Vacuum Casting ensures flawless insulation and protection of automotive parts such as stators, rotors, ignition coils, batteries and sensors. It is an effective process to protect windings from humidity and contaminants, and is ideal for high-volume mass production. Huntsman designs amine and anhydride cured epoxy resin systems that meet the processing and performance requirements of Vacuum Casting.
Huntsman resin systems exhibit optimal viscosities at processing temperatures, which translates to excellent impregnation and gap filling capability. Our resins are formulated to meet customers’ needs in terms of materials management and processing—they are supplied in bulk containers and exhibit minimal filler sedimentation during transport and storage. Their low coefficient of thermal expansion results in less stress and shrinkage.
Glass transition temperature (Tg):
210°C
Thermal conductivity:
0.7 W/(m.K)
Suitable for:
Superior flow and gap filling capabilities enabling fast processing times. High Tg enabling low thermal expansion within the complete operation range. Very high thermal and chemical endurance (Class N).
Glass transition temperature (Tg):
200°C
Thermal conductivity:
0.6 W/(m.K)
Suitable for:
Developed for rotor potting. Very low CTE, highest modulus and strength between -40°C and + 180°C. Very good intra-coil impregnation, high Tg. Outstanding resistance at elevated temperatures and high rotation speed.
Glass transition temperature (Tg):
200°C
Thermal conductivity:
0.95 W/(m.K)
Suitable for:
Highest modulus and strength between -40°C and + 180°C. Very good intra-coil impregnation. Developed for rotor potting with improved heat dissipation.
Glass transition temperature (Tg):
170°C
Thermal conductivity:
0.6 W/(m.K)
Suitable for:
Very good impregnation. Developed for rotor potting. Toughened with reinforcing fillers for superior crack and thermal shock resistance.
Glass transition temperature (Tg):
165°C
Thermal conductivity:
3.0 W/(m.K)
Suitable for:
1-c epoxy system with deep viscosity drop above 60°C for fast processing. Very high thermal conductivity and endurance. Excellent resistance to atmospheric and chemical degradation.
Glass transition temperature (Tg):
140°C
Thermal conductivity:
0.7 W/(m.K)
Suitable for:
Fast fill and cure times enabling fast processing. Low coefficient of thermal expansion (28·10-6 1/K). Flammability certification UL 94 V-0 (6.0 mm) and thermal endurance (Class H).
Glass transition temperature (Tg):
115°C
Thermal conductivity:
0.7 W/(m.K)
Suitable for:
Excellent gap filling capability and heat conductivity. Toughened resin with reinforcing fillers for superior crack and thermoshock resistance. Very high thermal and chemical endurance.
Glass transition temperature (Tg):
133°C
Thermal conductivity:
0.6 W/(m.K)
Suitable for:
REACH compliant, mineral filled resin with excellent impregnation capability and high crack resistance. Sedimentation free enabling IBC packaging.
Glass transition temperature (Tg):
100°C
Thermal conductivity:
1.2 W/(m.K)
Suitable for:
Well balanced properties: good heat conductivity, very good crack resistance, media and thermal resistance. Excellent flow properties allow for fast filling times and good impregnation.
Glass transition temperature (Tg):
85°C
Thermal conductivity:
1.0 W/(m.K)
Suitable for:
Excellent crack and thermal shock resistance with good filling factor and thermal conductivity. Superior mechanical and electrical properties. Thermal Class H, recommended for stators encapsulation.
Glass transition temperature (Tg):
75°C
Thermal conductivity:
0.9 W/(m.K)
Suitable for:
Good heat conductivity and thermal endurance (Class H). Flammability certification UL 94 V-0 (3.0 mm) and HB (1.5 mm).
Glass transition temperature (Tg):
60 - 65°C
Thermal conductivity:
0.8 - 1.1 W/(m.K)
Suitable for:
Fast processing and curing comparable to impregnation processes. Excellent flow and gap filling with adaptable viscosity and thermal conductivity. High temperature and crack resistance. Recommended for hairpin windings.
Glass transition temperature (Tg):
20°C
Thermal conductivity:
0.5 W/(m.K)
Suitable for:
Polyurethane, halogen free, casting and impregnating system for processing and curing at room temperature. Soft multipurpose polyurethane system for pressure sensitive devices. Available in various colors. Flammability certification UL 94 V-0 (6.0 mm)
Glass transition temperature (Tg):
20°C
Thermal conductivity:
1.1 W/(m.K)
Suitable for:
Increased heat conductivity. Flammability certification UL 94 V-0 (3.2 mm). Low curing temperature and Tg enabling low thermally induced stress.
In the vacuum casting process, resin and hardener are separately degassed, heated and stirred into vacuum tanks. This operation guarantees homogeneity, low viscosity and the absence of air for both components, which enhance the quality of the final casting.
The unit to be cast is pre-heated and placed into a vacuum chamber, in which a preliminary “dry” vacuum cycle takes place in order to remove residual humidity from windings and insulating materials. The addition of heat, together with the lowest possible vacuum value, helps this step to be faster and more effective. Residual pressure is then increased to the processing value, and resin and hardener flow to the mixing head and into the part at a defined rate of speed, to completely cover the windings.
The last step in the process is the curing cycle, which brings the resin to its final glass transition temperature (Tg) and mechanical properties.
Huntsman’s automotive products are the result of many years of leadership in the global electrical insulation sector. We continuously study and improve our materials in order to deliver fast curing cycles in serial production and meet the most challenging productivity targets.
Huntsman technical support is available to guide customers through the setup phase of all processing parameters by using industrial vacuum casting machines available at our application laboratories. We offer a training program aimed to understand both insulating materials and processing technologies, including production of sample parts by simulation of casting processes.
Discover our ARALDITE® encapsulants for electric motors, battery and power electronics.
Vacuum Casting is an excellent choice for parts that are subject to high temperatures, high voltage and/or high rotation speeds and vibrations. Examples include electric motor stators and rotors, ignition coils, battery components and sensors.
Vacuum Casting ensures perfect impregnation of high-voltage windings and provides reliable electrical insulation as well as excellent chemical and mechanical protection. Its short cycle times make it suitable for fully automatic continuous production lines, enabling mass production with maximum productivity.
Resin systems for Vacuum Casting must exhibit low viscosity and a low coefficient of thermal expansion. Other requirements include high heat conductivity, thermal durability (thermal class), dielectric strength and crack resistance.
ARALDITE® CW 30407 resin / ARADUR® HW 30408 hardener enables fast process times. A two-step cure process is recommended to minimize shrinkage-induced stress. Cycle times for Vacuum Casting are competitive with impregnation processes.
