Research at Saint-Gobain Performance Plastics has shown a direct link between its product material mix (bronze, zinc, filled PTFE) and its customers mating components in regards to corrosion (commonly known as rust) protection. For NORGLIDE® bearings, corrosion resistance is currently of a very high standard. However by making a switch from concentrating just on NORGLIDE® corrosion resistance bearings to an assessment of the galvanic properties of the entire assembly Saint-Gobain can offer the customer the highest level of reassurance.
NORGLIDE® bearings are mechanically zinc plated components that suffer no hydrogen embrittlement. Also by using passivation, a thin film of corrosion products forms on the metal's surface acting as a barrier to further oxidation, it serves as an indirect kinetic barrier. An additional organic sealer can also be applied. NORGLIDE® bearings are also available as galvanic plated components.
The result is that NORGLIDE® bearings offer a very high standard of corrosion resistance.
The galvanic series (or electro-potential series) determines the nobility of metals and semi-metals. When two metals are submerged in an electrolyte, while electrically connected, the less noble (base) will experience galvanic corrosion. The rate of corrosion is determined by the electrolyte and the difference in nobility.
Likewise when using the galvanic series to determine the nobility of the customers mating components, NORGLIDE® bearings can be optimized to achieve even better corrosion resistance. The solution, put in simple terms, is to offer materials that are close together in the galvanic series and to ensure that the least noble material has a larger surface area.
Additionally, the zinc coating on NORGLIDE® bearings may not always be required-depending on the mating components-so the product can be offered at a lower price, giving even better value to the customer.
Many manufacturers use a corrosion cycle test:
- 5% salt solution for 15 minutes
- Drain and dry for 3 hours
- Environmental cabinet 50°C for 21 hours
They repeat this for at least 10 cycles.
Testing conditions are from Testing Standard SAE J2334 (VDA 621-415)
Saint-Gobain imitates these tests during their design and manufacturing process to ensure the highest quality and satisfaction for their customer. These include a salt spray chamber (according to DIN ISO 9227) and thickness testing (according to EN ISO 12683 & DIN 2064).
These tests have shown that single-tested NORGLIDE® bearings can last for up to 480 hours in extreme conditions before showing signs of base metal corrosion, and often even longer in assembled conditions.
Salt Spray Chamber
» For more details on products for Corrosion Protection benefits please visit Sales and Support for regional contact information or Email Us directly with your enquiry.