ISO 5347-16:1993

Overview

ISO 5347-16:1993 specifies instrumentation and procedures for measuring the mounting torque sensitivity of vibration and shock pick-ups (e.g., accelerometers) that are mounted with screws, bolts or other threaded fasteners. The standard defines how to determine the change in calibration factor caused by different mounting torques, and applies to tests at one-half of the specified mounting torque, the specified value, and twice the specified value.

Key topics and requirements

• Scope: Tests apply to pick-ups mounted by threaded fasteners; measures change in calibration factor with mounting torque.
• Test range: Three torque points - one-half of the specified torque, the specified torque, and twice the specified torque.
• Test environment: Room temperature maintained at 23 °C ± 3 °C.
• Vibration source: Use vibration equipment that complies with ISO 5347-3 (secondary vibration calibration).
• Fixture and mechanical tolerances:
  • Steel fixture thickness ≥ three times the mounting-screw length, minimum 20 mm.
  • Fixture surface roughness (arithmetical mean deviation) Ra < 1 µm.
  • Surface flatness within two parallel planes 5 µm apart.
  • Drilled/tapped holes perpendicularity: centreline must lie within a cylindrical zone 10 µm in diameter and a height equal to hole depth.
• Torque-measuring equipment: Must have a specified maximum total mounting torque error (the standard indicates less than about 15% of reading).
• Procedure essentials:
  • Use recommended interface and thread lubrication and record it.
  • Apply torque from zero to each test torque in one continuous procedure.
  • Determine calibration factor at the reference frequency and amplitude for each torque.
• Result expression: Torque sensitivity ST (percentage) is calculated from the calibration factors. In general form:
  • ST = ((s_torque – s_specified) / s_specified) × 100
  • Report the maximum torque sensitivity observed.

Applications and users

• Calibration laboratories performing vibration sensor calibration and verification.
• Manufacturers of accelerometers and vibration transducers for production and quality control.
• Test houses and R&D teams assessing the effect of mounting practices on sensor performance.
• Engineers specifying sensor installation requirements for field measurements where mounting torque may affect accuracy.

Related standards

• ISO 5347 series - Methods for the calibration of vibration and shock pick-ups (notably ISO 5347‑3 for secondary vibration calibration).
• Other parts in the ISO 5347 family cover primary/secondary calibration methods, transverse sensitivity, acoustic sensitivity, temperature sensitivity, magnetic sensitivity, and more.

Keywords: ISO 5347-16, mounting torque sensitivity, vibration pick-up calibration, accelerometer mounting torque, vibration sensor calibration, ISO 5347.