英语论文网

sed in the cell range from developing process-level standardized work to system-level standardized work. The main part to be focused in this chapter is on the new ways to reduce the cycle time of the process. As said earlier, the word cell used in this work loosely refers to 6 machines which are grouped together to make a single product.

The main bottleneck operation is on a machine which does all the turning operations in the cell. There are two such machines in the cell to perform the same operation. These machines perform 4 different operations at different parts of the same product. The machining time for each of these four operations varies from 2 hours to 90 hours. This time variation leads to a lot of confusion to the operators in the shop floor, as many times they are not sure when the operation will start and when it will end. There are also a lot of communication problems between the first shift and the second shift operators regarding the process troubles in each part due to the unpredictable timings and also due to the low repeatability of jobs in the shop floor. This instability makes the operators not so confident in their operation eventually taking a lot of extra time to complete the task.

The actual time taken to complete the third operation in this machine varies about 60 to 90 hours depending on the diameter of the part and the material type. The standard time to complete this process is only 40 hrs. The process is not stable as per the standard guidelines and it also depends very much on the skill of the operator. The main reason for the delay in this process was observed in detail by a number of cycle time studies.

4.1 Initial Observations

A lot of time was spent in observing this bottleneck process as the machining takes a lot of time depending on the part size and material, as the working time is very long for a single part it is difficult to predict where the time is lost in the operation, so the standard routing time was compared with the actual process and there was about 50% more time used than the standard time in most cases. The difference in time was about 2 days of working time when compared to the standard. Since the opportunity is big, a time study was done to note down the time taken for each and every operation.

The entire 3rd operation was divided into 13 small operations and the time for each operation was noted and documented and was also compared with the standards. With the help of the time study it was found that 4 operations out of the 13 are taking about 50% of the time i.e. nearly 30-50 hrs.

As the impact in these 4 operations is high, the major work in this chapter is focused in reducing the cycle time in these operations. These 4 operations are used to make a pocket in the center of the work piece. The CNC program used for this turning operation was observed. As per the program there are about 12 passes to complete this operation for the part size which is of maximum demand. In reality, from the time study it was noted that each pass out of the twelve was re passed at least 2 or 3 times. This happened due to very fast insert wear, insert break or no proper cut or push offs. It was noted that the machine was本论文由英语论文网提供整理，提供论文代写，英语论文代写，代写论文，代写英语论文，代写留学生论文，代写英文论文，留学生论文代写相关核心关键词搜索。