Freudenberg Examines Sealing Requirements for Heavy-Duty Equipment
The seals and the hydraulic systems of any piece of mining, construction, agricultural or other heavy industry equipment operate under extreme conditions. Variable temperatures, aggressive hydraulic oils, dust and extended periods of operation place seals and their tribological systems under continuous duress. A new generation of material, 94 AU 30000, expands the boundaries for polyurethane use. This innovative compound can be used in standard cylinder applications where higher pressures, larger extrusion gaps, reduced internal friction, improved hydrolysis resistance and compatibility with bio fluids, among other factors, are important. DMRW2 hydraulic wipers made from 94 AU 30000 and sheet metal and the availability of this polyurethane as part of Freudenberg Sealing Technologies’ Xpress rapid replacement part service are applications discussed in the following article.
Today’s extreme environmental climates place extreme demands on the material and structure of the hydraulic seals used to maintain the performance and operation of heavy-duty equipment. The excavators, tractors, backhoes and tunnel boring machines that grind through the earth every day must work harder, longer, cleaner and more cost efficiently than ever to feed the plant, build its infrastructure and harvest its natural resources.
Sealing requirements for these machines must now include high values for tensile strength and elongation at break, resistance to oils and ozone, high elasticity and abrasion resistance. Polyurethane materials (PU) have traditionally met these industrial requirements. In comparison with elastomers, PU has a four times greater capacity for mechanical resistance, as well as outstanding resistance to ozone. At the same time, it stands up well to the stresses of mineral-based fluids.
Freudenberg Sealing Technologies has introduced a new generation of polyurethane for seals that set new standards. Freudenberg's development of its own materials is an important core competency. The company has succeeded in manufacturing a basic material for seals with a far longer operating life than the polyurethane materials used so far.
Watch the video below to see how the seals of today are fulfilling the requirements of tomorrow.
Thanks to their high elasticity and their very good resistance to wear and abrasion, elastomers made of rubber are generally superbly suited to seals. But they also have disadvantages: Due to their limited Shore hardness (a maximum of 90 SH A), they are not suited to applications at all levels of pressure. Dynamic applications are only achievable with the use of lubricants. Freudenberg Sealing Technologies polyurethane materials offer an alternative in cases where rubber elastomers cannot be used or where highly specialized elastomers are out of the question for cost-related reasons.
History
Dr. Otto Bayer" width="200" height="227"> Dr. Otto Bayer
In 1937, a research group at I.G. Farben led by Dr. Otto Bayer (1902–1982) produced polyurethane (PU) synthetically for the first time, and the material made its triumphant march around the world. The industrial production of PU began in 1940. The first foam material based on PU was developed between 1952 and 1954. Many additional developments based on PU followed over the course of decades. As early as 1960, the production of PU foam material came to 45,000 tons. Global demand has greatly increased since then. At present, more than 12 million tons are processed annually. Today it is difficult to imagine our everyday lives without polyurethanes. They are actually one of the most multifaceted categories of plastic. We encounter them as soft polyester foams, as thermal insulating materials, in the soles of our shoes and in the steering wheels of our cars. Polyurethanes above all owe their wide distribution to two special attributes: They can be produced by mixing liquid feed materials. This can even be done in small processing operations. And since innumerable feed materials are available, it is possible to manufacture made-to-order materials in consistencies ranging from soft to hard or from foamed to compact, for a broad range of applications.
The Engineered Polymer Systems Division of Parker Hannifin Corporation, the global leader in motion and control technologies, has launched a new material, Resilon® 4350 Polyurethane, delivering unmatched high temperature seal performance and reliability for a wide range of applications. This new material extends the high temperature sealing range of polyurethanes by over 20°F.
Parker’s Resilon Polyurethane is the established industry leader in high performance hydraulic sealing systems. This newest addition, Resilon 4350, increases the high temperature operating window from 230°F to 250°F for continuous use in many applications while other critical performance attributes such as wear resistance, extrusion resistance, glass transition temperature, and rebound remain best in class. All of this adds up to a new solution for seal designers as they push the envelope in temperature extremes.
