Procurement Glossary
Series release: quality assurance for the start of series production
November 19, 2025
The series release is a decisive milestone in the product development process, in which the quality and production readiness of a product is finally validated before series production begins. It ensures that all quality requirements are met and series production can begin. Find out below what series release means, which methods are used and how you can successfully minimize risks.
Key Facts
- Final quality validation before the start of series production through systematic test procedures
- Based on defined criteria such as process capability, quality indicators and supplier audits
- Reduces series start-up risks and prevents costly quality problems
- Requires interdisciplinary cooperation between Procurement, Quality and Development
- Documented by release certificates and test reports for traceability
Contents
Definition: Series release
Series release is the formal process for validating the suitability of a product or component for series production before the start of large-scale production.
Core elements of the series release
The series release includes several critical components:
- Validation of process capability through statistical evaluations
- Proof of compliance with all specifications and tolerances
- Confirmation of supplier capability through supplier audits
- Documentation through PPAP documents and test certificates
Series release vs. initial sampling
While the initial sampling represents the initial quality assessment of prototypes, the series release validates the final production readiness under series conditions. It takes place after successful pilot production and confirms the stability of all processes.
Importance of series release in Procurement
For Procurement , series approval is a central quality gate that minimizes supplier risks and reduces quality costs. It forms the basis for long-term supplier partnerships and ensures compliance with quality agreements.
Methods and procedures
The series release follows structured methods for systematic quality validation and risk minimization.
PPAP procedure (Production Part Approval Process)
The PPAP process forms the backbone of series release. It comprises 18 defined elements from design approval to process validation. Suppliers must provide all the required evidence before series approval is granted.
Statistical process validation
The process capability is assessed using Cpk values and SPC analyses. Minimum requirements such as Cpk ≥ 1.33 must be verified. Long-term studies on process stability are also carried out.
Audit and evaluation procedures
Systematic layered process audits validate compliance with quality standards. FMEA analyses identify potential risks and define appropriate preventive measures for the start of series production.
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Key figures for controlling series releases
Effective KPIs enable the measurement and optimization of series release processes for continuous improvement.
Process KPIs
The processing time from the approval request to the final approval measures the process efficiency. First-pass yield of the approval processes shows the quality of the preparation. The number of follow-up requests per approval identifies potential for improvement in supplier preparation.
Quality KPIs
Cpk values and process capability indices evaluate the statistical process stability. Quality costs due to series start-up problems measure the effectiveness of the release processes. PPM rates (parts per million) in the first months of series production validate the release quality.
Supplier KPIs
PPAP completeness and supplier adherence to deadlines evaluate the cooperation. Number of deviation approvals per project shows development quality. Audit results and implementation of corrective measures measure continuous improvement.
Risks, dependencies and countermeasures
Series release processes involve various risks that can be minimized through systematic preventive measures.
Quality and process risks
Insufficient process validation can lead to series start-up problems. Unstable processes cause quality fluctuations and rework. Countermeasures include strict control plans and continuous MSA validation of test equipment.
Supplier dependencies
Delays at suppliers can jeopardize the start of series production. Incomplete PPAP documentation leads to release delays. Risks are minimized through early supplier integration and regular lessons learned from previous projects.
Compliance and documentation risks
Missing or incomplete documentation can have legal consequences. ISO 9001 requirements must be met in full. Systematic checklists and digital workflows ensure complete documentation and traceability.
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Practical example
An automotive supplier carries out the series release for a critical safety component. After successful pilot production, 300 parts are manufactured under series conditions and statistically evaluated. The Cpk values of all critical characteristics exceed 1.67, the FMEA evaluation shows no critical risks. A layered process audit is carried out in parallel with a positive result.
- Complete PPAP documentation is submitted and validated
- Process capability studies confirm stable series production
- Final release takes place after a positive overall assessment
Trends & developments around series releases
Digitalization and new technologies are fundamentally changing series approval processes and enabling more efficient quality validation.
Digital quality documentation
Digital platforms replace paper-based processes and enable real-time tracking of approval statuses. Cloud-based systems significantly improve collaboration between suppliers and OEMs. Traceability is optimized through digital traceability systems.
AI-supported quality analysis
Artificial intelligence is revolutionizing data evaluation for series releases. Machine learning algorithms automatically recognize quality patterns and anomalies. Predictive analytics enables early risk identification and proactive quality control.
Integrated supplier evaluation
Modern approaches combine series releases with continuous supplier evaluation. Real-time monitoring of delivery quality flows directly into approval decisions. Blockchain technology guarantees tamper-proof proof of quality.
Conclusion
Series release is an indispensable quality instrument that minimizes series start-up risks and ensures long-term product quality. Systematic validation of processes and supplier capabilities avoids costly quality problems. Digital technologies and AI-supported analyses are revolutionizing the efficiency and precision of approval processes. Successful series approvals form the foundation for stable supplier partnerships and sustainable quality excellence.
FAQ
What is the difference between series release and initial sampling?
Initial sampling validates prototypes and pre-series, while series release confirms final production readiness under series conditions. It takes place after successful pilot production and includes more extensive statistical evidence of process stability.
Which documents are required for a series release?
Complete PPAP documents, process capability studies, FMEA analyses, audit reports and test certificates are required. Control plans, MSA studies and long-term stability certificates must also be available.
How long does a typical series release take?
The lead time varies between 2-8 weeks depending on the complexity. Critical safety components require longer validation times. Complete supplier preparation and digital processes can significantly reduce the duration.
What happens in the event of a negative series release?
In the event of a negative assessment, identified defects must be rectified. Containment measures prevent defective parts in the supply chain. Following corrective measures, a new assessment is carried out until positive release.
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