Competition in all manufacturing industries has determined that firms that wish to survive and continue to grow are faced with the ultimate need to cut costs. Methods of achieving cost reduction include increasing productivity and machine "up time," improved quality levels and reducing production time and inventories, among others.

To start to achieve this, it is necessary to implement a number of " preventive controls " in the manufacturing facility. In this case, preventive controls means the establishment of rapid response measures which, with active supervisory support, will help to prevent the generation of poor results and defects before they have the chance to take place.

In most firms, the identified method of "progress control " has usually been more of a post mortem, where production is checked at the end of the working day to determine whether produced volumes were in keeping with the desired plan. If the figures show that the plan has not been achieved, very little can be done to redress the situation. If, on the other hand, progress is monitored each hour, it becomes possible to take corrective actions if it becomes apparent that output is falling behind the schedule.

This is what is meant by "preventive control." It is a way of maintaining an accurate, real time picture of a constantly changing workplace, so that corrective actions can be implemented immediately as soon as any sign of a problem or abnormality occurs. This will then maintain the work place in a normal condition.

To implement preventive control measures correctly, and gain the desirable results, the work place needs to be set up so that all problems,abnormalities and types of waste can be seen immediately.

In such a work place, the controls which can be implemented are known as visual controls.