1. Introduction

CRRC Ziyang Co., Ltd. (“CRRC Ziyang”) is one of China’s core enterprises in rail transit equipment manufacturing and maintenance, specializing in the R&D, manufacturing, and lifecycle services of high-power diesel locomotives, electric locomotives, and their key components. With rail transit equipment evolving towards heavy-duty, high efficiency, and intelligence, and many locomotives entering advanced maintenance cycles, CRRC Ziyang faces urgent demands for fast and precise inspection of large critical parts such as diesel engine blocks, crankshafts, and bogies to ensure operational safety. To overcome the passive situation of relying on outsourced inspections, which cause long cycles, high costs, and disconnected data, CRRC Ziyang partnered with Xi’an AEH Measurement Equipment Co., Ltd. (“AEH”) to establish a workshop-level large precision measurement center covering “inspection-calibration-analysis” within its plant. This world-class precision measurement capability extension to production and maintenance frontline significantly enhances the company’s autonomous quality assurance and rapid response capabilities.

2. Case Background

CRRC Ziyang’s production and maintenance face severe challenges in precise measurement of large, heavy parts:

• First, the huge size and weight of parts like diesel engine blocks, crankshafts, and large gears make external inspection inconvenient, expensive, risky, and time-consuming—outsourced testing can take weeks, severely limiting production and maintenance schedules.
• Second, on-site maintenance lacks high-precision references: key installation surfaces’ flatness and hole position tolerances cannot be measured with sufficiently precise and range-capable tools in the workshop, causing reliance on experience-based judgments.
• Third, quality data chains are broken: external inspection reports are paper-based or simple electronic files, hard to integrate with internal MES or PLM systems, preventing continuous quality data assets for process analysis and predictive maintenance.
  Building an autonomous, efficient, and digital localized precision measurement capability became a strategic choice to enhance CRRC Ziyang’s core competitiveness.

3. Key Approaches

1. Concept Integration: Establishing an upgrade path of “inspection capability sinking, data assets cloudification.”

The project’s core idea is to introduce national-level metrology capabilities into the workshop and let measurement data drive operation and maintenance decisions. The goal is not just installing equipment but building a localized capability center integrating high-precision inspection, equipment calibration, technical training, and data analysis, firmly controlling quality proactively. This aligns with AEH’s strategy as an empowerment partner providing sustainable capability systems.

2. Hard-Core Implementation: Deploying a combined “fixed + portable” measurement solution.

To meet full-scenario needs from fixed part inspection to on-site assembly:

• Fixed large precision measurement fortress: A gantry CMM with ultra-large size (6 meters plus) is installed in a temperature-controlled workshop. It features high-rigidity closed-loop design, precision linear scales, and multifunction probe systems (long stylus contact probes and laser scanners), designed for full-size precision inspection of ultra-large, heavy, and complex parts like engine blocks and gearbox housings.
• Portable on-site measurement tool: A high-precision laser tracker is deployed for maintenance workshops and final assembly lines. Portable and flexible, it achieves micron-level accuracy over tens of meters, solving in-situ measurement challenges for large parts that cannot be moved, such as bogie frame key dimension verification and on-site assembly adjustments.

3. Software-Driven: Realizing seamless intelligent data flow from inspection execution to analysis.

All measurement devices are uniformly driven by AEH’s NET.DMIS measurement software platform, certified by Germany’s PTB, ensuring authoritative data sources.

• Specialized programs improve efficiency: Automated standardized inspection programs for typical parts like crankshafts and camshafts enable operators to quickly measure and evaluate hundreds of parameters, reducing single-piece inspection time by over 50%.
• EMRP platform as data hub: All measurement data (fixed CMM and portable laser tracker) are uploaded in real-time to the EMRP intelligent quality management platform. The platform manages inspection reports and strongly associates each measurement with specific locomotive numbers, part serial numbers, and maintenance work orders. Long-term data accumulation enables analysis of wear trends on key parts (e.g., crankshafts), providing scientific support for predictive maintenance and spare parts inventory optimization, shifting from reactive repair to predictive maintenance.

4. Lessons Learned

The successful establishment of CRRC Ziyang’s localized precision measurement center offers a practical model for China’s large equipment manufacturing and maintenance enterprises to overcome the bottleneck of “measurement reliance on external sources.” It proves that for high-value, frequently inspected, and specialized large enterprises, investing in independent high-end measurement capabilities is a high-return, long-term moat-building strategic move.

The project’s value is first reflected economically: achieving 100% local inspection of key large parts, reducing average inspection cycle from 2 weeks to less than 2 days, and greatly saving costly external logistics and fees. More strategically, it grants CRRC Ziyang “data sovereignty” over the lifecycle health of its core products (locomotives). These continuously accumulated, high-precision measured data become valuable assets for optimizing next-generation product design, formulating scientific maintenance strategies, and developing data value-added services. The “CRRC Ziyang-AEH” model strongly promotes the transition of advanced measurement technology from labs to production frontlines, truly realizing “quality control at the source,” providing crucial support for high-quality and autonomous development in rail transit and heavy equipment industries.