The CNC’s precision has been greatly improved, and the original fitter function has been largely stripped.
The fitter function is divided into several categories:
1. When the machining accuracy of the machine tool is insufficient, it is necessary to achieve the assembly i precision by the fitting of the fitter. This function is due to the improvement of the precision of CNC processing equipment. The function of this part of the fitter has become lower and lower. In developed countries such as Europe and the United States, this part of the work has been peeled off from the fitter.
2. The assembly of the mold, this work must be carried out by the fitter and cannot be replaced.
3. Mold modification, adjustment and disassembly, etc. must also be carried out by the fitter.
The generalized fitter needs to have very good manual work, and can carry out various types of machined parts through manual research and development to meet the needs of machine and equipment. Since the CNC machining precision has been improved, such fitter functions have become weaker and weaker. Most of them are just assembly workers.

I believe that advances in technology will eliminate a lot of manual work, but it is impossible to completely replace people.
Let me make three points for discussion.
1. Minimum step size problem: Any machine has a minimum step size, which alone will greatly deviate from the ideal model. And people can be solved by repeated grinding, which is very easy to solve relative to the machine.
2. Degree of freedom degree of freedom (DOF) and kinematics:
The hand has 25 degrees of freedom (not counting the arm) to win the machine, which is why the man is more flexible than the machine;
The movement of the machine is completely under the control of the dynamic model, and for people, it seems that no one needs to establish the equation before the exercise;
Machines (such as robots) must constantly use the attitude transformation matrix to adjust the pose, and continuously solve the pose equations inversely. The human hand is a real-time feedback sensor that adjusts the pose in real time, continuously, and without calculation.
3. The machine’s ability to control the output force is lower than the ability of the human brain’s nervous system to control motion, plus the difference between visual and tactile feedback and processing. (Because there is no research on biology, I dare not say more)