Limitations of Precision Transfer: No machine can produce parts that are more precise than itself. This is because the errors inherent in the machine itself will be transferred to the parts being processed, thereby preventing the parts from achieving a higher precision than the machine itself.
Error Accumulation: During the machining process, errors from the machine tool, cutting tools, and operational procedures all contribute to a decline in part precision. This accumulation of errors means that the precision of the parts cannot exceed that of the mother machine.
The Impact of the Maternal Nature Principle
Technical Difficulty and Cost: To manufacture high-precision parts, higher-precision mother machines are required, which significantly increases the technical difficulty and cost. For example, to produce a lithography machine worktable with a precision of 0.1 micrometers, at least five generations of machine tool upgrades may be necessary.
Precision Degradation: Precision degrades exponentially. The precision of parts produced in each generation of machining will decrease. For instance, engineers at Makino, a Japanese machine tool company, conducted a limit test and found that after using the same machine to replicate a spindle three times in succession, the precision of the third-generation spindle plummeted by 40%.
Methods to Address the Maternal Nature Principle
Iterative High-Precision Machines: Continuously iterating and upgrading high-precision machine tools to gradually improve machining precision. For example, using ultra-precision machining centers to manufacture more precise parts.
Process Compensation: Employing process techniques and specialized tools to compensate for the shortcomings of the machine tool. For example, Okuma, a Japanese machine tool company, uses a scraping process that leverages oil film tension to offset geometric errors, significantly enhancing machine precision.
Intelligent Compensation Systems: Utilizing advanced sensors and compensation systems to monitor and adjust errors in real-time during the machining process. For example, the thermal, vibrational, and force tri-field coupling compensation system in Trumpf laser cutting machines can predict deformation trends up to 15 minutes in advance and dynamically adjust the tool path.
Breaking Through the Maternal Nature Principle
Creative Machining Principles: Adopting an "evolutionary" machining principle to break through the limitations of the traditional maternal nature principle through innovative machining methods and techniques. For example, by designing special processes and selecting appropriate materials, it is possible to manufacture parts that are more precise than the mother machine.
Improvements in Basic Materials and Processes: Achieving breakthroughs in basic material science and machining processes to enhance the overall performance of both machine tools and parts. For example, using high-precision hydrostatic and gas hydrostatic bearing technologies to achieve micrometer and even nanometer-level machining.
The principle of maternal nature is an important concept in the field of mechanical machining. It reveals the relationship between the precision of machine tools and the precision of machined parts, while also providing direction and ideas for improving machining precision.
