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ASME B18.18.7M-2009 — Quality Assurance Plan for Fasteners Produced in a Customer Approved Control Plan
🔩 ASME B18.18.7M-2009 is the flagship of “preventive quality assurance” in the B18.18 family, succeeding the 1998 edition (developed from IFI-151). It defines how a manufacturer organizes quality assurance when fasteners are produced under a customer approved control plan. The core idea: a written control plan that outlines the fastener manufacturing process and identifies its control points provides an orderly procedure for controlling and minimizing process and product variation. The control plan covers receiving, in-process manufacturing, and out-going operations, with strategies for continued updating and improvement.
💡 Unlike traditional end-of-line sorting, B18.18.7M relies on prevention — control plans plus process monitoring — to significantly reduce nonconformances. In selective applications, performance testing has even replaced traditional final inspection.
1. Scope and Core Concepts 📌
The plan is based on the concept that a written control plan outlining the manufacturing process and identifying its control points provides an orderly procedure for controlling and minimizing process and product variation. Factors usually considered when developing a control plan include:
- Past history: prior quality performance of similar products.
- Machine capacity and capability: process capability of the equipment.
- New or special customer requirement(s): additional or special requests from the customer.
- PFMEA (potential failure mode and effects analysis): systematic identification of potential failure modes and assessment of their effects.
The control plan typically identifies actions at each phase of manufacturing — receiving, in-process, and out-going — distinguishes continuing versus periodic requirements, and provides strategies for continued updating and improvement. Section 2 lists referenced standards, and Fig. 1 shows a typical process flow diagram.
⚠️ Control plan content legitimately varies between manufacturers — control strategies and process charting depend on machinery, plant layout, sensing devices, and product mix. Actual plans may differ significantly, but the authoritative basis is always the written agreement between manufacturer and purchaser.
2. Written Agreement and Part Qualification 🔧
The control plan shall define the respective control elements, including the characteristics and/or process parameters to be verified and the frequency of verification, and shall be agreed to in writing between manufacturer and purchaser. This written-agreement requirement is a defining feature that distinguishes B18.18.7M from other B18.18 documents — quality assurance is no longer decided unilaterally by the manufacturer but confirmed jointly by both parties.
Part qualification is a preproduction assessment of parts for their suitability in intended applications. The purchaser’s assessment varies depending on part usage and previous product history; engineering tests of part and joint function are typically completed with appropriate test records maintained.
| Quality Element | Requirement | Purpose |
|---|---|---|
| Written agreement | Control elements, characteristics/parameters to be verified, and verification frequency agreed in writing | Define quality responsibilities and acceptance criteria |
| Part qualification | Preproduction assessment of part suitability; functional engineering tests with records | Ensure parts satisfy intended application |
| PFMEA | Identify potential failure modes and assess effects and risks | Preventive identification and control of risk |
| Process flow diagram | Outline the manufacturing process and control points | Orderly control of process variation |
3. Lot Controls and Traceability 📊
The Standard sets explicit lot-control requirements:
- Raw material traceability: raw material shall be supplied to the manufacturer traceable to a mill heat of material.
- Subcontracted process control: subcontracted processes, including plating and heat treating, shall be controlled to avoid product lot contamination.
- Finished lot traceability: finished lots shall be traceable to the corresponding records.
Together these requirements form a complete traceability chain from mill heat to finished lot — an essential part of the preventive quality assurance system.
🚨 Raw material traceability and subcontracted process control are both indispensable: uncontrolled plating or heat treating can cause lot contamination or mix-ups that invalidate all prior inspection. Specify process control requirements and traceability documents in subcontracts.
4. Engineering Practice Essentials 🛠️
- 🔍 Customer audit first: the Foreword requires the purchaser to audit the manufacturer’s plant before the written agreement, to verify capability of compliance with the agreed control plan. Schedule a site audit early for first-time cooperation.
- 🔧 Dynamic control plan maintenance: a control plan is not a static document; update it continuously with process improvements and changing customer requirements, distinguishing continuing versus periodic requirements.
- 📋 Apply PFMEA: use PFMEA as an input to control plan development to systematically identify failure modes and set control points and monitoring methods.
- 📐 Build the traceability chain: start traceability records from the mill heat number, covering subcontract operations such as plating and heat treating, through to finished lots.
- 📝 Keep written agreements on file: retain the agreed control plan, control elements, and verification frequencies in writing as the basis for resolving quality disputes.
✅ Practice tip: organize the control plan around a typical process flow diagram, include key characteristics and key process parameters (e.g., heat-treat temperature, plating thickness) in periodic monitoring, and establish a clear cadence for continuing/periodic verification.
5. Frequently Asked Questions ❓
❓ Q: How does B18.18.7M differ from the B18.18.1–4 series?
A: B18.18.1–4 focus on inspection frequencies and sampling plans, while B18.18.7M centers on the customer approved control plan, emphasizing written agreement between the parties, preventive process control, and continuous improvement — with the possibility of replacing final inspection with performance testing.
A: B18.18.1–4 focus on inspection frequencies and sampling plans, while B18.18.7M centers on the customer approved control plan, emphasizing written agreement between the parties, preventive process control, and continuous improvement — with the possibility of replacing final inspection with performance testing.
❓ Q: What is part qualification?
A: It is a preproduction assessment of parts for their suitability in intended applications. The depth of the assessment depends on part usage and prior product history, typically accompanied by engineering tests of part and joint function with test records retained.
A: It is a preproduction assessment of parts for their suitability in intended applications. The depth of the assessment depends on part usage and prior product history, typically accompanied by engineering tests of part and joint function with test records retained.
❓ Q: What must a control plan contain?
A: At minimum, the characteristics and/or process parameters to be verified and the frequency of verification, with actions covering receiving, in-process, and out-going phases. Specific content may vary by machinery, layout, and product mix, subject to the written agreement.
A: At minimum, the characteristics and/or process parameters to be verified and the frequency of verification, with actions covering receiving, in-process, and out-going phases. Specific content may vary by machinery, layout, and product mix, subject to the written agreement.
❓ Q: What are the raw material and lot control requirements?
A: Raw material must be traceable to a mill heat; subcontracted processes such as plating and heat treating must be controlled to avoid lot contamination; finished lots must be traceable to the corresponding records, forming a complete traceability chain.
A: Raw material must be traceable to a mill heat; subcontracted processes such as plating and heat treating must be controlled to avoid lot contamination; finished lots must be traceable to the corresponding records, forming a complete traceability chain.
