Formula 1 in the production process:
How is your changeover time?
You’ve probably seen it, the impressive footage of a Formula 1 car arriving at the pit lane. The mechanics (sometimes as many as 18!) are ready to change the wheels, adjust parts or carry out emergency repairs. Often you don’t even see what exactly is happening, because the driver has already left to continue his race within a few second.
Flexible production requires a good pit stop
All manufacturing companies know; the market changes. Customers expect a more diverse or even personalised offer. As a manufacturer you have to respond to this adequately. Flexible production and setting up your production line accordingly is becoming increasingly important. This change of production also means you do not need to have a large inventory. You only produce what you need, when you need it.
This required flexibility creates new challenges. Production lines have to be adapted more often and more quickly for the next product. At many manufacturing companies, these are still manual actions. This includes changing moulds, stamps, carriers, reprogramming the machine, loading materials and performing maintenance.
The duration of these changeovers, so-called changeover times, plays a role in the efficient running of a production process. A longer changeover time is a waste of time. An efficient F1 pit stop can make the difference between winning and losing. Waste of time is one of the eight wastes that are characterised withing Lean and can be tackled with the SMED method (Single Minute Exchange of Dies).
Company A produces pipe fittings, for which they have 5 production lines that are in operation 24 hours a day. 3 to 8 different pipe fittings can be produced on one production line. An operating production line can make an average of 400 products in one hour. Changing a production line to another product takes an average of 3 hours and is done twice a day. That is a waste of 25% production time. In theory, production could be done during this time. This means there is a loss of 12,000 products per day.
Separating internal and external actions in the changeover time
According to the SMED, internal and external actions should be distinguished first. Internal actions can only take place when the production machinery is stopped. For example, changing moulds or cleaning moving parts. The external actions can also be executed when the machine is in production, such as preparing materials and tools for the next product.
The easiest gain is achieved by executing external actions, that are happening during the changeover, before or after stopping the machinery. In addition, it is important that all operators or technicians are aware of the tasks they have to execute during the changeover. Instructing the staff is an external action. Create a pit stop where everything and everyone is ready before the machine stops moving.
When converting a production line within company A, various actions have to be done. There are two technicians responsible for the changeover. One unloads and loads the machine with materials and does the cleaning. The second technicians replaces the tools and pre-sets the machine for the new product. Some preparations for these actions are not started until the machine has already stopped, such as retrieving the cleaning equipment or reading through the new settings. These are external settings that can be executed during production before the changeover starts.
Converting internal actions to external actions outside the changeover time
When minimizing the internal actions, it is important to split them up into partial actions. For every partial actions you can ask; Can this be done externally? How can we do this? And what is needed? Sometimes (major) adjustments to machines and tool will be necessary, a cost-benefit analysis will give insight for this. For example, the purchase of an adjustment stations with which tools can be pre-set before the changeover, so this does not have to be done on the machine itself.
Company A’s production machines operate at high temperatures. In the current situation, when changing products, it is necessary to wait until a machine has cooled down before the technicians can safely do their work. The machine and tool have to preheat again before operating again.
By using a heat-resistant pick & place tool, for example a robot, the heat is no longer a constraint in the changeover. This means tools do not have to cool down completely before removing them from the machine. The new tools can be preheated and placed using the pick & place tool. Cooling down and preheating the tools have thus become external actions. In addition, the machine cools down less during the changeover due to the time saved.
Fasten internal actions
Ultimately, there are actions that cannot be made externally. These actions take place during downtime or during booting. Not every production line can produce correct products (products within quality margins) directly after the changeover. It is often necessary to adjust the machine before it runs properly. That is why changeover time is calculated from stop to the first correct new product.
Actions during downtime
During downtime, moulds, tools and other parts are exchanged. This should be done as quickly, safely and simply as possible. It is profitable to standardise actions and tools for this. For example, by using quick-change joints to (dis)assemble parts of the machine.
Actions are standardised in clear work protocols. In addition, you can speed up actions during downtime by deploying more staff. After all, many hand make light work. The most efficient pit stop has enough technicians ready for all of them to execute a specific task simultaneously.
The technicians at company A clearly divide their tasks during changeover. But there is no protocol on how these tasks should be executed. For example, it sometimes happens that the second technician has not yet been able to clean the machine. Mechanic two then has to wait until his colleague is ready before continuing his tasks.
Actions during booting
Not every company will be able to produce immediately after converting the machine. Machine output may vary after starting production. Usually, the new settings are (largely) fixed in instructions. But in reality, setting may well be adjusted after starting production, depending on the operator or output. Standardising and pre-programming the correct settings can save a lot of time and production waste. Reprogramming and adjusting the settings can even be fully automated in a closed loop system.
At company A, a different shift is at work with each changeover. The machine settings of each product are stated in the instruction, but this is often deviated from. Operators sometimes adjust the machine whey they see that the output varies. Others have been working at A for so long that they do the changeover by heart and use alternative setting from experience. These settings must be corrected again at the next changeover. This takes a lot of time and deviations are not always immediately notices. Sometimes it takes a while before the machine is properly set for the next product.
A changeover-friendly product
In addition to improving changeovers themselves, it is also useful to take a look at the products that are produced. Can certain specifications be standardised? For example, the dimensions of (parts of) operations. Also check the order in which the products are produced, perhaps fewer changes or cleaning operations are required when you have semi-identical products succeed each other.
The power of the pit stop: a motivated pit crew
With all actions you take to improve your changeover times, it is good to get your mechanics or operators, the pit crew, along. They must have sufficient support to carry out and maintain the actions. Ultimately, this applies to the entire company, if everyone sees the benefit of Lean production, you will be able to take steps faster and hold on to the results.
Curious about how changeover times can be improved at your company? Our colleagues at STT Products are happy to look at and think along with you. We have been helping manufacturing companies optimise their production process for 35 years. We do this through consultancy, engineering and the realisation of smart technical solutions.