The highest strength to weight mateirals
Lightweight Polymer Fasteners
One of the best methods to save considerable weight is to replace metallic fasteners with lightweight, metal-like polymer fasteners. Recent developments in polymer technology have finally produced lightweight polymers that can rival metals in may of their physical and mechanical properties. Taking weight into consideration, polymers such as lightweight PEEK and PAI (Torlon®), can provide specific strengths that exceed that of metallic fasteners.
Lightweight Aluminum Fasteners
If a polymer can't be used, perhaps the best choice for many lightweight fastener applications is Aluminum 7075 bolts. Often used in aerospace for their light weight strength, Aluminum 7075 screws offer strength that is comparible to many grades of steel at a fraction of the density. They can also be tempered to several conditions including 7075-T6 for different levels of strength. In comparison to Titanium grade 5, 7075 is not as strong (83ksi tensile strength vs 148 if titanium), but they are lighter weight.
Lightweight Titanium Fasteners
One property that stands out when compared to other metal fasteners is that titanium screws, especially titanium grade 5 screws, have the highest strength-to-weight ratio that is commercially available. This makes titanium fasteners ideal for applications that require both lightness of weight and excellent strength such as oil & gas (down-hole), military and sporting goods. Titanium screws made of grade 5 titanium are 4 times stronger than 316 stainless steel at nearly half the weight.
The chart below can be used to compare the properties of our lightweight, metal-like polymer fasteners with the properties of metallic fasteners.