Designing surgical, dental, and dermatological tools is difficult enough. But engineers must also ensure the motors they specify for such devices can be cleaned and sterilized when needed. That's why designers at Maxon Precision Motors Inc., Burlingame, Calif., (maxonmotorusa) put their EC-16 in a sterilizable package. The brushless motor also features coils outside the rotor for good heat dissipation and high overload capability. The motor measures 16-mm in diameter (0.63 in.), and 56 mm long (2.2 in.). Continuous output power is 40 W, and maximum speed is 50,000 rpm. Maximum continuous torque ranges up to 12.6 mNm (1.78 oz-in) but depends on the windings used. High-energy neodymium magnets give the motor a mechanical time constant of 5 sec while helping minimize overall package size. The company also makes a sterilizable gearhead available in 55 gear ratios ranging from 3.8:1 to 4,592:1. The gearhead is rated for up to 2 Nm (283 oz-in.) continuous torque and a maximum input speed of 8,000 rpm. The motor can be sterilized at least 100 times at 134°C (273°F) at 2.3 bar for 20 minutes.