New sizes of Crane Electronics' ProWrench Opta digital torque wrenches have been introduced. In addition to the 25, 75 and 180Nm, the high end tools are now available in 300, 340, 750 and 1500 Nm versions. This is in direct response to the growing need by quality departments for accurate torque/angle measurement and paperless documentation. With three measurement modes peak torque, move-on torque and yield, ProWrench Opta has an optional angle measurement function.

The angle function is critical as it is not sufficient to look at the peak torque value to ensure the correct fastening of joints. The clamp load of the fastening process can be influenced by the individual operator, contamination of the thread and friction of the joint. Hence the torque reading on its own is not enough to determine the integrity of the joint. For critical joints additional information of the joint such as angle measurement is essential.

The same applies for auditing already bolted joints by "move-on" or "break-away" tests. The "move-on" or audit test works by setting an audit angle, for example, two degrees. When the digital wrench detects that the joint has moved these two degrees, it records and displays that audit value. To aid the operator, the wrench also gives a visual and audible indication when this audit angle has been reached. To check the operator's performance in measuring the "move-on" torque, the wrench will also display for comparison the final torque achieved. A small difference between the audit and final torque value indicates that the operator has not over-torqued the joint.

Operator acceptance and correct tightening is ensured by the clean user interface. Torque and angle status, e.g. high, ok, low, is clearly indicated by selectable and audible alarms. An extremely useful feature is the graphical representation of applied torque and angle in "real-time". With the help of a bar graph, the operator can see how much torque or angle he is applying and whether the correct level of torque or angle has been reached. Again, upper and lower limits can be set for this feature. It is also possible to display the bar graphs of either torque or angle at the same time as the numerical values.

Crane's digital wrenches are point of load insensitive. This means that the tightening process can be done in a time efficient manner without worrying how the operator is holding the wrench. In particular with the angle function correct measurement is assured even if the operator has to reposition the wrench or use it in ratchet mode. The electronic wrench can be supplied either as a dovetail (Sturtevant Richmont) or DIN standard version.

Setting the torque parameters can be done from a PC or directly on the wrench. Through password protection there is no danger of operator interference or manipulation. The wrench has a large enough memory function to cover most shifts and data load to a PC or network is easy.

Learn more about the ProWrench Opta