Quality You Can Measure: Inside Unionfab's End-to-End Inspection Capabilities

When sourcing parts from an overseas manufacturer, the fundamental question isn't just "can they make it?" — it's "can they prove it meets spec?" Lead time and unit price matter, but they're secondary to the confidence that parts will pass your incoming inspection, assembly line, or field validation the first time.

At Unionfab, quality control is not a checkbox at the end of the line. It is a structured, process-driven system built on 20+ years of industrial manufacturing experience inherited from our parent company, Uniontech — a world-class innovator in 3D printing equipment, material and software R&D. Whether you're ordering rapid prototypes or NPI bridge production, every order goes through a defined inspection workflow before it ships.

This article breaks down exactly what that looks like: which checks are performed on every order by default, which can be requested at no charge, and which advanced metrology services are available as paid add-ons for projects with tighter tolerances or compliance requirements.

Our Quality Philosophy: Delivery Certainty

Unionfab operates on a core principle we call delivery certainty — the commitment that what we quote is what we deliver, on time and to specification. This is operationalized through three practices:

• Early-stage DFM review: Our engineering sales team conducts Design for Manufacturability analysis before an order is confirmed, catching geometric, tolerance, and material compatibility issues at the source.

• In-process quality gates: Key dimensions and process parameters are monitored during production, not just at final inspection.

• Digital QC report with every shipment: A structured inspection record accompanies each order, giving you traceable evidence of what was checked and what results were recorded.

The inspection capabilities below are the backbone of this system.

3D Printing Inspection Capabilities

Standard Inspections — Included by Default (Free)

Every 3D printed order receives the following checks before dispatch, at no additional cost:

XYZ Dimensional Inspection

Overall bounding dimensions are verified against drawing or file specifications. This confirms that the part has not warped, shrunk beyond tolerance, or been produced on incorrect scale settings.

Appearance & Surface Quality Inspection

A comprehensive visual inspection covering: burrs, scratches, impact marks, deformation, color inconsistency, and surface roughness (Ra/Rz). For SLA parts in particular, we assess resin cure uniformity and surface finish consistency against the specified post-processing level.

Surface Defect Detail Inspection

Targeted review of additive-specific surface artifacts including: layer line visibility, sink marks, blistering or swelling, and support witness marks. This inspection is performed against Unionfab's internal acceptance criteria and any customer-specified cosmetic standards.

On-Request Inspections — Available at No Charge

The following checks are not applied by default but can be requested at no additional cost. Specify your requirement at time of order or through your project engineer.

Assembly Fit & Clearance Inspection

Verification of mating interfaces against a reference component or assembly drawing: fit clearances, insertion/extraction force (where applicable), and fastener torque-locking force for threaded features.

Thread & Fastener Inspection

Go/no-go gauge verification of threaded features (internal and external). Confirms thread form, pitch, and depth against specification. Particularly relevant for 3D printed metal parts where thread quality can be affected by build orientation.

Seal Integrity Test

Applicable to enclosed or hollow parts where fluid or gas retention is required. Performed via pressure decay or submersion method. Requested in advance and facilitated through our supplier network.

Post Heat Treatment Hardness Inspection

For metal 3D printed parts undergoing stress relief, HIP, or age hardening, hardness verification (HRC/HRB/Vickers as appropriate) confirms the heat treatment cycle achieved the intended material properties. Supplier-generated test certification is required.

Advanced Metrology — Paid Add-On Services

For parts where standard visual and dimensional checks are insufficient — such as functional prototypes, regulatory submissions, or flight/medical hardware — Unionfab offers the following advanced inspection services. All are performed by certified technicians using calibrated equipment. Pricing is available on request; all services below are paid.

Mechanical Properties Testing (Full Suite) Comprehensive characterization of printed material performance, including:

• Room Temperature Tensile Test: Yield strength, ultimate tensile strength, elongation at break, per standard test coupon geometry

• Low Temperature Tensile Test: Performed at -196°C (liquid nitrogen) — relevant for cryogenic application qualification

• High Temperature Tensile Test: Available across multiple temperature bands:

  • 300°C – 650°C

  • 651°C – 800°C

  • 801°C – 900°C

  • 901°C – 1000°C

  • 1001°C – 1100°C

• Hardness Test: Includes sample preparation and measurement (HRC, Vickers, or Brinell as specified)

• Metallographic & Grain Size Analysis: Cross-sectional mount preparation, etching, and microstructural examination; grain size per ASTM E112 or equivalent

All mechanical tests are performed per batch with dedicated test coupons printed alongside your production parts (coupon design per agreement).

Density / Porosity Measurement (Archimedes Method)

Relative density measurement for metal SLA/SLM parts, applicable across all alloy grades. Critical for applications where internal porosity affects fatigue life, pressure tightness, or structural integrity.

Radiographic Inspection (X-Ray)

Non-destructive internal defect detection. Available in two formats:

• Standard film / small format: Suitable for small-section components

• Large format: For larger cross-sections or multi-part panels

Detects: voids, cracks, un-fused regions, inclusions, and significant porosity. Report includes film/image archive and written evaluation.

CMM Dimensional Inspection (GD&T)

Full geometric dimensioning and tolerancing verification using a Coordinate Measuring Machine:

• Small parts (≤200mm): Linear dimensions, bore diameters, thread verification, perpendicularity, parallelism, and coaxiality per drawing GD&T callouts

• Medium parts (400–600mm): Same scope, extended envelope

CMM inspection generates a dimensioned report with nominal vs. actual values and pass/fail status per feature.

3D Scanning Full-surface deviation analysis using structured light or laser scanning:

• Small parts (≤200mm): Full surface scan with color deviation map against nominal CAD

• Medium parts (400–600mm): Same scope, extended fixture setup

3D scan reports provide a visual deviation map overlaid on the CAD model, alongside quantitative analysis of maximum deviation, Cpk (where sample size permits), and feature-level GD&T callout comparison.

CNC Machining Inspection Capabilities

CNC machined parts are held to tighter absolute tolerances by default and carry a correspondingly more comprehensive standard inspection suite.

Standard Inspections — Included by Default (Free)

Full Dimensional & GD&T Inspection

All linear dimensions, bore diameters, thread specifications, and geometric tolerances (perpendicularity, parallelism, coaxiality, etc.) are inspected per drawing GD&T callouts. This is a 100% inspection of all print-specified features as a default, not a sampling-based check.

High-Precision Form Tolerance Inspection

Dedicated verification of tight form tolerances: roundness, cylindricity, and flatness — measured using appropriate gauging (roundness testers, granite surface plate, indicators) calibrated to the tolerance band on drawing.

Machined Surface Quality Inspection

Assessment of all machined surfaces for: tool marks and chatter, thermal burn indicators (grinding burn, heat discoloration), vibration patterns, and chamfer/radius consistency.

Critical-Feature In-Process Dimensional Monitoring

For features where rework is not possible after a subsequent operation (e.g., deep bores, undercuts, press-fit diameters), real-time dimensional feedback is recorded during CNC operation and logged as part of the job traveler.

Burr & Sharp Edge Inspection

Post-machining verification that all edges have been deburred to specification: burr height limits, chamfer dimensions, and edge-break consistency across production quantities.

Thread & Fastener Inspection

Go/no-go thread gauging on all tapped or threaded features — standard on CNC as a default inspection step.

Appearance & Surface Quality Inspection

Final cosmetic review covering: scratches, handling damage, surface roughness Ra/Rz, dimensional distortion, and coating adhesion where surface treatments have been applied.

Internal Defect Inspection

For metal machined parts, inspection for sub-surface discontinuities: porosity, cracks, cold shuts, inclusions, and un-fused material. Method depends on geometry and material; specified at quoting stage.

On-Request Inspections — Available at No Charge

Post Heat Treatment Hardness Inspection

For machined parts undergoing case hardening, through hardening, nitriding, or other thermal processes, hardness verification confirms the treatment outcome. Supplier test certification required.

Advanced Metrology — Paid Add-On Services

3D Scanning (GD&T Overlay)

Same capability as described for 3D printing above. Particularly useful for complex machined surfaces (sculptured forms, contoured datums) where CMM point sampling is insufficient to characterize surface conformance.

• Small parts (≤200mm): Full surface scan, deviation map, GD&T comparison

• Medium parts (400–600mm): Extended setup, same deliverables

All paid add-on services for machining are priced on request.

Digital QC Report

Every Unionfab shipment is accompanied by a digital inspection report. Depending on the inspection scope agreed at order placement, this includes:

• Part identification (order number, material, process, revision)

• Inspection method and equipment reference

• Nominal vs. measured values for all checked features

• Pass/fail status per feature

• Inspector sign-off and inspection date

• Material compliance documentation where applicable (e.g., RoHS declaration, material cert)

Reports are delivered in PDF format alongside the shipment notification, and are accessible via the Unionfab customer portal for the duration of your account history.

How to Specify Your Inspection Requirements

For standard parts: Default inspections are applied automatically. No action required.

For optional free inspections: Indicate required checks in your order notes or communicate directly to your project engineer at time of quoting.

For paid metrology services: Request during the quoting stage. Our engineering team will confirm scope, sampling plan, coupon requirements (for mechanical testing), and lead time impact before order confirmation.

For compliance or regulated applications: Contact us with your applicable standard (e.g., AS9100, ISO 13485, IATF 16949 traceability requirements) before placing an order. We will advise on which inspection services align with your documentation requirements.

Summary: Inspection Scope by Service Type

Have a project with specific inspection or compliance requirements? Reach out to our engineering team — we'll review your drawings and advise on the right QC scope before you commit to an order.