Testing Overview

As common off-the-self solutions, bolted joints are often designed and implemented without significant analysis. However, ensuring any bolted joint is reliable will always require at least one of the following:

  • An application where there are no working loads acting on the joints
  • An application where one can  afford to overdesign each joint to a comfortable degree
  • A lot of luck, over an indefinite period of time
  • Testing

Why? First, threaded fasteners are very often the most highly stressed element in a product. That high stress amplifies the impact of all the dimensional and material variation inherent in an assembly. Predicting this variation during analysis is a grim task. Second, because it is rarely practical totighten a production fastener to a given tension (the quantity on which the joint design is based), other parameters such as torque are used instead. The relationship between torque and bolt tension is directly impacted by this same dimensional and material variation, creating another source of uncertainty.

Fix Problem Joints Permanently
Specialized equipment and experience beats trial and error when tasked with trouble-shooting the latest joint problem. Getting to the root of the problem solves them permanently.
Measure Bolt Tension Directly
Tension, not torque, determines bolted joint capacity. Buying more accurate torque wrenches doesn’taddress the real problem of understanding the torque-tension relationship. Our test methods do – without joint modification.
  Which Locking Method is Best?
Selecting the right locking hardware or adhesive for your application can be difficult because the basis of performance claimsare often unknown, unsuitable or biased. We have developed a unique test capability to provide reliable and objective answers.
  Determine Installation Torque
Reference tables for installation torque are often highly inaccurate, particularly for parts that aren’t carbon steel. We can determine values specific to your application.
  Settle Competitive Debates
Third-party benchmarking and testing provides impartial test data and interpretation. Effective decision-making requires this objectivity.

Tests Commonly Performed by Archetype Joint

  • Establish recommended target torque
  • Calculate bolt friction coefficient (K factor)
  • Bench top torque-angle-tension testing (with load cell)
  • In-joint torque-angle-tension testing (with ultrasonics)
  • In-joint torque-angle testing
  • Measure and monitor clamp load real-time with ultrasonics
  • Measure residual torque in assembled joints
  • Determine joint rates (hard, soft joint) and presence of component yield
  • Determine deflection curves for gaskets or joints.
  • Establish bolt tightening strategies and parameters
  • Joint slip load or coefficient of friction testing
  • Hardness testing
  • Monitor joint relaxation(temperature/humidity available)
  • Troubleshoot inefficiencies or poor yield of production joints
  • Fastener selection – head/drive/thread form
  • Installation tool accuracy and repeatability
  • Competitive benchmarking of fastener use and installation strategy

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