A fundamental requirement of successfully achieving jig-less assembly is the ability to repeatedly produce tight tolerance workpieces.
Often these workpieces will be procured from multiple national and international sources, resulting in manufacture in a diverse range of environments.
The resultant effect of these, often non-temperature controlled environments will be inconsistent process repeatability. Consideration of the fact that thermal changes effect the workpiece (aluminum has a coefficient of expansion of 11 ppm/degree F), the machine structure and the position feedback device illustrates some of the many process variables.
Thermal error sources could be drastically reduced if the machine’s position feedback system was insensitive to ambient temperature variation and thermal workpiece effects could be taken into account during machining.
This becomes a practical reality when interferometric laser scales that include real time compensation are installed onto the machine to provide linear position feedback.