What's On The End Of Your Torque Wrench?

Interchangeable heads are NOT all the same. This section of our website walks through the differences and why those differences truly matter. 

Two-Piece Welded Heads

One method cuts the head from a wrench and welds it onto a plug or stay. A two-piece head that was welded together is fast to make and the cost of creating that head can be relatively inexpensive.

We are not saying that the two-piece welded heads are bad and should not be used because that is not true. What is true is that with the cut and weld approach comes a number of questions that must be asked to determine if this approach is right for you:

  • Do the types of metal used in the head and the plug match?
  • Is the surface where the head and the plug meet large enough to withstand the amount of stress being placed on the weld?
  • Was the weld done correctly or are there imperfections and fissures that damage the structural integrity of the piece?
  • How was weld quality determined? Did they Magna flux, Xray, or just visual inspection?
  • Will all the heads fit on all of the wrenches or must I buy multiple wrenches and heads to cover different fastener sizes within the same torque range?
  • Were both pieces of metal heat treated? If so were they both heat-treated in identical ways and at an identical place in the manufacturing sequence?
  • Were the separate pieces stress relieved? If so, how far into each piece?
  • What type of welding was used to create the head?
  • Are the welded pieces straight? 
  • Is a common centerline maintained across all cut and weld heads?
  • What is the likelihood of the piece snapping or breaking?
  • How much backup stock will I have to inventory and control?
  • When it breaks, what is the cost of injury and equipment loss?

If you are considering buying welded heads you should get very satisfactory answers to the questions listed above before purchasing them. There is no universal standard for rating cut and weld heads. Each company creates its own.

One-piece heads have both a proof and fatigue rating that tells you how much stress those heads can take. 

The bigger issue we see with cut and weld heads is the need to buy multiple heads and wrenches to cover the same torque value with different size fasteners. This goes back to the question of the head and plug surface area is large enough to withstand the force placed on them. Larger fasteners require larger heads. Larger heads require larger plugs. Larger plugs require different wrenches. Fully evaluate everything before buying the cut and weld heads. 

One Piece Heads

One piece, cast interchangeable heads for torque wrenchesThe other is to carefully design and cast a one-piece head. Engineering and casting a one-piece head takes time and the cost of creating that head is higher.  Like anything else, you get what you pay for. 

The total cost of ownership of one-piece heads tends to be much lower than cut and weld heads when you account for the total required inventory of heads and wrenches, breakage, etc. 

The Sturtevant Richmont interchangeable heads solution offers accuracy, reliability, durability, and lower cost of ownership.  Part of what determines durability is materials. Part of durability is designed in. 

For example, our heads have interior and exterior rounded corners. While that may not seem to be significant, there is more to it. Airplane windows started out being square. The vibration and stress factor vectors met at the window corners. As a result of the vector intersection, the windows cracked and broke. That is not a comforting event at 35,000 ft.  The airlines learned quickly and redesigned their windows to have rounded corners so the stress vectors dissipated. 

When considering the number of tools and heads in your plant, explore all aspects of performance and cost. You'll see the difference.



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 Sturtevant Richmont tools are proudly made in Carol Stream, Illinois by highly capable hands.