C1100 Copper vs. C3604 Brass: Which Material for a CNC-Machined Part?

C1100 is a JIS electrolytic tough-pitch copper grade selected when electrical conductivity, thermal conductivity, and formability are primary. C3604 is a free-cutting brass used for turned parts, fittings, bushings, screws, and components requiring productive machining. They differ in composition, strength, density, color, corrosion behavior, and environmental compliance. UNS C11000 and C36000 are closely named international grades, but they should not be treated as automatically identical to JIS C1100 or C3604 without reviewing the applicable specification and material certificate.

• Pure copper — Đồng tinh khiết — 純銅
• Free-cutting brass — Đồng thau dễ cắt — 快削黄銅
• Electrical conductivity — Độ dẫn điện — 導電率
• Machinability — Khả năng gia công — 被削性

Pure copper combines ductility with high thermal conductivity. A dull edge or poor chip evacuation can promote built-up edge, burrs, and surface dragging. Excessive clamping may dent a thin component, while insufficient clamping reduces stability. Sharp tooling, suitable rake geometry, controlled tool engagement, and reliable chip evacuation improve consistency. For electrodes or contact faces, scratches, flatness, contamination, and cleaning must be controlled because a visually bright surface does not by itself guarantee low contact resistance.

C3604 generally forms short chips and is well suited to turning, drilling, tapping, and repeat production. Good machinability does not eliminate process risk: worn tools, runout, chatter, and poor centering can still affect thread quality, roundness, and finish. Thin walls, deep grooves, and multiple reversals require a controlled datum and setup plan. Brass surfaces may tarnish from oil, fingerprints, or storage conditions, so cleaning and packaging requirements should be separated from dimensional acceptance.

• Suitable for threaded, grooved, and stepped turned parts
• Control chips in deep bores and internal threads
• Avoid excessive polishing that rounds edges or changes size
• Verify material by certificate rather than visual color

Copper and brass expand with temperature; machining heat and handling can affect close measurements. C1100 is softer and more sensitive to measuring force and clamping. Small diameters and thicknesses require appropriate measuring force and stable temperature. Thin-plate flatness must be evaluated in an agreed free or supported condition. For an electrical contact, the drawing should separately control geometry, roughness, coating, cleanliness, and any electrical performance requirement.

C1100 is supplied in different tempers, while C3604 also varies by product form and condition. Calling out only copper or brass is insufficient. Nickel plating, tin plating, anti-tarnish treatment, or exposed conductive areas require defined coverage, thickness, and masking. Material certification, RoHS/REACH declarations, or composition limits should be requested before stock procurement. Equivalent material should be used only after customer or design approval.

• Grade and standard: JIS, UNS, EN, or customer specification
• Temper and stock form
• Composition or environmental-compliance limits
• Plating thickness and no-plate zones

Complete input allows VietTech to review material sourcing, workholding, tooling, inspection, cleaning, and packaging. Machining feasibility is confirmed against the drawing rather than grade name alone.

• Exact C1100, C3604, or alternative grade and standard
• Temper and certification requirements
• Revision-controlled 2D drawing and 3D model
• Tolerances, roughness, and conductivity or thermal requirements
• Plating, masking, cleanliness, and cosmetic requirements
• Quantity, repeat demand, packaging, and delivery date