1、 Instrument calibration and calibration

1. Regular calibration (core steps)

-Calibration cycle:

-The new instrument needs to be calibrated before first use, and then calibrated at least once a week thereafter; If high frequency or precision is required for measurement, daily calibration is necessary.

-If not used for a long time (more than 1 month) or repaired, recalibration is required.

-Calibration tool:

-Standard board: Use high gloss standard boards (such as black glass, with known and stable gloss values) and low gloss standard boards (such as ceramic boards) that are compatible with the instrument.

-Calibration process:

1. Clean the surface of the standard board with a soft cloth to avoid fingerprints or dust affecting the reflectivity.

2. Preheat the machine for 10-15 minutes (ensuring stable light source and detector), first calibrate the "full degree" with a high gloss standard plate (if set to 1000 GU), and then calibrate the "zero point" or verify the error with a low gloss standard plate (the error should be less than ± 1%).

After calibration, repeat the measurement three times with a standard plate to confirm that the reading fluctuation is less than ± 2 GU, otherwise recalibration is required.

2. Periodic verification (validation during non calibration periods)

-Before each measurement, use a standard plate to quickly verify whether the instrument reading is within the allowable error range (such as ± 3 GU). If it exceeds the tolerance, recalibration is required.

-If the surface of the standard board is worn, scratched, or contaminated (such as a change in glossiness value>5%), it should be replaced or returned to the factory for calibration in a timely manner.

2、 Sample preparation and processing

1. Surface cleaning

-Wipe metal surfaces with anhydrous ethanol or specialized cleaning agents in conjunction with a dust-free cloth to remove oil stains, fingerprints, oxide scales, or coating debris.

-Avoid using rough wiping materials (such as steel wire balls) to prevent human scratching of the surface from affecting the measurement results.

2. Sample state control

-Temperature and humidity: Metal samples should be placed in a constant temperature and humidity environment (such as 23 ± 2 ℃, humidity 50 ± 5% RH) for at least 2 hours to avoid surface condensation or thermal deformation caused by temperature gradients.

-Shape and size:

-Flat sample: The measurement area should be larger than the instrument measurement window (usually 30mm × 30mm), and the edges should be flat and free of burrs.

-Surface sample: Use a surface adapter or select an instrument with a small measurement window to ensure that the probe is tightly attached to the surface and avoid light leakage.

-Coating uniformity: If it is a coated metal (such as electroplated or sprayed parts), it is necessary to confirm that the coating has no bubbles, sagging, or uneven thickness. It is recommended to measure 3 points in the same area and take the average value.

3、 Operating standards and skills

1. Selection of measurement angle

-Select the standard angle based on the level of metallic luster (key principle):

-High gloss metals (such as polished stainless steel and chrome plated parts): Use a 20 ° or 60 ° angle to avoid detector saturation caused by strong light overload.

-Low gloss metals (such as sandblasted aluminum, oxidized parts): Use a 60 ° or 85 ° angle to improve the detection sensitivity of diffuse reflection light.

-The same batch of samples should be measured at the same angle to avoid data comparability caused by angle differences.

2. Instrument bonding method

-Hold the instrument vertically to ensure that the measurement window is in contact with the surface of the sample, avoiding tilting or hanging that may cause ambient light to enter the optical path.

-For soft metals that are prone to deformation (such as aluminum foil), it is necessary to lightly press the instrument to avoid surface indentation caused by excessive pressure.

3. Multiple measurements and point distribution

-At least 3 different areas (such as upper left, middle, and lower right) should be measured for each sample. If the surface texture uniformity is poor (such as brushed metal), additional measurement points (5-7 points) should be added.

-Record the values of each point, calculate the mean and standard deviation. The standard deviation should be less than 5%, otherwise the surface uniformity needs to be checked or remeasured.

4、 Environmental control

1. Lighting and vibration

-The measurement should be conducted in a dark room or shaded environment without direct light or strong ambient light, to avoid interference from light and window reflections on the collection of reflected light.

-The instrument is placed on a stable platform, away from vibration sources such as machine tools and fans, to prevent vibration from causing optical path deviation or reading fluctuations.

2. Temperature and humidity stability

-The fluctuation of environmental temperature should be less than ± 1 ℃/h, and the humidity should be less than 65% RH to avoid high temperature causing aging of internal components of the instrument or moisture causing mold growth in the optical path.

-If measuring in a high humidity environment, dry nitrogen can be used to blow the inside of the instrument or the surface of the sample to prevent condensation from affecting the measurement.

5、 Instrument maintenance and troubleshooting

1. Daily maintenance

-Light path cleaning: Dip a small amount of anhydrous ethanol into lens paper every week to wipe the measuring window and internal lens of the instrument, removing dust or stains (to avoid scratching the lens).

-Battery and Circuit: Regularly check the battery level (if it is a portable instrument) to avoid unstable light source intensity caused by low voltage; The connecting wires must be undamaged and have good contact.

2. Common faults and their solutions

Problem phenomenon	Possible reasons	solution
The reading fluctuates greatly	Unstable light source, rough sample surface	Re calibrate the instrument and check the cleanliness of the sample surface
The deviation between the numerical value and the expected value is significant	Calibration error, improper angle selection	Re calibrate and verify if the measurement angle matches the standard
Display abnormality or crash	Circuit malfunction, software error	Restart the instrument. If it is ineffective, it needs to be returned to the factory for repair
Low intensity of reflected light	Standard board contamination, detector aging	Clean the standard board and contact the manufacturer to replace the detector

6、 Personnel training and record management

1. Operator training

-New employees need to pass theoretical assessments (such as glossiness principles, standard specifications) and practical assessments (such as calibration processes, sample processing) to ensure proficiency in instrument operation.

-Regularly organize technical exchanges (such as once a year) and update industry standards (such as the latest requirements of ISO 2813:2024).

2. Data recording and traceability

-Establish a measurement record ledger, including:

-Sample information (material, surface treatment process, number);

-Instrument information (model, calibration date, standard plate number);

-Measurement parameters (angle, light source type, ambient temperature and humidity);

-Raw data, average value, and signature of measurement personnel.

-Record retention period ≥ 3 years for quality traceability or third-party audit purposes.

summary

The measurement accuracy of BoS glossiness meter depends on the full process control - from the "source accuracy" of instrument calibration to the "process specification" of sample processing, and then to the "detail control" of environment and operation. Through standardized operations, regular maintenance, and data tracing, the reliability of metal glossiness detection can be effectively improved, providing scientific basis for production quality control and material research and development.