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论老子

道,领导也。领导必需要不断呼唤,教导下属以及以身作则。下属的过和错皆因领导懒惰。

 
 
 

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Chapter 7: WIP tracking  

2012-06-24 12:39:55|  分类: Buffer Mentality |  标签: |举报 |字号 订阅

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On my first day to the Bintan factory, Samuel brought me to a plant tour. He stopped by the Kansas line #4. Together with me were the operations manager, Tan Woon Kit and the assistant operations manager, Benny.

Samuel asked me, “What do you think the lean visual board we had put up here. The three of us had spent more than 6 months determining what indicators to put up at this lean visual board. As far as I can remember, this is the fourth major change. Ignore the minor changes that had occurred without my notice.”

I told a quick look at the visual board. In my mind I could not be given a straight answer as ‘Good’ since he is expecting me to make improvements to this lean visual board. I zoomed in to review the WIP tracking table. It was divided into ten columns: namely, Final Assembly, Alignment, Pre-test, Burn-in, Final test, Manual final, Box-up, Source inspection, Shipping, E-Tech.

I noticed several of the columns were blank. Which mean there was zero WIP at the following station: Final Assembly, Alignment, Pre-test, Final test, Manual final and Box-up.

Several pieces of square magnetic labels indicated there were up to 8 units of products staging as Burn-in WIP. These square magnetic labels are of different color with each color representing a different product. At Source inspection and Shipping columns, there were 2 square magnetic labels each. Under the E-tech column, there were more than 10 square magnetic labels and of different colors. Some of the magnetic labels indicated it represent 2 or 4 pieces of WIP.

I replied, “It is not really necessary to divide up the WIP tracking on this visual board for all ten processes. Just track the key station such as Burn-in and E-Tech will do. That will be good enough. By the way, the WIP for all other processes is zero most of the time.”

Samuel was very unhappy with my comment. He asked, “What do you think the current tracking of the WIP status can be improved further.”

I replied, “I suggest it is better to remove the WIP table from the lean visual board completely.”

Samuel pulled a long face. He said, “You do not understand the purpose of having this lean visual board. When I walk right up here at the entrance of this production line, at one glance I can read the status of what is actually happening in this line. This includes the WIP status. This is the purpose of lean visual management.”

I was a little stunned to hear Samuel’s explanation. I could not quite understand the purpose of the lean visual board. I said, “Do you mean you will stop right here and find out what is going on in this line and then walk away without walking right into the production cell?”

Samuel explained, “Yes, after reading the lean visual board, I would have known enough of what is happening here. If I feel that there is something that I want to know more, I will proceed to walk right up to the particular station and check it out for myself. If not, I will turn around and walk to another line. This saves me time.”

I said, “For WIP status, it is always best to see for myself where exactly the WIP is. I strongly believed the WIP status updated on this lean visual board is not current. It has to be a few hours old. But the way how often do the operators update this lean visual board?”

Benny replied, “Thrice a day. They are at 8:00am shift starts, at 12:00 noon before lunch break and at 5:00pm just before shift ends.”

I added, “The WIP status written on the lean visual board is not current. What is the use of updating the WIP status on to this board when the WIP status fluctuates immediate as the production operators commence with their work?”

Samuel asked, “What do you think you should do. Do you think the status for the three periodic intervals you mentioned is good enough?”

I defended my opinion, “The best way to tell the WIP status is to walk down the line and see the actual inventory as of now. The actual WIP at each work station must be made visual and not infrequently updated onto the visual board.”

Samuel was not amused. He thought updating the lean visual board three times a day is the right thing to do. He did not want to discuss about this subject anymore.

He then asked Benny what is the status of the E-Tech WIP inventory tracking. Had he made a purchase of the WIP shelf that he suggested several weeks ago.

Benny replied, “Yes, it is on the way. The sub-contractor is making them.”

I have no idea what the WIP shelf is.

Two weeks later I saw the first WIP shelf put up at one of the E-Tech station. My goodness! It is a pigeon hole with 5 rows and 6 columns. This shelf is mean to hold 30 pieces of WIP waiting for rework. I already had a fair bit of idea of the daily production volume. It ranges from 2 units per shift to 8 units per shift. 30 pieces mean it has the capacity to hold at least 3 days’ worth of output as rework.

The story of WIP tracking did not end here. Samuel came and asked Benny, “Do you know at a glance how long a piece of product is already at the E-Tech station?”

Benny could not make out when the time a unit was placed there. He picked up the process data sheet and read the latest production record. It stated Feb 21, 2008. It was already sitting there for 5 days. He replied, “5 days.”

Samuel said, “Do you see there is a need to do something to make it more visual? Meaning, you know at a glance which unit has been sitting at the E-Tech station for 2 days or less, a week old, 2 weeks old, a month old and more than a month. Make it visual.”

Benny nodded his head and said, “Yes, I will do it.”

A week later when I walked the production floor, from afar I saw the WIP shelf at all the E-tech station was painted colorfully. Blue color is for WIP that are less than one week old. Yellow color is for WIP that is more than one week but less than two weeks. Red color is for WIP that are more than 2 weeks old. Impressive lean visual, I thought.

Figure 7-1: WIP shelf at the E-Tech station

      But back in my mind, the purpose of such lean visual which is designed to stop at providing an update of the WIP status does not mean anything much. I am afraid it serves to give Samuel, the operations managers, facilitators a fairly good excuse in that, “See, I have made the WIP status on the line visual. Everybody can tell at one glance what the WIP status is, be it at the front end of the production line where he can read the WIP status off the lean visual board and at the E-Tech station. I can even tell the age of the individual units staged at the E-Tech station from afar.”

But did Samuel ever ask the question, “What has been done to reduce this WIP? Did anyone follow up to make sure the relevant support group gives due support to expedite on the reduction of the E-Tech WIP?

Ideally, the E-Tech WIP should be as close to zero as possible. Get the support group to assist the E-Tech technician to bring the WIP down to zero. That is the mission.”

On the other hand, did anyone try to ensure that the WIP status along the entire production process is kept at its minimum? I knew the answer. When the maximum capacity of the 19 production cells is 12 units per shift, it takes about 0.67 hours to produce one unit of product. In other words, at every 0.67 hours, one unit of product flows into the production cell. Or a unit should be flowing into the cell at one-piece-flow rate at an interval of 0.67 hours a unit.

What should be the number of WIP staged in-front of each process? The answer is either one or zero. Of course, the burn-in chamber should be holding up to its maximum capacity of 10 units of product. The WIP in-between two processes should be setup clearly to restrict the WIP to a maximum of one unit.

At any process station if the WIP is more than one unit, the operators should stop production and inform the facilitator of the abnormal situation. This is the principle behind the lean production system. That is, surface problems and force the support group to address the issue immediately.

I am afraid by putting up of an elaborate WIP status lean visual and the tracking of WIP at E-Tech station by different age period gives a buffer mentality that “Arh! I have done my best to track the WIP status and the age of the units sitting at the E-tech station. There is no necessity for me to do anything more than these.” 

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