ISRA VISION’s new solution enables shape measurement and defect detection of high-gloss surfaces

components with highly reflective surfaces face strict quality requirements. Reflective surfaces and curved surfaces are usually extremely sensitive and therefore difficult to detect, but for manufacturers, it is essential to have an accurate quality control process. ISRA VISION launched the SpecGAGE3D product series, which provides an ideal solution for the quality inspection of reflective surfaces (such as injection molded parts).

Components with highly reflective surfaces face strict quality requirements. Reflective surfaces and curved surfaces are usually extremely sensitive and therefore difficult to detect, but for manufacturers, it is essential to have an accurate quality control process. ISRA VISION launched the SpecGAGE3D product series, which provides an ideal solution for the quality inspection of reflective surfaces (such as injection molded parts).

High-gloss reflective surfaces can often create high-quality personalized designs. As a result, the market’s demand for reflective surface products continues to increase, including housing parts for Electronic equipment, displays, rearview mirrors or head-up Display deflector mirrors, and automotive exterior components such as B-pillars, panels, trim strips, fuel tank caps or headlights . Nowadays, piano black is used as a high-gloss discoloration on the plastic surface of automobile interiors, and it has almost become a standard for high-quality automobile manufacturing.

These products are usually manufactured using an injection molding process, which injects high-temperature liquid plastic into a mold shell or mold and then allows it to cool and harden. In an ideal situation, after the plastic is completely cooled and the mold is opened, the hardened plastic should have a precise shape and fit perfectly in the hollow part of the vehicle. However, machining errors can cause a large number of defects and defects in the components. In terms of quality control, manufacturers must distinguish two challenges:

The first challenge: reliable detection of appearance defects

Appearance defects such as joint burrs, impurities or inclusions are usually caused by incorrect injection pressure. Whether these defects need to be corrected or not in the downstream process depends on the component. If it is a non-transparent component, or the component needs to be polished, painted, or coated after the injection molding stage, the surface defects are usually not critical to the process at this stage. However, if there are defects (including scratches or orange peel) after coating or painting, the situation is different. The appearance defects on these high-gloss components can be clearly seen by the naked eye. However, common inspection procedures (such as streak light or diffuse reflection-based photogrammetry) can hardly detect these defects and convert them into usable measurement data. Measurement techniques such as white light interferometry are also unreliable because the measurement range is usually not large enough. At the same time, the manual surface inspection of these parts is a laborious, expensive and error-prone process.

The second challenge: Reliable detection of shape defects

Excessive deformation is still one of the typical defects of injection molded parts. Among other reasons, this can also happen if the temperature of the mold or injected plastic is set incorrectly. Distortions and dents appear when the surface collapses. For example, the plastic component shrinks deep or the amount of plastic injected is insufficient.

For optical components (such as a head-up Display), the distortion in a very small refractive range may seriously affect the performance of the component. Compared with appearance defects, these distortions are invisible to the naked eye, so manual inspection cannot be performed.

Deflection method can simultaneously detect shape and any defects in a single measurement step

For the measurement of reflective surfaces or partially reflective surfaces, the phase deflection method is a particularly reliable process. ISRA VISION’s SpecGAGE3D sensor series set a new standard and complete this process.

The system projects the fringe pattern onto the reflective surface to be measured. Then, multiple cameras record and evaluate the reflection fringe pattern from different angles. Based on the distortion of the recorded fringe pattern, the system can calculate the topology of the component.

The topology determined through this process will be compared with the CAD model (digital model of the component), which takes only a few seconds to complete. The height difference map accurate to micrometers can show the deviation from the expected model. At the same time, the sensor can also detect local unevenness and appearance defects on the surface.

In a time-saving single measurement, SpecGAGE3D can reliably detect the shape and any defects of high-gloss injection molded parts and other reflective or transparent components. By comparing the image with the CAD model, the system can detect deviations as low as the micro-diopter range, and the detectable accuracy of local defects can reach the nanometer level. Paint defects, impurities, injection molding defects and other defects can be quickly detected, classified and filed. The conclusions drawn from these tests can help manufacturers quickly adjust the process, thereby optimizing production efficiency, saving resources and reducing machine running time. In addition, shortening the measurement time can also improve the production cycle. Whether from a technical or economic point of view, this complete measurement process can achieve zero defect quality.

ISRA VISION’s new solution enables shape measurement and defect detection of high-gloss surfaces
Deflection detection (R) ISRA VISION of high-light B-pillar

ISRA VISION’s new solution enables shape measurement and defect detection of high-gloss surfaces
Deflection mirror height and curvature deviation graph (R) ISRA VISION

ISRA VISION’s new solution enables shape measurement and defect detection of high-gloss surfaces
Defect detection of headlight housing; typical defect size: 70-100 µm (R)ISRA VISION

ISRA VISION’s new solution enables shape measurement and defect detection of high-gloss surfaces
Automotive interior high-gloss panel (R) ISRA VISION

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