Catalogue data and standard-part designations in this guide follow the cBallast C-Parts range, supplied through Bufab (Värnamo, Sweden). Values are nominal reference data; confirm against the controlling standard revision before procurement.What C-parts are, why they carry 60–80 % of a plant's part numbers but only 5–10 % of purchase value, how their process cost outweighs their unit price, and how to run them: ABC/XYZ classification, total-cost-of-ownership breakdown, a comparison of direct purchase, blanket orders, two-bin kanban, VMI and single-source consolidation, a specification checklist for every fastener line, and the certificates (EN 10204 2.1/2.2/3.1/3.2) and quality systems (ISO 16426) to ask for.
Catalogue data and standard-part designations in this guide follow the cBallast C-Parts range, supplied through Bufab (Värnamo, Sweden). Values are nominal reference data; confirm against the controlling standard revision before procurement.
C-parts are the low-value, high-volume items every plant, yard and workshop consumes without thinking about them: bolts, screws, nuts, washers, pins, rivets, retaining rings, plugs, cable ties, O-rings. In an ABC analysis by purchase value they sit in class C — typically 60–80 % of all part numbers and 5–10 % of annual spend — yet each of those part numbers still needs a purchase order, a goods receipt, a stock location, a pick and a line-side bin. The administrative and handling cost per line is therefore roughly the same as for an A-part costing a thousand times more, which is why the total cost of owning a C-part is normally two to five times its price. Managing C-parts is not a purchasing problem; it is a process-design problem.
| Supply model | Who owns the stock | Replenishment trigger | Admin load per line | Best fit | Watch-outs |
|---|---|---|---|---|---|
| Direct purchase (PO per need) | Buyer, after receipt | Requisition | Highest — PO, receipt, invoice per order | One-off, non-repeating parts | Stock-outs and expediting; every line costs 30–80 € to process |
| Blanket order + call-off | Buyer | Call-off against annual quantity | Medium — one PO, many receipts | Stable annual consumption, few suppliers | Forecast error; price locked while volumes drift |
| Two-bin kanban | Buyer (bins on site) | Empty bin returned or scanned | Low — no requisition, fixed lot | Shop floor, assembly cells, maintenance stores | Bin sizes must be recalculated when takt or BOM changes |
| Vendor-managed inventory (VMI) | Supplier until consumption | Supplier counts / scans on schedule | Very low — consolidated monthly invoice | Sites with 500+ C-part numbers and one dominant supplier | Contractual min/max levels, consumption reporting, exit clause |
| Single-source consolidation | Depends (often supplier) | Combined kanban / VMI across all C-parts | Lowest overall — one supplier, one logistics loop | Multi-site groups standardising parts and finishes | Supplier dependency; needs a QA-audited partner (ISO 9001, ISO 16426) |
| Line-side supermarket | Buyer | Pull from supermarket, replenished by milk run | Low | High-volume assembly lines | Space and discipline; combine with kanban upstream |
For a typical industrial C-part the purchase price is the smallest slice. Published supply-chain studies and supplier data put the process cost of a purchase order line at €30–€100 (requisition, ordering, receiving, inspection, booking, invoice matching), storage and handling at 10–20 % of stock value per year, and the cost of a stock-out (line stop, expediting, air freight) far above both. A €0.10 screw ordered 12 times a year on its own PO line costs the organisation several hundred euros in process cost. The lever is therefore the number of transactions and touches, not the unit price — which is why kanban, VMI and consolidation pay back even when the unit price is slightly higher than the cheapest spot quote.
ISO 9001 certification of the supplier is the baseline. ISO 16426 (fasteners — quality assurance system) defines the fastener-specific requirements, including batch traceability from steel heat to shipped carton, marking of property class and manufacturer identification on the head or nut face, and sampling plans for mechanical tests. For safety-relevant joints (lifting, structural, pressure), specify the certificate type at order and retain it with the maintenance record — the certificate is only useful if it can be tied to the installed batch.
Browse the C-Parts range · Bufab · Related: fastener standards cross-reference · torque wrench calibration (ISO 6789) · ASTM A193 B7 stud bolts.