A Mill Test Report (MTR) is the only legal document that proves your copper isn't a low-grade substitute. In high-stakes sectors like UHV (Ultra-High Vacuum) and semiconductor manufacturing, accepting a generic "Certificate of Conformity" is a major risk. If your 99.99% purity claim isn't backed by a batch-specific chemical analysis and gas test, you risk Hydrogen Embrittlement during vacuum brazing. As a specialized C10100 copper plate supplier, GNEE METAL provides full traceability for every C10100 thick copper board, ensuring the 101% IACS conductivity is verified, not just estimated.
Why is the Gas Analysis (ONH) the most critical part of an MTR?
Standard spectrographic analysis often misses the most dangerous impurity in copper: Oxygen. To qualify as ASTM B170 Grade 1, the oxygen content must be strictly below 5ppm (0.0005%).
On a genuine MTR from an OFE copper tubing manufacturer, look for the ONH (Oxygen, Nitrogen, Hydrogen) test section. If the oxygen is listed as "N/A" or is above 5ppm, the material is technically C10200 or C11000. Using such material for a high vacuum copper pipe will result in outgassing and structural failure. This is the primary C10100 sourcing trap that leads to ruined CNC machining hours.
MTR Verification Checklist for ASTM B170 Grade 1
| Parameter | Required Value | Engineering Impact |
| Copper (Cu + Ag) | 99.99% Min | Ensures base electrical/thermal performance |
| Oxygen (O) | Max 5 ppm | Prevents weld cracking & "Virtual Leaks" |
| Phosphorus (P) | Max 3 ppm | Protects 101% IACS conductivity |
| Conductivity | 101% IACS Min | Reduces I-squared R heating in busbars |
| ASTM F68 | Micro-cleanliness | Mandatory for UHV and Medical Linacs |
How to verify 101% IACS Conductivity and RRR Values?
Electrical conductivity is the most accurate indicator of metallic purity. While standard ETP copper hits 100% IACS, C10100 must hit 101% IACS. If the MTR shows 100.1%, it likely contains trace iron or arsenic that will increase I-squared R losses in high-current OFE copper flat bar assemblies.
For cryogenic projects, an OFE copper wire manufacturer must also provide RRR (Residual Resistivity Ratio) data. Our 4N pure copper wire typically achieves RRR values of 100 to 450. If these values are missing from your oxygen free copper wire spool report, the material may not handle the extreme thermal gradients of liquid helium environments.
Which ASTM standards should appear on your C10100 bar and plate reports?
A reliable ASTM F68 copper plate wholesale partner will list multiple standards to cover both chemical purity and mechanical tolerances.
ASTM B170 Grade 1: The definitive standard for 99.99% Oxygen-Free Electronic copper.
ASTM B187 / B152: Defines the dimensional tolerances for C10100 copper round bar and plates.
ASTM F68: The "Cleanliness Standard." It verifies the absence of cuprous oxide inclusions via microscopic examination-essential for OFE copper sheet cut to size used in vacuum gaskets.
Identifying Mechanical Properties on the MTR
| Property | Typical Value | Relevance to Machining |
| Hardness | 40 - 90 HRF | Determines C10100 machinability rating |
| OFE copper rod tensile strength | 30 - 50 ksi | Critical for structural extruded OFE copper bar |
| Elongation | 15% - 45% | Affects bending of OFE copper strip temper |
| Flatness | 0.005" - 0.015" | Meets C10100 plate flatness tolerance |
FAQ
1. What if the MTR says "99.99% Cu" but doesn't list oxygen levels?
This is a red flag. Many suppliers use "99.99%" as a marketing term for C10200. Without a specific gas analysis showing < 5ppm Oxygen, the material is not suitable for vacuum brazing or high-frequency C10100 surface finish Ra applications.
2. Why is the heat number (melt number) so important?
The heat number links the physical OFE copper sheet standard sizes to the original VIM (Vacuum Induction Melting) batch. This ensures total traceability for aerospace audits and prevents "batch mixing" where lower-grade copper is sold as C10100.
3. How do I verify the C10100 machinability rating on the MTR?
Machinability isn't a direct value on the MTR, but the OFE copper strip temper and hardness are. Harder tempers (H02 or H04) always provide a better C10100 machinability rating because they reduce the "smearing" effect discussed in our machining guides.
4. Does an OFE copper tubing manufacturer provide C10100 tube concentricity data?
Yes. For ASTM F68 capillary tube or C10100 seamless copper tube, the MTR should include dimensional checks for wall thickness and C10100 tube concentricity. This is vital for uniform thermal transfer in induction coils.
5. Can I trust an MTR that lists "Copper + Silver"?
ASTM B170 allows silver to be counted as copper for the 99.99% purity calculation. However, the report must still prove that other impurities like Zinc and Phosphorus are within the sub-ppm limits to maintain 101% IACS performance.
6. Why should I check the OFE copper rod tensile strength?
In high-vibration EV chassis, a bar with low tensile strength will fail prematurely. Verify that your C10100 copper round bar meets the specific mechanical yield points required for your safety factor.
GNEE METAL Product Range
| Product Type | Shapes Available | Common Grades | Diameter/Thickness Range | Length/Width Range | Applications |
|---|---|---|---|---|---|
| Copper Tubes | Round, Square, Rectangular, Coiled | C10100, C10200, C11000, C12200, C12000 | OD: 0.5mm - 300mm Wall: 0.1mm - 20mm | Up to 6000mm or custom | HVAC, Plumbing, Heat Exchangers, Refrigeration, Hydraulic Lines |
| Copper Plates & Sheets | Flat Sheets, Perforated, Embossed, Tread Plate | C10100, C11000, C12200, C23000, C26000 | Thickness: 0.1mm - 200mm | Width: Up to 2500mm Length: Up to 6000mm | Electrical Busbars, Roofing, Cladding, Gaskets, Transformers |
| Copper Bars & Rods | Round Bar, Square Bar, Hexagonal Bar, Flat Bar | C10100, C11000, C14500, C17200, C18200 | Diameter: 1mm - 300mm | Length: 1000mm - 4000mm | Machined Components, Electrical Contacts, Busbars, Fasteners |
| Copper Wires | Round Wire, Flat Wire, Square Wire, Stranded, Braided | C11000, C11600, C17200, C17510 | Diameter: 0.05mm - 12mm | Coil weights: 1kg - 500kg | Electrical Wiring, Cables, Springs, Mesh, Welding Wire |
| Copper Strips & Coils | Thin Strip, Foil, Slit Coil, Profile Strip | C11000, C12200, C19400, C26000, C26800 | Thickness: 0.03mm - 5mm | Width: 2mm - 1000mm Coil ID: 300mm - 600mm | Transformers, Radiators, Shielding, Terminals, Connectors |
About Our Factory
We operate a full range of production lines including extrusion presses, cold drawing benches, high-speed rolling mills, slitting lines, and precision CNC machining centers, enabling us to produce copper tubes, plates, bars, wires, and strips entirely in-house. For quality assurance, we maintain a dedicated inspection laboratory equipped with spectral analyzers, universal testing machines, hardness testers, surface roughness testers, and optical measuring instruments. Every batch is tested for chemical composition, mechanical properties, and dimensional accuracy before shipment. Our production capacity reaches 500+ tons per month, and we hold ISO 9001:2015 certification with full traceability from raw material to finished product. Whether you need standard mill stock or custom-processed components, we deliver precision copper products with short lead times and complete material certification.
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