GVDA Coating Thickness Gauge GD198

1. Introduction

The GVDA GD198 Coating Thickness Gauge is designed to measure the thickness of plated and coated sheets on various metal substrates. This includes paint, enamel, or chrome on steel, and paint or anodizing coatings on aluminum or copper. The gauge utilizes a precision integrated probe and operates on the principles of electro-magnetic induction and the eddy current effect, automatically identifying the substrate material properties.

This device is ideal for non-destructive measurement of coating and painting thickness. It is widely used in manufacturing, metal-processing, chemical industries, and commodity inspection. It performs reliably in laboratory, workshop, and outdoor environments.

2. Operating Principle

The GD198 gauge employs two main principles for measurement:

• F Probe (Magnetic Induction): Used for detecting the thickness of non-magnetic coatings such as chrome, copper, zinc, varnish, or rubber on iron/steel substrates.
• N Probe (Eddy Current Effect): Used for detecting the thickness of insulating coatings such as paint, anodizing, or ceramics on aluminum, copper, or brass substrates.

3. Package Contents

Upon opening the package, please verify that all items listed below are present:

• Coating Thickness Gauge (GD198)
• Substrates (Ferrous and Non-Ferrous)
• Five Standard Calibration Foils (50um, 100um, 250um, 500um, 1000um)
• User Guide (This manual)
• Protective Case (if included in your specific package)

4. Product Description and Parts Identification

Refer to the diagram below for identification of the main components:

1. Measured Reading Display
2. Function Buttons (MODE, ZERO, Read, Units)
3. Anti-Skid Slot
4. Probe
5. V-Groove
6. Non-slip mat
7. Battery Compartment
8. Anti-Skid Slot

5. Display Items

The LCD screen displays various symbols and readings:

• Auto Power Off: Indicates automatic shutdown after 15 minutes of inactivity.
• SNG: Single-point detection mode.
• Battery Icon: Indicates battery level.
• CON: Continuous test mode.
• CAL: Calibration mode.
• ZERO: Zero calibration indicator.
• NF: Indicates a non-ferrous substrate (e.g., aluminum, copper).
• Fe: Indicates a ferrous substrate (e.g., iron, steel).
• mil: Measurement unit (1 mil = 1/1000 inch = 0.0254 mm).
• µm: Measurement unit (1 µm = 0.001 mm).
• NO. (e.g., NO. 18): Automatic storage data number.
• Read: Indicates reading of stored data.

6. Technical Specifications

Note: The final specifications may be upgraded without prior notification. For more details, please consult with your supplier.

7. Factors Affecting Measurement Accuracy

To ensure accurate readings, users should be aware of the following factors that can influence measurement precision:

• Curvature radius convex < 1.5mm
• Curvature radius concave < 25mm
• Diameter of measuring area < 6mm
• Thickness of substrate < 0.5mm
• Surface roughness
• Adhesive substances: Ensure the probe and coating surface are clean.
• Strong magnetic fields in the vicinity.
• Operating outside the specified temperature and humidity ranges.
• Low battery level.

8. Setup

1. Read Instructions: Familiarize yourself with the factors affecting measurement accuracy (Section 7).
2. Install Batteries: Insert two AAA 1.5V batteries into the battery compartment (7).
3. Prepare Test Object: Ensure the test object is clean and ready for measurement.
4. Power On and Initial Positioning: Keep the instrument probe at least 5 cm away from any metal surface before turning it on. The instrument will automatically perform an initial test mode correction.

9. Operating Instructions

9.1. Unit Switching

Press the Units button to switch between measurement units: "µm" (micrometers) or "mil" (mils).

9.2. Measurement Modes

Press the MODE button to select the desired measurement mode:

• SNG (Single Mode - Default): For single-point detection. Vertically and rapidly place the probe on the sample. The reading will display on the LCD with a single beep. To clear the statistics, press the ZERO key. Lift the probe more than 5cm away from the metal surface before taking the next measurement.



• CON (Continuous Measurement Mode): For continuous measurement. Vertically and directly place the probe on the sample. The readings will continuously update as the probe moves across the surface.



Note: The ZERO key in CON mode is used for calibration. Do not press it unless performing calibration. Refer to the calibration section for more information.

9.3. Auto Power Off

The device automatically powers off after 15 minutes of inactivity to conserve battery life.

9.4. Data Storage

The GD198 can store up to 20 groups of measurement data automatically. Use the Read button to access stored data.

9.5. System Reset

To perform a system reset, press and hold the Units button until the full screen displays with two beeps. This indicates that the system resetting is complete.

Note: System resetting is primarily used to recover from error operations or incorrect calibration settings.

10. Calibration

Calibration is essential to maintain the accuracy of the gauge. Factors like probe wear, prolonged disuse, hostile environments, or special substrates can affect accuracy. The gauge supports calibration at 6 points: 0, 50, 100, 250, 500, and 1000µm. Other points (e.g., 750µm) are not supported.

10.1. Preparation for Calibration

1. Take out the two provided substrates (ferrous and aluminum).
2. Take out the five standard calibration foils (50µm, 100µm, 250µm, 500µm, 1000µm).
3. Place the substrates and foils horizontally on a stable surface. You may also use your own bare metal substrate if it matches the material you intend to measure.

10.2. Zero Calibration

1. Press the MODE button to enter Continuous Measurement Mode (CON will be displayed on the LCD).
2. Place the probe directly onto the bare substrate.
3. If the reading on the LCD is not zero, hold the gauge steady and press the ZERO key.
4. The screen should display "00.0". This indicates that zero calibration is complete.
5. You can now perform a test measurement to verify.

10.3. Calibration with Standard Films (e.g., 50µm film)

1. After zero calibration, place the 50µm standard film onto the substrate.
2. Place the probe onto the film.
3. If the reading is not 50.0, press the ZERO key until the display shows 50.0.

The calibration process for 100µm, 250µm, 500µm, and 1000µm films is identical. Simply switch to the corresponding film on the substrate and adjust the reading using the ZERO key.

Important: If you perform an incorrect operation during calibration, press and hold the Units button for 3 seconds to reset the gauge to factory defaults.

11. Maintenance

• Environmental Conditions: Avoid operating the gauge in hostile environments, including areas with high risk of collision, excessive dust, hyperthermia (extreme heat), high humidity, or strong magnetic fields.
• Cleaning: Keep the probe and the measurement surface clean and free of adhesive substances to ensure accurate readings.
• Battery Handling: If the gauge is unresponsive or fails to power on, remove the batteries, wait for a few minutes, and then reinstall them.
• Storage: Store the gauge in its protective case when not in use to prevent damage.

12. Troubleshooting

• Gauge is unresponsive or won't power on:
  1. Check battery installation and ensure batteries are not depleted. Replace if necessary.
  2. Remove batteries, wait a few minutes, then reinstall.
  3. If the issue persists, contact your supplier for assistance.
• Inconsistent or inaccurate readings:
  1. Ensure the probe and the measurement surface are clean.
  2. Perform a full calibration (Zero and with standard films) as described in Section 10.
  3. Verify that environmental conditions (temperature, humidity, magnetic fields) are within specified limits.
  4. Check for low battery indication.
  5. Ensure proper probe placement (vertical and rapid contact) and sufficient distance from metal between measurements in SNG mode.
• Error during calibration:
  1. Press and hold the Units button for 3 seconds to perform a system reset and return to factory defaults. Then attempt calibration again.

13. User Tips

• For Consistent Readings: Some users have noted initial inconsistencies. To achieve reliable results, ensure thorough calibration before use, maintain a clean probe and surface, and practice consistent probe placement technique.
• Measurement on Plastic Parts: This gauge is designed to measure the thickness of coatings and paint films on metal substrates (ferrous and non-ferrous). It is not intended for measuring the thickness of solid plastic parts themselves, unless the plastic is an insulating coating on a metal base.
• Battery Life: The auto power-off feature helps conserve battery. Always ensure fresh batteries for critical measurements, especially if experiencing inconsistent readings.

14. Warranty and Support

For warranty information, technical support, or any issues not covered in this manual, please contact your original supplier or the GVDA Official Store directly. Keep your purchase receipt or proof of purchase handy when seeking support.

An external PDF user manual may also be available for download from the seller's website: View User Manual (PDF)