FAQ

Frequently Asked Questions


INDEXING NUMBER AND INDEX ANGLE
Index number means the number of stops that an output shaft of an index drive stops while it makes one rotation. For example, if an output shaft stops at 4 times at the points of equal distance while it makes a rotation (360°), its indexing number is 4, and it moves 90° at a time making its equally divided index angle 90°
INDEXING ANGLE / DWELL ANGLE / INDEXING TIME / DWELL TIME
The groove of cam inside (360°) consists of straight part and curved part. In the straight part, output shaft makes no rotation even if input shaft (cam) rotates. In the curve part however, output shaft makes spiral rotation by input shaft's rotations, and the degree of angle that cam moves during this rotation is called Indexing Angle (or, Indexing Period), while the rest degree (straight part) deducted from 360° makes Dwell Angle. The time taken to rotate as far as the indexing angle is called Indexing time and the time taken for making dwell angle means Dwell time. The total of the both (indexing time + dwell time) makes 1 cycle time.
OUTPUT ACCRACY / DWELL ACCURACY
Even if the shaft is set to index according to the indexing angles, its actual rotating angles can be slightly different from the setting ones. This difference between the actual and setting angles indicates Indexing Accuracy. In case that the output shaft is divided into 4 with 90°, Indexing Accuracy can be calculated as shown in the following table.

INDEX NUMER SET INDEX ANGLE ACTUAL ROTATING ANGLE DIFFERENCE INDEXING ACCRACY
1 90 90˚00'15" 15" (MAX-MIN)/2
= (15-(-3))/2
= ± 9 sec
2 180 180˚00'10" 10"
3 270 269˚59"57" -3"
4 360 360˚00'00" 0"

Dwell Accuracy indicates the rotating angle of output shaft when the input shaft rotates within dwell section of cam. Theoretically, output shaft is supposed to keep still (stationary) in the dwell period but it virtually has slight motion due to some machining errors. The maximum value of this angle is called dwell accuracy and represented with arcsec.
IN CASE THAT THE OUTPUT SHAFT SHAKES WHILE THE CAN IS IN DWELLING PERIOD
1. Check the shaft whether it stopped within dwell period of index cam. The output shaft shaking occurs if it stops at an indexing period.
2. Check rigidity of coupling to the index output shaft and the table. If the center of rotating body is far from the output shaft, tension of its connecting part may cause shaking. It's recommended that the distance between output shaft and the rotating body become as close as possible when design the system.
IN CASE THAT THE OUTPUT SHAFT SHAKES WHILE ROTATING :
1. Examine the rotating workload and the dynamic rated output torque. Check if the size of index drive is selected properly. Wrong selection can cause shaking due to insufficient torque. (Select the product model based on workload and torque data, or contact us for sizing inquiry.)
2. Check the rigidity of power driving part (motor, reducer, etc.). If the index drive is connected with indirect driving sources using chain or timing belt, any residual vibration or inertial movement from them can affect to the index output. (Installing or adjusting tensioner is recommended for indirect driving mode)
IN CASE THAT THE MOTOR HAS NOT ENOUGH CAPACITY
1. Please ensure to select proper motor considering pre-load of index and inside friction of reducer, etc.
2. Please note that motor efficiency also lowered once motor rpm falls down by using inverter.
3. Please check if the electric voltage and frequency of the motor are right for the motor type.
IN CASE THAT INDEXING PITCH GOES INCONSISTENT WHILE CHAIN OR TIMING BELT IS DRIVING :
Check how many teeth the timing pulley or the sprocket has. If the index number is not proportioned to teeth number, inconsistent transfer pitch can occur.
IN CASE THAT OIL LEAKS
Once an index drive is attached to equipment, please replace oil cap bolt with air deflating bolt. Otherwise, high inner pressure causes oil to leak when the index drive operates. Make sure to switch the plugs to deflate air before applying an index drive to a machine.