| Material Control | Implant-grade titanium specification | Titanium alloy conforming to the approved specification, commonly Ti-6Al-4V ELI under ASTM F136 or ISO 5832-3, where applicable. | Material certificate with heat or lot number, chemical composition, mechanical properties, supplier traceability, and certificate review records. | Material chemistry and strength influence fatigue life, corrosion resistance, and biological safety. | High |
| Material Control | Lot traceability | Traceability from incoming bar stock to machining lot, inspection records, packaging, and final release documentation. | Lot genealogy, traveler or batch record, barcode or serial tracking, and nonconformance history. | Supports recalls, root-cause investigation, and regulatory device-history requirements. | High |
| Machining Precision | Critical dimensional accuracy | Use drawing-defined limits for overall length, major diameter, head geometry, thread diameter, and cannulation. For many precision features, a starting capability target is Cpk ≥ 1.33, subject to risk and validation. | Validated inspection method, calibrated equipment records, capability study, first-article inspection, and in-process inspection data. | Controls fit, insertion behavior, interface performance, and consistency across production lots. | High |
| Machining Precision | Thread profile and pitch | Thread form, pitch, major diameter, minor diameter, flank geometry, and runout must conform to the approved implant drawing and validated gauge system. | Optical measurement or thread measurement report, certified GO/NO-GO gauges, thread-profile records, and gauge calibration certificates. | Thread accuracy affects insertion torque, pull-out performance, bone purchase, and mating compatibility. | High |
| Machining Precision | Concentricity and runout | Set a product-specific limit for shaft, thread, head, and drive-feature alignment; verify using a validated datum system. | Coordinate-measuring-machine report, optical comparator results, roundness or runout measurements, and datum-control documentation. | Reduces eccentric loading, insertion deviation, driver mismatch, and localized stress concentration. | High |
| Surface Quality | Surface roughness | Define Ra or other surface parameters separately for bone-contacting, mating, and non-functional surfaces. Do not apply one generic value to every feature. | Profilometer results from representative locations, measurement-method validation, and surface-finish mapping. | Surface condition affects debris generation, friction, corrosion behavior, and tissue or bone interaction. | High |
| Surface Quality | Burrs, sharp edges, and tool marks | No loose burrs, harmful sharp edges, torn metal, chatter, or tool damage on functional or patient-contacting surfaces. | Defined visual standard, magnified inspection, edge-condition criteria, sampling plan, and defect photographs. | Loose particles and sharp edges can increase tissue irritation, debris risk, and assembly problems. | High |
| Process Capability | Swiss turning process stability | Documented control of bar guide setup, tool wear, coolant condition, chip evacuation, and thermal variation; monitor critical characteristics statistically. | Process flow, control plan, SPC charts, tool-life studies, preventive-maintenance records, and validated setup instructions. | Long, slender screws are sensitive to deflection, vibration, tool wear, and dimensional drift. | High |
| Inspection System | Measurement system adequacy | Use calibrated equipment with suitable resolution and validated methods. As a general practice, measurement uncertainty should be small relative to the product tolerance. | Calibration certificates, MSA or gauge R&R study, inspection work instructions, and equipment-resolution records. | Prevents false acceptance or rejection of critical dimensions and strengthens release decisions. | High |
| Mechanical Performance | Insertion torque and torsional strength | Define product-specific insertion-torque limits and verify that the screw withstands the specified torsional and torsional-yield requirements without unacceptable deformation. | Validated test method, torque-to-failure data, batch test results, fixture qualification, and applicable standard justification. | Protects against driver interface failure, screw breakage, and incomplete insertion during surgery. | High |
| Mechanical Performance | Fatigue and static strength | Evaluate according to the intended implant application and applicable requirements, commonly including ASTM F543 testing for metallic bone screws where relevant. | Static torsion, axial pull-out, bending, fatigue, and test-condition reports with specimen traceability. | Bone screws experience cyclic loading; fatigue performance is critical to long-term fixation reliability. | High |
| Cleaning & Contamination | Particulate and process-residue control | Validated cleaning process with defined limits for particulate, oil, coolant, metal residue, and processing chemicals before final packaging. | Cleaning validation, rinse-water or extract testing, particulate analysis, detergent control, and process-monitoring records. | Residues may compromise biocompatibility, sterilization, packaging, or implant performance. | High |
| Cleaning & Contamination | Foreign material and cross-contamination prevention | Dedicated or controlled handling for titanium components, with segregation from incompatible metals and documented contamination-prevention procedures. | Material-segregation procedure, workstation-cleaning records, handling controls, and foreign-material inspection results. | Cross-contamination can affect corrosion resistance, appearance, and biological safety. | High |
| Medical Compliance | Quality management system | A certified medical-device quality system aligned with ISO 13485:2016, with scope covering the supplied machining and inspection activities. | Current certificate, certification scope, audit history, corrective-action records, and quality manual or process overview. | Demonstrates controlled processes, documented responsibilities, risk-based controls, and traceable records. | High |
| Medical Compliance | Risk and change management | Supplier procedures should support risk management aligned with ISO 14971 and require formal approval for material, process, tooling, software, or sub-supplier changes. | Change-control procedure, notification timeline, risk-assessment inputs, validation plan, and change-history examples. | Uncontrolled changes can alter dimensions, fatigue strength, cleanliness, or biological performance. | High |
| Medical Compliance | Biological safety support | Provide process and material information needed for the device manufacturer’s biological evaluation under ISO 10993; machining suppliers should not claim biological compliance without evidence. | Material and chemical declarations, cleaning-process information, residue data, and support for extractables or cytotoxicity assessment when required. | Biological evaluation depends on the finished device, materials, residues, and manufacturing process. | High |
| Validation | Special-process validation | Validate processes whose output cannot be fully verified by later inspection, such as cleaning, passivation, coating, marking, or sterilization-related operations. | Validation protocols, acceptance criteria, revalidation schedule, process-challenge results, and deviation history. | Ensures repeatable results when final inspection alone cannot establish process quality. | High |
| Packaging & Logistics | Protective packaging and shelf-life support | Packaging should protect threads, drive features, surface finish, cleanliness, and traceability through handling and transport. | Packaging specification, transit testing where applicable, seal or closure controls, labeling samples, and storage-condition requirements. | Prevents damage, contamination, mix-ups, and loss of identification before final assembly or sterilization. | Medium |
| Supplier Reliability | Capacity and lead-time control | Evaluate demonstrated capacity for the forecast volume, documented cycle-time assumptions, backup equipment, and contingency planning for critical operations. | Capacity model, on-time-delivery history, production schedule, business-continuity plan, and subcontractor controls. | Stable supply reduces production interruptions and urgent process changes that may increase quality risk. | Medium |
| Supplier Selection | Technical communication and documentation | Supplier should provide complete drawing review, manufacturability feedback, inspection reports, certificates of conformity, and prompt nonconformance communication. | Sample quality agreement, technical-review record, inspection-report format, deviation workflow, and corrective-action response time. | Clear documentation supports design transfer, audits, release decisions, and continuous improvement. | Medium |
