Product Details
AgW70 Heavy-Duty Contact
AgW70 is the workhorse grade for severe-duty LV electrical apparatus, motor starters, heavy-cycle contactors, air circuit breakers at higher current ratings...
Technical Description
AgW70 Heavy-Duty Contact
AgW70 is the workhorse grade for severe-duty LV electrical apparatus — motor starters, heavy-cycle contactors, air circuit breakers at higher current ratings, and any LV application where arc-erosion resistance matters more than maximum conductivity. The 30:70 silver-to-tungsten ratio gives a balance: enough silver to keep contact resistance manageable for continuous LV duty, enough tungsten to outlast lower-tungsten grades through repeated heavy-current switching.
For general-purpose lower-duty LV applications (relays, smaller contactors), see AgW Contact Tip with AgW30–50 grades. For higher-tungsten grades (AgW75 / AgW80) in extreme-duty applications, those are available on request — discuss your duty cycle.
Specifications (Per GB/T 8320-2025 AgW70)
| Property | Value |
|---|---|
| Material Grade | AgW70 (Silver 30±2.0%, Tungsten balance) |
| Form | Contact tip, button, or custom geometry (per drawing) |
| Electrical Conductivity | ≥45% IACS per GB/T 8320-2025 |
| Density | ≥14.90 g/cm³ per GB/T 8320-2025 |
| Hardness | ≥155 HB per GB/T 8320-2025 |
| Bending Strength | ≥657 MPa per GB/T 8320-2025 |
| Impurity Limit | ≤0.5 wt% total |
| Surface Treatment | As machined; polished face on request |
| Mounting Interface | Brazed onto copper alloy carrier or riveted per drawing |
| Thermal Stability (solid-phase sintered) | 970°C / 1 min: no deformation / cracking / blistering per GB/T 8320-2025 |
Exact certified properties for your lot are available with material documentation on request.
Applications
- AC motor starter main contacts (DOL, reversing, soft-start applications)
- Heavy-duty AC contactors at higher current ratings (above general distribution duty)
- LV air circuit breakers requiring AgW arc-resistant contacts
- High-cycle industrial control switches with severe duty cycles
- Replacement contacts for installed heavy-duty LV apparatus
Technical Notes
AgW70's value proposition compared to lower-tungsten AgW grades is service life under arc duty. At AgW70's 70 wt% tungsten content, the arc-erosion rate per operation is significantly lower than at AgW30 or AgW40. The trade-off is contact resistance: ≥45% IACS vs ≥75% for AgW30. For continuous-current LV duty, this is enough conductivity to keep contact heating manageable; for severe-arc duty, the wear advantage dominates.
For motor starter applications specifically, the cycle profile includes high inrush currents (typically 6–8x rated current during motor start) and frequent operations (in some processes, hundreds of starts per day). AgW70 is the typical specification across major motor starter OEM designs.
If your duty cycle is even more severe — heavy switching at high voltage class within LV (≥1000V applications, high-cycle ACBs) — AgW75 or AgW80 may justify the additional cost. Discuss your application duty when sourcing.
Sourcing & OEM
Custom AgW70 contacts to your drawing are routine. Specify the form (tip, rivet, custom geometry), dimensions, mounting interface, and any thickness for service life optimization; contact us for a project-specific quote.
Technical FAQ
Common questions about this product.
Why AgW70 specifically for heavy-duty applications?
AgW70 is the industry default for severe-duty LV apparatus: motor starters, heavy contactors, LV ACBs. The 70 wt% tungsten content gives a good balance: enough tungsten for arc-erosion resistance through high-cycle service, enough silver to keep contact resistance manageable for continuous LV duty. Lower-tungsten AgW grades have higher contact resistance under arc; higher-tungsten grades cost more without proportional service-life gain at typical LV duty.
When should I go higher than AgW70 (AgW75 / AgW80)?
For LV applications with extreme arc duty: very high cycle counts, high voltage class within LV (≥1000V apparatus), heavy short-circuit duty in ACBs. The conductivity drop from AgW70 (≥45% IACS) to AgW80 (≥37% IACS) needs to be weighed against the longer service life. Discuss your duty cycle when sourcing.
Can AgW70 be supplied in riveted form for high-volume production?
Yes. See AgW Contact Rivet for riveted contact assemblies; specify AgW70 head for heavy-duty production. Riveting is the typical assembly method for high-volume motor starter and contactor production.
Are matched contact sets (fixed + moving) available?
Yes. For new motor starter or contactor builds, ordering matched AgW70 fixed and moving contact sets ensures consistent properties on both sides. Specify both drawings.
Are AgW70 contacts compliant with GB/T 8320-2025?
Yes. Material specifications follow GB/T 8320-2025 Table 6 AgW70 minimums (≥45% IACS, ≥14.90 g/cm³, ≥155 HB, ≥657 MPa bending strength). Material certification per lot available on request.
What is the typical lead time?
Lead time varies by form, dimensions, mounting interface, and quantity. Contact us with your specifications.
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