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Yoshihiro Mizutani et al. / Energy Procedia 89 (2016) 318 – 322
In the common method, 1 process takes 1 day. Hence the whole production requires 50 hours and 10 minutes (3,010min). When the cycle time of a single sheet is compared, Production Method with Every Processes Conducted in Parallel is 150min ×60sec ÷ 12,000 sheets ˙ 0.75sec/sheet, while the common method is 3,010min×60sec ÷ 12,000 sheets ˙ 15.05 sec/sheet. This means our production method can reduce the production time to approximately 1/20 of the common method.
Production Method with Every Processes Conducted in Parallel Preparation time is set at 10 minutes, production time at 120 minutes
Process
Process
Common production method
120min
Preparation time is set at 10 minutes, production time at 120 minutes
1st Process 120min
10min
(a)
(b)
10min + 120min
10min + 120min
10min + 120min
2nd Process
1st Process
2nd Process
3rd Process
10min
120min
First Day Work-in-progress Work-in-progress Second Day
3rd Process
10min
Third Day
Time
Time
3010min
Start of Production
Start of Production
150min
Fig. 1. (a) Production method of every process; (b) Common production method.
5. Batch production and single unit flowing production (Fig. 2) Commonly, it is called batch production (method producing multiple lots in a batch), it is expected to reduce production cost with its stable and efficient process for mass production. However, there is little chance for small and medium size factories to compete with the large companies using the same production method, it is considered that they should strengthen their ability to produce diverse types of product in small lots. In batch production, if for instance there is an assignment to deliver a case containing 500 sheets every day for five days, it is common to produce 2500 sheets on the first day, deliver the first 500 and store the remaining 2,000, shipping 500 sheets for the rest of the days from the storage. However, in this method, there is a need for in total 8 storing and shipping operation, and it also requires storage space and management of the stock. Moreover, it is inflexible in responding to the change in order (specification or quantity), and there are possibilities for demerits such as damage caused during storage. Especially, when producing products to be stored, it delays the starting of next lot and its completion, making it difficult to shorten L/T. On the other hand, Single Piece Flowing Production is literally the method to produce with a single unit. For instance, in the case discussed above, this method will produce 500 sheets to be delivered each day, it will eliminate WKHSURGXFWLRQWLPHIRUHDFKORW¶VSURGXFWLRQWREHVWRUHGPDNLQJWKHVWDUWLQJWLPHRIWKHIROORZLQJORWWRPRYHXS and quickens the start and completion of every process. Furthermore, not only there will be no necessity for going back and forth for 8 times inside the factory for transport, it will also lead to reduction of transportation vehicles such as forklifts. In fact, at Jpacks, we managed to reduce forklifts from 5 to 2 without affecting the productivity. Commonly, lease fee for a forklift is around 30,000JPY per month, meaning it lead to 90,000JPY per month or 1,080,000JPY per year reduction of operational cost. In addition, this method eliminates the necessity for storage space, allowing us to utilize the storage space for expanding production capacity, leading to the increase in productivity as well as using the time for stock management for other tasks.
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