This diagram captures what the machine operator is doing and what the machine is doing and plots them in one diagram. This scheme is of importance when a single operator is required to operate more than one machine. It helps us to identify the effective time and the ineffective time. In the following example, you notice that the worker waits most of the time. We can take advantage of waiting time for other business.
It may come to mind that the worker operating more than one machine is an exploitation of him, but this has administrative goals.
First, the waiting time is a problem, as the worker feels bored, so it is better to take advantage of his abilities in another job, as this makes him himself motivated and satisfied with his work.
Secondly, when the operator operates another different machine, it gives him an opportunity to acquire new skills and makes work experiences diversified, and this is a kind of motivation.
Third, manufacturing cells are a feature of the Toyota production system. These cells each consist of several machines operated by a single worker or a small number of workers. Each cell produces an integrated part of the product, as it is like a small factory.
Among the benefits of these cells is the reduction of manufacturing time by reducing transportation and waiting time, in addition to the worker or workers in each cell feeling fully responsible for the products of the cell. This scheme helps us to arrange work in such cells.
The same scheme can be drawn for one worker with several machines that he operates, or for one machine with several workers that they operate. The chart can be used to draw several tasks that the worker performs at the same time, such as operating machines and writing a report. In all of these cases, each machine, worker, or work is represented by a special column in the diagram.
Two Hand Process Chart This chart is useful for analyzing repetitive manual work. It charts what both the right hand and the left hand do during a manual process such as assembling a product or typing on a computer. This diagram shows us opportunities to speed up the process by making better use of the hands, especially the left hand.
Have you ever noticed someone typing with one finger on a computer keyboard? Did you notice the extreme slowness with which he writes? A diagram like this helps him know that he is using only one hand, but one finger on one hand. The importance of this scheme appears in repetitive work, as it may help us reduce working time, which means increased productivity, as well as balancing the work done by each hand.
In this example, you notice that the left hand kept holding the cover throughout the process. Can the process be improved? What if we use mask for the cover? This enables us to use the left hand for assembly, thus shortening the assembly time. If we shortened assembly time by three seconds, productivity would increase by about 25%.
We notice in this example that the right hand is the one who collects while the left hand is holding the part. We can make a holder for the part so that both hands can be used for assembly. This diagram also helps us to distinguish inefficient work done by both hands. For example, the process of searching for the appropriate screw is an ineffective process because we can place the screws for the assembly process in fixed places in front of the worker, so he does not need to search and choose.
Stopping to think is also wasted time because if the process were done according to specific steps, the worker would not stop between one step and another to think about what to do. The process of adjusting the position of one part in relation to another part can be accelerated by designing the parts so that they can only be positioned in the correct position. Moreover, this scheme invites us to reduce the time of active operations. We can reduce assembly time by designing parts so that they are easy to assemble and with markings showing the correct assembly direction.
And we can reduce the time of movement of the hands by placing the parts in a suitable order. The chart of the hands makes us look at precise matters that we did not care about before, and these things may help us increase productivity by a large percentage and may help us reduce the worker’s effort a lot.