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| articles:source_inspections [2022/01/13 18:00] – [What are Source Inspections?] rrandall | articles:source_inspections [2022/01/14 09:47] (current) – [What are Source Inspections?] rrandall |
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| ===== What are Source Inspections? ===== | ===== What are Source Inspections? ===== |
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| A “Source Inspection" is different from a “Supplier Audit” (or Product Audit) because it is an “__inspection__” (not an audit). Unlike a Supplier/Product Audit (which follows a product through its entire production process – verifying that requirements have been met). A Source Inspection either takes place at: | A “Source Inspection" is different from a “Supplier Audit” (or Product Audit) because it is an “__inspection__” (not an audit). Unlike a Supplier/Product Audit (which follows a product through its entire production process – verifying that requirements have been met), a Source Inspection either takes place at: |
| * the end of the production line (e.g., inspecting a sampling of completed/finished parts/assemblies within a lot/batch or of a single part/assembly representative of the first production lot/batch (i.e., a First Article Inspection)) | * the end of the production line (e.g., inspecting a sampling of completed/finished parts/assemblies within a lot/batch or of a single part/assembly representative of the first production lot/batch (i.e., a First Article Inspection)) |
| * at a specific point in the process (i.e., an "in-process" inspection) | * at a specific point in the process (i.e., an "in-process" inspection) |
| * the raw material certifications (e.g., Certificate of Analysis, Material Test Reports) supports that the material used complies with the requirements for the finished product. | * the raw material certifications (e.g., Certificate of Analysis, Material Test Reports) supports that the material used complies with the requirements for the finished product. |
| * that any “Special Processes” are supported by certificates from the processing operation (whether in-house or outsourced). The Aerospace industry usually requires those special processes to be [[https://p-r-i.org/nadcap/accreditation/|Nadcap accredited]]. | * that any “Special Processes” are supported by certificates from the processing operation (whether in-house or outsourced). The Aerospace industry usually requires those special processes to be [[https://p-r-i.org/nadcap/accreditation/|Nadcap accredited]]. |
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| | While a "Source Inspection" typically involves the Inspector personally performing the inspection activities, there are valid reasons for why an Inspector may instead, choose to "witness" a supplier's employee(s) performing the inspection activities. The most common reason for this is that the Inspector does not have the portable measuring instruments necessary for performing the inspection. While the Customer may require the Supplier to provide the necessary measuring instrumentation, this can introduce a liability (e.g., the Inspector inadvertently damaging the supplier's measuring instrumentation). Witnessing, rather than performing the inspection, greatly mitigates this liability. |
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| | Witnessing an inspection activity, rather than performing it, also provides some benefits. For example, witnessing the inspection(s) allows the "Source Inspector" to verify that the supplier's employee(s), whether production personnel or quality control inspectors - possess the knowledge, skills, and ability (KSA) to: |
| | * Read and understand applicable drawings/specifications (e.g., GD&T - Geometric Dimensioning and Tolerancing) |
| | * Verify correct raw material was used (e.g., through associated Material Test Reports, Chemical Analysis Reports) |
| | * Verify correct welding/brazing filler material was used (e.g., through associated Certified Material Test Reports) |
| | * Verify correct soldering material (solder wire, solder paste, solder bar) was used (e.g., lead-free solder vs. lead solder) |
| | * Availability and proper use of measuring instruments required for the inspection |
| | * Maintain an acceptable accuracy ratio (between the measuring instrument accuracy and the tolerance(s) being measured) |
| | * Verify consistency of any visual inspections with the specifications |
| | * Verify proper understanding and use of representative standards (e.g., visual inspections) |
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| === Sampling === | === Sampling === |
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| When a Source Inspection takes place at the end of the Production Line, it usually involves a much larger sampling of finished products (based on the AQL or AOQL selected) than would be possible during a "Product Audit". The AQL is the "Acceptance Quality Limit"... which is defined as the “//quality level that is the worst tolerable process average//” (Ref. [[https://www.iso.org/standard/1141.html|ISO 2859-1:1999, sec. 3.1.26]]). The AQL is normally based on sampling tables contained in either the [[https://asq.org/quality-resources/z14-z19|ASQ/ANSI Z1.4 or Z1.9 Standard]]. The AOQL is the "Average Outgoing Quality Limit" and is typically based on tables contained in the book "[[https://www.amazon.com/Acceptance-Number-Sampling-Plans-Fifth/dp/0873897390/|Zero Acceptance Number Sampling Plans]]", (Fifth Edition) by Nicholas L. Squeglia. | When a Source Inspection takes place at the end of the Production Line, it usually involves a much larger sampling (e.g., including parts/assemblies from multiple shifts and multiple workers) of finished products (based on the AQL or AOQL selected) than would be possible during a "Product Audit". The AQL is the "Acceptance Quality Limit"... which is defined as the “//quality level that is the worst tolerable process average//” (Ref. [[https://www.iso.org/standard/1141.html|ISO 2859-1:1999, sec. 3.1.26]]). The AQL is normally based on sampling tables contained in either the [[https://asq.org/quality-resources/z14-z19|ASQ/ANSI Z1.4 or Z1.9 Standard]]. The AOQL is the "Average Outgoing Quality Limit" and is typically based on tables contained in the book "[[https://www.amazon.com/Acceptance-Number-Sampling-Plans-Fifth/dp/0873897390/|Zero Acceptance Number Sampling Plans]]", (Fifth Edition) by Nicholas L. Squeglia. |
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| The most practical difference between choosing an AQL or AOQL is that the [[https://asq.org/quality-resources/z14-z19|ASQ/ANSI Z1.4 & Z1.9 Standards]] allow a certain number of defective products to be identified in the sample, and the entire lot/batch can still be accepted. In contrast, when using the sampling approach described in the book "[[https://www.amazon.com/Acceptance-Number-Sampling-Plans-Fifth/dp/0873897390/|Zero Acceptance Number Sampling Plans]]", if a single defect is found, then the entire lot/batch must be rejected and undergo a 100% inspection. | The most practical difference between choosing an AQL or AOQL is that the [[https://asq.org/quality-resources/z14-z19|ASQ/ANSI Z1.4 & Z1.9 Standards]] allow a certain number of defective products to be identified in the sample, and the entire lot/batch can still be accepted. In contrast, when using the sampling approach described in the book "[[https://www.amazon.com/Acceptance-Number-Sampling-Plans-Fifth/dp/0873897390/|Zero Acceptance Number Sampling Plans]]", if a single defect is found, then the entire lot/batch must be rejected and undergo a 100% inspection. |
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| (e.g., from multiple shifts and multiple workers). So the likelihood of a nonconformity being identified during a Source Inspection is greater than what might be found during a Supplier/Product audit. | |
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| === First Article Inspection === | === First Article Inspection === |
| Where a sufficient sample size has been taken, the "Source Inspection" results "may" be used as justification for parts/assemblies to bypass any Receiving Inspection process (as this has already been performed at the supplier's site). | Where a sufficient sample size has been taken, the "Source Inspection" results "may" be used as justification for parts/assemblies to bypass any Receiving Inspection process (as this has already been performed at the supplier's site). |
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| | And where nonconformities are identified during the "Source Inspection" these issues can be addressed prior to parts/assemblies leaving the supplier's facility. In addition to reducing time and transportation expenses, it also allows for the supplier to correct its processes to better ensure that only conforming product is produced. |
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