Manufacturing of electrical contacts for industrial use

Context and industrial relevance

Manufacturing of electrical contacts is a core element of industrial electrical engineering and automation. Electrical contacts must switch or conduct currents and signals reliably—often over very high numbers of operating cycles. The functional reliability of an electromechanical system depends strongly on the reproducibility of contact manufacturing.

In industrial applications, contacts are not treated as isolated parts but as functional interfaces within assemblies, for example in contact assemblies. Requirements from series production, automation, quality assurance and cost control directly influence process design.

Typical application fields include electrical engineering, installation technology, and—often with additional requirements regarding process stability and traceability—the automotive sector.

Requirements in industrial contact manufacturing

Industrial production of electrical contacts is subject to higher requirements than the manufacture of simple metal parts. Besides geometric precision, electrical, thermal and mechanical properties must be maintained over long periods and large production volumes.

Key requirements typically include:

• reproducible electrical properties (in particular stable contact resistance within the system)
• controlled erosion and controlled tendency to weld under application-specific switching loads
• mechanical stability and defined bond/adhesion strength
• series-capable processes with tight tolerances
• economical use of contact materials, especially precious metal content

These requirements can only be achieved through coordinated material selection, suitable manufacturing processes and consistent process monitoring.

Materials as the starting point

Contact manufacturing starts with the selection of suitable contact materials and carrier materials. In industrial practice, silver-based materials and composite/multilayer materials are common. Copper and copper alloys are widely used as carrier materials to provide conductivity and mechanical function.

Material choice affects not only performance in the application but also formability, feasible geometries and process windows. Depending on the design strategy, contacts are realized as contact tips, contact rivets or contact profiles, each with specific manufacturing implications.

Wire and strip as semi-finished products

In industrial contact manufacturing, electrical contacts are frequently produced from wire or strip material. These semi-finished products enable automation, stable series processes and reproducible quality.

Wire is used in particular for contact rivets, wire contacts and formed contact parts. Depending on the design, solid, composite or multilayer wires are applied. Strip and profile materials are used for stamping/forming processes or implemented as integrated contact profiles.

Key prerequisites are:

• homogeneous material distribution and defined microstructural condition
• tight diameter and thickness tolerances
• clean surfaces as a basis for forming and joining steps

Deviations in semi-finished products directly affect formability, dimensional stability and later contact properties.

Forming processes

Cold forming

Cold forming is one of the most important processes in contact manufacturing. It enables high dimensional accuracy, good surface quality and high production volumes.

Typical applications include:

• manufacturing of contact rivets
• forming of wire contacts
• pre-forming of contact heads and shanks

The feasible forming degree is closely linked to the ductility of the contact material. Melt-metallurgical silver alloys are generally more tolerant of high forming degrees than powder-metallurgical silver metal-oxide materials, where higher risk of cracking or local inhomogeneity can occur.

Warm forming and annealing steps

Intermediate annealing can be used to restore formability or to set defined hardness conditions. These steps must be controlled carefully because microstructure and functional behavior may be affected.

Process window and series stability

In industrial contact manufacturing, a single setpoint is rarely sufficient. What matters is a stable process window. Even small variations in semi-finished tolerances, tool condition or line speed can influence the contact’s functional behavior.

A process window designed too tightly increases scrap risk and dimensional deviations. A process window defined too broadly often results in dispersion of geometry and surface condition—and therefore in dispersion of contact performance. The goal is a reproducible balance between formability, dimensional stability and surface quality.

Typical factors influencing series stability include:

• microstructural variation in wire or strip material
• tool wear and changes in seating/guidance behavior
• thermal effects (friction, intermediate anneals, process heat)
• cycle time, automation level and equipment condition

Continuous monitoring and a clear definition of critical characteristics are prerequisites for stable series production.

Material–process interactions

In practice, contact material and manufacturing process cannot be separated. A material that shows good electrical properties under controlled laboratory conditions may become critical in series production if formability, surface condition or bond strength are not considered sufficiently.

Powder-metallurgical materials often react more sensitively to high forming degrees. Composite and multilayer materials add requirements for tooling and process control because interfaces and transition zones must remain stable over life. Thermal processes—such as welding or annealing—can cause microstructural changes that influence contact behavior.

Functional reliability therefore requires a coordinated view of material, geometry and process parameters—including counter-contact, contact force and application-specific load profiles.

Stamping and stamping-bending processes

Stamping and stamping-bending processes are widely used in contact manufacturing. They enable cost-effective production of complex geometries from strip, for example contact springs, switching arms or carrier parts for subsequent contact joining steps.

Tool design strongly affects burr formation, dimensional stability and surface condition. Clean edges and defined formed states are particularly important when subsequent joining or contacting steps follow.

Joining contact material and carrier

Riveting

Riveting is an established joining method to connect contact material with the carrier. With contact rivets, the contact head is fixed in the carrier by a rivet shank (form-fit). Advantages include low thermal impact, a reproducible contact position and good suitability for automated series processes.

Welding

Welding processes are used to create a metallurgical bond between contact material and carrier, for example for contact tips. Precise control is required because thermal input can modify material condition. In practice, the coordination of energy input, surface condition and part handling is process-critical.

Composite and multilayer solutions

Composite and multilayer concepts are widely used to place precious metals only where needed and to separate mechanical from electrical functions. Typical implementations include bimetal/trimetal designs and contact profiles, where the contact zone is positioned in a defined way.

Surface preparation and coatings

Surface preparation influences contact stability and long-term behavior. Besides cleaning and defined surface conditions, coatings may be used.

Gold coatings are typically used for signal and low-current contacts to support stable contact resistance at low contact forces. For switching contacts under higher loads, gold is usually not suitable because functional layers can be impaired quickly under arcing. Coating systems must always be evaluated together with the base material and the application.

Quality assurance

Quality assurance starts with incoming inspection of semi-finished products and extends to testing of the finished contact part or assembly. The objective is consistent function over the entire series lifetime.

Typical inspections include:

• dimensional and form checks (critical characteristics, process capability)
• microstructure and hardness checks (material- and process-dependent)
• bond/adhesion strength checks for composite materials
• electrical tests in the assembled state (system-relevant)

Because contact performance is strongly system-dependent, functional and lifetime tests are often performed in the real assembly.

Selection criteria for engineering and purchasing

Engineering perspective

Development, design and process engineering focus on process capability, reproducible contact properties and service life. The key is to match manufacturing processes to material, geometry and the application load profile. Processes should be designed so that variation remains controllable and critical characteristics remain stable in series production.

Purchasing perspective

Technical purchasing evaluates manufacturing and supply concepts in terms of cost and organizational stability. Important are stable supply chains, reproducible quality, economical material usage (especially precious metal content) and traceable documentation of inspection and release processes. Close alignment with engineering helps avoid conservative overdesign.

Typical failure modes (practice)

Issues often become visible only in endurance testing or in the field. Root causes are frequently not a single defect but an unfavorable combination of material, geometry and process control.

Typical failure modes include:

• unstable contact resistance despite specification-compliant materials
• dimensional drift due to tool wear or insufficient process adjustments
• bond/interface issues in bimetal and trimetal designs
• microcracks or local inhomogeneity caused by excessive forming
• increased dispersion of contact properties during series ramp-up

Systematic analysis of such patterns is a key element of robust contact manufacturing—especially when material substitutions, cost pressure or process changes introduce new boundary conditions.

FAQ about manufacturing electrical contacts

Further technical information on contact parts, materials and applications can be found in the knowledge section of AX-METALS GmbH. For technical questions or project-related coordination, please contact us via the contact page.