*3.3.3 Manufacturing technology of CNC machine tool by using FMA*

Manufacturing technology is important to guarantee the reliability of CNC machine tools. Assembly, the last step of manufacture, also inadvertently affects the reliability of CNC machine tools. The research on CNC machine tools' assembly reliability by using FMA can be categorized into the following two areas:

1. Assembly error transfer link graph.

Screw loosening

• geometric position error;

**Table 3.**

**59**

*MU-FMEA (partial).*

**Metaaction**

Worm rotation **Mode Failure mode**

Rotation No

action of worm rotation

*DOI: http://dx.doi.org/10.5772/intechopen.85163*

Worm vibration Servo motor damaged

*Reliability Technology Based on Meta-Action for CNC Machine Tool*

Coupling broken Bearing jammed

Bearing vibration

Bad assembly of bearings Bearing cannot keep correct position Nut loosening Entry of foreign bodies Bad lubrication Worm root broken Teeth pitting, wear or gluing Wear, pitting, and gluing of upper gear disc surfaces Bad assembly of large bearings Bad lubrication of large bearing

**Failure cause Failure effects Detection Improvement**

Hindering the parts processing

Hindering the parts processing

**Final effects**

**effects**

Loss worm's and gear shaft's function

Worm and gear shaft vibration

**measures Local**

Instruments Maintaining or

Instruments Maintaining or

type.

Strengthening the assembly accuracy control of bearings. Improving assembly process of the bearings. Strengthening the assembly quality inspection measures. Inspecting the state of nuts and bearings regularly

replacing the couplings, nuts. Improving protection and sealing structures. Changing the lubricating mode or

replacing the motors, couplings, bearings. Improving assembly process of bearings and couplings. Strengthening the assembly quality inspection. Inspecting the state of bearings regularly

• geometrical shape error;

• assembly position error;

The assembly errors of the MU can be categorized into five aspects, namely:

