Single use systems are great for simplifying facility design and saving money. But what about efficiency during changeover? Customised, disposable solutions are complex, and take time to set up. Enter “single minute exchange of dies” (SMED) - a lean production method used in many other industries (and NASCAR pit stops). Could this be the single use system game changer?
Sound like a dream come true? It should. Put simply, the core goal of SMED is to simplify and speed up changover. It does this by: a) making as many changeover steps as possible “external” – so performed before changeover and while production is still running and b) by simplifying any “internal” steps that need to happen while production is on pause.
The result? Fewer and less complicated steps during changeover, making everything quicker, simpler and more accurate.
Start using SMED in pharma production: Six steps
A good example of SMED in practice is a NASCAR pit-stop. If you’ve ever seen a pit crew change four tyres in under 15 seconds then you get how meticulously organised the whole process is. Pit crews coordinate teams so that they work in parallel, they use standardised and optimised processes, and they do as much as they can in advance - so when they change those tyres, they change those tyres quickly.
But these SMED methods can apply anywhere, and although the practice varies, implementation follows these six steps:
- Study and observe the current changeover method.
- Work out which tasks and activities are internal (can only happen when the process is idle) and which are external (can be performed while production is running or once the next batch has begun).
- Work out which internal activities can be changed to external activities, and shift them over.
- Then, streamline the remaining internal activities by simplifying and removing tasks of no value. Focus on tasks that require the most resources.
- Streamline external activities so that they are of a similar scale to internal activities.
- Make a procedure and practice the new changeover process – like anything, practice makes perfect, and this reveals any areas or opportunities for improvement.
A match made in heaven? Fix common problems with single use systems
Single-use technologies are great for implementing SMED, and SMED principles can fix several common SUS issues. These include:
1. Receipt inspection – an external process
After receiving an SUS and removing the packaging, it is important to check that each component is correct. This includes how the SUS is arranged, indexed and labelled, the length of the various tubing sets, and quality control of the joints and connections.
Typically this happens during staging and deployment activities, while the primary process is idle. All of these verifications need to be performed within a classified environment (Grade C or D) so there is minimal external contamination and bioburden. This is particularly important to prevent downstream aseptic complications in higher classified spaces.
But what if we were to follow SMED principals? These activities would be evaluated and changed to an external process – performed before the process has be. This way they could be performed at the same time as the ongoing batch and ready to be deployed immediately upon line clearance and process availability. These external verifications can also be scheduled so that any failures can be fixed without impacting the operational critical path
2. Integrity and connectivity
Another common issue with SUS is when joint and connectors fail. There are many possible reasons for integrity problems, such as tolerance variation of the polymeric components, quality control of the methods and tools used for forming the connections, or flexing of connections during gamma irradiation and transportation.
Connector failure or leaks during processing pose serious risks to product pathway asepsis. Ultimately, this could mean losing the batch. As a result, it is essential that you verify the integrity of an SUS before process execution. Integrity testing may be as complex as helium leak detection and pressure decay, or as simple as visual inspection. Either way, you need to manipulate the SUS set to confirm there are no leaks or other issues.
However, if we were to do this the SMED way, this would be an external activity done before deployment. This would then also be a critical “rejection gate”, allowing you to correct problems and order a replacement set before the problem affects operations.
3. Standardised for success
Another good example of SMED implementation is using standardised process tools, such as SUS layout platforms and shadow-box fixtures. These platforms organise and protect SUS components in a logical sequence. They stabilise the various connectors, valves and tubing sets to help organise and deploy them systematically. These portable layout platforms also help you to inspect the SUS externally and to test the integrity of an SUS before it is deployed.
Last but not least, carefully considering the design of customised alignment tools, colour coding, and indexing connectors can speed up changeover. By simplifying and breaking down the steps it takes to assemble an SUS onto a checklist, and ensuring that critical aseptic connections can be put together intuitively and easily, you reduce the risk of human error and improve the consistency of execution.
SMED concepts have revolutionised the automobile industry and NASCAR pitstops. They are, in fact, somewhat old news. Yet SMED still hasn’t been fully embraced by the pharmaceutical community. Combined with thoughtful engineering, using SMED principles to fully assess SUS changeover steps will save you time, improve process efficiency and ultimately protect the product and the patient.