Copper Machining and Fabrication in Waco, TX — C101 OFE, C110, and Tellurium Copper for Defense Electronics

C101 OFE copper (99.99 percent minimum copper, ASTM F68) is specified wherever maximum electrical conductivity and hydrogen embrittlement resistance are required. At 101 percent IACS (International Annealed Copper Standard) conductivity, it outperforms C110 ETP copper's 100 percent IACS rating marginally, but its real advantage is zero oxygen content — eliminating the hydrogen embrittlement risk that makes C110 unsuitable for brazing and high-temperature applications in forming gas or hydrogen atmospheres. In Waco's L3Harris defense electronics supply chain, C101 appears in RF waveguide components, microwave structures, vacuum-environment feedthroughs, and high-reliability bus bar assemblies where both electrical performance and long-term reliability under thermal cycling are required. Machining C101 is technically straightforward — it's a soft, ductile material — but surface contamination from tooling lubricants, handling oils, or iron-based fixtures can degrade the oxide-free surface and compromise solderability and conductivity at contact interfaces. Waco shops with defense electronics experience maintain dedicated C101 setups with non-iron tooling, clean gloves during handling, and solvent-cleaned parts before packaging. C101 flat bar, round bar, and plate are available from DFW electrical metals distributors on 5-10 day lead in standard sizes. For thin sheet under 0.020 inch and foil forms used in EMI shielding, specialty electrical foil distributors with next-day DFW delivery serve the Waco market. Specify ASTM B170 for OFE copper and verify the oxygen content specification on the CMTR — distributors sometimes substitute C110 when C101 is out of stock without alerting the buyer.

C110 electrolytic tough pitch copper is the most commonly produced and stocked copper grade — 99.9 percent copper content, 100 percent IACS conductivity, and 0.02-0.04 percent oxygen from the ETP refining process. For bus bars, grounding straps, switchgear components, heat exchanger plates, and general electrical fabrication, C110 is the cost-effective default grade that Waco fabricators, electrical shops, and industrial facilities use daily. The I-35 corridor's industrial base — including construction equipment manufacturing, utility infrastructure fabrication, and commercial electrical work — consumes C110 in sheet, bar, and tube form. Fabricators form C110 sheet on press brakes (it forms similarly to mild steel in ductile condition), shear it to bus bar blanks, and drill or punch connector holes before silver-plating or tinning contact surfaces. At 0.5 inch thick and below, C110 plate shears cleanly; heavier sections are waterjet or plasma cut, though plasma introduces an oxidized HAZ that requires mechanical removal before soldering or plating. Heat from welding, brazing, or soldering degrades the ETP copper microstructure differently than OFE — the oxygen in C110 forms copper oxide at grain boundaries when heated above 400°F in hydrogen-containing atmospheres, causing embrittlement. This is not a concern for silver-solder brazing in air, which is the most common copper joining process in Waco industrial shops, but it precludes C110 from applications involving hydrogen atmosphere furnace brazing or vacuum brazing — where C101 or C102 is the correct specification.

Tellurium copper (C145, UNS C14500) is to copper what 12L14 is to steel: the machinable grade. The addition of 0.4-0.7 percent tellurium produces free-machining chip breakage that dramatically reduces cycle time and improves surface finish on turned parts compared to C101 or C110. At 90-95 percent IACS conductivity, it gives up roughly 5-10 percentage points of conductivity compared to pure copper grades — a trade that is acceptable in most connector pin, switch component, and electromechanical hardware applications. In Waco's defense electronics supply chain, tellurium copper is specified for connector bodies, contact pins, terminal hardware, and precision machined electromechanical components where the combination of electrical conductivity and tight machined tolerances — bores to ±0.0005 inch, turned diameters to ±0.001 inch — would be difficult or cost-prohibitive in C110 or C101. CNC Swiss turning centers and multi-spindle screw machines run tellurium copper bar at feeds and speeds approaching free-machining steel, producing connector pin volumes in the thousands per shift that would be impractical in gummy pure copper. Tellurium copper bar stock in 0.125 inch to 3 inch diameter is available from DFW electrical metals distributors on 3-7 day lead in ASTM B301 spec with certs. For defense and aerospace applications requiring material traceability, specify ASTM B301 with full chemical analysis and confirm the distributor can provide country-of-origin documentation — tellurium supply concentration in foreign sources makes this an occasional issue for DFARS-sensitive programs.