NR, SBR, CR, EPDM, HNBR, PU… sounds like alphabet soup, right? But let’s step out of the kitchen and onto the playing field. Each of these rubbers has its own personality and purpose, and together they form the all-star lineup that powers our belts. At Mitsuboshi, we put these athletes to work so our power transmission belts can handle everything from lawnmowers and combines to ATMs, snowmobiles, and even washers and dryers. Come meet the team, discover what makes each player unique, and see where they shine in everyday life.
The Basketball Player: NR/SBR (Natural Rubber + Styrene-Butadiene Rubber)
Natural ru
bber (NR) comes straight from nature, tapped from the latex of the Hevea brasiliensis tree grown mainly in Southeast Asia. It’s strong, stretchy, and wonderfully grippy. Add SBR, a man-made synthetic designed for extra toughness, and you get a balanced blend that’s flexible, quick, and reliable. Like a basketball player, NR/SBR is agile, versatile, and always in motion—ready to perform consistently day after day.
- Everyday example: Car tires, shoe soles, rubber bands
- In our belts: Classical V-belts, Narrow (metric) V-belts
- Where they shine: Cost-effective, reliable performance in combines, balers, grain elevators, irrigation pumps, air compressors, machine tools, fans and blowers, lawnmowers, snowblowers, tillers, and older automotive accessory drives
The Football Lineman: CR (Chloroprene Rubber, also known as Neoprene)
Unlike natural rubber, CR is fully synthetic. First made by DuPont in the 1930s, it is produced by polymerizing chloroprene. This process gives it natural resistance to heat, oil, weather, ozone, and even flames. CR is less elastic than natural rubber but far more dependable when conditions get rough. Like a football lineman, CR is strong, reliable, and always there to protect and perform when the environment is toughest.
- Everyday example: Wetsuits, orthopedic braces, mousepads, car seat covers
- In our belts: Most wedge and raw-edge cogged V-belts, clutching V-belts such as SUPER KB and SUPER WEDGE II, and standard timing belts including SUPER TORQUE G, Timing Belt G, and the H Series. Also used in SUPER VS, our industrial variable-speed belt
- Where they shine: Heat-, oil-, and workload-heavy applications such as HVAC blowers, crushers, grain augers, small engine applications, milling machines, woodworking equipment, riding mowers, continuous compressors, go-karts, printers, copiers, robotics, and sorting equipment
The Cross-Country Runner: EPDM (Ethylene Propylene Diene Monomer)
EPDM is a fully synthetic rubber made from ethylene, propylene, and diene monomer. Its specialty is incredible resistance to heat, ozone, and sunlight. If NR/SBR cracks in the sun and CR loses elasticity over time, EPDM just keeps going. Like a cross-country runner, EPDM is built to perform under the toughest outdoor conditions, mile after mile.
- Everyday example: Window and door seals, outdoor equipment covers, garden hoses
- In our belts: MEGA TORQUE EP Timing Belt, MAXSTAR POWER EP-X Raw-Edge Cogged V-Belt, RIBSTAR G (CR/EPDM with PU ribs)
- Where they shine: Long-service-life applications requiring heat, ozone, and sunlight resistance, such as automotive serpentine and EPS belts, bus and truck accessory drives, fin fans in petrochemical plants, irrigation pumps, outdoor engines, and washers/dryers
The Weightlifter: HNBR (Hydrogenated Nitrile Rubber)
HNBR begins as nitrile rubber (NBR) and is then reinforced through hydrogenation, which swaps out weak bonds for strong ones. The result is a rubber that thrives under pressure and resists heat, oils, fuels, and chemicals better than CR or EPDM. Like a weightlifter, HNBR is strong, durable, and built to handle extreme loads without flinching while still delivering the precision and quiet operation needed for today’s advanced machines.
- Everyday example: Fuel system seals, dishwasher seals, hydraulic hoses
- In our belts: GIGA TORQUE GX and MEGA TORQUE G Series Timing Belts
- Where they shine: High-demand environments requiring strength, precision, and quiet performance, ideal for automotive timing belts, turbocharged engines, auxiliary systems in hybrid vehicles, industrial robots, packaging machinery, high-load conveyors, refrigerated semis, cotton pickers, and pump jacks.
The Gymnast: Polyurethane (PU)
Polyurethane isn’t technically a rubber, but it belongs to the elastomer family. It’s created by reacting polyols with isocyanates and can be formulated to be either rigid or flexible. In belts, PU stands out for its precision and wear resistance. While it may not excel in high heat, it delivers lightweight agility and accuracy. Like a gymnast, PU is flexible, controlled, and capable of routines that demand precision. PU belts are also known for quiet, clean performance, ideal in environments where smooth operation matters most.
- Everyday example: Skateboard wheels, phone cases, athletic gear
- In our belts: Polyurethane timing belts, FREESPAN, POLYMAX, MB Belt, RIBSTAR U, FLEXSTAR, rope belts
- Where they shine: Applications needing precision, clean operation, and quiet performance, such as automotive EPS systems, conveyors, airport baggage handling, seed planters, food processing, printers, copiers, ATMs
Final Score
So next time you fire up a lawnmower, watch a combine in action, or swipe your card at an ATM, remember: there’s an athlete hiding in every belt. From the basketball player (NR/SBR) to the football lineman (CR), the cross-country runner (EPDM), the weightlifter (HNBR), and the gymnast (PU), each material plays its position to keep machinery moving.
At Mitsuboshi, we make sure the right athlete is on the right team, whether powering a tractor in the field, an engine on the highway, or a snowmobile on the trail. Rubber may not make headlines, but in the game of performance and reliability, it’s always the MVP. 🏆
