Motor sleeves and magnet overwinds
Automated fiber placement (AFP) of thermoplastic composites offers unique advantages to motor sleeves and magnet overwinds, ultimately creating improved motor efficiencies.
An overwind in this case refers to high-tension fiber placement of thermoplastic composites around a magnet, motor, or generator, creating a type of motor can. Wrapping with advanced composite materials provides added strength and improved performance.
Specifically, these benefits center on increased mechanical and electromagnetic performance compared to alternative materials and manufacturing processes. Such alternatives include metal casings, which create electrical losses, and wet-wound (filament wound) thermoset composites, which fall short of the performance offered by AFP and thermoplastics.
AFP and thermoplastic composites
Taking a closer look at AFP and thermoplastics reveals many benefits to motor casing design:
- High-tension fiber placement, up to tensile failure of tape. This pre-stress provides significant radial compression on the motor and allows for faster motor spin.
- Further radial compression can be achieved during processing through active-chilling on the substrate.
- Mid to high-modulus composite tape can be used, nearing or exceeding modulus of steel, without the electrical losses or additional weight of steel.
- Thick-wall composite cylinders can be manufactured with low residual stress due to the ply-by-ply bonding process of in-situ AFP.
- Thermoplastic composite material absorbs less than 0.2% of water by weight, just 1/10th of competing thermoset composites, thereby minimizing volumetric swell in hot-wet environments.
- Consistency achieved through automation, throughout composite volume, is critical for highly-stressed parts.
- Part repeatability is delivered through tight control of both raw material and the fiber placement process.
- No post-process heat cycle eliminates the possibility of the metal substrate expanding into composite then shrinking away upon cooling.
Jet engine generators, subsea motors, and other industrial magnet overwinds realize significant cost savings from improved efficiencies over metal magnet casings. Customized composite designs and a proven, repeatable manufacturing process build on these savings by reducing mean time between failures. Some components are designed to last up to 30 years in service.
Composite hybrid pipe
Similar applications in the oilfield include hybrid pipes. Automated Dynamics (now part of Trelleborg Group) has the capability to join steel with continuous-fiber composites, creating lightweight solutions that improve strength and performance.
Using continuous carbon or glass fiber composites to overwind steel pipe offers advantages including:
- Lighter tensile loads on sections of pipe used in deep water environments
- Added hoop strength for higher PSI capability compared to steel pipe of the same thickness
- Resistance to sudden or continuous attacks of H2S gas and carbon gas
- Improved fatigue properties compared to metals
- Reduced corrosion concerns in deep water environments
Companies: Automated Dynamics
Industries: Equipment and Machinery
Technologies: Fiber Placement