GRAVITY CASTING – STRENGTH AND PRECISION
Gravity casting is quite different to Die (Pressure) Casting used by many longboard truck manufacturers. It is more expensive to produce as fewer trucks can be made on a “tree” (which is why Sabre Cast trucks cost more), but allows the use of stronger aluminium alloys, with fewer air bubbles. The result is a stronger, less brittle finished truck.
Molten Aluminium is hand-poured into the mould – as opposed to die casting where molten metal is injected into the mould at high pressure. The mould is then inverted, allowing the pull of gravity to fill the mould cavities with molten metal. The end result is a strong, consistent cast right through the truck.
Gravity cast skateboard trucks can be cast using sand moulds (“Sand Casting”) or heat-treated steel moulds. We use Steel Moulds – a more expensive option, but we feel the precision finish that is attained is worth the extra cost. Areas that require high tolerances (pivots, kingpin holes, hanger faces etc) are CNC’d to give a precise fitting prior to heat treatment.
Gravity casting allows us to use 356 aluminium, not ADC10 or ADC 12, or 356 that has been “diluted” with ADC to reduce the viscosity of the aluminium for die casting (Commonly called “356.2″).
We use Gravity Cast 356 Aluminium in Precision Steel Moulds for our “GC series” components because it is the process that gives us the best balance of strength and precision.