Nano Scale Seal-Glide Coating
Seal-Glide®, an innovative surface treatment from Trelleborg Sealing Solutions, significantly improves friction and stick-slip properties of elastomer seals while having little or no effect on the performance of the compounds the seals are made from. The coating is just a few hundred nanometers, ten to 50 times less than typical coating thicknesses. Even though it is so thin, the coating significantly reduces the friction coefficient of elastomer seals and improves their stick-slip properties considerably, facilitating effective automated assembly.
Seal-Glide® is suited for coating classic O-Rings and complex molded parts for a wide range of applications and is available in two versions: Seal-Glide® Nano for automotive and industrial uses and Seal-Glide® Medical. Typically Seal-Glide® coatings are less than 450 nanometers. It therefore imparts the benefits of a surface coating, without affecting the bulk properties of the seals. As a result, the original elastic properties of the elastomers are virtually unaltered but the seals have a higher service life due to reduced wear when in motion or on start-up.
Andreas Schmiedel, Technical Manager for Healthcare and Medical in Europe at Trelleborg Sealing Solutions, says: “The Seal-Glide® Medical coating is ideal for use in healthcare and medical applications as the new process has a very high level of stability. This makes it resistant against sterilization with gamma radiation, ethylene oxide and hot steam, which is essential for the multiple use of medical devices, valves or syringes.
“To this end, the coating process satisfies the strict requirements for medical, bio-technology and pharmaceutical applications as prescribed by the authorities such as the American FDA (Food and Drug Administration) or European standards such as DIN EN ISO 10993 for the biological evaluation of medical devices.”
In automotive or industrial applications, Seal-Glide® Nano gives distinct advantages in high volume automated assembly lines.
Gordon Micallef, Operations Director at Trelleborg Sealing Solutions in Malta, where Seal-Glide® Nano was developed, says: “The strong surface tackiness of elastomer seals is an inherent property, which can cause issues such as the creation of high assembly forces, disruptions in automatic assembly lines as well as reduced performance in dynamic applications.
“On many assembly lines, overall speed is limited by the elastomer parts feed rate. Due to the reduction in co-efficient of friction, the use of the Seal-Glide® Nano coating will result in significant efficiency gains, by considerably improving the feed rate in automatic assembly lines.”
Elastomers without a surface treatment tend to stick, either to each other during automatic assembly or to counter surfaces in dynamic use. A particular issue is after periods of rest, when due to an elastomer’s inherent stickiness, there can be a stick-slip-effect. In this, the elastomer seal sticks to its counterpart and when moved elastomer is pulled off the seal reducing seal life. In addition, extra energy is required to move the seal from a stationary position.
This stick-slip effect can be minimized or even virtually eradicated through effective surface treatment of a seal. This is also important in healthcare and medical applications.
Schmiedel continues: “When coated, O-Rings or complex molded parts can be installed more easily and securely in components due to better separation of the seals. Using the friction-reducing coating, the components can be assembled smoothly and without damage so that the entire assembly process is completed simply and securely. Feed issues are minimized, reducing the probability of production stops.”
Another advantage of Seal-Glide® is that due to its thinness, the coating has a high level of transparency and does not cover the original color of the elastomer. The color of seals can play a central role in assembly. O-Rings are mostly black, but are often dyed in order to visually highlight differences in composition, diameter, thickness or positioning within a component. With our innovative coating, this color coding is retained, even after the coating.
Seal-Glide® is suitable for many types of elastomer and thermoplastic seal material types. These include LSR (Liquid Silicone Rubber), Ethylene Propylene Diene Monomer Rubber (EPDM), Fluorocarbon (FKM), Fluorosilicone (FVMQ), Nitrile Butadine rubber (NBR), Hydrogenated Nitrile Butadiene Rubber (HNBR), Ethylene Acrylate Rubber (AEM), and silicone rubber (VMQ) as well as thermoplastic polyurethane (TPU).