ASTM E2658 | Universal Testing Machines | Calibration
ASTM E2658 describes the procedures for the calibration and verification of speed measuring systems, which are comprised of a speed transducer and associated instrumentation or a displacement transducer with associated timer and instrumentation.
Numerous material testing applications rely on repeatable and predictable testing machine speed, which is a measurement of displacement divided by time. This standard is written to verify testing machine speed within +/-1.0% of selected setting and/or testing machine indication. By following the procedures in this standard, the accuracy of the speed value becomes known and traceable to the National Institute of Standards and Technology (NIST).
The speed measuring system classification is based Table 1 of ASTM E2658, seen below. It is recommended that the testing machine displacement is calibrated and verified per ASTM E2309 prior to performing the speed verification.
Classification |
Resolution % of Reading |
Percent Error |
| A | ±0.25 | ±0.5 |
| B | ±0.5 | ±1.0 |
| C | ±1.0 | ±2.0 |
| D | ±2.5 | ±5.0 |
| E | ±5.0 | ±10 |
| F | ±10 | ±20 |
Before conducting ASTM E2658, it is important to read the entire specification in the relevant ASTM publication.
ASTM E2658 | 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.
- The minimum recommendation for selecting calibration test points is to check the displacement speeds at the lowest and highest test speeds used by the customer.
- 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.
- Determine the displacement at which the verification run will start based on when the system is able to reach a constant speed. Also determine the displacement at which the system should travel during the verification run.
- Set the system to perform a position controlled test at the speed to be calibrated.
- When the system has reached a constant speed, press the trigger on the GB2-Calibrator Unit to start the data acquisition.
- Once the system has reached the predetermined end displacement, press the trigger again.
- The system will then show you a graph of the data. Make sure the y axis is set to position and the x axis is set to time. Select the two points closest to your start and end displacement to find the speed of the system.
- Compute the indicated speed error in % and indicate the Class of the system using Table 1.
- A minimum of two runs of readings is required for ASTM E2658 calibration.
- If an out of tolerance condition is noted, record this data and include it in the calibration certificate.
ASTM E2658 | Universal Testing Machines | Calibration
| ASTM E2658 | Recommended Equipment |
|---|---|
| Calibration Equipment |
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