DC Micro Motor
DC Motor is the generic term for motors that use direct current. Within the various fields in the world that use DC motors, Namiki specializes in small diameter motors; in 1973, Namiki developed a 10mmOD coreless DC Motor ? the smallest in the world at the time ? based on a coil winding patent introduced from Germany.
What is a DC Micro Motor;
If a "small motor" is defined as having an output of less than 75W, then "micro motor" has an output of less than 3W and dimensions that do not exceed 50mm. At this size, less power is needed to rotate, so the power source can be smaller as well, like a battery. Therefore micro motors are normally DC powered. AC powered "micro motors," as defined above, are not seen in the field, because at high voltages, there is risk that the motor will short circuit or catch fire. Our mission is to reach one fifth, one tenth, even one fiftieth the size of the 50mm micro motor ? in other words, to create a 1mm OD "super micro" motor.
Challenge for the world's smallest
Picture with scale is the φ1.5mm geared motor developed in collaboration with NEDO and Tohoku University. Injection molded metallic glass made this super micro motor practical. A variety of sizes of sun gear, planetary gear are available and the combination creates high torque. Metallic glass itself has a beefier structure than conventional steels, which gives longer life to geared motors.
The world's smallest is our motto. We developed a φ1.5mm geared motor as part of a NEDO project in 2004 when we heard about a 1.9mm motor developed by a Swiss company. The 1.5mm came into a practical use almost immediately. Since the parts in this size range are in micro meter units, even Namiki's extreme skill in precision processing could not easily machine them. Hence, we developed a metallic glass molding method. This enabled a 4 stage gear train to produce a torque of 2070μ, a value 1609 times larger than the motor itself and 80 times larger than that of a φ4mm motor which is main stream today. This φ1.5mm geared motor was expected to be applied in medical fields such as in ultrasonic endoscopes and cardiac catheters. With this size motor set at the tip of the catheter, the location of disease is reachable to sever blood clots, something which was not feasible with conventional actuator sizes. We assumed this was a great achievement, however, since φ1.5mm can only go into the main artery, medical professionals required a diameter under 1mm to enter the even deeper area of the peripheral vessels.This led us to take on the challenge of a φ0.9mm geared motor,which is in practical stage now. Thus, Namiki’s mission to ward [ultimate smallness] and [the world's smallest] continues.