How to design manufacturing lines

Guide for Engineer ---How to design manufacturing Lines　　　　　　　　　　　　June 11, 2012 revision 　　　　 6122

CONTENTS
①  Don’t　show off your lines
②  Which is the best
③  What is important?
④  Engineer’s Disposition
⑤  Motion study

1. Don't　show off your lines

　Some competitor companies may want to know your manufacturing methods. 　Even your customers may try to steal your factory methods and may inform your competitor’s company.　 I have some experience　with a famous electric appearance manufacturing company　that stole some information when they visited our factory as an auditor.

　You should seal the parts of machine where you think having important technological method.

　I like to see manufacturing plant. In most cases,there are many hints to design machines and work spaces.

　Some of them might not be so useful. But I used to get, at least, two or more technological hints at one site.

I always think　that a line has many treasures!

2. Which is the best ?

　Which is the best　manufacturing　system
　I think that there is no　best system. Systems should be designed by considering　their product’s feature.

　Canon Corp. is famous for its manufacturing　system　called “cell production”.
They abolished their belt conveyed manufacturing　 lines.　 Instead of their conveyor, they　let　 their　 individual 　workers 　assemble all　 processes　 by 　one　 worker.　Some people say　that it is the best way to make the best of Japanese workers’ power.　But　I don’t think so.　 Some time, it is correct but some time, 　it is incorrect.

　If the life time of the product is as long as five or six months, the line using conveyor may be best.
Under　the“cell　production”system,　 workers often require 　to be trained in all processes　of lines.　 So, it takes time till they make up their manufacturing line to become well operated.

　There is another factor to be considered. 　Quantity of daily product will decide the style of the line, too.
Lines with belt conveyors will be good for 6 seconds to 30 seconds of　its manufacturing cycle. It will be 900 to 4200 units of product per 8　hours.

　But cell production line has more flexibility in their capacity. The number of workers can be changed immediately.　It is one of the strong points that cell production lines have. 　You can do same in lines with belt conveyor by increasing or decreasing the number of lines.　But ,it may take　some time.

3.　What　is important?

　I think most important thing to be considered is that managers or workers can find easily　any troubles occurring in those lines .　 “Just in time system “ are well known in TOYOTA motors manufacturing. If there are any troubles, the line will stop soon.
A line can be continued when each process has a stock of a certain amount of semimanufactured goods.
However, discovery of a trouble may be overdue and a damage may become large.
As a result, much time may be needed for restoration of the trouble which occurred.

　I used to settle lines that their starting point close to the ending point.　
　So, a worker can find the difference between input and output. 　It’s one method for finding the problem of a production line.

4.　Engineer Disposition

　If　you have some to manage　people who design machinery you should rule them by the　standard of machinery of your company lines.　 Many times engineers might hate restrictions　 But you should determine the rule with considering their opinions.
Considering is different from accepting their　claims. 　You should decide the rule by yourself. 　The line should be designed using a certain　doctrine.

5.　Motion study

　I had　 aimed to establish efficient manufacturing lines where human resources are esteemed.

　It’s necessary to use worker’s power effectively.
Only poor profits can be yielded when manufacturing efficiency falls. 　One of　reasons is that there are some waiting times occurred.

　In many　case you might not be able to find out the waiting time.　The workers tend to work according to the　cycle time of the line. 　So, the standard　labor time should be estimated by using the P.T.S. (Predetermined Time　Standard)　　I used to determine the time by using R.W.F. (Ready Work Factor) that is　one of P.T.S. methods.
　Some　room time should be added to the result.
By the added time can be compared with the　cycle time of the line. Then you can judge whether there is waiting time or not.

　But before this you should consider those motions of workers.

　I also have been interested in method　engineering. The method engineering is the study of workers motion.
By the result, I can choose best way of manufacturing.
　But, recently manufacturing　are often done by machinery instead of workers. I think in many factories　there are lots　of waiting delays in machine movements. Therefore, we should remove such waiting times and then the cycle time of machine will shorten. Some mechanical engineer may not be able to find such waiting times, without　knowledge of the motion study. Using video recorder, you might find some problems of machinery movement.

To　be continued!
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