Making Mechanical Gears Lighter, Quieter and Longer-Lasting
DuPont combines performance materials and application knowledge to help make mechanical gears better.
DuPont materials are helping to make the mechanical gears that drive automotive components, such as actuators, office copiers and other machines, lighter, stronger, quieter and more durable.
Delrin® and Zytel®: Geared For Strength
For greater strength and modulus at elevated temperatures than competitive copolymers, look to Delrin® acetal resins and the polyamide PA 66 grades of Zytel® nylon resins. Delrin® and Zytel® offer multiple performance benefits that make them suited to a wide range of gears.
The Advantages of Delrin®
- Most frequently used polymer for gears.
- Superior dimensional stability and low water absorption.
- Superior strength, modulus, flexural fatigue endurance, and high surface hardness.
- Lower coefficient of friction against steel.
- Available in a variety of lubricated compositions for improved friction and wear performance.
The Advantages of Zytel®
- Performs at higher service temperatures.
- Resin of choice for worm gears.
- Used as a dissimilar material against Delrin® to reduce gear wear and noise.
- Lower surface hardness and modulus, reducing mesh noise against steel.
- Better resistance to mild acids and bases.
- Provides more forgiving, tougher gear teeth.
Putting Plans Ahead of Products
DuPont offers a broad portfolio of materials with high temperature resistance and strength, as well as wear and friction properties. Our experienced team of application engineers can get involved early in the development process, to help customers determine the ideal material for a specific gear and use, and make recommendations regarding design resources.
We have technical resources across the DuPont global network and technical service laboratories equipped to handle prototype testing and manufacturing, in more than two dozen locations across four continents.
Matching Properties and Applications
DuPont polymers can be used to manufacture light-weight mechanical gears that offer the strength and stiffness of metal. Lighter plastic gear teeth are able to carry the same load on a gear as heavier metal gears, because the plastic deflects, bends, and flexes, whereas the metal does not and will break under the same conditions. A broad polymer portfolio allows users to make more precise matches from DuPont materials for mechanical gears across a wide range of applications and key properties, including:
• Lubricity: A variety of internally lubricated polymer compositions are available to improve wear resistance and reduce friction, without the expense or inconvenience of external lubricants. For example, DuPont™ Delrin® acetal resin, DuPont™ Zytel® nylon resin and other DuPont polymers offer a low coefficient of friction that provides a distinct performance advantage over metals in applications that do not allow for external lubrication.
• Shock Resistance: DuPont™ Delrin® acetal resin and DuPont™ Zytel® nylon resin provide superior damping of moderate shock or impact loads. Toughened grades of Delrin® and Zytel® are also available for high-shock applications.
• Noise Reduction: Metal gears can be noisy. Pliable plastic gears offer smoother, quieter operation, and when designed with adequate clearance, plastic gear teeth will deflect slightly under loading. This deflection makes small differences in pitch and profile less critical, thus helping to reduce noise from meshing teeth. Toughened resins are more flexible, and help to enhance this effect. For highly sliding meshes, like those found in worm or helical gear arrangements, potential plastic squeak can be prevented by selecting one of the many internally lubricated polymers from DuPont.
• Cost Efficiency: Gears made with DuPont performance polymers are a cost-effective alternative to metal. The nature of molded plastic permits parts consolidation, and reduces costly manufacturing and assembly operations. Cams, bearings, ratchets and gear shafts can be designed as an integral part of an injection-molded plastic gear. Multiple gear clusters also may be molded as a unit, decreasing part count and increasing costs savings.
• Durability: In low-stress environments, plastic gears typically offer longer-lasting performance than metal alternatives. Delrin® and Zytel® both exhibit excellent friction, wear, and mechanical properties, which can be enhanced through modifications. These modifications are based on the expected potential failure mode, such as wear, fatigue, tooth shear, or bending. Selecting a polymer family and modifications that balance friction and wear properties, strength, and fatigue resistance at all operating temperatures can maximize gear life.
• Chemical Resistance: Compared with most metals, plastics offer superior resistance to the corrosive effects of a wide range of chemicals. Gears made of Delrin®, Zytel®, and other semi-crystalline DuPont performance polymers resist oils, lubricants, and solvents.
• Weight Reduction: Plastics have lower density than metals, even when reinforced with glass and other materials. Gears made with DuPont performance polymers can significantly reduce inertia and total assembly weight.
INFORMATION & IDEAS
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