A pull system is a lean manufacturing technique to reduce waste from any production process. The application of a pull system allows starting a new job only when there is a demand for the product from the customer. This provides the opportunity to reduce overhead and optimize storage costs..
Pull systems are part of the lean manufacturing principles, born in the late 1940s. A pull system is intended to create a workflow where work is done only if there is a demand for it.
In this type of system, the components used in the manufacturing process are only replaced once they have been consumed, so companies only manufacture enough products to meet customer demand..
This means that all company resources are only used to make products that will sell and make a profit immediately..
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Today, the concept of the pull system is widely used in different industries. Professionals use it not only in manufacturing, but also in software development, customer support, and more.
In office work, the concept of the pull system can be applied in the same way as in manufacturing: a work item should be in process only if there is demand for it.
With an environment based on the pull system, it can be delivered on time, meet customer demand and improve supply chain reliability.
The goal of a pull-based lean manufacturing environment is to do nothing until there is demand. Finished products are not manufactured without a specific customer order.
Essentially, a pull system works the other way around, starting with the customer's order and then using visual cues to drive action at each previous step in the process. Product is pulled through the manufacturing process by consumer demand.
It is equivalent to a work order. Upstream stations do not start producing parts until they receive a signal. In this way, the Kanban signals control the movement of raw materials and products in process, through subsequent workstations..
Pull manufacturing works best when demand is high and constant for a relatively small variety of products.
A pull system allows workers to perform their next task only if they have the signal to start working on it.
This can help to better prioritize tasks and prevent work teams from being overloaded. By doing so, the team can stay focused on executing the most important work just in time..
To achieve the highest levels of productivity and workflow efficiency, using a pull system, you must:
First, you need to establish pull signals. The best way to do this is by creating a visual workflow, where all valuable information can be recorded and tracked..
This first step will help to get an overview of the entire work process and to capture all the important signals.
The signs that allow you to replace production materials are called kanban, which means “sign” in Japanese. These signals use visual communication to implement a pull system..
A kanban will be located where the crafting components are stored, and a sign will be placed when they need to be replenished. With this process, the necessary items will always be available and will not be replenished if there is no signal from the next production process..
Kanban signals can be in many forms. The most common type of signal is kanban cards. These cards are sent to the previous step of the manufacturing process to indicate that more products or parts are needed.
However, a kanban can be as simple as an empty container that a worker can see that needs to be refilled. The kanban will provide information to the worker to restock the items, such as the order quantity and part numbers.
Kanban signals provide the most effective way to implement a pull system. This will make an overall business more organized, efficient and profitable..
After building the visual pull system, you need to know how to control it. One of the most common ways to manage the pull system effectively is by limiting the jobs in progress. This is one of the main practices of the kanban method, which is a generalized pull system.
For example, in a Kanban board, the workflow is divided into different stages, such as "Ready to start", "In process", "Awaiting review", "Ready to deliver", etc..
By limiting the jobs that can be in process at each stage, you will be able to create a smooth flow of work and identify problem parts in it..
Contrary to common belief, which says that you should multitask in order to finish more jobs, limiting work-in-progress will actually allow team members to focus on a single task to completion..
As long as the work team is focused, excellence can be achieved throughout the flow. In this way the work can be delivered much faster.
However, limiting work in progress will not be enough to build a sustainable pull system. The time that an item can spend in the system should also be limited..
This limit may vary depending on the size of the task. If this is not done, some tasks can spend a great deal of time in process and reduce flow efficiency..
The main benefit of the pull system is avoiding excess inventory, along with the overhead required to manage that excess inventory.
That is, it reduces waste within the company, by not overproducing. It also frees up space in the workplace and reduces the cost of storing excess inventory..
Companies using the pull system experience higher customer satisfaction as products are specifically manufactured to meet their requests.
Since products are manufactured in small quantities, quality problems will be identified faster.
A pull system saves time spent planning future demand and manufacturing products that will never be sold.
Greater flexibility is also experienced, as it can respond quickly to changes in demand..
Each of these advantages reduces total costs to the business, either directly or indirectly, resulting in greater profit..
By using the principles of the pull system it can be much more predictable to plan future work. How is this possible?
Pull systems allow you to collect historical data on workflow and average task cycle time.
Using this data in combination with different forecasting techniques, such as Monte Carlo simulation, will give a probable forecast of how much work can be processed in a predefined period of time..
The main disadvantage is the susceptibility of the system to interruption. A defective material or a process breakdown can be very troublesome. This requires anticipating to correct potential problems before they occur..
Another disadvantage of the pull system is that you are very likely to encounter dilemmas when ordering. For example, a supplier cannot ship on time.
This leaves the company unable to fulfill the customer's request and contributes to their dissatisfaction..
If a car is being driven through town and you notice a red light on your gas gauge, plans will likely be made to refill your tank in a timely manner.
In doing so, it has become part of a pull system based on pull signals. This simple but effective mechanism allows you to replace only what has been consumed at the right time.
Pull programming in a manufacturing system is not that far removed from the simple example of replacing gas in the car just by seeing a red light on the gas meter..
For many companies today, purchases are not made based on fixed schedules or sales projections. They are done through timely inventory control signals and customer relationship management tools.
In today's economy, large fulfillment systems are an excellent example of delivery processes based on limiting waste in the system..
Color-coded electronic cards, which are easily visible, are used to reflect areas that are falling outside of production standards.
The signals can also be sent directly to people via text messages. This allows targeted activities to be carried out exactly when and where they are needed..
Apple is one of the brightest examples of how a pull system can be successful. Have you ever seen the long waiting lines in front of Apple stores during the release of the latest version of the iPhone?
Apple always creates a buzz around its new products and consumers are always ready to buy them. They want to extract the product from the stores.
Apple does not deliver excess inventory to its stores or retail partners. The company waits to see if there is additional demand and if it increases, then they produce more. In this way, the company optimizes its resources and achieves high cost efficiency..
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