How to Reduce Bucket Loss During Style Changeover

Style changeover is a challenging task in apparel manufacturing. Normally, garment manufacturing factories need to work with a large variety of apparel products in small order quantities. This causes practical difficulty in changing the tools and methods within stipulated time frame.

Planning department release monthly plan based on the order delivery date. From the monthly plan weekly plan is created by the team which is handed over to the HODs of IE, Engineering Department, Production Department and Technical Department. According to the plan all the respective department starts the preparation on that.

What is Bucket Loss?

Bucket loss is being noticed when transition happens between the production of two products. It indicates efficiency drop when old style changes to new style.

Why the loss is called bucket loss?

During style changeover, one of the extreme cases which is observed when the efficiency drops down to zero and the same is maintained for some hours, this makes the graph between line efficiency and time looks like a bucket (Figure-1). This is the reason the loss observed is known as bucket loss in style changeover process.

Different scenarios of bucket loss have been shown below.

Figure-1: Bucket loss graph

In the above graph as we can see that production has gone to zero in the 4th hour which is maintained till 5th hour of the production and then the efficiency started increasing. Since the zero efficiency was maintained for an hour the bucket loss is very high in this scenario. Our aim is to reduce that loss.If the efficiency is dropped to zero we should make sure that the zero efficiency is not maintained in the next hour. By doing that bottom rim (AA’) as well as the top rim (BB’) of the bucket would be reduced which will eventually reduce the overall bucket loss.

Figure-2: Bucket loss graph after improvement

In the above case the bucket loss is very less because the bottom rim is not there in the graph. This is possible because the efficiency was not dropped to zero during style change. To achieve this; many lean tools and methods are being used by various manufacturing industries. One of the effective lean tool is SMED (Single Minute Exchange of Die).SMED implies that any changeover time should be in single digit. Using this tool we need to ensure that maximum activities during feeding should be done externally without disturbing the ongoing production in the line. The list of some activities that can be done prior to feeding is mentioned below:

• Machine pre-setting
• Operator pre-training
• Critical operation identification
• Operator absenteeism forecast

The concept of SMED deals with two elements- External element and Internal element. External elements are those activities which can be performed without disturbing the sewing line. For example setting of the machine which are required in the new style in the pre-setting area prior to feeding.

Whereas internal elements are those activities for which we have to stop the sewing line or sometimes we have to wait until the last piece of the previous style is out. For example, changing some setting of the machines for new style which were present for the previous running style.

The aim is to convert most of the internal activities into external activities so the feeding time will be reduced and quick changeover will be possible.

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Related article: How to reduce style changeover time (COT) in garment manufacturing

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Challenges faced during style changeover

Industries in which small garments are manufactured specially lingerie; faces frequent style change due to very small SMV. It becomes very challenging for those industries to maintain the efficiency of the line during the changeover period. There are many predictable and unpredictable challenges out of which I am trying to list down few of them:

• Blockage due to previous style
• Sudden Plan change
• Cut panels not ready for the new style during feeding
• Layout not ready
• Trim card delay
• Trims not issued
• External machines not pre-set
• Time to set internal Machine
• Operator allocation
• Operator training during line feeding
• Achieving required quality takes time at initial stage
• No proper monitoring method of the line after feeding

 

Apart from the above mentioned technical challenges few more issues are faced during feeding which are mentioned below:

• Communication gap
• Indiscipline in the workers

 

To overcome the challenges the following checklists can be followed:

Checklist of the activities 1 week before style change

The above checklist is a tool to monitor the style changeover process. Generally, if any activity is not done on time then for that no one wants to take responsibility. One team blames the other, so to avoid that situation it is important to go to the root cause of that issue and the responsible person should find the possible counter measure for that.

This is also important because in future the issues can be avoided.

 

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Related Article: How to get maximum efficiency in short-run order

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Conclusion:

Applying the SMED methodology can considerably reduce and channel style changeover time with minimal budgetary impact. Giving merely recommendations for the SMED concept’s application as a style changeover will not be effective if we do not take into account the problems and difficulties.

So, to overcome the issues during style changeover, we need to counter the root causes of the problems.