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Precision CNC Swiss-Type Turned Brass Electrical Pin in C36000 Free-Cutting Brass with Tin Plating and Nickel Barrier for Connectors and Terminals

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Precision CNC Swiss-Type Turned Brass Electrical Pin in C36000 Free-Cutting Brass with Tin Plating and Nickel Barrier for Connectors and Terminals

Detail Information

Product Description

Detail Information

Material:

C36000, C69300, C35300

Diameter Tolerance:

+/-0.01mm

Concentricity Tolerance:

+/-0.005mm

Length Tolerance:

+/-0.05mm

Surface Finish:

Ra 0.4 (contact), Ra 0.8 (general)

Plating Thickness:

Tin 3-5um, Nickel 1-2um

Product Description

CNC Turned Brass Electrical Pin for Connector and Terminal Applications

Brass electrical pins are the contact interface in every connector, terminal block, and plug-and-socket assembly you've ever seen. They look simple—a thin brass rod, maybe with a bulge in the middle and a split at one end. But that simplicity is deceptive. The pin's diameter tolerance determines insertion force. Its surface finish determines contact resistance. Its spring properties determine how many mate-unmate cycles it survives before the contact force drops below spec.

We turn brass electrical pins from C36000 (CZ121) free-cutting brass rod on CNC Swiss-type lathes. Swiss-type is the right machine for this—the bar stock feeds through a guide bushing right next to the cutting tool, so the part never deflects regardless of how long and thin it gets. A 2mm diameter pin that's 30mm long would chatter on a conventional lathe. On a Swiss-type, it's stable because the support is 2mm from the cut point.

The material choice matters more than people think. C36000 has 3% lead content, which is what makes it "free-cutting"—the lead acts as a chip breaker and lubricant at the tool tip. But lead is restricted under RoHS for certain applications. If you need a lead-free brass pin, we switch to C69300 (eco-brass)—it machines about 20% slower and the tool life is shorter, but it's fully RoHS compliant without exemptions. The electrical conductivity is similar (26% IACS for C36000 vs 24% for C69300).

The plating on a brass electrical pin is where most quality problems show up. Tin plating (3-5um) is standard—it prevents oxidation and provides a solderable surface. But tin whiskers are a real failure mode in lead-free tin plating, especially in high-temperature, high-humidity environments. For critical applications, we specify a nickel barrier layer (1-2um) under the tin, which virtually eliminates whisker growth. The nickel adds cost but prevents field failures that are almost impossible to diagnose.

Key Features

C36000 Free-Cutting Brass: 26% IACS conductivity, excellent machinability (100% on the machinability scale—it's the benchmark material). Chips break cleanly, surface finish is smooth, tool life is long. The standard for electrical pins.
Swiss-Type Precision Turning: Diameter tolerance +/-0.01mm on pin contact surfaces. Concentricity within 0.005mm. Length tolerance +/-0.05mm. Swiss-type lathes produce the tightest diameters on long, thin parts.
Tin Plating with Nickel Barrier: 3-5um tin over 1-2um nickel barrier on C36000. Nickel prevents zinc migration from the brass through the tin (which causes contact resistance to increase over time). Plating thickness verified by XRF.
Spring Contact Features: Machined beam slots, cantilever contacts, or tulip contacts for spring-force insertion. Contact normal force calculated per application requirements (typically 1-5N per contact beam). Force tested with spring gauges.
High-Volume Capability: Swiss-type lathes run at 8,000-12,000 RPM with bar feeders. Production rates of 500-2,000 pieces per hour depending on complexity. Lights-out operation for standard pin geometries.

Technical Specifications

Product Name	CNC Turned Brass Electrical Pin
Material Options	C36000 (standard), C69300 (lead-free/RoHS), C35300 (high-tensile)
Tolerance	+/-0.01mm (pin diameter), +/-0.005mm (concentricity), +/-0.05mm (length)
Surface Finish	Ra 0.4 (contact surfaces), Ra 0.8 (general)
Plating	Tin 3-5um, Nickel barrier 1-2um, Silver 2-3um (optional)
Conductivity	26% IACS (C36000), 24% IACS (C69300)
Pin Diameter Range	0.5mm - 10mm
Max Pin Length	80mm
Certifications	ISO 9001:2015, IATF 16949, RoHS, CE
Lead Time - Prototype	5-7 days
Lead Time - Production	7-12 days
MOQ	1,000 pieces (standard), 500 pieces (prototype)
Origin	Dongguan, China

Applications

Board-to-Board Connectors: Male and female contact pins for PCB connectors. Diameter tolerance critical for proper insertion force.
Wire-to-Board Terminals: Crimp pins and socket contacts for wire-to-board terminal blocks. Brass pins with tin plating for solderless terminations.
Automotive Connectors: Brass contact pins for automotive wiring harness connectors. IATF 16949 quality system with PPAP documentation.
Battery Contact Pins: Spring-loaded brass pins for battery contacts in consumer electronics and industrial equipment.
Test Probe Pins: Precision brass pins for IC test sockets and PCB test fixtures. Tight diameter tolerance for consistent contact.
Industrial Plug Connectors: Power pins for industrial plug-and-socket connectors (16A to 125A). Larger diameter brass pins with silver plating for high-current carrying capacity.

Why Choose Sinbo Precision

Swiss-Type Lathe Capability: We run Swiss-type CNC lathes specifically designed for long, thin turned parts with better diameter control and surface finish.
Plating Quality Control: We coordinate tin and silver plating through certified partners with automotive-spec plating lines and XRF thickness verification.
Contact Force Testing: For spring-contact pins, we measure insertion force and withdrawal force to ensure proper contact resistance and long-term reliability.
Automotive PPAP: Full PPAP Level 3 documentation, SPC on critical dimensions, and batch traceability from brass rod to plated pin.
Lead-Free Option: C69300 eco-brass available for applications requiring RoHS compliance without lead exemptions.
Bar Feeder Production: Standard brass pins run on bar-fed Swiss-type lathes with minimal operator intervention for high-volume production.

Manufacturing Process

Design Review: Pin geometry review for Swiss-type turning feasibility, contact surface requirements, plating specification, and material selection.
Material Preparation: C36000 brass rod preparation with material certificates verification and rod straightness checking.
Swiss-Type CNC Turning: All turning operations in single setup with spindle speed 8,000-12,000 RPM and guide bushing support.
Secondary Operations: Cross-hole drilling, slot milling, and comprehensive deburring to ensure no burrs on contact surfaces.
Plating: Barrel or rack plating with nickel barrier under tin for whisker prevention and XRF thickness verification.
Inspection: Optical measurement, insertion/withdrawal force testing, plating thickness verification, and visual inspection under magnification.

Frequently Asked Questions

C36000 or C69300 for my pins?

C36000 if RoHS lead exemption applies to your application (most automotive and industrial connectors qualify). It machines faster, costs less, and has slightly better conductivity. C69300 if you need fully lead-free compliance (consumer electronics, some telecommunications equipment). The cost premium for C69300 is about 15-20%.

Tin or silver plating?

Tin for 95% of connector pin applications. It's solderable, adequate contact resistance, and cost-effective. Silver for high-current pins (above 10A per pin) where the lower contact resistance matters. Silver is about 3x the plating cost of tin.

Why use a nickel barrier under the tin?

Two reasons. First, zinc from the brass migrates through tin over time, forming zinc oxide on the surface that increases contact resistance. The nickel layer blocks this migration. Second, nickel virtually eliminates tin whisker growth, which is a known failure mode in lead-free tin plating. For any connector expected to last 10+ years in the field, the nickel barrier is cheap insurance.

What insertion force should I specify?

It depends on the connector design. Typical insertion force per pin is 1-3N for signal connectors, 5-15N for power connectors. The total connector insertion force is the per-pin force multiplied by the number of pins. A 50-pin connector with 2N per pin requires 100N to mate—that's about 10kg of force. Design accordingly.

Can you supply pins on tape and reel?

Yes. We package brass pins on tape-and-reel for automated assembly (pick-and-place machines, automated crimping). Standard reel sizes: 2,000-10,000 pieces per reel. Custom packaging for specific equipment (KOMAX, Schleuniger, etc.).

What's the minimum diameter pin you can turn?

0.5mm diameter on Swiss-type lathes. Below 0.5mm, the material becomes too flexible and we lose diameter control. For pins under 0.5mm, wire EDM is an alternative, but the cost per piece increases significantly.

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products details

CNC Mechanical Parts

CNC Turning Parts

CNC Milling Parts

CNC Machining Services

Cold Forging Parts

CNC Turning Milling Parts

CNC Aluminum Parts

CNC Stainless Steel Parts

CNC Brass Parts

CNC Stamping Parts

Machining Plastic Parts

Bending Sheet Metal Parts

New Energy Auto Parts

Energy Storage Connectors

Contactor Terminal

Battery Terminal Connector

CNC Manufacturing Solutions

Precision CNC Swiss-Type Turned Brass Electrical Pin in C36000 Free-Cutting Brass with Tin Plating and Nickel Barrier for Connectors and Terminals