Manufacture of Silver Impregnated Contacts (SIG) Certified & Approved by Railway RDSO
Manufacture of Silver Impregnated Contact (SIG)
Manufacture of Silver-Impregnated Contacts (SIG)
Manufacture of Silver Impregnated Graphite Contact
Manufacture of Silver-Impregnated Graphite Contacts
Manufacture of Silver Impregnated Graphite Relay Contact
Manufacture of Silver-Impregnated Graphite Relay Contacts
Manufacture of SIG Contact
Manufacture of SIG Contacts
Manufacture of S.I.G Contact
Manufacture of S.I.G Contacts
Manufacture of RDSO Approved Silver Impregnated Contact (SIG)
Manufacture of RDSO Certified Silver-Impregnated Contacts (SIG)
Manufacture of RDSO Approved Silver Impregnated Graphite Contact
Manufacture of RDSO Certified Silver-Impregnated Graphite Contacts
Manufacture of RDSO Approved Silver Impregnated Graphite Relay Contact
Manufacture of RDSO Certified Silver-Impregnated Graphite Relay Contacts
Manufacture of RDSO Approved SIG Contact
Manufacture of RDSO Certified SIG Contacts
Manufacture of RDSO Approved S.I.G Contact
Manufacture of RDSO Certified S.I.G Contacts
Manufacture of Silver Impregnated Contact (SIG) Approved by Indian Railway
Manufacture of Silver-Impregnated Contacts (SIG) Certified by Indian Railways
Manufacture of Silver Impregnated Graphite Contact Approved by Indian Railway
Manufacture of Silver-Impregnated Graphite Contacts Certified by Indian Railways
Manufacture of Silver Impregnated Graphite Relay Contact Approved by Indian Railway
Manufacture of Silver-Impregnated Graphite Relay Contacts Certified by Indian Railways
Manufacture of SIG Contact Approved by Indian Railway
Manufacture of SIG Contacts Certified by Indian Railways
Manufacture of S.I.G Contact Approved by Indian Railway
Manufacture of S.I.G Contacts Certified by Indian Railways
Silver Impregnated Graphite (SIG) contacts are used in high safety applications of railway signaling, traffic signaling, and numerous other applications due to high silver content that eliminates the risk of welding in the presence of graphite. High contact resistance (>200mO) was observed in the SIG contacts in a railway signaling operation after a few thousand operations of the relay. The high contact resistance was discovered to be a result of loose dust/foreign particles residing between the two contacts. Silver had been preferentially removed from the contacting surfaces during switching operations by an abrading effect of the dust/foreign particles, leaving only graphite on the contact area. Wear was accentuated by the presence of porosity and low hardness of the contacts, leading to improper interaction between the mating surfaces.
Silver Impregnated Graphite relay contacts combine the best properties of silver (electrical/thermal conductivity) and graphite (refractory nature) into a composite material. Distinctive features of the SIG material include its hard fusing characteristic, better conduction of heat and electricity, and easy brazing. Graphite carbon has high heat of vaporization and appreciably low material transfer in the localized high temperature spots developed during mating of contacts. Additionally, due to a high percentage of silver, the desired electrical properties are retained with practically no risk of welding. This combination of properties makes these contacts suitable for high safety applications such as railway signaling, traffic signaling, and numerous other applications.
Silver Impregnated Graphite contacts are generally tested for dimensions, crushing strength, silver content, hardness, ash content, distribution of silver in the graphite matrix, contact resistance, X-ray mapping of silver, microstructure, life test, surface finish, and bulk density. The quality assurance of electrical contacts is often treated as an evaluation of “components in great quantity” and tested with statistical methods. This maybe the reasonable for the registration of fabrication defects, but consideration is also required for systematic failures related to specific materials, environmental influences during processing, application, and so forth. Failures caused by environmental influence occur late in the lifetime of the contact or component and may not be detected by early evaluations. Additionally, contamination on the surface of contacts and have deleterious effect on the contact and switching properties and may, in extreme cases, lead to early failure of devices.
BRIEF OF OUR PRODUCT:
Our product is SILVER IMPREGNATED GRAPHITE CONTACTS (SIG CONTACTS), which are extensively used as contact material for various Signaling Relay applications.
SIG CONTACTS are Non-Weld able Graphite contacts which have 55-60 % of Silver impregnated in their matrix due to which these have a very-very low Contact Resistance of less than 20 m-ohms. These are Electroplated with Silver (one side) to make them weld able & can be attached to various relay. SIG CONTACTS are made of various shapes & size to cater the demands of various Relay .
CHARACTERISTICS OF OUR PRODUCT
Our company specializes in manufacture of SILVER IMPREGNATED GRAPHITE CONTACTS.
We are involve in making customize SILVER IMPREGNATED GRAPHITE CONTACTS for Indian railways& other relay manufactures, which are intern used for various Shelf type line & track relays confirming to IRS: S53 & BS: 1659 For signaling purposes. Silver impregnated relay contacts combine the best properties of conducting silver & refractory graphite metal. These contacts are widely used in railway signaling relay. The distinctive feature of the silver impregnated carbon material is its hard fusing characteristics, better conduction of heat & electricity, easy brazing etc.
Silver impregnated graphite (SIG) contacts are used in high safety applications of railway signaling, traffic signaling, and numerous other applications due to high silver content that eliminates the risk of welding in the presence of graphite. High contact resistance (>200 mO) was observed in SIG contacts in a railway signaling operation after a few thousand operations of the relay. The high contact resistance was discovered to be a result of loose dust/foreign particles residing between the two contacts. Silver had been preferentially removed from the contacting surfaces during switching operations by an abrading effect of the dust/foreign particles, leaving only graphite on the contact area. Wear was accentuated by the presence of porosity and low hardness of the contacts, leading to improper interaction between the mating surfaces.
Silver Impregnated Graphite contacts used in metal to carbon relays combine the best properties of conducting silver
and refractory graphite carbon. The distinctive features of
the silver-carbon material are its hard fusing characteristics,
better conduction of heat and electricity, easy brazing etc.
The electro – graphite for these SIG contacts is manufactured using the Press-Sinter-Infiltrate (PSI) process of powder metallurgy, which provides the highest density material.
Silver impregnation is done to achieve high level of electrical conductivity. The SIG contacts are made from graphite
blocks, by several cutting, machining & shaping processes.
Impregnation is carried out by soaking the graphite pieces in
silver nitrate solution under high vacuum for adequate time
and then washing the pieces gently by triple distilled water
to remove any sticking silver nitrate from the surface. Then
the silver nitrate is reduced into silver through the process of
‘firing’ and then electroplated on backside for soldering. Finally, three-stage cleaning of SIG contacts is done to remove
any water – soluble impurities remaining after electroplating.
The final product, as shown in figure 1, shall contain 55% to
60% by weight of silver (without considering the silver plated
portion) and the distribution of silver throughout the volume
of contact, as seen in micrographs, shall be uniform and free
from defects viz. seams, threads, or silver globules [1]. The
specific resistance of impregnated graphite shall not exceed
2×10-4 ohms-cm, while the compressive strength of contact
shall not be less than 700 kg/cm2 [1]. The hardness of contact shall not be less than 22 VPN. The water-soluble impurities in the finished contacts shall not exceed 0.25% [1].
Inspection & Approval Certificates : C/W Certificate (Calibration Works Certificate) EN 10204 3.1 / DIN 50049 3.1 / ISO 10474 3.1 Mill Test Certificate,
NACE HIC TM-0284 / NACE MR-0103 / NACE MR-0175 / ISO 15166, CE Marked, European Pressure Equipment Directive PED-2014/68/EU, AD-2000-WO,
ASME Boiler & Pressure Vessel Code Section-II Part A Edition 2019, API 6A (American Petroleum Institute), with 3.2 Certificate duly Certified &
Approved by IBR (Indian Boiler Regulations), LR Class (Lloyd’s Register), GL (Germanischer Lloyd), BV (Bureau Veritas), DNV (Det Norske Veritas),
ABS Class (American Bureau of Shipping), SGS, TUV, RINA, IR Class (Indian Register of Shipping), NORSOK Approved Standard M-630, M-650 Rev.3
If you have any requirement of above items, please feel free to contact us
Regards,
CONTACT PERSON :
MUKESH SHAH
Director
Mobile No. 0091 – 9820292499
Email – marketing@rolexmetals.com
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