Product
Product Details
Copper Machined Washers
Copper Machined Washers
Pricing: US$ 15.80 / Kilogram (FOB India | MOQ: 25 Kg | Custom profiles on request)
Electrical Accessories India manufactures and exports precision CNC-machined copper washers conforming to DIN 7603, ASME B16.21, ISO 887, and IS 2016 standards. Machined from high-conductivity copper grades C10100 (OFHC), C11000 (ETP), C12200 (DHP), and C14500 (tellurium copper), these copper precision washers deliver tighter dimensional tolerances, superior surface finish, and custom profiles not achievable through stamping alone. They serve as flat washers, lock washers, sealing washers, spacer washers, earth bond washers, insulating distance washers, and precision shim washers across electrical OEM, power utility, EPC contracting, process instrumentation, and industrial manufacturing applications. With high machinability, excellent corrosion resistance, and inherent electrical conductivity, copper machined washers are specified globally by engineering procurement teams across North America, Europe, Middle East, and Asia-Pacific.
Product Overview – Copper Machined Washers
Copper machined washers—also specified as copper turned washers, copper CNC washers, copper precision flat washers, copper lathe-turned washers, copper plain washers, copper spacing washers, copper shim washers, copper thrust washers, copper spring washers (machined), and copper distance pieces—are manufactured on CNC lathes, Swiss-type screw machines, and multi-spindle automatics to deliver dimensional repeatability and surface quality exceeding the capability of pressed or stamped washers. The machining process produces clean, burr-free edges, tight bore concentricity, and controlled face flatness critical for precision assemblies.
Dimensional Precision and Concentricity
CNC-machined copper washers achieve bore-to-OD concentricity within TIR 0.02 mm, face parallelism within 0.01 mm, and surface roughness Ra 0.8–1.6 μm (N6–N7). These tolerances are critical for high-pressure instrumentation fittings (up to 700 bar), GIS (gas-insulated switchgear) interface flanges, current transformer (CT) primary bar insulation spacers, precision metering equipment terminal interfaces, and aerospace hydraulic system sealing. Dimensional inspection is performed on CMM (coordinate measuring machine) for critical aerospace and defence applications, and by calibrated digital micrometer/bore gauge for standard industrial applications. Part-to-part repeatability is maintained within ±0.02 mm for all CNC-turned production runs.
Custom Profiles and Non-Standard Geometries
Unlike pressed washers limited to flat profiles, CNC-machined copper washers are produced in stepped bores, countersunk faces, chamfered edges, O-ring grooves, serrated faces, hexagonal ODs (for anti-rotation), tabbed profiles, and custom multi-bore patterns. Profiled sealing faces—including spiral serrations, concentric grooves, and raised seating lands—are machined for high-pressure valve body interfaces, manifold block sealing, and heat exchanger cover plates. Internal threads, external threads, and keyways can be integrated into machined washer/spacer assemblies in a single setup on CNC turn-mill centres, reducing assembly complexity for OEM electrical equipment manufacturers.
Material Selection for Copper Machined Washers
C11000 ETP copper is the standard grade for electrical bonding and general-purpose sealing washers, providing ≥98% IACS conductivity and excellent machinability. C10100 OFHC copper is specified for vacuum interrupter interfaces, precision earthing in substations, and clean-room electronics assembly where oxygen content must be below 0.0005%. C12200 DHP copper is preferred for brazing applications, steam system fitting seals, and hot-water system connections. C14500 tellurium copper (free-machining, with 0.4–0.7% tellurium) delivers 5–10× better machinability than C11000, enabling high-speed CNC production of complex profiles; it is specified for precision switchgear components, connector body washers, and watch/instrument gear-adjacent components. C17200 beryllium copper can be offered for spring washer applications requiring high strength (up to 1,400 MPa).
Surface Finish and Treatment Options
Machined copper washers are supplied in the following surface conditions: bright machine finish (Ra 1.6 μm); electrolytically polished (Ra 0.4 μm) for vacuum and high-purity applications; chemical bright-dipped (acid-cleaned and passivated); tin-plated (ASTM B545, 3–8 μm) for corrosion resistance; silver-plated (ASTM B700, 5–10 μm) for GIS interfaces and high-current CT primary connections; nickel-plated (ASTM B689, 5–8 μm) for harsh environment resistance; gold-plated (ASTM B488, 0.5–2 μm) for precision electronic connector washers; and PTFE-coated for chemical resistance. All plating processes are RoHS 2 and REACH compliant, with plating thickness verified by XRF per ASTM B568.
Copper Machined Washers in Electrical Applications
In bus-bar assembly systems, copper machined washers function as precision spacers maintaining exact inter-phase clearance in enclosed bus-duct (EBD) systems and SF6 GIS. In transformer terminal assemblies, they serve as insulation distance pieces and conductor spacers. In switchgear panels, machined copper washers are used as terminal pad contact washers under cable lug bolts, ensuring full contact area at rated current. In earthing systems (IEEE Std 80, IEC 61936), copper bond washers with machined flat faces ensure reliable mechanical and electrical connection between ground conductors and electrode rods. In motor control centres (MCCs) and variable frequency drives (VFDs), copper spacer washers maintain precise axial clearance in busbar modules and DIN rail assemblies.
Copper Machined Washers in Hydraulic and Pneumatic Systems
For high-pressure hydraulic systems (SAE J1231, ISO 8434), machined copper washers with controlled OD/ID/thickness tolerances provide reliable metallic sealing at pressures up to 700 bar when installed in banjo bolt connections, adaptor port fittings, manifold block ports, and hydraulic cylinder end caps. In pneumatic systems (ISO 6150), copper washers seal instrument air connections at 10–16 bar in process plants. Their advantage over elastomeric seals in these applications: no compression set failure, no chemical compatibility restrictions, no temperature limitations (serviceable from –200°C to +250°C), and no UV degradation.
Supply Chain and Traceability
All copper machined washer production is traceable to prime copper rod/bar conforming to ASTM B187, BS EN 13601, or IS 191. Mill test certificates (MTCs) per EN 10204 Type 3.1 are available for every production batch. Heat number, lot number, material grade, and production date are recorded in our quality management system (QMS) per ISO 9001:2015. Export documentation includes: EN 10204 MTC, RoHS/REACH compliance declaration, dimensional inspection report, certificate of origin (Chamber of Commerce), commercial invoice, and packing list. Third-party inspection by SGS, Bureau Veritas, or TÜV Rheinland can be arranged at additional cost for export orders above 500 kg.
Standard vs. Custom Machined Washer Programs
Standard catalog machined washers (DIN 126, DIN 440, ISO 887) in C11000 ETP copper are stocked in M5 to M36 sizes, with 1–3 day dispatch from stock. Custom machined washers against OEM drawings are produced with 5–7 working days for prototypes and 2–4 weeks for production quantities. For high-volume OEM supply (above 50,000 pieces/year), dedicated tooling, Kanban inventory management, and consignment stock programs are available. CAD/CAM files (STEP, IGES, DXF) are accepted for reverse-engineering and new product introduction. First article inspection (FAI) reports per AS9102 are available for aerospace customers.
Key Features
- CNC-machined to ±0.02 mm bore/OD; face parallelism ±0.01 mm
- Concentricity TIR ≤ 0.02 mm (standard); ≤ 0.005 mm (precision grade)
- Available in C10100, C11000, C12200, C14500, C17200 copper grades
- Surface Ra: 1.6 μm standard; 0.8 μm or 0.4 μm on request
- Operating temperature: –200°C to +250°C
- EN 10204 3.1 MTCs standard; third-party inspection available
- RoHS 2 and REACH compliant surface treatments
- Custom profiles: stepped, countersunk, serrated, O-ring groove, hexagonal OD
Superior Dimensional Accuracy vs. Stamped Washers
Stamped washers, produced on progressive dies from copper strip, have inherent rollover and burr at shear zones, edge-to-bore runout of 0.1–0.3 mm, and thickness variation of ±0.05–0.10 mm. CNC-machined copper washers eliminate these limitations: controlled single-point tool geometry produces true circular bore and OD, zero rollover, negligible burr (de-burred in secondary operation if present), and thickness uniformity within ±0.01 mm. For precision assemblies in switchgear, GIS equipment, precision instrumentation, and aerospace actuators, the dimensional superiority of machined washers justifies their higher unit cost relative to stamped equivalents.
Multi-Grade Copper Machinability
Copper’s machinability varies significantly with alloy composition. C11000 ETP copper has machinability index 20% (relative to free-cutting brass C36000 = 100%), requiring rigid tooling and optimized cutting parameters. C14500 tellurium copper achieves machinability index 85–90%, enabling high-speed CNC turning at 150–300 m/min with carbide tools, producing excellent chip control and surface finish. C17200 beryllium copper (H temper) achieves machinability 20–30% but provides tensile strength up to 1,400 MPa for spring washer applications. Our CNC machinists are trained in copper-specific tooling (high-positive rake angle PCD/carbide tools, mist lubrication) to optimize tool life and surface finish across all copper grades.
Electrical Bonding Performance
Machined copper flat washers used as electrical bond washers under grounding studs and terminal bolts deliver contact resistance below 0.5 mΩ at 10 A DC due to their flat, burr-free machined contact faces. Compared to stamped washers (which have a slight rollover causing line-contact rather than face-contact), machined washers provide 2–5× greater real contact area, directly reducing thermal resistance at the joint. This is critical in high-fault-current installations (≥50 kA) where joint resistance contributes to heating and potential arc flash hazard. Bond washers in compliance with IEC 61439 and IEEE Std 80 grounding requirements are supplied with CMM measurement reports on request.
Corrosion Resistance and Longevity
CNC-machined copper washers—whether in natural copper finish, tin-plated, silver-plated, or nickel-plated—resist atmospheric oxidation, H₂S and SO₂ chemical attack in process plants, salt spray (500 h per ASTM B117 for plated variants), and galvanic corrosion when assembled in all-copper or copper-alloy systems. For coastal, offshore, and tropical environments, tin-plated machined washers (5 μm minimum) are specified. For GIS and AIS substation interfaces where oxidation-free contact is mandatory, silver-plated washers (8–10 μm) per ASTM B700 are used. Nickel-plated washers are preferred for chemical plant electrical bonding where elevated temperature and acid mist exposure occur.
Compliance and Export Documentation
All machined copper washers are produced under ISO 9001:2015 QMS with full export documentation capability. EN 10204 Type 3.1 material test certificates, REACH/RoHS compliance declarations, FAI dimensional reports, and CMM measurement reports are supplied per customer requirements. For US importers, HTS classification 7419.80.5060 applies; for EU importers, CN code 7419 80 applies. Country of Origin certificates (Chamber of Commerce attested) are issued with every shipment. Letter of Credit (LC), DA/DP, and advance TT payment terms are supported for regular and new export customers respectively.
Technical Specifications
| Parameter | Specification |
|---|---|
| Product | Copper Machined Washer / Copper CNC Washer / Copper Precision Washer |
| Standards | DIN 7603, DIN 126, ISO 887, ASME B16.21, IS 2016 |
| Material Grades | C10100, C11000, C12200, C14500, C17200 (see table) |
| Bore (ID) Range | 2 mm to 200 mm (custom up to 500 mm) |
| OD Range | 5 mm to 300 mm (custom larger on request) |
| Thickness Range | 0.3 mm to 50 mm |
| Bore Tolerance (standard) | ±0.02 mm |
| OD Tolerance (standard) | ±0.02 mm |
| Thickness Tolerance | ±0.01 mm |
| Concentricity TIR | ≤ 0.02 mm standard; ≤ 0.005 mm precision grade |
| Face Parallelism | ≤ 0.01 mm per 100 mm diameter |
| Surface Roughness | Ra 1.6 μm standard; Ra 0.8–0.4 μm on request |
| Conductivity | 98–101% IACS (depends on grade) |
| Hardness (C11000 annealed) | 40–70 HV |
| Operating Temperature | –200°C to +250°C |
| Surface Finish | Bright machined / Tin-plated / Silver-plated / Nickel-plated / Gold-plated |
| Lead Time | Standard: 2–3 weeks; Prototype: 5–7 working days |
| Pricing | US$ 15.80 / Kilogram (FOB India) |
Copper Raw Material Grades and International Equivalents
| UNS (USA) | EN (Europe) | BS (UK) | DIN (Germany) | IS (India) | JIS (Japan) | Description |
|---|---|---|---|---|---|---|
| C10100 | CW008A | C101 | E-Cu99.99 | — | C1011 | Oxygen-Free High Conductivity (OFHC) |
| C11000 | CW004A | C101 | E-Cu58 ETP | ETP Copper | C1100 | Electrolytic Tough Pitch (ETP) |
| C12200 | CW024A | C106 | SF-Cu | DHP Copper | C1220 | Phosphorus Deoxidized (DHP) |
| C14500 | CW118C | C109 | CuTeP | — | C1450 | Tellurium Copper (Free-Machining) |
| C17200 | CW101C | CB101 | CuBe2 | — | C1720 | Beryllium Copper (High Strength) |
Product Types and Variants
| Type | Standard | Size Range | Typical Application |
|---|---|---|---|
| Flat Plain Washer (Machined) | DIN 126 / ISO 887 | M3–M100 | General fastener bearing surface, bus-bar joints |
| Sealing Washer (Machined) | DIN 7603 / ASME B16.21 | M6–M100 / NPS 1/4–4 | High-precision hydraulic, instrumentation sealing |
| Spacer / Distance Washer | Customer drawing | Custom | GIS spacers, bus-duct phase clearance, VFD modules |
| Countersunk Washer | DIN 7989 equivalent | M6–M36 | Flush-head bolt assemblies, panel mounting |
| Serrated Bond Washer | DIN 6798 equivalent | M5–M24 | EMI bonding, electrical earthing, anti-loosening |
| Thrust Washer | Customer drawing | ID 10–100 mm | Rotating machinery bearing interfaces |
| O-Ring Face Groove Washer | Customer drawing | Custom | Manifold block sealing, hydraulic adaptor interfaces |
| Hexagonal OD Washer | Customer drawing | M6–M30 | Anti-rotation in blind-hole assemblies |
Applications by Industry
| Industry | Application |
|---|---|
| Power Transmission and Distribution | Bus-duct phase spacers, transformer terminal bond washers, GIS interface spacers |
| Oil and Gas / Petrochemical | High-pressure instrumentation port seals, HPU manifold washers, wellhead terminal bond washers |
| Renewable Energy (Solar/Wind) | Inverter bus-bar spacers, DC combiner box bond washers, cable tray earth bond washers |
| Process Instrumentation | Pressure transmitter port seals, flow meter flange washers, control valve actuator bond washers |
| Railways and Metro | OHE fitting spacers, traction system bond washers, rolling stock earthing spacers |
| Aerospace and Defence | Hydraulic system sealing washers, EMI bond washers, aircraft bonding jumper interfaces |
| Marine and Offshore | Hull fitting precision seals, shaft bonding washers, shore power interface washers |
| Electronics and Telecom | PCB mounting spacers, RF connector ground washers, base station earth bond washers |
Manufacturing Process
Copper machined washers are produced through a precision-controlled CNC machining process. (1) Raw Material Incoming Inspection: copper rod/bar is tested for chemical composition (ICP spectroscopy), conductivity (eddy-current, ASTM E1004), hardness (Vickers, ASTM E92), and dimensional conformance before production release. (2) CNC Turning (Roughing): bar stock is centre-drilled and roughed to near-net shape on CNC lathe with carbide/PCD inserts; high-positive-rake-angle tools are used to minimize built-up edge on copper. Cutting speed: 80–250 m/min; feed: 0.05–0.15 mm/rev; depth of cut: 0.5–3 mm. (3) CNC Turning (Finishing): semi-finish and finish passes bring bore, OD, and thickness to drawing dimensions ±0.02 mm; surface roughness to Ra 1.6 μm or better. (4) Secondary Operations: drilling, milling (for hex OD, keyways), broaching, thread cutting, and deburring are performed as required. (5) Annealing (where specified): soft-annealing at 350–500°C for sealing washers requiring high ductility. (6) Surface Treatment: electroplating (tin, nickel, silver, gold) per customer spec; plating thickness by XRF per ASTM B568. (7) Inspection: CMM dimensional check (100% for critical aerospace/defence; AQL 1.0 sampling per ISO 2859 for standard industrial); conductivity spot-check; surface roughness measurement; hardness verification. (8) Packing and Documentation: VCI polybag, labelled carton, EN 10204 MTC, dimensional report, compliance declarations, export documents.
Quality Standards and Certifications
| Standard / Certification | Scope |
|---|---|
| ISO 9001:2015 | Quality Management System |
| DIN 7603 / DIN 126 / ISO 887 | Washer dimensions and sealing washer specifications |
| ASTM B187 / BS EN 13601 | Copper rod and bar – chemical composition and mechanical properties |
| ASTM E1004 | Eddy-current electrical conductivity test |
| EN 10204 Type 3.1 | Material test certificate with independent inspection body |
| ASTM B568 | XRF plating thickness measurement |
| RoHS 2 (2011/65/EU) | Hazardous substances restriction – plating and surface treatments |
| REACH (EC 1907/2006) | Chemical compliance for all process materials |
| ISO 2859-1 (AQL 1.0) | Sampling inspection procedures |
| AS9102 (on request) | First Article Inspection (FAI) for aerospace customers |
Why Choose Electrical Accessories India for Copper Machined Washers?
Electrical Accessories India operates a dedicated copper CNC machining facility with Swiss-type screw machines, multi-spindle automatics, and precision CNC lathes equipped for copper-specific tooling. Our quality system—ISO 9001:2015 certified—includes in-house CMM, eddy-current conductivity testers, XRF plating thickness gauges, and NABL-traceable calibration infrastructure. We offer: US$ 15.80/kg FOB India competitive pricing; 5–7 day prototype turnaround; full EN 10204 3.1 material certification; AQL 1.0 dimensional inspection with data reports; RoHS/REACH compliance declarations; ISPM-15 export packaging; and dedicated technical support for OEM drawing review and material selection. We export to clients in USA, UK, Germany, France, Italy, UAE, Australia, Singapore, South Africa, Brazil, and Canada.
Frequently Asked Questions (FAQ)
Q1. What is the minimum order quantity for copper machined washers?
Standard MOQ is 25 kg for catalogue sizes (DIN 126/ISO 887) in C11000 ETP copper. For custom non-standard profiles or special alloys (C10100 OFHC, C17200 beryllium copper), MOQ is 50–100 kg depending on profile complexity. Prototype samples of 50–200 pieces are accepted for OEM qualification programs.
Q2. What tolerance class is standard for CNC-machined copper washers?
Our standard production tolerance is ±0.02 mm on bore, OD, and thickness, with concentricity TIR ≤ 0.02 mm. Precision grade (±0.005 mm, TIR ≤ 0.005 mm) is available for GIS interfaces, aerospace actuators, and precision instrumentation applications at a premium. All tolerances are verified with NABL-calibrated instruments.
Q3. What is the difference between copper machined washers and copper sealing washers?
Copper sealing washers (DIN 7603) are typically stamped from annealed copper sheet and are used for crush-type hydraulic sealing. Copper machined washers are CNC-turned to tighter tolerances and can serve multiple functions: flat bearing washers, precision spacers, high-accuracy sealing washers, and electrical bond washers. Machined washers are used where stamped washers lack the required dimensional accuracy, surface finish, or profile complexity.
Q4. Can you machine copper washers from customer-supplied drawings?
Yes. We accept customer drawings in DXF, DWG, STEP, and PDF formats. Our engineering team reviews drawings for manufacturability within 24 business hours and provides a formal quotation. Prototype machined washers against customer drawings are typically delivered in 5–7 working days.
Q5. Which copper grade is recommended for GIS switchgear spacers?
C10100 OFHC (oxygen-free high conductivity) or C11000 ETP copper is standard for GIS spacers and interface washers. These grades provide ≥98–100% IACS conductivity and are free from hydrogen embrittlement risk (critical in sealed SF6 environments). Silver-plated surface finish (ASTM B700, 8 μm) is typically specified to prevent tarnishing in the sealed GIS compartment.
Q6. Do you supply EN 10204 3.1 material test certificates?
Yes. EN 10204 Type 3.1 material test certificates from the copper rod/bar manufacturer are supplied as standard with all production orders. Type 3.2 (third-party witnessed) is available from SGS, Bureau Veritas, or TÜV at additional cost for export orders above 200 kg.
Q7. What is the lead time for CNC-machined copper washers?
Prototype quantities (50–200 pieces): 5–7 working days. Standard production quantities in catalogue sizes: 2–3 weeks. Custom complex profiles requiring special tooling: 3–5 weeks (including tool fabrication). Express 1-week delivery is available for previously tooled/produced parts.
Q8. Are copper machined washers suitable for food and pharmaceutical applications?
Plain (unplated) C12200 DHP copper washers are acceptable for potable water (WRAS, NSF/ANSI 61) and some food-contact applications where copper is permitted by local regulations (e.g., brewery and dairy fitting connections). For pharmaceutical and clean-room applications, electropolished C10100 OFHC copper washers with validated surface cleanliness may be specified; please consult our technical team for application-specific guidance.
Q9. Can you produce large-diameter copper machined washers (above 100 mm OD)?
Yes. We produce copper machined washers and flanges up to 500 mm OD on large-capacity CNC lathes from copper plate/disc blanks. These are used for transformer tank flange seals, large-bore valve covers, bus-duct end flanges, and cable box base plates. Dimensional inspection for large-diameter parts uses a CMM with a 500 mm measurement range.
Q10. What packaging is used for export shipments of machined washers?
Machined washers are individually sleeved in VCI-treated polybags for corrosion protection, then counted and packed in inner polybag packs with part number and lot number labels, placed in corrugated cartons complying with ISPM-15 phytosanitary requirements. Gross weight, net weight, part number, material grade, and COO (India) are marked on each carton. Air (DHL, FedEx) and sea freight options are available.
Multilingual Equivalent Terms
| Language | Equivalent Terms |
|---|---|
| Spanish | Arandelas mecanizadas de cobre, Arandelas de cobre torneadas, Arandelas de precisión de cobre |
| Russian | Медные обработанные шайбы, Медные токарные шайбы, Прецизионные медные шайбы |
| French | Rondelles usinées en cuivre, Rondelles tournées en cuivre, Rondelles de précision en cuivre |
| Portuguese | Arruelas usinadas de cobre, Arruelas torneadas de cobre, Arruelas de precisão de cobre |
| Italian | Rondelle lavorate in rame, Rondelle tornite in rame, Rondelle di precisione in rame |
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Request a Quote – Copper Machined Washers
Electrical Accessories India | Manufacturer & Exporter of Copper Machined Washers and Precision Copper Parts
Email: info@elecaccs.com | Website: elecaccs.com
Price: US$ 15.80 / Kilogram (FOB India)
Lead Time: 2–3 weeks (prototype: 5–7 days) | MOQ: 25 Kg | Custom profiles accepted
Submit your drawing, specification, or sample for a detailed technical quotation within 24 business hours. We serve clients across India, USA, UK, Germany, UAE, Australia, Canada, Singapore, South Africa, France, Italy, and Spain.