Industrializing a new era of precision coating technology

A leading automotive components manufacturer has stood out over the years for its commitment to operational excellence and continuous improvement, employing innovative approaches to optimize processes and ensure customer satisfaction.

The company and its contribution to the future of mobility

For more than 60 years, the group has driven groundbreaking innovations in motion technology. Through advanced technologies, products, and services in electromobility, CO₂-efficient drives, and renewable energy, the company enables customers to operate more efficiently, intelligently, and sustainably throughout the component’s entire lifecycle.

Within this global mobility ecosystem, the company manages the aftermarket business, providing repair and service solutions for passenger cars, light and heavy commercial vehicles, tractors, and two-wheelers. The plant has evolved into a modern solutions provider, combining strong industrial expertise with continuous technological advancement.

The industrialization challenge

The industrialization project focused on developing a coating process for miniature valve balls used in high-pressure gasoline injectors operating under extreme pressure conditions. At the outset:

• The first pass yield (FPY) was just over 5%.
• No suitable DLC (Diamond-Like Carbon) coating process for this application existed.
• Tens of thousands of balls per batch required extremely tight coating tolerances and hardness specifications.
• A fully Automated Optical Inspection (AOI) system capable of rapidly detecting micro-scale defects within a short inspection cycle did not exist.
• Additional unplanned machinery investments of ~€ 2M were looming if process stability could not be achieved.

The project required developing a new coating technology and a fully automated inspection method, supported by rigorous problem-solving routines and strong cross-functional collaboration.

Project objectives: Pioneering innovation and precision for enhanced performance

The industrialization effort was guided by a clear set of goals aimed at achieving excellence in quality, efficiency, and customer satisfaction:

1. Achieve excellence in quality and delivery reliability, reaching an FPY of at least 70%.
2. Develop a new DLC coating process capable of coating tens of thousands of valve balls with uniform thickness.
3. Design an effective ball holder enabling a key customer feature: the uncoated diameter.
4. Develop a 100% AOI system capable of rapidly detecting micro-scale surface defects within a short inspection cycle.
5. Avoid additional unplanned machinery investments by optimizing existing assets.
6. Apply structured problem-solving methodologies to all emerging issues.
7. Ensure 5S, maintenance, and cleaning discipline across all primary and secondary processes.
8. Expand production capacity on time by aligning assets, resources, and workforce.

These were the objectives set for the project, each serving as a cornerstone for driving improvements and ensuring successful industrialization.

Process improvements and kaizen activities

The project embodied the kaizen philosophy, systematically improving output, quality, and competitiveness through targeted enhancements along the entire process chain. To address the technical and operational challenges identified, a series of coordinated improvement initiatives were implemented across each key stage of the production process:

Raw part stage

To ensure a stable foundation for the coating process, significant improvements were implemented at the raw part stage:

• Internal SEM (Scanning Electron Microscope) analysis was performed to reduce surface defects.
• Development of an appropriate heat-treatment process was carried out to meet the required hardness specifications.
• Optimization of the supplier’s cleaning strategy was completed to minimize contamination.
• Introduction of improved packaging dimensions and padding helped protect parts during transport.

These actions helped secure the required raw part quality, minimizing upstream variability and stabilizing subsequent production steps.

Washing stage

A more controlled and contamination-free washing process was essential to prepare the components for coating, resulting in:

• Enhanced filtration and more frequent bath changes, improving overall component cleanliness.
• A contamination-controlled coating environment, preventing recontamination of parts prior to coating.
• Optimized washing baskets and batch sizes, reducing drying stains and ensuring components entered the coating process in optimal condition.

This ensured that every component entered the coating process in an optimal state of cleanliness, reducing defect risk.

Loading stage

The loading stage was redesigned to support higher precision, consistency, and automation through the following improvements:

• An automated loading process engineered with a 2-second cycle time, significantly improving efficiency.
• Application of the shainin methodology to identify and eliminate hidden sources of defects.
• Design enhancements across all component-contact surfaces, ensuring uniformity and minimizing defect risks.
• Introduction of a flow box for contamination-free intermediate storage, preserving part integrity prior to coating.

These improvements strengthened process stability and ensured a repeatable, contamination-free transfer into coating.

Coating stage

The development of a new DLC coating solution required a comprehensive rethinking of the entire coating technology:

• A new coating formula was developed to meet customer specifications for durability and performance.
• Carousel geometry was optimized to ensure homogeneous plasma distribution across the parts.
• A comprehensive cleaning concept was defined, including sandblasting, CO₂ cleaning, and washing, to maintain a clean coating environment.
• Minimum chamber reuse time was defined to ensure the stability of the coating surface.
• A high-vacuum system was implemented for ultra-fine pre-cleaning, ensuring no contamination.

Together, these enhancements enabled a uniform, high-quality coating that met strict customer requirements.

Automated Optical Inspection (AOI)

To guarantee full traceability and reliable defect detection at production speed, Automated Optical Inspection was implemented with the following key elements:

• AOI system capable of detecting surface defects in 2 seconds, producing 30 images per sphere.
• Separate test program developed for early raw-part screening.
• PowerBI dashboard implemented to detect error patterns in grippers, camera stations, and rotary tables.

This robust inspection setup ensured end-to-end quality control and fast identification of deviations.

Magnetic holder

To ensure long-term reliability and consistent part positioning during coating, the magnetic holder concept was enhanced through the following measures:

• The magnetic holder concept was co-developed with the supplier to improve stability during the coating process.
• The lifetime of the holder was extended after multiple design iterations.
• Optimized external decoating ensured complete removal of chemical residues, while the use of particle-free packaging materials prevented contamination during storage and handling.

These adjustments ensured stable holder performance over repeated cycles, contributing directly to coating quality and process longevity.

Tangible outcomes and breakthrough results

The industrialization of the new DLC coating process delivered significant gains across quality, efficiency, and delivery performance. The results reflect the impact of rigorous problem-solving, cross-functional collaboration, and the development of robust processes that support long-term operational excellence.

Major performance gains

The project delivered substantial improvements in quality and efficiency, exceeding all initial expectations.

• FPY increased from 5% to 85%, surpassing the target.
• €5 million reduction in scrap costs.
• Avoidance of ~€2 million in unplanned machinery investment.

Delivery reliability

Process stability and robust planning ensured consistently high delivery performance.

• More than 850,000 valve balls supplied in 45 shipments.
• 95% delivery reliability, resulting in an A-supplier rating.

Stable quality

Since the start of series production, all customer-critical characteristics have met capability requirements, validating the long-term stability of the new process.

Knowledge transfer and transparency

Digital monitoring and structured problem-solving methodologies supported continuous learning and process optimization throughout the project. Successful practices and process improvements developed during the program were subsequently replicated across other customer projects, extending the impact and scalability of the implemented solutions.

Investment avoidance and total savings

Process optimization and scrap reduction enabled the avoidance of approximately €2 million in additional machinery and equipment, contributing to total savings of €5,500,000.

Figure 1 – Project performance cycle

Achieving excellence: A journey of continuous improvement

The project’s success underscores how structured problem solving, disciplined process development, and a sustained commitment to continuous improvement drive measurable results. By creating a completely new DLC coating and inspection process, the team not only achieved substantial gains in quality, efficiency, and delivery reliability but also established a scalable and future-proof manufacturing capability. The learnings and methodologies developed have already influenced other customer programs, reinforcing the company’s position as a reliable partner in the mobility ecosystem.

This project stands as a testament to what can be achieved when expertise, collaboration, and innovation converge toward a shared vision of operational excellence.

The Kaizen Institute supports automotive manufacturers in developing robust processes, enhancing product quality, and ensuring reliable, scalable production. Through structured problem-solving methodologies and a sustained commitment to continuous improvement, we help companies achieve breakthrough results in the automotive industry.

We respect our clients’ confidentiality agreements. While names have been changed or omitted, the results are real.