The SMED Method and Its Stages – How to Reduce Machine Setup Time
Rising labor costs and the increasing demand for small-batch production make SMED a continually growing method for reducing machine and equipment setup times. Before explaining what SMED entails, it is essential to define the concept of "setup," as companies often interpret it differently. From a lean perspective and considering what constitutes added value for the customer, setup time is calculated from the moment the last good, fully functional unit of the previous product type (Type A) is completed to the moment the first good unit of the new product type (Type B) is produced. Therefore, setup includes:
- adjustments
- washing and cleaning machines after completing an order
- calibrations
- changing tools and/or materials
What is the SMED Method?
SMED, an acronym for "Single Minute Exchange of Die," literally means changing a die within a single-digit number of minutes. The SMED method was developed by Shigeo Shingo, a Japanese engineer working at Toyota who made significant contributions to the development of the Toyota Production System (TPS). It consists of several repeatable steps and utilizes simple tools and techniques that, due to their versatility, can be applied across any industry. These tools will be presented in the subsequent sections of the article.
Principles of the SMED Method
The process proposed by Shigeo Shingo, popularly known as SMED, aims to analyze and reduce the setup time of a machine or production line by:
- appropriately separating setup activities,
- standardizing and simplifying the entire process,
- using as few tools as possible.
Considering the organization of setups in traditionally managed companies, the initial stages of implementing this method can achieve a reduction in time of up to 50% without additional investments. For many companies, this presents an excellent opportunity to virtually cost-free increase machine availability and enhance the company's profitability.
Stages of Implementing the SMED Method and Utilized Techniques
Consistency is crucial in the SMED method. Each stage must be executed sequentially, without skipping or jumping between them. Failing to adhere to this principle and the order of stages can lead to additional, unnecessary costs for the organization. Why? The process is intentionally designed to first compel us to optimize setup times without additional investments. Only subsequent steps may require additional resources. However, this is only the case if the time reduction achieved through the initial actions is not sufficient. Below, the four main stages of setup time reduction using the SMED method are described.
Stage 0: Analyzing the Current Process
Properly conducting SMED workshops requires a thorough and detailed analysis of the entire setup process. At this stage, we confront our assumptions and beliefs with reality, which may prove surprising. In this part, it is particularly important to ensure:
- Video recording of the setup
- Time analysis of individual segments
- Analysis of operator movements (spaghetti diagram)
- A list of documents, tools, and settings
As far as the video recording itself is concerned, we recommend that this is discussed in advance with the worker or workers who will be carrying out the changeover. It should be clearly and comprehensibly explained to the operators why we need a video recording of the entire process. Focus on recording the activities themselves, not the workers and their faces. Depending on the level of complexity of the changeover, we can analyse the times of the individual parts either by using a stopwatch or by analysing the video recording.
The spaghetti diagram, on the other hand, allows us to map the movements of the operator and his movements around the machine or production line. All that is needed is a sheet of paper and a pen. When observing a changeover, it is also important to note all the documents, tools and also the parameters that the operator uses.
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Stage 1: Separating Internal and External Activities
Internal activities are those that can be performed while the machine is running, meaning during the execution of the production process. In contrast, external activities require the machine to be stopped. This straightforward division and its proper understanding allow us to isolate parts of the activities outside of machine downtime, thereby increasing the utilization of available machine time. The following diagram illustrates this concept effectively.
How to Secure the Process to Be Conducted This Way? Here are a few simple tools:
- Workplace Organization (5S)
- Control Cards
- Operation Cards
Using 5S to optimally organise the workplace will allow us to make sure that all the jigs, tools and documents necessary for the changeover are available. This should be checked while the previous production order is still in production.
Checklists - or popular "check lists" - are a great tool to prevent forgetfulness. A well-prepared list should include all the points to be made in preparation for changeovers and after production has resumed.
It is still possible to encounter situations in companies where changeover downtime is prolonged because of non-functioning equipment - assembled instruments are faulty or not ready to work. The function sheets are intended to reassure us that the equipment, once removed from the machine, has been checked, secured and is ready to work again.
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Stage 2: Transformation of Setups
At this stage, it is expected that all external activities have been transferred beyond the stop time of the production line or machine and the new process is standardised and implemented. Operators or setters should work with the new sequence of activities for a few weeks before moving on to the next step.
Changeover transformation is the conversion of internal to external activities. This is, of course, as long as it is possible and businesslike to do so. It is worth doing the changeover observation again at this stage and doing an idea generation session with the whole team involved in the SMED workshop. Such a meeting will generate many valuable solutions to transform the activity. Experience with such workshops shows that the solutions proposed are most often based on:
- intermediate mounting devices
- advanced work preparation
- function standardization
Stage 3: Improving Changeovers
It’s time for the final stage. If we can no longer convert any internal activities into external ones, and during downtime we focus solely on executing those changeover steps that must be performed while the machine is stopped, then it’s time for kaizen. We reach a point where we need to analyze all the steps in the process, looking for savings and time reductions. We recommend focusing on the following points, in the order they have been listed:
- Parallel operations
- Elimination of adjustments
- Tool storage
- Mechanization
Examples of SMED Method Application in Practice
Here are a few examples where SMED has proven effective in practice and has brought the expected benefits to companies:
- Production of hygiene products – the main production line for products and machines for automatic packaging of goods
- Frozen food production – changeover of the entire line between product families
- Pharmaceutical industry – changing tablet formats
- Plastics processing – exchange of molds and dies
What Benefits Does the Implementation of the SMED Method Bring?
A significant advantage of practicing the Single Minute Exchange of Die methodology is the measurable benefits that can be realized very quickly after implementation. It turns out that after dividing activities into external and internal ones, and properly reorganizing the process, one can expect a reduction in time of up to 50%. In summary, we can speak of the following benefits of SMED:
- Reduction of machine downtime
- Increased availability of machines and equipment
- Enhanced production flexibility
- Real reduction in operational costs
- Ability to work with smaller production batches
- Improvement in operator efficiency
- Faster response to changes in production
Summary – Why Is It Worth Implementing the SMED Method?
Implementing the SMED method in the form of practical workshops guarantees cost reduction and represents another step towards more flexible and lean production. This directly impacts the total lead time and thus increases the competitiveness of the offered products. The versatility of the method means that it can be applied in virtually any industry. In practice, examples can even be found in restaurants or truck loading operations.
