Introduction to Industrial Automation

10.3   Packaging System of Different Balls

Figure 10.3 shows a packaging system of balls in packets of six different items. There are 12 feed-

ing lines, each one with different design. The balls come from all lines in a random way and at 

relatively slow rate. The packaging system is controlled by a PLC and operates according to the 

following specifications:

 

◾

With the momentary signal START, the machine produces 15 packets of 6 items (90 balls) 

and waits for the next start signal.

 

◾

Each ball, coming from the corresponding feeding pipe, falls on an inclined plane only if 

the solenoid SL

i

 is energized, and is detected by the photo-switch F

i

. After detection, the 

solenoid is deactivated in order to block the falling of the same second ball, since the packet 

must contain different balls (i = 1–12).

 

◾

Each ball falling on the plane rolls towards to point A and is detected by the photo-switch 

F

0

. The completion of six balls is verified by the permanent activation of photo-switch F

0

.

 

◾

Just after six balls fall, the other balls stop falling, and after the completion of six balls, the 

wrapping is started at point A. The wrapping is performed by rotating the geared motor M 

by 360°, and the end of rotation is detected by the proximity switch S

0

.

 

◾

If during the production of 90 balls, the number of balls from the same feeding line is 

greater or equal to 21, then this kind of ball is excluded from the next two sets of 90 balls in 

production and is reverted normally in the following set of 90.

Twelve different

colors and designs

Wrapping machine

M

A

Six-pack of balls

Oblique plane

S

0

SL

1

SL

2

SL

3

SL

12

F

1

F

0

F

2

F

3

F

12