Improving a Car Assembly Line (Student Question)



hello everybody,
i need your help my final year project in improving car assembly line that using jit(just in time) method in installtion of accssories and some parts . could u help me in method to improve the production line using lean manufactoring,jit techniques.
i will descripe the process below in the plant to make clear .

First the yearly report (Riro) prepared by (VLD) department which include the number of cars to be produced and their types ( Camry,corala, ) this year.
Then the (N-2) which the two days before production . In this stage report of selected vehicles to be produced sent to parts Warehouse for confirmation of the availability parts and accessories required.
After that (N-1) stage which the day before production , In this stage Parts submit to the workstation from the warehouse and then they are grouped and putted in a plastic containers and classified by the car model in the preparation area .
Also the cars are arrived to the plant yard from port. Scanning for vehicle Vin number by the worker to arrange the sequence of vehicles & parts.

Finally the (N) stage which is the production day . This stage located at the workstation .
The stages will start with the role of entering the car from the plant yard to the workstation which consist of Lines with their own Stages where the process of assembling the accessories & parts to the car is done. And the number of lines and stages different from one workstation to another.

There is also a standard time required to every car to finish the processes in the line and stages and called “TAKT Time”. The takt time differs from models.

And there are trolleys loaded with required parts to be installed in the cars, and the car sheet that prepared in (n-1) which have the car number, model, color, line number, the parts required in the process. Then the car gets in to the first stage in the line, the trolley goes with the car until the last stage is over. This done with all cars.

In each stage there is sheet that shows the processes to be done in the stage with their standard takt time for one person , ITEMS, WORKING/OPERATION, TIME, TAKT TIME, TOOLS REQUIRED, quantity, MATERIAL, and PRODUCTION QC(quality control) CHECK.

Through the process there is in-line inspection check, during this inspection the worker fill in the checklist sheets about the work done in each stage, also the worker in each stage check the work done by the previous stage before starting his own work .
In each line there is the warning system “Andon system” which is A tool of visual management, originating from the Japanese word for 'lamp'. It is a line/process stop.In case of any problem or error during the process in the stage the worker press the button then the lamp is lighten and alarm makes sound and, in order to call the supervisor of the group to solve the problem in a timely manner to complete the production and non-stop of the work.
If there is a problem or defect that need long time to solve and can’t be done immediately then the supervisor starts to fill in the Back job rework history sheet which include: problem description, investigation &Rework ,QC final inspection .then sends it to the rework area to fix it . The sheet must have three copies one to the plant manager, second to Rework, and third to the book for archive.
And there is a Visual Control Board which is a simple, yet highly visible electronic sign in a work area which displays the status of every production line, pulling plan, the actual pulling plan, N-production plan, Actual production plan, inspected ok car, dispatched car. It notifies management immediately with Remaining puling ,Remaining production , vehicles waiting for dispatch, and alerting team members to emerging problems.
Also there is a Progress Table in the workstation; the table shows the number of cars achieved during the working hours by each line team, and the rework job and its reason if there. The table is placed in a white board and it is filled manually by the worker with plastic numbers.
The process in the plant is continues work without interruption that stop the production, except the worker have breaks during the working hours which is scheduled in advance because if it stops work on any (Stage) will be discontinued in all .
There is also a PDI section (Preparation delivery instruction) where the check of the car after it gets out of the workstation is done , and solve any error or defect if there before delivery to the exhibition or the customer.
Finally the car will be gone to the parking in the plant yard ,then a sticker will be placed in the car which show the truck number that will deliver it to the exhibition ,and the name of the exhibition that will go to .



Quite Involved in Discussions
In general focus on where waste is in the above described process. What seems to not "make sense". This may be a good starting point.

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