Technology

All of Mettec bolts are made from aircraft-grade titanium alloy. One of the outstanding benefits of Mettec bolts is that they feature forged heads for superior strength. The threads are then rolled to produce greater fatigue durability and reduce galling.

Mettec bolts exceed minimum Ultimate Tensile Strength (UTS) of 120,000 psi. Mettec can also make titanium bolts that exceed 160,000 psi in Ultimate Tensile Strength (UTS). Both styles of bolts conform to DIN and ASTM specifications. Titanium bolts can replace both grade 5 and grade 8 steel bolts which have minimum UTS requirements of 120,000 psi and 150,000 psi respectively. Metric bolts with an 8.8 rating can be replaced with titanium while bolts with a 10.9 rating can sometimes be replaced with titanium depending on intended use. Any bolts with a rating over 10.9 rating should not be replaced with titanium.

Torque accuracy on fasteners

Screw threads appear to be a simple concept yet much confusion and inconsistency exist regarding torque values. The mechanics of the screw thread are actually very complex and have numerous interacting variables. Sliding friction is affected by materials (like steel or aluminum on titanium), surface roughness, bearing area, material hardness, lubrication and so on.

Accuracy: Tightening is not an accurate science, look at the pre-loading accuracy published in the "Machinery's Handbook, 25th Edition, page 1404".

Recommended torque spec's for titanium fasteners

Use torque values specified by your equipment manufacturer, when available. For titanium fasteners the torque values are listed below. Mettec recommends anti-seize or moly paste be applied to the threads.

The importance of correct application cannot be overemphasized. Undertorque can result in unnecessary wear of nuts and bolts as well as the parts they hold together. When insufficient pressures are applied, uneven loads will be transmitted throughout the assembly which may result in excessive wear or premature failure due to fatigue. Overtorque can be equally damaging because of failure of the bolt or nut from over-stressing the thread areas.