System and method for correcting extrinsic loading effects on kinematic accuracy of a machining assembly

A machining assembly comprising:

• a machining tank;
• a positioning system disposed within the machining tank, the positioning system including a base, a cantilevered arm, and a rotary table,
• the cantilevered arm extends between and to a first arm end and a second arm end along a first axis of the cantilevered arm, the cantilevered arm is moveably mounted to the base at the first arm end, and
• the rotary table is mounted to the cantilevered arm at the second arm end, the rotary table is rotatable about a second axis of the rotary table;
• a computer numerical control (CNC) controller configured to control movement of the cantilevered arm and the rotary table, the CNC controller including a processor connected in signal communication with a non-transitory memory storing instructions which, when executed by the processor, cause the processor to:
• determine, using position and orientation correction factors for the first axis and the second axis based on a position and orientation deviation of the first axis and the second axis in a first condition of the machining assembly from the first axis and the second axis in a second condition of the machining assembly, a first estimated position and a first estimated orientation of the first axis and a second estimated position and a second estimated orientation of the second axis, the machining tank empty of a dielectric fluid in the first condition, the machining tank filled with the dielectric fluid in the second condition;
• and
• control movement of the cantilevered arm the rotary table for a machining process of a workpiece installed on the rotary table using the position and orientation correction factors.

A method for correcting extrinsic loading effects on kinematic accuracy of a machining assembly, the method comprising:

• determining,
• for an unloaded condition of a positioning system of the machining assembly including a rotary table, a base, and a cantilevered arm, the rotary table, the base, and the cantilevered arm disposed within a machining tank of the machining assembly, the cantilevered arm movably mounted to and between the base and the rotary table, the rotary table rotatable about a second axis of the rotary table,
• a second unloaded position and a second unloaded orientation of the second axis;
• installing a load on a rotary table;
• filling the machining tank with a dielectric fluid such that at least a portion of the base, the cantilevered arm, and the load is immersed in the dielectric fluid;
• determining, for a loaded condition of the position system subsequent to filling the machining tank with the dielectric fluid, a second loaded position and a second loaded orientation of the second axis;
• determining position and orientation correction factors for the second axis using a position and orientation deviation of the second axis in the loaded condition from the second axis in the unloaded condition;
• and
• machining a workpiece installed on the rotary table with a machining system of the machining assembly by controlling the positioning system, with a controller of the machining assembly, to position the workpiece using the position and orientation correction factors.