Before investing in equipment to tighten threaded fasteners, engineers should consider these questions.

If the tool is being replaced due to breakdown or wear, there is usually no need to evaluate what tool to specify for its replacement. It’s a simply question of finding a direct replacement or backup tool of the same type and torque capacity.

However, if the torque specification or tightening strategy changes, it’s prudent to determine whether the new requirements justify a new fastening system. In that event, engineers should consider the following questions:

  • Can the current tool handle the new requirements?
  • What are the torque or angle tolerances? Is statistical process control required?
  • Has the existing process been troublesome? Have there been frequent breakdowns or operator complaints about excessive weight, noise, torque reaction or difficulties with maneuverability?
  • Is the fastening workstation a bottleneck? Is there enough cycle time? Would a multispindle power head improve productivity?
  • Is it a good opportunity to re-evaluate the assembly process? Can non-value-added tasks, such as click-wrenching, be eliminated by using a fastening system with closed-loop feedback? Would this save an operator?
  • Should we include a visible indication that the process was completed successfully? Do we need a label printer, paint marker or data acquisition system?
  • What are the warranty costs on this assembly? Can we reduce them by improving the fastening process?
  • Should we look at different types of assembly tools?
  • Does the tool now require fixturing due to high torque requirements? Will ergonomics be compromised?
  • Have the sockets or accessories changed? Are they available?
  • How will the new fastening system affect the power supply? Is a larger air line required? Will it cause fluctuations in electrical power?
  • Is the new fastening specification accompanied by a change in the parts or fasteners? Will this cause increased friction or galling?
  • Will the change affect how the process is audited? Will new measurement equipment be required?
  • Will spare parts be available?
  • Will the supplier offer service and support?
  • Do the operators need training?
  • What procedures should be followed if an assembly is rejected? How will the rejects be tagged?
  • What are we trying to achieve? How will we measure success or failure?