ASTM C1651 Measurement of Roll Wave Optical Distortion in Heat-Treated Flat Glass

Get Certified ASTM C1651 Testing for Reliable Flat Glass Optical Quality

Heat-treated flat glass can have a roll wave formed during processing that can impact the visual appearance and optical quality of the material. ASTM C1651 provides a standardized procedure for measuring this distortion, so that manufacturers and engineers can monitor the quality of heat-treated glass products. The results will aid quality control, manufacturing-process evaluation, material-comparison, and specification-assessment for applications in which optical appearance is of concern.

The scope of ASTM C1651 includes:

• Material type: Flat, heat-treated architectural glass substrates processed in continuous or oscillating conveyance ovens.
• Purpose: Determination of roll wave deformation and the resulting optical distortion in heat-treated flat glass.
• Properties evaluated: Peak-to-valley depth, peak-to-peak distance, and optical distortion associated with roll wave.
• Testing method: Measures the deformation of the glass using the specified optical measurement arrangement and evaluates the roll wave characteristics.
• Results: Results include measurements of roll wave depth, peak-to-peak distance, and the calculated optical distortion.
• Test limitations: ASTM C1651 addresses roll wave and does not evaluate other flatness issues such as edge kink, ream, pocket distortion, bow, or unrelated glass distortions.
• Use conditions: Technicians perform measurements with the glass specimen, target, optical equipment, lighting, and test setup positioned according to the applicable procedure.
• Applications: Heat-treated architectural glass evaluation, quality control, manufacturing-process monitoring, product comparison, and specification assessment.

What are the Uses of ASTM C1651 Testing?

ASTM C1651 testing helps manufacturers and engineers evaluate roll wave optical distortion in heat-treated flat glass. The measured results provide information about the magnitude and distribution of roll waves and help identify processing conditions that may affect the visual quality of glass products. This standard-

• Measures roll wave optical distortion in heat-treated flat glass.
• Determines the peak-to-valley depth of roll wave.
• Determines the peak-to-peak distance of the roll wave.
• Provides measurements used to calculate optical distortion.
• Supports monitoring of heat-treated glass production.
• Helps compare optical quality between glass products or production conditions.
• Supports quality control and manufacturing-process evaluation.
• Provides data for product specifications and performance assessment.

Which materials can be tested under ASTM C1651?

ASTM C1651 applies to flat, heat-treated architectural glass substrates processed in heat-processing continuous or oscillating conveyance ovens. Heat-strengthened and fully tempered flat glass can be evaluated when the applicable product and processing conditions fall within the method’s scope. These glass products are commonly used in architectural glazing and other applications where visual appearance and optical quality are important.

Why is ASTM C1651 Important?

ASTM C1651 provides a standardized method for measuring roll wave optical distortion in heat-treated flat glass. Roll wave can affect the appearance of reflected or transmitted images and may reduce the visual quality of a finished glass product. By measuring the depth and spacing of the roll wave, engineers and manufacturers can monitor processing conditions, compare products, support quality control, and evaluate glass against applicable specifications. The results are particularly useful for identifying and controlling distortion associated with roller-based heat-treatment processes.

ASTM C1651 Testing Process and Data Collection

The analyst selects a representative heat-treated flat glass specimen and determines the required measurement arrangement. Technicians clean and position the specimen on a stable support and align the target and optical measurement equipment. The operator then observes the target through the glass and collects measurements of the roll wave distortion. Technicians obtain multiple measurements to characterize the magnitude and distribution of the distortion. Analysts determine the peak-to-valley depth and peak-to-peak distance, calculate the applicable optical distortion, and record the results for quality evaluation and comparison.

Common Challenges and Troubleshooting

Accurate ASTM C1651 results require proper specimen preparation, optical alignment, stable support, controlled lighting, and calibrated measurement equipment. Dust, fingerprints, surface contamination, vibration, or incorrect positioning can affect optical measurements. Technicians should clean the glass surface, verify the alignment of the target and optical equipment, and maintain a stable testing environment before measurement. If measurements appear inconsistent, the operator should check equipment alignment, calibration, specimen positioning, lighting conditions, and environmental vibration. Analysts should also review multiple measurements for unusual variations before accepting the final results.

• The technician records the glass identification, specimen information, measurement setup, and applicable test conditions.
• The analyst records the measured peak-to-valley depth of the roll wave.
• The technician records the measured peak-to-peak distance or wavelength of the roll wave.
• The analyst calculates the applicable optical distortion using the measurements obtained during testing.
• The engineer evaluates the magnitude and distribution of the roll wave to assess the optical quality of the heat-treated glass.
• The analyst documents relevant observations, measurement variations, or conditions that could affect interpretation of the results.
• The report presents the measured roll wave characteristics and optical distortion so engineers can compare glass products or evaluate the results against applicable specifications.

Link to ASTM C1651