A contour that was easy to measure yesterday now looks ragged. Raising the edge threshold makes the result appear stable, but we first ask whether the camera is seeing the same surface condition. On an Instant Vision Measuring Machine, dust, oil and handling residues can become part of the visible boundary. Changing the programme before checking that boundary may turn a preparation problem into a persistent measurement bias.

The video demonstrates our vertical and horizontal integrated equipment. It is a product demonstration, not a controlled cleanliness experiment. Capture-time and efficiency statements in promotional material depend on the part, programme and operating conditions; preparation and verification remain part of the inspection process.

Separate three possible locations

We start by distinguishing the workpiece from the support surface and the optical path. A fibre on the part can travel with the part. Residue on the stage may remain at the same location when another clean sample is loaded. Contamination on an accessible optical window can reduce contrast over a wider region. These observations guide an investigation, but we do not treat one image as definitive proof of where a defect originates.

For a Desktop Instant Vision Measuring Machine, an empty-stage inspection under the normal illumination is a useful initial observation. We then examine a known suitable clean sample using the released programme. Keeping the lighting and edge settings fixed during this comparison avoids changing several variables at once. If a suspicious mark remains, we follow the equipment maintenance instructions rather than improvising a repair.

Define the condition that should be measured

“Clean the part” is incomplete as an inspection instruction. Some components arrive with an intentional protective film, lubricant or functional coating. Removing that layer can change the product condition that the drawing or inspection plan requires. We first establish whether the specified dimension refers to the delivered condition, a defined cleaned condition or a particular production stage. Operators should not have to make that engineering decision for each sample.

For removable contamination, the preparation method should identify an approved material-compatible process, its drying requirement and the permitted handling afterwards. We avoid prescribing one solvent for all plastics, coatings and metals. A process suitable for an uncoated metal part may damage a polymer surface or leave a film on another material. Where compatibility is uncertain, the relevant material and equipment guidance takes priority.

Inspect the boundary before accepting the number

With a Vision Measuring System, we inspect the captured edge and the selected measurement region as well as the numerical output. A droplet can bridge a narrow gap; a fibre can create a false protrusion; a residue patch can change contrast. The effect depends on illumination and geometry, so a clean-looking overview does not guarantee that the actual measurement region is unaffected.

We retain representative images from an investigation and identify the affected feature. If an approved cleaning step changes the result, that is evidence to investigate preparation sensitivity. It does not by itself identify which number is correct. We compare the observation with the feature definition and, where needed, an appropriate independent method. Agreement between repeated contaminated images would demonstrate consistency under that condition, not reliable measurement of the intended edge.

Keep preparation changes separate from programme changes

On an Automatic Video Measuring Machine, a threshold adjustment can be repeated across many parts very quickly. We therefore preserve the existing settings while investigating cleanliness. Once the approved surface condition has been restored, we check whether the original programme again finds the intended boundary. We change illumination or edge settings only when the defined measurement method requires it, and we retain a reason for the change.

If both preparation and settings must change, we compare them in a controlled sequence. Otherwise, it becomes difficult to know whether improved repeatability came from cleaning, a different boundary selection or a combination of both. A programme that rejects a visible fibre should still measure legitimate small features correctly. We avoid making a detection setting so insensitive that it hides relevant geometry along with the contamination.

Make the preparation route repeatable between operators

A Manual Video Measuring Machine and an automated station can share the same preparation weakness: different operators may wipe different areas or wait different amounts of time before measurement. We turn the accepted method into a short instruction with representative examples. The instruction should explain where a part may be held, what condition triggers further preparation and how to handle a surface that cannot be cleaned without altering it.

We also control the clean-to-measure interval when the application shows that it matters. Clean trays and approved handling methods help prevent immediate recontamination. Equipment cleaning follows the manufacturer’s procedure, including which surfaces operators may service. Internal optics, protected scales and other sensitive assemblies are not treated as ordinary workbench surfaces.

Before releasing the routine, we check representative parts across the intended preparation variation and confirm that the Optical Measuring Machine identifies the same defined features. We retain the preparation instruction beside the inspection programme so the two remain connected. For an application review, contact DONGGUAN CITY HANDING OPTICAL INSTRUMENT CO., LTD. at handing3d@163.com with the material, surface condition and feature of interest. We can discuss a suitable demonstration using the condition your production team actually needs to inspect.