For B2B buyers producing solid carbide end mills, drills, reamers, and PCB micro-tools, the tungsten carbide rod is not a commodity item—it is the raw backbone of tool performance. A wrong grade choice or inconsistent sinter can scrap an entire grinding batch. This guide outlines what professional buyers must verify before issuing a PO to a carbide rod manufacturer.
A tungsten carbide rod is a cylindrical blank made from tungsten carbide (WC) powder bonded with a cobalt (Co) or nickel binder. After compaction and vacuum/HIP sintering, it forms a dense, pore-free structure. Rods are supplied as unground sintered blanks or precision ground bars (h5/h6/h7) for downstream CNC flute grinding.
Do not send only "diameter x length." A complete specification must include:
Diameter Range: From micro-drill rods (Ø0.1 mm) to heavy wear bars (Ø50 mm+).
Length: Standard 310 mm / 330 mm bars, or cut-to-length (10–330 mm+).
Surface Condition: Unground (sintered) vs. centerless ground & polished (h5/h6, Ra ≤ 0.2 µm).
Coolant Hole Geometry: Solid, single straight hole, double straight hole, or 30° helical hole for deep-hole drilling.
Grade / ISO Class: K05–K40 mapping, cobalt content 6–12%, grain size 0.2–1.2 µm.
Tolerance & Straightness: Diameter h5/h6; straightness ≤ 0.05 mm/100 mm; concentricity of coolant hole ≤ 0.05 mm.
Grade selection is the #1 cost driver. Match the rod to the workpiece, not just the price.
Application | Recommended Grade | Cobalt % | Grain Size | Hardness (HRA) | TRS (MPa) |
|---|---|---|---|---|---|
PCB micro-drills, non-ferrous finishing | K05–K10 | 6–9% | Ultrafine 0.2–0.4 µm | 93.5–94.0 | ≥3000 |
General end mills (steel/stainless) | K20–K30 | 10% | Submicron 0.4–0.6 µm | 91.5–92.5 | ≥3800 |
Titanium, hardened steel HRC55+ | K30 | 10–12% | Fine 0.4–0.8 µm | 88–92.6 | ≥4000 |
Stamping dies, high-impact wear parts | K40 | 15–20% | Medium 0.6–1.0 µm | 86–88 | ≥3800 |
Rule of thumb: Lower cobalt and finer grain deliver sharper edges and better wear resistance but lower impact toughness. Higher cobalt increases shock resistance at the cost of slight hardness reduction.
Evaluate if the manufacturer controls these critical stages in-house:
Powder Preparation: Virgin WC powder with spray-drying for uniform cobalt distribution.
Forming: Extrusion for small diameters; CIP (Cold Isostatic Pressing) for large diameters.
Sintering: Vacuum sintering plus HIP (Hot Isostatic Pressing) at 10 MPa class to eliminate microporosity (density ≥ 14.1 g/cm³ for K20–K30).
Grinding: CNC centerless grinding to h5/h6 with chamfered ends.
Inspection: HRA hardness, density, TRS, magnetic crack detection, and grain structure micrographs.
A credible carbide rod mill must provide:
ISO 9001 certification (ISO 14001 preferred).
Material Test Report (MTR) per batch: HRA, density, Co%, grain size, TRS, and dimensions.
RoHS/REACH Declaration: Confirming compliance with EU hazardous substance regulations.
Mill Certificate: Traceable to the specific sintering batch number.
Packaging: Each rod is wrapped in VCI (Vapor Corrosion Inhibitor) paper, capped, foam-separated, and packed in custom wooden crates or reinforced cartons. Small diameters (<3 mm) are shipped in PVC tubes to prevent chipping.
Lead Times: Samples (3–5 days); standard stock Ø0.5–16 mm (2–3 weeks); custom coolant-hole or large diameters >20 mm (3–4 weeks).
Inability to provide batch-specific MTRs (only "typical values" offered).
No HIP sintering capability (higher porosity risk).
Uncontrolled cobalt variation (e.g., labeled YG8 but ranging 7.5–9% across batches).
Outsourced grinding, leading to tolerance loss.
Excessive MOQ requirements before sample qualification.
Solid carbide end mills, drills, taps, reamers
PCB micro-drills (0.1–1.0 mm)
Gun drills with helical coolant holes
Wear parts: plungers, guide rails, nozzles, measuring styli
Punches and die cores for stamping and cold heading
Bottom Line for Procurement: A tungsten carbide rod is only as good as its sinter consistency and documented grade. Explicitly specify grain size, cobalt content, tolerance class, and coolant-hole geometry. Always qualify a new manufacturer with a 5–10 piece trial grind before committing to large-scale orders.
Quote based on drawings
Phone: 0731-28214800
tel: +86 17773379950
E-mail: sales@chinahardalloy.com