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Solvay’s Torlon polyamide-imide in clutch system from FTE Automotive

News International-French

7 Dec 2015

The global supplier of high-performance thermoplastics, announces that its Torlon polyamide-imide (PAI) technology forms several key components in a high-performing dual concentric slave cylinder (dCSC) developed by FTE Automotive, a producer of automotive drivetrain and brake systems.

Signaling the first time Solvay’s Torlon materials have been specified for this type of application, FTE Automotive’s dCSC forms the heart of the new SGM X44F Dual Clutch Transmission from an automaker, SAIC General Motors Co., Ltd. The transmission was launched on the 2015 Chevrolet Cruze platform for vehicles produced and sold in China.

The critical core of an automotive clutch system, concentric slave cylinders are positioned directly around the drive shaft and on the clutch. They are consequently subject to extreme loads each time a car shifts gear. FTE Automotive offers various CSC designs for light and heavy commercial vehicles that, depending on the application, are more typically fabricated from aluminum or engineering polymers.

“The intrinsically high wear-resistance of Torlon PAI makes it a natural candidate for seal rings and other high-wear applications in both dual clutch and automatic transmissions” said Brian Baleno, global automotive business development manager for Solvay Specialty Polymers. “A parallel trend is the increasingly frequent replacement of needle bearings with bearings made of Torlon polymers. This conversion allows space savings of about 2.5 mm, which allows engineers to downsize metal castings and thereby achieve significant weight reduction without compromising on performance or reliability.”

Both hydraulic chambers within FTE Automotive’s dCSC each incorporate two seal rings made of Torlon 4275 to ensure reliable and durable performance over the transmission’s lifetime. The seal rings have small cross-sections with relatively large diameters. Yet, due to Torlon PAI’s elongation properties, they maintain flexibility for easy assembly.

Formulated to provide a combination of wear resistance and dimensional stability, Torlon 4275 PAI allows the seal rings to ensure consistent contact with the cylinder’s chamber walls to maintain cleanliness in the transmission’s high-cycle, high-pressure environment while minimizing friction. The material provides a durable, tight seal to allow FTE Automotive’s new dCSC to operate reliably despite constant exposure to dirt, dust and debris, automotive transmission fluids and temperatures cycling between -40°C and 160°C (-40°F and 320°F).

FTE Automotive chose a different grade, Torlon 7130 PAI reinforced with 30 percent carbon fiber loading, to fabricate an innovative locking device that maintains precise radial positioning within the dCSC throughout the transmission's life cycle requirements, while contributing little friction and exhibiting low wear. In addition, the good lubricity and fatigue resistance of this grade enables the locking device to withstand millions of loading cycles from the torsional excitation of the clutch.

As a class of materials, Solvay’s Torlon PAIs combine the performance of thermoset polyimides with the melt-processing advantage of thermoplastics. Wear-resistance grades offer unsurpassed performance in both dry and lubricated environments. High-strength grades retain their superb toughness, strength and stiffness up to 275°C (527°F), making Solvay’s material the industry's highest performing thermoplastic. Its broad chemical resistance includes strong acids and most organics.

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