Frequently Asked Questions (FAQ) about Rapid Prototyping

Rapid prototyping pulls together additive and subtractive processes to accelerate learning: form, fit, and functional validation before you lock designs and invest in production tooling. This FAQ is organized for three roles—procurement, product design, and mechanical engineering—so you can quickly find the answers you need and move a project forward.

Quick snapshot: common prototyping processes and what they’re good at ?

Procurement FAQs

1) Which certifications matter for prototyping suppliers in regulated sectors?

Sector-specific quality systems improve consistency and traceability, even at the prototype stage. 

Common frameworks include ISO 9001 (general QMS), AS9100 for aerospace, ISO 13485 for medical devices, IATF 16949 for automotive, and ISO 14001 for environmental management. 

When you need aerospace-level documentation, vendors operating under AS9100 typically run stronger configuration control and FAIR workflows; for medical devices, ISO 13485 helps ensure controlled materials and records. Aerospace programs frequently reference First Article Inspection (FAI) per the 2023 revision of SAE AS9102.

2) What inspection documentation should we ask for—and when?

Use inspection progressively, matching program risk. Early prototypes benefit from basic dimensional checks on critical features, while full FAI/FAIR is warranted for the first conforming part that sets your baseline. 

In aerospace, FAI/FAIR follows AS9102’s three-form structure—part accountability, materials/processes, and characteristic measurements—and you should request it before flight tests when traceability is required; reference the AS9102 framework via SAE’s AS9102 (2023) guidance. 

3) What inputs produce an accurate quote—and how do we specify inspection?

Accurate quotes rely on complete data. Upload a neutral 3D CAD file (STEP/IGES recommended; STL for additive) and attach a 2D drawing for dimensions, GD&T, threads, inserts, and surface requirements. Configure the RFQ with process, material, quantity, finish, and inspection level. 

4) How do lead times vary by process, and what reliably speeds them up?

Lead time depends on geometry, queue, material availability, finishing, inspection, and shipping. 

Additive (SLA/SLS/MJF/FDM) often turns parts in days to a week for straightforward builds. 

CNC and sheet metal span days to a couple of weeks; complex setups and tight tolerances extend time. 

Urethane casting usually requires one to two weeks once the master is approved. 

Prototype injection molding adds weeks for tooling, followed by faster iterations once the mold is cut. To accelerate delivery, simplify geometries, loosen non-critical tolerances, select stocked materials, limit cosmetic steps, and align inspection scope to risk.

5) How should we handle IP protection and export-controlled data?

For sensitive work, combine contractual and technical controls. Execute NDAs with export-control clauses that define data classification and access limits. Use secure portals or SFTP, encrypt files at rest and in transit, minimize retention, and require documented destruction or return. For defense work, select vendors that align with CMMC/NIST 800‑171 and ITAR handling.

Product Designer FAQs

6) Which process should I choose for form/fit vs. cosmetic models vs. functional tests?

Form/fit checks often start with FDM and SLS/MJF for quick, robust parts; if you need crisper edges and smooth surfaces, move to SLA/DLP. 

Cosmetic models favor SLA/DLP for smooth, paint-ready finishes, while urethane casting replicates a polished master and offers color/texture options for short runs. 

Functional tests lean on CNC in metal or engineering plastics for loads and heat; SLS/MJF produces durable nylon parts; metal PBF enables complex metal geometries before machining critical faces. A staged approach is common: early FDM mock-up → SLA cosmetic model → SLS/MJF or CNC for functional testing → urethane casting for short runs → prototype injection molding to validate resin behavior and draft.

7) What surface finish and color options can I expect—and what post-processing helps?

For polymers, SLA yields smooth, paint-ready surfaces; SLS/MJF are matte/grainy but improve with bead blasting and tumbling; FDM shows layer lines and benefits from sanding, priming, or solvent smoothing where applicable. 

For metals, metal PBF surfaces are rough as-built and typically need heat treatment, HIP, and machining for cosmetics and precision, while CNC can deliver polished or brushed finishes depending on operations. Urethane casting and injection molding reproduce master/tool surfaces, so specify texture and color in the master or RFQ.

8) What DFM constraints should I respect early to avoid rework?

Keep prototypes moldable and machinable even if you’re printing first. Provide draft on features that may be molded and keep wall thickness uniform. Avoid knife edges and ultra-thin walls; if a thin local feature is essential, plan secondary machining or inserts. Maintain realistic hole sizes for tapping or reaming and specify threads and tolerances on the drawing. For sheet metal, respect bend radii and hole-to-edge distances and plan reliefs. For quantitative guidance.

Mechanical Engineer FAQs

9) What tolerances are realistic—and when should I plan secondary machining?

CNC typically achieves thousandths-of-an-inch control on many features, with tighter local control via reaming and grinding. Additive processes exhibit orientation- and geometry-dependent variation; for precision bores or sealing faces, print oversize and finish by CNC. 

Sheet metal bends and hole positions follow process-specific tolerances and benefit from drawings with datums and critical dimensions. Casting and molding parts are influenced by resin shrink and tool steel accuracy; validate with samples and measurement, and machine critical fits when required.

10) How should I communicate GD&T and critical features so they’re inspected correctly?

Put GD&T callouts on a 2D drawing and define datums consistent with fixturing and function. Identify critical-to-quality features and specify sampling or 100% inspection where needed. Note threads, inserts, and surface roughness targets explicitly. For practical drawing preparation, and when you submit the RFQ, configure inspection expectations.

11) How do I plan materials for heat, chemicals, and structural loads in prototypes?

Select metals such as aluminum for speed and weight, moving to stainless or tool steels for heat and chemical resistance; for complex metal geometries, consider metal PBF with post-machining. 

In plastics, nylon (PA) from SLS/MJF offers toughness, ABS/PC blends from FDM deliver robust fixtures, and SLA resins vary widely in heat deflection and brittleness—choose per datasheet and test.

For elastomers, urethane casting covers a broad durometer range; verify long-term stability if parts face heat or chemicals. Where uncertainty remains, run a small test matrix and document results before pilot runs.

Bridging prototypes to production

12) What’s a practical path from first builds to pilot runs and soft/production tooling?

A staged plan reduces risk and cost while building confidence. Print early geometry for quick feedback (FDM/SLA), then validate functional load paths and assembly with SLS/MJF or CNC. Use urethane casting for short runs to exercise assembly and logistics. Cut soft tooling or prototype injection molds to validate draft, gates, vents, and resin behavior. 

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