Quality Assurance
Rigorous in-process and final inspection with profile projectors, digital measuring systems, and full dimensional traceability. First-article inspection reports available on request.
Our Quality Philosophy
Quality is not a post-process inspection step — it is built into every stage of production. From first-article verification through volume production, Sze Loi maintains rigorous in-process and final inspection protocols that catch and prevent defects before they reach the customer.
Our quality system is built on statistical process control (SPC), with continuous monitoring of machine performance and dimensional trends. As variation approaches specification limits, we adjust and re-verify machine setup to prevent defects. For ultra-tight tolerances parts, 100% full inspection is a standard practice, to ensure no nonconforming parts leave our facility. This disciplined approach drives consistent, zero-defect delivery trusted by all of our customers that has earned us reputations and repeated businesses.
Inspection Equipment
Sze Loi's quality laboratory is equipped with precision instruments covering dimensional, geometric, and surface-finish verification.
Profile Projector
(Optical Comparator)
Contour and profile verification against scaled engineering drawings. Used for complex geometries and dimensional profiles where traditional calipers cannot reach.
Digital Measuring System
(PC-based)
Automated dimensional data recording and SPC trending. Multi-axis coordinate verification linked to quality management system for batch traceability.
Stereomicroscope
Visual Inspection
Surface quality and finish assessment. Burr detection, edge-break verification, and visual inspection for scratches, dents, or contamination.
Electronic Vernier Calipers
Dimension Measurement
Linear dimension measurement on parts. Digital display with 0.01mm resolution for quick in-process and final verification.
Electronic Micrometers
Precision Diameter/Thickness
High-precision diameter and thickness measurement. Digital display with 0.001mm resolution for tight tolerance verification on critical features.
Gauge Sets
Go/No-Go Acceptance
Block, ring, plug, pin, and thread gauges for go/no-go functional acceptance testing. Certified to ISO 1938 standards.
Quality Assurance Process
Drawing Review
Verify all geometric and dimensional requirements before first set-up.
First Article Inspection
100% dimensional verification on initial sample before volume production.
In-Process QC
Periodic sampling and SPC monitoring during production run.
Final Inspection
100% visual and dimensional verification before packaging.
Shipping Inspection
Final spot-check and documentation before customer dispatch.
Drawing Review
Verify all geometric and dimensional requirements before first set-up.
First Article Inspection
100% dimensional verification on initial sample before volume production.
In-Process QC
Periodic sampling and SPC monitoring during production run.
Final Inspection
100% visual and dimensional verification before packaging.
Shipping Inspection
Final spot-check and documentation before customer dispatch.
Tolerancing Capabilities
Our Swiss turning process routinely achieves tight tolerances across all feature types. The "Typical" column represents standard production capability; "Best Achievable" reflects optimized conditions for critical applications.
| Feature | Typical Tolerance | Best Achievable | Notes |
|---|---|---|---|
| Diameter tolerance | ±0.010mm | ±0.005mm | Applies to turned diameters; achieved through careful tool wear management and SPC monitoring. |
| Length tolerance | ±0.020mm | ±0.010mm | Axial dimension control. Best case assumes repeatable fixturing and minimal tool deflection. |
| Surface roughness | Ra 0.8µm | Ra 0.4µm | Finish quality depends on tool geometry, spindle speed, and feed rate optimisation. |
| Roundness (TIR) | 0.005mm | 0.002mm | Guide bush support minimises deflection; best results with reduced tool overhang. |
| Thread class | 6H / 6g | 4H / 4g | Metric or imperial threads. Premium class (4H/4g) requires tight speed/feed and tool offset management. |
Disclaimer: Tolerances beyond the "Typical" column require pre-production trials and design agreement. Some exotic materials or complex geometries may require relaxed tolerances. Contact our engineers for specific capability discussion.
Confidence in Quality
Have a quality question?
We are happy to discuss your tolerance requirements, surface finish specifications, or first-article inspection needs. Submit your drawing and we'll advise on feasibility and process approach.
Response within 1 business day · STEP, IGS, DWG, PDF accepted