| Quality Management | Documented quality management system | Current quality procedures covering incoming materials, production, inspection, nonconforming products, corrective action, and record retention. ISO 9001:2015 | Request a valid certificate, certification scope, issuing body, audit status, and a sample of controlled inspection records. | High |
| Product Standards | Use of recognized O-ring specifications | Drawings and inspection plans should define inside diameter, cross-section, tolerances, material, hardness, surface condition, and acceptance criteria. Common references include ISO 3601 and AS568 where applicable. ISO 3601 / AS568 | Compare the supplier drawing with the application drawing and confirm whether dimensions are controlled under the same standard. | High |
| Material Traceability | Traceable rubber compound and batch control | Each production batch should be linked to raw-material records, compound formulation or approved compound code, mixing date, cure date, and final inspection results. | Ask for a sample batch card, material certificate, incoming inspection record, and traceability procedure from finished part to raw material. | High |
| Material Selection | Elastomer matched to temperature, fluid, pressure, and environment | Material selection should be based on actual service conditions. Typical elastomer families include NBR for many petroleum-based fluids, EPDM for hot water and certain polar fluids, FKM for higher-temperature and chemical resistance, and silicone for wide-temperature flexibility where compatible. | Provide the complete media list, operating temperature range, pressure, motion, and exposure conditions. Request compatibility data and application-specific validation. | High |
| Hardness Control | Stable and correctly specified rubber hardness | Hardness should be specified in Shore A according to the agreed standard and measured with calibrated equipment. Common O-ring grades may be approximately 70 Shore A, but the correct value depends on sealing design and operating conditions. | Check the approved material specification, test method, calibration records, and batch results. Confirm the permitted tolerance before production approval. | High |
| Dimensional Accuracy | Control of inside diameter and cross-section | Dimensions should be inspected using calibrated gauges or suitable optical and contact measuring equipment. Acceptance limits must follow the approved drawing or applicable O-ring dimensional standard. | Request a dimensional inspection report from multiple samples and confirm the sampling plan, measurement method, equipment accuracy, and lot identification. | High |
| Visual Quality | No critical surface defects | Parts should be free from cuts, cracks, blisters, excessive flash, flow marks, foreign material, poor joints, and other defects that could affect sealing performance. Visual limits should be documented. | Review the supplier's visual inspection standard and approve physical samples under defined lighting and inspection conditions. | High |
| Curing Process | Controlled vulcanization and mold process | The factory should control compound preparation, mold condition, curing temperature, curing time, pressure, mold release, and post-curing requirements where applicable. | Review process parameters, equipment maintenance records, first-article approval, and evidence that changes are formally authorized. | High |
| Performance Testing | Testing relevant to the intended application | Depending on the design, testing may include tensile strength, elongation, compression set, heat aging, low-temperature flexibility, fluid resistance, ozone resistance, and leakage or pressure testing. | Request test methods, laboratory equipment lists, calibration records, and reports showing sample identification, conditions, results, and acceptance limits. | High |
| Compression Set | Resistance to permanent deformation | Compression-set requirements must be selected according to material, temperature, time, and application. A lower measured compression set generally indicates better retained sealing force under the specified test conditions. | Confirm the test standard and conditions, such as temperature and duration, rather than comparing percentages without the test conditions. | Medium |
| Tooling Capability | Suitable molds and engineering support for OEM parts | The supplier should be able to manage mold design, parting-line control, cavity consistency, flash control, mold maintenance, and revision history for customized O-rings. | Review mold drawings, cavity layout, trial samples, mold maintenance records, spare-part planning, and ownership terms in the tooling agreement. | Medium |
| Production Capacity | Capacity matched to forecast and delivery schedule | Capacity should be evaluated by available molding equipment, cavity count, shift pattern, curing cycle, inspection resources, material availability, and current committed orders—not only by a stated monthly quantity. | Request a capacity calculation, recent delivery performance, production plan, contingency arrangements, and lead-time assumptions for tooling, samples, and mass production. | Medium |
| Packaging and Storage | Protection against contamination, deformation, heat, light, and ozone | Finished O-rings should be packed to prevent dust, moisture, mixing of materials, and mechanical deformation. Storage should follow applicable elastomer storage guidance, including control of heat, light, humidity, and ozone exposure. ISO 2230 | Inspect the warehouse, labeling system, packing method, shelf-life controls, stock rotation process, and storage records. | Medium |
| Compliance Documentation | Regulatory and customer-specific documentation | Documentation may include material declarations, restricted-substance statements, safety data information where applicable, conflict-minerals information when requested, and product-specific compliance records. | Define the destination-market requirements in advance and verify that documents apply to the exact material, compound, and part number being supplied. | Medium |
| Supplier Audit | Ability to pass an independent or customer audit | A qualified factory should provide controlled access to relevant production areas, quality records, laboratories, warehouses, corrective-action files, and responsible technical personnel. | Use a documented audit checklist and score evidence for process control, cleanliness, traceability, inspection, equipment calibration, and corrective-action effectiveness. | High |
| Sample Approval | Formal first-article and pre-production approval | Production should not begin without an approved drawing, material specification, sample, inspection plan, packaging standard, and agreed change-control process. | Require a signed sample approval record and retain reference samples with clear revision, date, material, and dimensional information. | High |
| Change Management | Advance notification of material, tooling, process, or site changes | Changes that may affect fit, form, function, performance, compliance, or supply continuity should be reviewed and approved before implementation. | Include written change-notification requirements in the purchase agreement and define when requalification or customer approval is required. | High |
| Commercial Reliability | Transparent quotation and stable communication | Quotations should clearly state material, hardness, dimensions, tooling cost, minimum order quantity, packaging, inspection scope, lead time, payment terms, and delivery terms. | Compare quotations on the same technical basis and assess response time, engineering communication, English documentation quality, and issue-resolution process. | Medium |
| Final Selection | Evidence-based supplier approval | Select the factory using a weighted scorecard rather than price alone. A practical model is to give higher weight to quality, material suitability, traceability, testing, and delivery reliability. | Complete document review, sample testing, factory audit, commercial review, and a controlled trial order before long-term sourcing. | High |
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