TurnaSure Bolting Technology for Automotive Applications

Caterpillar Carrier

Many of the benefits described for engineers designing steel structures above also apply to these bolting applications. Direct Tension Indicators (DTIs) are now standardized for many of these applications under ASTM standard F2437.

DTIs guard against vibration loosening. A bolting technology research conducted at SPS Contract Research in Jenkintown PA, USA using the Junker's loosening testing methods, found that at the same degree of clamping forces the connections with DTIs in the grip of the bolts did not loosen, where as the bolts without DTIs tended to loosen more readily.

DTIs help control cyclical stresses. On direct tension connections which are subjected to stress cycles, and a very common connection here, high accurate clamping forces, greater than the cycles of applied loading and the one guard against fatigue failure or simply the subsequent loosening of the fasteners. DTIs provide, unequivocally, easily verifiable tension levels in an installed fastener. DTIs can show these levels of tension have been achieved. The yield point of the fastener is where one gets the "most bang for your bolt". This is often the "target" in many automotive applications.

DTIs guard against permanent loss of load after a prying forces has been applied. An independent University Study in Leeds, England shows that contrary to assumptions, a DTI helps the assembly recover its load after an over load or prying force is applied to the connection. This is like a catastrophic over load. The conclusions are that there is more spring, or "bounce back" in the protrusions than there is in the bolts themselves. TurnaSure’s high end bolting technology, DTIs, therefore can act like a shock absorber.

ASTM F 2437-06 for Carbon Steel Compressible-Washer-Type Direct Tension Indicators for use with Cap Screws.