Vision Systems
Multi-sensor optical inspection for high-throughput dimensional control of small, flat or delicate parts. Independent guidance for UK manufacturers - free for the end user.
How it works
A vision system measures features by imaging the part with a calibrated camera and edge-detection algorithms. Backlight and coaxial illumination create high-contrast edges; sub-pixel algorithms locate them to a fraction of a pixel. Systems progress from manual toolmakers' microscopes to fully automated CNC vision CMMs with autofocus, touch probes, laser and chromatic sensors on the same axis system.
Typical accuracy
Modern CNC vision CMMs (OGP SmartScope, Zeiss O-INSPECT, Werth) achieve E1 length errors of 1.5-3.0 microns + L/200 in optical mode and 1.5-2.5 microns + L/400 with a tactile probe fitted.
Applications
- 2D dimensional control of stamped, machined and moulded parts
- Electronics: connectors, PCBs, micro-features
- Medical devices: needles, cannulae, small implants
- Cutting-tool geometry and edge inspection
- First-article and in-process inspection for small parts
- High-throughput SPC on high-volume components
Strengths
- • Non-contact - ideal for delicate, soft or thin parts
- • Fast for 2D features - hundreds of points per second
- • Automated edge detection removes operator bias
- • Multi-sensor options combine optical, tactile and laser on one datum
Limitations
- • Limited Z-axis range compared to a full CMM
- • Optical measurement is sensitive to lighting, surface finish and edge quality
- • Deep bores, undercuts and complex 3D geometry need contact or CT
- • Field-of-view trade-off between accuracy and coverage
Where vision wins
Vision systems excel on small, flat or thin parts where a tactile probe would deflect the feature, mark the surface, or simply be too slow. Stamped connectors, moulded plastics, cutting tools, hypodermic tubing and PCB features are natural fits.
Multi-sensor optical CMMs
Multi-sensor machines (OGP SmartScope Flash / Vantage, Zeiss O-INSPECT, Werth VideoCheck) combine vision with tactile scanning and often chromatic white-light or laser sensors on the same axes. They avoid the datum-transfer error of measuring the same part on two different machines and are the pragmatic choice for parts that mix optical and tactile features.
Lighting is the measurement
In vision, illumination design is as important as the lens. Telecentric backlights give near-zero parallax for silhouette features; coaxial and ring lights bring out surface detail; programmable multi-segment rings resolve edges on shiny or textured surfaces. Getting lighting right at the buying stage prevents years of programming pain.
Buying considerations
- Optical resolution vs field of view - telecentric lenses matter
- Lighting: backlight, coaxial, ring, programmable multi-segment
- CNC vs manual - operator time dominates cost of ownership
- Multi-sensor: touch probe, laser, chromatic - all on one coordinate system
- Software: GD&T support, CAD import, SPC integration
FAQs
Vision or tactile CMM?+
Small, flat, delicate or shiny parts - vision. Prismatic, deep, or 3D-form parts - tactile. Mixed - multi-sensor optical CMM.
How repeatable are edge measurements?+
With good lighting and sub-pixel algorithms, 2D edge repeatability is routinely sub-micron on a well-specified system.