In this article, we will dive deeper into SMED. We will discuss how to prioritize machines and activities for implementing SMED, define economic lot size quantity, and will provide tips and techniques.
In our first article on SMED, we discussed SMED in detail. We explained what it is and why it matters. If you have yet to read the article, here is the gist: the SMED methodology emphasizes its role in reducing downtime for higher productivity and its role in lean manufacturing for today’s world.
We covered the steps involved in implementing a sustainable SMED system. We also discussed how to reduce throughput times and the significance of smaller batch sizes. Additionally, we explored how the separation and conversion of internal and external activities can aid in the continuous improvement process.
Of course, I recommend reading the full article for a better understanding of SMED and its sustainable implementation.
How to Select the Machine for SMED Implementation
SMED is a lean methodology designed to perform changeovers in less than 10 minutes. Achieving successful SMED implementation requires a lot of effort and time. By doing this, we can realize tangible benefits, such as shorter throughput times and increased flexibility for the organization.
However, to fully reap the benefits that enhance productivity and customer satisfaction, we must prioritize SMED implementation with the help of data. Are you excited to know how? Let’s discuss this in detail below.
Methods of selecting the machine for SMED implementation
- High changeover time machines (e.g., those with changeover times exceeding 100 minutes)
- The top three machines with the highest changeover times in the system (top 3 out of n machines)
- Utilizing OEE data
- High frequency of changeovers at any machine in the system
- Request from production team (without data)
Selecting machines using the above-mentioned methods seems reasonable, but do those machines really require SMED implementation? Yes, they do. However, we cannot always qualify them with data based on the organization’s current requirements.
Here is an example using cycle time and takt time data to qualify a machine for successful SMED implementation.
An example to understand how to select a machine for SMED
Let’s have a quick quiz without any marks. Consider two machines, A and B. Machine A has a setup time of 193 minutes, while machine B has a setup time of 21 minutes. Their demands are 10,000 units and 70,000 units, with cycle times of 14 minutes and 4 minutes, respectively. Each machine has a similar lot size of 50 units in the system. (Please refer the image for more details and calculation purpose)
When both machines handle a similar lot size (e.g., 50 units), the changeover calculations are as follows:
- Machine A:
With an annual production of 10,000 units, Machine A requires 10,000/50=200 changeovers per year. Each changeover takes 193 minutes, resulting in a total of 200×193=38,600 changeover minutes per year. - Machine B:
With an annual production of 70,000 units, Machine B requires 70,000/50=1,400 changeovers per year. Each changeover takes 21 minutes, resulting in a total of 1,400×21=29,400 changeover minutes per year.
At first glance we will select Machine A, its wrong. We need a deeper understanding of the concept.
Don’t worry we will solve this issue in a simple way.
For better understanding refer the table below. The table in excel format can be downloaded from below.
Referring the above table, considering the changeover per year also both machines can meet the customer demand. But refer the demand / capacity ratio in the last column.
For machine A its 46% and for Machine B 79%. That means machine B is at higher risk of not meeting the customer demand, if any other machine breakdown or other delays occur.
Hence we prioritize the Machine B over Machine A, to do SMED first.
How to select optimum lot size for changeovers
So, after SMED implementation we have reduced the changeover time.
Good right!
But there is a problem here, what if we do change overs more frequently? This will result in the increased downtime of the machine, even though we have successfully implemented SMED.
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Thank you for sharing this article
great information