A plan is what, a schedule is when. It takes both a plan and a schedule to get things done.” – Peter Turla
The Japanese word for levelling out the workload is heijunka (平準化). Heijunka is quite a broad term that has been narrowed by the traditional understanding of the interpretation in Toyota – to mean level scheduling.
Heijunka is a key component of the Toyota Production System, which focuses on reducing unevenness in production to improve efficiency and match customer demand.
The definition of Heijunka: “levelling, equalisation, alleviation, harmonisation”.
The principle of Heijunka is incredibly powerful and challenges us to understand the “load/demand” that is going through our processes and what we can do to try to balance it. We want to avoid the peaks and troughs. Imagine that you suddenly have one hundred items going through your process one minute, followed by ten the next. We are trying to avoid this and plan a steady demand.
The concept links directly to the previous principle – create a “steady flow”. Flow is at the heart of lean; a continuous flow of activities without delays happening at any stage of the process. You can learn more about the principle of flow here
Let’s have a look at some examples.
Supermarkets
Think about the checkout queues in supermarkets. During busy periods, the supermarkets increase the number of cashiers available to avoid the overburden and unlevelled schedules. Employees work part-time shifts to help bolster the peak demands. If they didn’t, customers would vote with their feet and go elsewhere. The “less than ten items” cashiers or “self-scanning” are all ways the supermarkets want to improve the management of the flow. The additional benefits are that it will reduce overheads with hopefully increase customer satisfaction increases as well.
Restaurants
A restaurant is a great example. Many restaurants require that you make a booking. The reservation will be made to accommodate your preferred time best, but it will also depend on the number of other diners already booked in at that time. Your reservation will be scheduled.
The idea is so simple – it stops everyone booking at 7:30 pm, all turning up at the same time and then with the kitchen overloaded with long delays and a drop off in quality. We all know from experience that we don’t want to turn up into a restaurant just after a large group has ordered.
Doctors and Hospitals
Think about scheduled doctor appointments. (Obviously ignoring the hour-long average wait as they are always behind their planned schedule).
Airports & Airlines
Other examples are the frequency of flights at specific parts of the day or perhaps the number of flights per week depending on the demand. We can also see scheduling going on with the baggage security lines. The number open will regularly change to accommodate the numbers of passengers. Hopefully anyway!
Smart Motorways
Check out the reasonably new concept of smart motorways: no hard shoulders but the ability to flex and change based on the number of cars, the flow of the vehicles and accidents. A variable speed limit is a way to balance the arrival schedule of other cars. If any of you has been travelling on the A23 in the UK recently, I feel for you and hope that when the roadworks finally stop, you will all see the benefits.
On a personal level, think about your workload. Are your weeks well scheduled? Without peaks of demands that cause stress, anxiety? Are all your meetings clumped together?
When things are super busy, our quality of focus and production drops. We know it, and it’s the same everywhere – we are just not very good at doing things about it!
So as you begin to identify opportunities for flow and begin to notice the peaks, the burrows, the downtimes, we need to be creative about how we balance the workload. It’s only fair on our customers, on our teams and ourselves.
Remember that “muda” is only one type of waste. It’s quick to understand how Hejiunka can support both Mura (imbalance) and Mura (unevenness). The key to balancing workload is to be able to manage the cycle times.
What is Heijunka?
Heijunka is a Japanese term that means “leveling” and is a cornerstone of Lean manufacturing. It refers to the practice of leveling production to create a smooth workflow that aligns with customer demand. By implementing Heijunka, organizations aim to reduce waste and minimize batch processing by producing products in smaller, more manageable batches. This approach often involves standardized work and techniques like Single-Minute Exchange of Die (SMED) to streamline production processes. The ultimate goal of Heijunka is to enhance production efficiency, reduce waste, and boost customer satisfaction by ensuring a steady and predictable production flow.
Benefits of Implementing Heijunka
Implementing Heijunka in manufacturing offers a multitude of benefits that can significantly enhance production processes. Firstly, it improves the production workflow, ensuring that it better matches customer orders and reduces the likelihood of overburden. By leveling demand and decreasing changeover time, Heijunka helps achieve predictability, flexibility, and stability in production. This method also averages production volume and type over the long term, leading to reduced lead times and improved value delivery to the customer. Ultimately, these improvements contribute to increased customer satisfaction, as products are delivered more consistently and efficiently.
Production Leveling by Volume
Production leveling by volume is a fundamental technique in Heijunka that focuses on calculating the optimal production volume based on historical customer order data. This method involves analyzing past customer orders over a selected time period to determine the average production volume required. By leveling production by volume, organizations can avoid the pitfalls of overproduction and underproduction, which are common sources of waste. This approach not only enhances efficiency but also ensures that production resources are utilized effectively, leading to a more streamlined and cost-effective manufacturing process.
Production Leveling by Type
Production leveling by type takes the concept of Heijunka a step further by incorporating product variation into the leveling process. This advanced method involves calculating the optimal production volume for each type of product based on historical customer order data. By leveling production by type, organizations can ensure that they are producing the right products in the right quantities to meet customer demand. This approach reduces waste and improves efficiency by aligning production more closely with actual customer needs, thereby enhancing overall production effectiveness and customer satisfaction.
Heijunka Tools and Techniques
Several tools and techniques are essential for successfully implementing Heijunka in a manufacturing environment. One of the primary tools is the Heijunka box, a visual scheduling tool that helps level production by type or volume. Kanban boards are also widely used, providing a visual representation of different production phases to streamline workflow. Digital work instructions offer detailed and visual guidance to employees, ensuring tasks are performed consistently and accurately. Regular audits and digital checklists are crucial for tracking progress and identifying quality issues. Quality management systems, often featuring centralized data dashboards, help visualize production data and pinpoint areas for improvement. Additionally, a skill matrix and targeted training programs are vital for equipping employees with the necessary skills and mindset for lean manufacturing and production leveling on the shop floor. These tools and techniques collectively support the implementation of Heijunka, leading to reduced waste, improved efficiency, and increased customer satisfaction.
