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Spotlight on Precision Motion Control

Originally Published MPMN July/August 2002

SPOTLIGHT

Spotlight on Precision Motion Control

Brushless dc motors

High-performance brushless dc motors with built-in electronics are compact and offer quiet, efficient, and smooth operation. The BND12 and BND23 models have torque ratings from 1.7 to 22.0 oz-in. with speeds up to 12,000 rpm. Each frame size is available in different lengths with the integrated electronics optimized for each motor's operating parameters. The brushless configuration reduces maintenance and downtime. Northrop Grumman Poly-Scientific, 1213 N. Main St., Blacksburg, VA 24060.


SCARA robots

Horizontally articulated robots are designed for use in small assembly environments. The units feature standard cycle times of 0.35 second for the HS 350-mm and 450-mm units and 0.29 second for the HM 600-mm and 700-mm models. When compared with previous models, the products offer greater power with 2.6 times the applicable maximum moment of inertia. Denso Corp., 3900 Via Oro Ave., Long Beach, CA 90810.


Miniature drive systems

Coreless dc micromotors, precision gearheads, feedback devices, and drive electronics are available, as well as brushless and brush-type motors with diameters ranging from 1.9 to 44 mm The company's patented low-inertia system Faulhaber skew-wound rotor coil provides a fast start and stop and servoing response. The micromotors feature smooth operation with no cogging and low starting voltages for smooth acceleration and deceleration, low current consumption, compact size, and high operational lifetimes. They are available in a variety of semistandard and custom configurations. Micro Mo Electronics Inc., 14881 Evergreen Ave., Clearwater, FL 33762.


Assemblies

Assemblies are available for use in medical manufacturing automation for positioning or scanning. Precision BiSlide assemblies have dual 45° opposing "v" ways to provide high rigidity in all directions. The carriage moves on low-friction PTFE compound bearings, which are fully adjustable to customize preloading. Both manual and motor-driven units are available. A modular design and external base T-slots enable unlimited multiaxis configurations without adapter plates or brackets. Travel ranges from 5 to 80 in.; load capacity is 300 lb; and thrust load is 100 lb maximum. Repeatability is 0.0002 in.; straight line accuracy is 0.003 in. over the entire travel distance. Velmex Inc., 7550 State Rtes. 5 & 20, Bloomfield, NY 14469-9389.


Miniature step motors

Miniature step motors are available in several versions including a small, threaded-shaft linear actuator with either an R16 planetary gearbox, a B16 spur gearbox, or a 12-line magnetic encoder. The two-phase 24-step P110 measures 16 mm in diameter and 19 mm in length, with a holding torque rating of 7 mN.m. The product's disk-magnet technology enables a rotor inertia of 0.40 x 10–7 kg/m2 and the phase current can be boosted intermittently—up to 1.5 times nominal. A very low detent torque makes the unit suitable for microstep operation, and its high start and stop frequency helps avoid the need for ramped acceleration. Danaher Controls, Motion Components Div., 45 Hazelwood Dr., Amherst, NY 14228.


Robots

Two selectively compliant articulated robot arm products offer quick cycle times and fast motion. The TH250 and TH350 feature payloads of up to 3 kg and repeatability of ±0.01 mm. Both robots have built-in programmable logic controllers and can be programmed using a ladder sequence code. Ethernet, Device Net, or Profibus connectivity are available options. Toshiba Machine Co. America, 755 Greenleaf Ave., Elk Grove Village, IL 60007.


Encoders

A line of incremental and absolute encoders offers different mechanical interfaces, housing styles, resolutions, and electronic features. CoreTech encoders provide incremental counts from 1 to 8192. Absolute encoders offer resolution between 2 and 32,768 steps. Both encoder types are supplied in a variety of solid-shaft, hub-shaft, and hollow-shaft versions, and 2- and 2.5-in. and 60-mm housings. Stegmann, 7496 Webster St., P.O. Box 13596, Dayton, OH 45413-13596.


Slotless motors

Slotless, brushless dc motors are suitable for applications in which small package size, speed, and accuracy are critical. The motor design enables small-sized motors to produce high power outputs in high- or low-speed continuous duty operation. The motors' slotless stator winding and rotor construction provide zero cogging torque and vibration. The stator winding, made of high-density copper and positioned inside a toothless stator ring, creates no preferred rotor position and reduces audible noise. Frame sizes range from 1.4 to 5.8 in. diam. The motors achieve speeds to 50,000 rpm with torque constants to more than 600 oz-in. per amp. EADmotors, 1 Progress Dr., Dover, NH 03820.


Autoclavable brushless dc servomotors


(click to enlarge)

High-performance, fully autoclavable, slotless, brushless dc servomotors are suitable for medical and surgical applications. The highly efficient design of the motors offers reliability, very high power density, virtually no vibration, and no RFI or EMI noise. The units have high-quality stainless-steel components and are available in sizes as small as ½ in. Xtreme Energy Inc., 9543 International Ct. N., St. Petersburg, FL 33716.


Rare-earth magnet motor

A motor's patented rhombic moving coil design provides for long life, low electrical noise, fast acceleration, and high efficiency. Four versions of the RE-max 24-mm-diam motor are available, with metal or graphite brushes, single or double shafts, and power ranges from 6.5 to 11 W. Maximum continuous torque is up to 12.4 mNm. The motors weigh 71 g, and the length (excluding shaft) is 31.9 mm. Ambient temperature range is –30° to 85°C, and the maximum efficiency can attain 90%, depending on the winding. Other options include ball bearings, sleeve bearings, and terminals and leads. Maxon Precision Motors, 838 Mitten Rd., Burlingame, CA 94010.


Synchronized motion control

A motion, vision, and I/O system features a high-performance, software-only controller that offers 32 axes of synchronized motion control. The Automation 3200 uses a distributed control architecture that enables it to maintain performance independent of the number of axes being controlled. This is accomplished by avoiding the processing bottleneck caused by single-processor control architecture. Aerotech Inc., 101 Zeta Dr., Pittsburgh, PA 15238-2897.

Copyright ©2002 Medical Product Manufacturing News

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