Bronze Contact Finger

Bronze contact fingers are spring-loaded contact elements where the body and spring action are combined in one piece. The bronze alloy is hard enough to act as the spring while still conducting current. This contrasts with the CuW Contact Finger, where a CuW tip handles arc duty on a copper or bronze body, and with copper fingers, which need a separate stainless or bronze spring behind them.

Phosphor bronze (C51000, C52400) is the typical alloy when spring action matters most. Aluminum bronze (C95400) shows up when the finger sees sliding wear under load and mechanical durability matters more than spring rate.

Specifications

Property	Value
Alloy	Phosphor bronze C51000 / C52400 (spring duty); aluminum bronze C95400 (wear duty)
Form	Spring-action finger (single piece, no separate spring)
Finger Length	Per drawing
Cross Section	Rectangular or shaped, per drawing
Tolerance	Per drawing
Surface Treatment	As machined or silver-plated on contact face
Conductivity	11–20% IACS depending on alloy
Hardness (HB)	75–225 depending on alloy and temper
Working Voltage	Common MV ratings: 12 / 24 / 40.5 kV
Working Current	Per-finger rating depends on cross-section and alloy

Exact certified properties for your lot are available with material documentation on request.

Applications

• Spring-action finger contacts in MV switchgear where the alloy provides both spring and current path
• Sliding contact elements in disconnector and isolator assemblies
• Contact fingers for applications where mechanical durability matters more than minimum contact resistance
• Replacement fingers for installed switchgear refurbishment

Technical Notes

The choice between phosphor bronze and aluminum bronze depends on duty cycle. Phosphor bronze has the better spring properties, higher elastic limit relative to its strength, so it returns to shape after repeated flexing. Aluminum bronze is harder and more wear-resistant but doesn't spring as well; use it where the finger sees sliding wear rather than repeated insertion cycles.

For most plug-in spring-finger applications, phosphor bronze C51000 or C52400 (the higher-tin variant) is the right starting point. For sliding-wear applications, aluminum bronze C95400 wins on service life despite lower conductivity.

Silver plating on the contact face is normal for low-resistance applications. The bronze underneath handles the mechanical work; the silver handles the electrical interface. Plating wears over insertion cycles; thickness specification matters for life.

Sourcing & OEM

Custom bronze contact fingers to your drawing are routine. Specify the alloy choice and any silver plating; contact us with your drawing for a project-specific quote.