reduced porosity or fluid absorption.

• Cosmetic presentation.

• UV or chemical protection.

• Friction control.

• Paint adhesion.

Ask for samples made with the same material and finish rather than approving from a digital image alone.

Standard Depowdering and Bead Blasting

After cooling, parts are excavated from the powder cake. Loose powder is brushed and blasted away. This standard process leaves a matte, slightly textured surface.

Complex parts may need manual cleaning of holes and channels. State cleanliness requirements and identify surfaces that must not be damaged by aggressive blasting.

Residual powder can remain in blind pockets, lattice structures and narrow passages. Weight checks, borescope inspection, airflow or sectioning may be appropriate for critical internal geometry.

Dyeing

Dyeing adds color by penetrating the nylon surface. It is common for black and other colors because it preserves detail better than a thick paint film.

Color can vary with material, surface density, batch, prior finishing and geometry. Dye may appear different on polished versus standard surfaces. Define whether parts from separate orders must match when assembled side by side.

Dyeing does not make a porous part automatically waterproof or UV stable. Request a separate sealing or performance review when those functions matter.

Tumbling and Mechanical Smoothing

Tumbling can reduce the grainy feel and soften layer-related texture. It also rounds sharp edges and can remove fine details.

Review:

• Minimum wall and feature robustness.

• Protection of threads and precision surfaces.

• Allowance for material removal.

• Effect on text and logos.

• Ability of media to enter and exit cavities.

• Risk of media becoming trapped.

Fragile clips, thin fins and delicate lattices may not be suitable for bulk tumbling.

Chemical or Vapor Smoothing

Qualified smoothing processes can create a more uniform, sealed-looking surface and improve cleanability. The result depends on polymer, equipment and geometry.

Smoothing may round features, alter dimensions, change gloss and affect fit. Internal surfaces may receive a different degree of treatment from accessible external faces.

For functional programs, test chemical resistance, friction, sealing, color and mechanical performance after the complete finishing cycle.

Sealing, Painting and Coating

SLS nylon can be sealed, primed and painted for improved appearance or reduced fluid absorption. Coatings introduce thickness and may crack when a flexible feature bends.

Specify:

• Color reference and gloss.

• Cosmetic viewing standard.

• Masked surfaces.

• Maximum coating thickness at fits.

• Adhesion or cross-hatch requirement.

• Chemical, UV or abrasion exposure.

• Flexing zones that must remain uncoated.

• Repair and touch-up rules.

Provide a physical color standard for color-critical work. Screen colors and uncalibrated photographs are not sufficient manufacturing references.

Secondary Machining

Machining is useful for sealing faces, bearing bores, datum pads, precise holes and threads. The printed part must include enough stock and a way to locate and hold it.

During design:

• Identify machined features on the drawing.

• Add controlled machining allowance.

• Create robust locating datums.

• Avoid clamping a thin flexible wall.

• Plan chip and coolant cleaning.

• Define whether dimensions apply before or after conditioning.

• Inspect the finished feature relative to functional datums.

Machining one critical interface is often more economical than demanding an unrealistic as-printed tolerance across the whole component.

Inserts and Assembly

Threaded inserts, bushings, magnets, pins and other hardware can be installed after printing. The joining method may use heat, ultrasonic energy, pressing, adhesive or mechanical capture.

Confirm:

• Insert manufacturer and part number.

• Hole preparation.

• Installation direction and tool access.

• Pull-out and torque requirements.

• Maximum local temperature.

• Electrical or corrosion considerations.

• Inspection and replacement method.

For press fits, nylon flexibility and moisture conditioning can influence retention. Validate the complete assembly rather than relying only on nominal CAD interference.

Watertightness and Air Tightness

Standard SLS parts should not automatically be assumed watertight or airtight. Surface-connected porosity, thin walls, internal powder and post-processing all influence leakage.

If a part carries fluid or pressure:

• State the medium, temperature and pressure.

• Define allowable leakage and test duration.

• Identify sealing faces and ports.

• Increase wall thickness where needed.

• Consider sealing or coating.

• Machine gasket and O-ring interfaces.

• Test representative production parts.

A part that holds water briefly may still fail a long-duration gas test. Specify the actual acceptance method.

Mechanical Performance and Anisotropy

SLS nylon can provide useful functional performance, but build orientation and process history can influence strength, elongation and fatigue. The degree of directionality depends on the qualified material and process.

For load-bearing parts:

• Share the load direction and magnitude.

• Use generous radii at stress concentrations.

• Avoid sharp internal notches.

• Consider orientation during build planning.

• Test representative finished parts.

• Account for temperature, moisture and aging.

• Use safety factors appropriate to the application.

Do not use a generic website tensile value as the sole basis for a safety-critical design.

Common SLS Nylon Defects and Corrective Actions

Treat this table as a troubleshooting starting point. Confirm the actual cause before changing CAD or processing.

Inspection and Quality Control

A practical SLS quality plan can include:

• CAD and drawing revision control.

• Material grade and batch traceability.

• Build identification and date.

• Visual inspection for damage, incomplete fusion and finish.

• Dimensional inspection of critical characteristics.

• Part weight where it helps detect trapped powder or missing material.

• Thread, insert and assembly checks.

• Dye or color comparison.

• Flatness or profile checks with defined restraint.

• Leak, flow, load or functional testing.

• Packaging inspection for fragile features.

Flexible or freeform parts require a clear inspection setup. Define whether the part is measured free-state, supported or assembled to a fixture.

First Article and Batch Approval

For a new design, order a small first batch before committing to a larger quantity. Use it to verify fit, strength, powder removal, finish and inspection method.

Record:

• Approved CAD and drawing revision.

• Material and finishing route.

• Build orientation if controlled.

• Critical measurement results.

• Assembly and functional findings.

• Approved color or texture sample.

• Deviations and corrective actions.

If the supplier changes machine type, powder system, production site or major finishing process, risk-based requalification may be appropriate.

Cost Drivers in SLS Nylon Printing

SLS pricing is not based only on part weight. Major cost drivers include:

• Bounding-box volume and nesting efficiency.

• Actual material volume.

• Build height.

• Quantity and scheduling.

• Manual depowdering difficulty.

• Fragile features and handling risk.

• Trapped-powder complexity.

• Dyeing, smoothing, sealing or painting.

• Secondary machining and inserts.

• Inspection, reports and testing.

• Packaging and traceability.

Because multiple customer parts may share a build, a supplier can sometimes offer better pricing when delivery is flexible. Urgent orders may require a dedicated or less efficiently packed build.

How to Reduce SLS Part Cost

• Hollow unnecessary solid volumes and add cleanable escape holes.

• Remove nonfunctional material.

• Avoid an oversized bounding box caused by one long feature.

• Consolidate an assembly only when it remains cleanable and serviceable.

• Use standard finish for internal prototypes.

• Machine only critical interfaces.

• Apply tight tolerances only where function requires them.

• Design repeated parts for efficient nesting.

• Protect fragile details to reduce scrap.

• Combine quantities when color and finish should match.

Do not reduce cost by creating a hollow cavity that cannot be depowdered. The apparent material saving may create rejection, contamination or extra labor.

SLS Nylon vs Injection Molding

SLS avoids dedicated tooling and supports rapid revisions, making it useful for prototypes, bridge production, customization and uncertain demand. Injection molding typically provides better economics at high volume, broader production-resin options, smoother repeatable surfaces and faster cycle-based output after tooling is complete.

Choose SLS when:

• Quantity is low or changing.

• Geometry benefits from additive manufacturing.

• Delivery is needed before tooling.

• Each part may be customized.

• Design revisions remain likely.

Choose injection molding when:

• Demand justifies tooling.

• The exact molded resin is required.

• Surface, cycle time and unit cost dominate.

• Long-term repeatability is needed at scale.

• Production validation must reflect the molded process.

SLS can also validate geometry before injection-mold tooling, but remember that SLS nylon and molded production resin may differ in surface, anisotropy, moisture response and feature behavior.

SLS Nylon vs CNC Machining

CNC machining is valuable for tight-tolerance interfaces, stock engineering plastics and parts with simple accessible geometry. SLS offers internal complexity, part consolidation and low setup cost for irregular forms.

Choose CNC when:

• Exact stock-material properties are essential.

• Tight tolerances and smooth machined surfaces dominate.

• Geometry is accessible to cutting tools.

• Low porosity is required without sealing.

Choose SLS when:

• Internal channels or organic forms are central.

• Many different parts share one order.

• Tool access would be difficult.

• A lightweight lattice or nested assembly adds value.

Hybrid production is often effective: print the complex body, then machine important holes, datums and sealing faces.

Files to Send for an SLS Quotation

Provide a complete package:

1. STEP or another suitable 3D CAD format.

2. STL or 3MF only when the mesh is intentional and checked.

3. Dimensioned 2D drawing with revision.

4. Quantity now and forecast quantity later.

5. Exact material or performance requirements.

6. Color and surface-finish specification.

7. Critical dimensions and datums.

8. Mating parts or assembly model.

9. Load, temperature, chemical and environmental conditions.

10. Thread, insert and secondary-operation details.

11. Leak, flow, strength or functional tests.

12. Inspection reports, certificates and traceability requirements.

13. Packaging and shipping destination.

14. Required delivery date.

For a broader comparison of additive options, review Aluprototype’s 3D printing services. If production-like molded appearance is more important than exact nylon behavior, our vacuum casting guide explains another low-volume route.

Questions to Ask an SLS Supplier

• Which exact nylon grade and machine system will you use?

• Can you provide a current material data sheet?

• How are powder refresh and material traceability controlled?

• What design rules apply to this specific geometry?

• Which dimensions require machining?

• How will internal powder be removed and verified?

• Will build orientation be controlled for repeat orders?

• Which finish samples can you provide?

• How does dyeing or smoothing affect dimensions?

• What first-article inspection is included?

• Can you install and test inserts?

• How will fragile parts be packaged?

• What changes require customer notification?

Specific answers are more useful than a generic claim of “high precision.”

SLS Nylon RFQ Checklist

Before sending the order, confirm:

• The CAD model is watertight and at the correct scale.

• Units are stated explicitly.

• Material grade is selected or performance needs are defined.

• Wall thickness suits feature height and load.

• Hollow parts have cleanable escape openings.

• Internal channels have a powder-removal plan.

• Moving assemblies include sufficient clearance.

• Critical holes and faces are marked for machining if needed.

• Cosmetic surfaces and finish are identified.

• Dye, paint, sealing or smoothing is specified.

• Threads and inserts include standards and loads.

• Inspection datums and critical tolerances are defined.

• Functional tests and conditioning are agreed.

• Quantity, packaging and delivery are clear.

Frequently Asked Questions

Is SLS nylon the same as injection-molded nylon?

No. The base polymer may be related, but powder-bed processing, thermal history, porosity, surface texture and directional behavior differ from injection molding. Use process-specific data and test representative parts.

Does SLS require support structures?

The surrounding powder supports the part, so attached support scaffolds are normally unnecessary. The design still needs adequate walls, clearances, thermal balance and powder-removal access.

Can SLS print moving assemblies in one piece?

Yes, if separate bodies have sufficient clearance and powder can be removed from the joint. Large facing areas and inaccessible mechanisms need greater care. Validate a representative sample.

Are SLS nylon parts waterproof?

Not automatically. Standard parts can have surface-connected porosity. Wall thickness, geometry and finishing influence leakage. Specify the fluid, pressure, duration and acceptance test; sealing may be required.

Can SLS nylon be dyed black?

Yes, black dye is a common finish. Color and penetration can vary with material, surface and batch. Use an approved physical sample when matching matters.

Can SLS parts be painted?

Yes. Sealing and priming are normally needed for a uniform cosmetic result. Define color, gloss, masking, adhesion and coating thickness at mating features.

What tolerance can SLS hold?

There is no single tolerance for every part. Size, geometry, orientation, material, thermal history, finishing and conditioning all matter. Ask the supplier to review the specific drawing and machine critical interfaces when necessary.

Can internal powder be removed from any channel?

No. Long, narrow, curved and dead-end channels may retain powder. Provide adequate openings and cleaning access, and define a verification method for critical passages.

Can threads be printed in SLS nylon?

Large coarse threads may be printable, but small or load-bearing threads are more reliable when tapped or fitted with inserts. State torque, pull-out and cycle requirements.

Does build orientation affect strength?

It can. The degree depends on material and qualified process. Share load directions with the supplier and test representative finished parts for critical use.

Is PA12 or PA11 better?

Neither is universally better. PA12 is widely used for balanced functional parts, while PA11 may be preferred for greater ductility or impact behavior. Compare the exact grade, environment and test requirement.

Can SLS be used for production parts?

Yes, especially for low-volume, customized or complex components. Production use requires controlled material, build, finishing, inspection, change management and application-specific validation.

Request an SLS Nylon 3D Printing Review

Aluprototype supports SLS, MJF, SLA and FDM prototyping, along with CNC machining, vacuum casting and injection molding for later production stages. Send your CAD model, drawing, quantity, preferred nylon, finish, critical dimensions and test requirements through our request-a-quote page.

We can review wall thickness, powder escape, moving clearances, orientation, finishing and inspection before production, helping you receive functional parts that match the real purpose of the design rather than merely reproducing its visible shape.