Design Considerations

■Locking

Since a special motor is built in, the coil does not burn out even if the motor roller is locked for a short time. However, if it should be repeatedly locked, rise in the coil temperature and gradual deterioration of the insulation would occur, causing the motor to burn out. If locking continues 10 sec. or more, the user need not turn off the motor roller but it is advisable to de-energize it using a limit switch or relay. In this case, the accumulator type is more suitable.

■Temperature rise

The motor roller should be used within an ambient temperature range of -10 to 40°C. In normal operation, the temperature of the roller outer surface is 20°C higher than the ambient temperature.

■Intermittent operation

Intermittent operation here means that motor rollers rotate and stop alternately as the power is turned on and off. Generally, in connection with coil temperature, the minimum cycle time for intermittent operation is as follows.

■Inertia

  • Due to the inertia of the motor and load, the rollers do not stop immediately even when the power is turned off.
  • The inertia differs depending on the motor rollers’ type and speed and the load’s type and weight and operating time.

■Overload

If the standard (S) type rollers are continuously used at a surface speed which is less than 60% of the one specified in this catalog, motor burnout would occur. For such an application, select the accumulator (A) type.

■Speed difference in a joint

In order to avoid giving a strong impact to motor rollers, make sure that there is no serious speed difference within a line or in a joint between lines.

■Conveying surface levelness

  • If the roller surface or the bottom of a load (particularly a heavy load) is not flat, roller idling or skewing of the load might occur.
  • If the weight of the load is below 5 kg, slippage may occur because of idle roller resistance, resulting in a conveyance failure. Manually rotate the idle rollers and check.
  • A packing band or a bulge on the bottom of the load may cause the load to skew. For use in such a condition, select a roller model with rubber-lined ends.

■Guidance for selection

In selecting the motor roller model, take the following three factors into consideration:

  1. Weight of the item to be conveyed and motor roller allowable load (see “Withstand Load.”)
  2. Tangential force
  3. The load’s bottom shape and size (Use two or more motor rollers for a cardboard box with an unsmooth bottom.)

■Installation Method

  • When the motor roller’s shaft has the same size as an idle roller, the shaft holes for the idle roller may be used for installation.
  • If the size is not the same, modify the shaft holes in the frame and install the motor roller so that it is flush with the idle rollers.
  • Depending on the material or flatness of the load (box), the motor roller may not touch it. In this case, use at least two motor rollers for one box or make the motor roller level slightly above the idle rollers (in the latter case, pay attention to the motor roller’s allowable load because it must bear the weight of the box by itself).

■How to determine the number of motor rollers

Generally the tangential force required for conveyance is calculated from the formula below (depending on the weight, bottom size, material and flatness of the load).

F = μ・9.8W
where F: required tangential force (N)
          W: weight of the load (g)
          μ: coefficient of rolling friction of the load material

Coefficient of rolling friction of the load material (μ)

Determine the number of motor rollers by comparison between the required tangential force F and the tangential force per motor roller f. Required number of motor rollers: F ÷ f

Example 1: 57S model 60 Hz

Select roller width 500, roller pitch 100 according to the shape and weight of the load.
If the load’s weight W is 30 kg and the coefficient of rolling friction μ is 0.075, then the required tangential force for conveyance F is:
F = μ・9.8W =0.075 x 9.8 x 30 = 22.05 (N)
As a tangential force of 22.05 N is applied to the load, the rollers start conveying it.

When 3-phase 200 V (60Hz) power is used, one unit of any of standard models 57S4 to 57S25 is enough to start.

The load which one motor roller bears is:
30 kg ÷ 4 (rollers) = 7.5 kg.
This is within its allowable load range. Even if only one motor roller bears the load, it is within the allowable range.

Example 2: 57S model 60 Hz

Select roller width 1000, roller pitch 100 according to the shape and weight of the load.
If the load’s weight W is 300 kg and the coefficient of rolling friction μ is 0.035,
then the required tangential force for conveyance F is:
F = μ・9.8W =0.035 x 9.8 x 300 = 102.9 (N)

When 3-phase 200 V (60Hz) power is used, one unit of any of standard models 57S4 to 57S6 is enough to start.

The load which one motor roller bears is:
300 kg ÷ 9 (rollers) = 33.3 kg.
Since the allowable load range for width 1000 is 50 kg, the motor roller can bear the load.

If the initial speed is important or the load bottom is not flat, use more rollers.
  • Straight rollers
  • Tapered rollers
  • DC roller
  • Options
  • Idle rollers
  • Terminal Brackets
  • Shafts
  • Compatibility with cleanroom system
  • Brake system
  • How to Select the Motor Roller Model
  • Design Considerations
  • Wiring instruction
  • Cautions in Handling & Safety Precautions
  • MRB