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Oil Film Inspection Unit

For assessing the application of oil-based release agents and lubricants

The Oil Film Inspection Unit allows users to view and assess the application or leakage of oil-based fluids and lubricants. This technology can also estimate the thickness of the oil film using image data and statistical processing.

1. Technological Overview

Many petroleum-based oils such as mold release agents, lubricating oils, and cutting oils have the property of emitting fluorescence when exposed to ultraviolet rays.

Ultraviolet rays are emitted towards the surface of an object, and the fluorescence emitted by the oil-based liquid on object is detected by a camera. To isolate the florescence emitted by the oil agent wavelengths consistent with ambient light and ultraviolet light are removed.

No Filter

UV transmission filter

Filter Visible Light

Remove reflected light

Remove reflected light

Extract Fluorescent emission

Fig. 2 Fluorescence squeezing by two types of optical filters

Fluorescence

Reflected light

Ambient Light

Reflected UV light is removed through UV illumination and optical filters (Fig. 2). Ambient light is removed through comparison of the image with and without UV illumination (Fig. 3).

2. Estimating Film Thickness

The thickness of the oil film is estimated from the amount of fluorescence emitted from the camera image using the correlation equation that holds between the amount of fluorescence emitted from the oil film on the metal surface and the thickness of the oil film. This correlation formula needs to be obtained by statistically processing the film thickness actually measured using an optical interference type film thickness meter or the like and the fluorescence emission amount information obtained from the camera image for each type of oil in advance (Fig. 5).

Fig. 4 Correlation between film thickness and fluorescence emission detected by camera

Other than film thickness, several factors including distance, angle and angle affect the fluorescence emissions. These factors can be limited through standardizing the shooting conditions. Statistical correlation distance, tilt angle, position, and fluorescent emissions are tracked to allow estimation of oil thickness.

3. Uses of Oil Film Inspection Unit

The Oil Film, Inspection Unit can be used to inspect for oil residue on machine parts, leakage of engine oil, application of lubricants on molds, and more. A comparative image can also be generated to allow comparison of multiple results.

Example 1: Assessing application of Lubricants on Mold

Ideal Application