Linear Motors

   

 

 

 

 




Advantages:
  • High speed. The maximum speed of a linear motor is limited only by the bus voltage and the speed of the control electronics. Typical speeds for linear motors are 3 m/s with 1 micron resolution and over 5 m/s, with coarser resolution.
  • High Precision. The accuracy, resolution, and repeatability of a linear motor driven device are controlled by the feedback device. With the wide range of linear feedback devices available, resolution and accuracy are primarily limited to budget and control system bandwidth.
  • Fast Response. The response rate of a linear motor driven device can be over 100 times higher than that of a mechanical transmission. This means faster accelerations and settling times, thus higher throughput.
  • Stiffness. Because there is no or simple mechanical linkage, increasing the stiffness could be simply a matter of gain and current. The spring rate of a linear motor driven system can be many times higher than that of a ball screw driven device. However it must be noted that this is limited by the motor peak force, the current available and the resolution of the feedback.
  • Zero Backlash. Without or with simple mechanical transmission components, there is no backlash, except one generated by rotations around co-ordinate axes. Resolution considerations do exist. That is the linear motor must be displaced by 1 feedback count before it will begin to correct its position.
  • Maintenance Free Operation - No (minimal) Friction. Nowdays linear motors have no contacting parts, so they do not wear.
Disadvantages:
  • Price. Linear Motors are expensive. This is due to the relative low volume produced, and the price of magnets. Since most linear motor designs mount rare earth magnets to the length of the rail, and the cost of these magnets is high, long travel motors become expensive. However as the popularity of linear motors continues, volume will rise and cost will decline. This process has begun. Linear feedback must also be considered in the cost of using a linear motor. Most importantly, if system accuracy requires linear encoder feedback, the cost difference between linear and rotary technology is greatly reduced.
  • Higher Bandwidth Drives and Controls. Since there is no or few mechanical links between the motor and the load, servo response, bandwidth, must be faster. This includes higher encoder bandwidth and servo update rates.
  • Force per Package Size. Linear motors are not compact force generators compared to a rotary motor with a transmission offering mechanical advantage.
  • Heating. In most linear motor applications, the forcer is attached to the load. Any Joule losses are then directly coupled to the load. If an application is sensitive to heat, thermal management techniques need to be applied. Air and water cooling options are popular and common.
  • Electromagnetic safety brake required.  For instance, a linear motor is traveling at 3 m/s and a power supply/drive system failure occurs. The slider moves then to a random position unless a safety brake system kicks in.
Rare Earth Permanent Magnet Ironless Linear Motor CLM 34 - 112 - 150e

Nd-Fe-B magnets, sinusoidal voltage. Primary is a moving laminated core with three-phase winding, thermistor PTC incorporated. Secondary with permanent magnets is stationary. Magnets are coated against rustiness.

 

 

 

 

 

 

 

 

  • Force:   150 N
  • Travel:  300 mm                                                                             datasheet (.pdf)
Linear Synchronous Motor LINSM 70 - 04 - 470 - S

 This is a linear synchronous motor with Nd-Fe-B magnets, sinusoidal voltage. Primary is a moving laminated core with three-phase winding, thermistor PTC incorporated. Secondary with permanent magnets is stationary. Magnets are coated against rustiness. 

Performances:

Static peak force (Fmax): 

133 N

Continuous force (Fc):

70 N

Travel:

470 mm

Force constant (kf):

50

Peak current (Imax)

2,7 A

Effective current:

1,4 A

Peak velocity (vmax):

3 m/s

Resistance at 25 °C (R):

16 Ω

Inductance (L):

47 mH

Back  EMF constant:

11 V/m/s

Magnetic attraction (Fa):

450 N







 

 

 Units 

Primary 

Secondary 
Length

 mm

 120

 470

Width

 mm

 118

 *118

Height

 mm

 44

 16.5

Mass

 kg

 4

 9.8

Air gap

mm

 0.9

 -

Thread

 -

 6 x M5x10

 -

 

 

 

 

 

 

 

 

 

 

 




* Width of the secondary without linear bearings is 60 mm 

Advantages:

  • Contactless operation without wear or friction
  • Smooth motion.
  • High degree of static and dynamic load stiffness

Ordering information LINSM 70 - 04 - 470;  This is a 4 pole motor with 70 N continuous force, 470 mm travel. 

Customers to provide for encoder mounting, coil and encoder cable carrier, without linear bearings.

Tubular linear motors/generators

Applications:

  • Wave energy generator
  • Stirling generator
  • Direct drives
  • Servodrives 

 

Linear Robot Track AL50-500-0.1

Linear robot track is an one-axis robot consisting of an Aluminum alloy base plate on which there are mounted two linear raceways , a linear synchronous motor, a linear encoder, power cables, limit switches, cables and track protection.

CLM 32-57-56 linear motors are permanent magnet brushless synchronous type, no iron, bilateral construction. Continuous force is 50 N. The maximum force is 150 N.

The engine has a coil without iron, representing the active, moving part. The passive part consists of two identical metal plates facing each other, fitted on the inside with permanent magnets with alternating polarities. There is no mechanical contact between the two sides. The motor is driven by three-phase sinusoidal voltages. Since there is no iron in the active site there are not  iron losses in the motor, there is no parasitic force between the magnet and the moving part, the forces of magnetic attraction between the active and the passive part is zero, unlike other permanent magnet motors. Movement is controlled (force, position, speed) using a digital servo drive. Precision of movement is given only by the encoder precision.

Applications:


Due to the light moving part, this type of linear track is used in applications requiring good dynamic characteristics and high precision.


  datasheet (.pdf)



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