ASTM E2309 | Universal Testing Machines | Calibration
ASTM E2309 describes the procedures for the calibration and verification of displacement measuring systems, which are comprised of displacement measuring instruments, the displacement display, and the associated cables and electronics.
Displacement is a measurement of a change in length of travel or movement of the moveable head or crosshead of a testing machine, and is often measured by the crosshead or actuator movement. By following the procedures in this standard, the accuracy of the displacement value becomes known and traceable to the National Institute of Standards and Technology (NIST).
Accuracy tolerance for all displacement devices is based on classification (A, B, C, or D) as listed in Table 1 of ASTM E2309, shown below. The tolerance is the greater of a fixed value or a percentage of reading.
Classification |
Lower Limit |
Resolution not to Exceed the greater of: |
Error not to Exceed the greater of: |
||
Fixed Error, mm (in) |
% of Reading |
Fixed Error, mm (in) |
% of Reading |
||
|---|---|---|---|---|---|
| A | ≥400x resolution | 0.013 (0.0005) | ±0.25 | ±0.025 (0.001) | ±0.5 |
| B | ≥200x resolution | 0.038 (0.0015) | ±0.5 | ±0.075 (0.003) | ±1.0 |
| C | ≥100x resolution | 0.064 (0.0025) | ±1.0 | ±0.125 (0.005) | ±2.0 |
| E | ≥67x resolution | 0.13 (0.005) | ±1.5 | ±0.25 (0.010) | ±3.0 |
Before conducting ASTM E2309, it is important to read the entire specification in the relevant ASTM publication.
ASTM E2309 | Universal Testing Machines | Calibration
- Place a calibrated thermometer near the load cell to monitor ambient conditions during the procedure.
- Allow the machine and the calibration device(s) to stabilize at ambient temperature for at least 15 minutes.
- Determine the upper and lower limits of the testing machine
- Make sure all appropriate safety procedures are followed.
- Place the encoder in the testing machine so that its base and string are aligned with the primary movement of the machine.
- Move the testing machine slightly in the direction to be certified in order to remove any backlash from the system. Test frames that are used in tension and compression shall be calibrated in both directions.
- Zero the calibration encoder and the displacement system’s displacement readout.
- Set the displacement system to the test points to be checked and record the calibration encoder reading at each point.
- A minimum of two runs of readings is required for ASTM E2309 calibration.
- If an out of tolerance condition is noted, record this data and include it in the calibration certificate.
- Verify that the repeatability at each test point is also within the tolerance limits for the desired class.
ASTM E2309 | Universal Testing Machines | Calibration
| ASTM E2658 | Recommended Equipment |
|---|---|
| Calibration Equipment |
|