HOW LOAD MEASUREMENT WORKS AND HOW WE IMPROVE IT
Direct determination of preload with the intellifast system
Measurement at any time with the Intellifast system
- Verification of the minimum preload
- Prevention of excessive load
- Independent of assembly process
- Display and analysis of preloads in bolted joints
Calibration of your application
- Determination of mechanical & temperature parameters to characterize the behaviour between time-of-flight and preload in joints
- Calibration report
- Export of measurements
What is preload?
- The function of a bolt is to apply load in a bolted joint.
- This clamp force is technically known as preload and is measured in Newtons.
- Preload is what makes a bolted joint work.
Why is preload important?
- Preload is what makes a bolted joint last.
- The correct preload ensures the systemâs safety and durability.
- Optimize bolted joint to save weight, cost and assembly time.
How is preload achieved?
- Either by torqueing or tensioning the bolts.
- There are various technologies and methods under each principle method in practice.
- The challenges with bolt methods are the friction (torqueing) and the relaxation which both vary with geometry, environment, materials, tools, components and much more.
How can preload be measured?
The measured variable âultrasonic time-of-flightâ increases with elongation.
Permanently-mounted transducers are applied to every single bolt and provide more accurate, objectively reproducible measurements and documentation. Two types are distinguished:
- Thin film plasma transducers are the most advanced transducer technology as they are certifiable, robust, environmentally durable and have the biggest temperature range. Moreover, plasma transducers are the only technology to comply with DIN EN 4859.
- Glued on ceramics transducers are advantageous with regard to lead-time and are often used in R&D and process capability studies.
Hand held contact probes are low cost but suffer from higher measurement inaccuracy (reattachment error) leading to high tolerances and reduced repeatability.
With STRAIN GAUGES
- Strain gauges area used to measure the stress inside or outside of the bolt.
- Strain gauges are accurate but expensive in preparation, lead-time and installation.
- Strain gauges usually require mechanical preparation and therefore modification of the bolt.
- The length of the bolt before and after tightening is measured while considering temperature, material and geometry.
- Mechanical or optical tools are used with limited accuracy and repeatability.