The Human Aspect of Production Leveling

Introduction

In 1988, Taiichi Ohno stated, “The slower but consistent tortoise causes less waste and is much more desirable than the speedy hare that races ahead and then stops occasionally to doze. The Toyota Production System can be realized only when all the workers become tortoises.” (Ohno, 1988). This metaphor is materialized in the company’s practice of Heijunka and finds its value in its ability to reduce the Mura (unevenness) and Muda (waste). (Dennis, 2007). Heijunka is defined as the extent to which production is leveled over a defined period in order to achieve constant flow of mixed parts and to minimize peaks and valleys in the workload. (Furmans, 2005). Simply put, it is a method in which the same amount of product is built everyday to ensure that no blips or bottlenecks occur. Its aim is to stabilize value flow by converting uneven customer pull into an even and predictable manufacturing process. (Deif, 2011).

Despite the overwhelming benefits of Heijunka, large-scale productions often find it very difficult to attain. Heijunka is a process, not an event. As such, there are several technical obstacles to overcome before enjoying a level load. Common obstacles include: lack large-scale tools, lack of large “finished goods” inventory, obsolescence of finished parts, lack of data – or worse, bad data. (Reyner & Fleming, 2004). However, once an organization has the technical expertise in place, “most lean practitioners view that the technical system can operate independently of management.” In fact, “it is argued that Toyota’s management system in production leveling is equally, if not more, important that its technical capabilities.” (Marksberry, 2012). It is the social factors of interdepartmental cooperation, employee relations, and management development that are much more complex and varied than resolving how to establish a production sequence. As such, this paper aims to investigate the impact that Human Resources (HR) has in the implementation of Heijunka across all employee levels.

Heijunka – A Friend to the “Little Guy”

In order to fully appreciate the power of Heijunka, it is important to recognize the alternative. Batching has been a commonly used method for organizing the manufacturing process since the invention of mass production. It is characterized by the production of “large product lots” without taking into account the fluctuation of customer demand and with the output not immediately purchased by the customer being placed in inventory. This traditional manufacturing process presents several drawbacks. First, because customer demand is rarely predictable, the manufacturer may experience confusion and disorder. Second, the demand on upstream processes is often erratic. These drawbacks combine to create the “Bullwhip Effect”, which occurs when the demand order variability in the supply chain are amplified as they move up the supply chain. (Lee et al., 1997). Third, The cost of unsold goods held in inventory decreases profitability. Ultimately, batching results in uneven product quality and overworked equipment and personnel, which combine to create eight different types of organizational waste:

• Transport (movement of products that does not add value)

• Inventory (any components, work-in-progress and supplies not being used in production)

• Motion (the motion of people or equipment that does not add value)

• Waiting

• Overproduction (producing more product than what is needed to meet demand)

• Over Processing (doing more work than is required to make the product)

• Defects (the costs of inspecting products and repairing defects)

• Products that do not meet the customer’s specifications.

Heijunka helps avoid the inefficiencies of manufacturing in large lots by putting the production process closer in line with customer demand. It accomplishes this through the execution of two steps. First, by leveling the daily workload – smoothing out variations in the overall takt time. (Coleman & Vaghefi, 1994). Second, by leveling the product mix within the daily workload – smoothing out variations in the demand from upstream processes. (Aartsengel & Kurtoglu, 2013). These steps afford a factory the ability to provide customers with exactly what they want, at the specific time they need it.

The overall benefits of Heijunka are three fold:

• Predictability – Happens when demand is level

• Flexibility – Achieved by reducing changeover time

• Stability – Averaging production volume and type over the long term

The trickle-down effects of this practice are legion – especially within the human resources department. The smoothing out of production means there are less very busy times, which need to have temporary staff brought in. Conversely, there are also less ‘dry’ times, when staff members are laid off. As a result, there is a stable workforce and because of this stability employees are more loyal and committed to the company, than if they are under threat of redundancy. In addition, eliminating the need for temporary staff means that they do not require intensive training, which will ultimately be poor value for money because they will leave in 3-6 months time.

Due to the fact that Heijunka is especially difficult to implement, every member of the company must see the benefit of and be devoted to “doing more with less.” (Womack & Jones, 1996). Through the use of Hoshin (Japanese for ‘strategic direction setting’) Toyota achieves production leveling because it is viewed as a company-wide activity that cuts across many departments in promoting manufacturing consistency. (Marksberry et al., 2011).

Heijunka – The Manager’s Challenge

The benefits of implementing lean principles are achieved through associated improvement techniques and methodologies (Katayama & Bennett, 1996), but they vary depending on the makeup and management of the manufacturing system. (Lima et al., n.d.). The social aspects of production leveling relate to the company’s ability to eliminate barriers that keep management from applying teamwork throughout the organization. (Marksberry, 2012). Without a clear channel of communication and a willingness to learn the inner workings of different departments within the organization, production leveling will be very short lived. Managers will have to be open and willing to spend significant time outside their department and be convinced that helping other managers benefits them and the company overall.

The Human Resources Department (HR) provides many vital elements in the achievement of production leveling—especially how managers are expected to cooperate in achieving companywide targets and goals. This is an important factor because production leveling introduces many unintended social mechanisms that can impede teamwork. For example, matching internal resources to external demand often causes resources to shift from one area to another. Without guidance, many managers naturally act with their best interest in mind and try to protect “their” resources from traveling down the chain. Because managers inherently will do whatever brings them gain and avoids problems for them, the end results is managers who are less committed in achieving another department’s target or goal. HR is essential in production leveling because it establishes the expectation for teamwork. (Marksberry, 2012).

HR acts as both a preventive and a regulatory function in reducing and responding to variety and complexity as they related to production leveling. HR’s role is to limit and exclude certain behaviors from the workplace, such as managers who are not willing to cooperate or work in a team. The way that HR limits this behavior is through the appraisal performance process. HR evaluates managers on how well they solicit understanding from impacted groups, as well as how often they participate in another group’s activities.

Conclusion

Heijunka, like many companywide initiatives puts a much higher degree of strain on management than staff. Managers must establish a culture where each team member feels complete responsibility for the even flow. What’s more, communication and learning channels need to be clear across every department. This is initially difficult and can require some interoffice political navigation. However, no matter the size of the operation, utilizing a strong Hoshin will overcome the majority of obstacles managers face. Ultimately, the successful practice of Heijunka is a clear sign of a dynamic organization and a robust human resource department.

Work Cited

• Ohno, T. (1988). Toyota production system: Beyond large-scale production. Portland, OR: Productivity Press.

• Dennis, P. (2007). Lean Production Simplified. Boca Raton, FL: CRC Press

• Furmans, K. (2005). Models of heijunka-leveled kanban-systems. Working paper. IFL, \ University of Karlsruhe (TH).

• Deif, A. (2011). Dynamic analysis of a lean cell under uncertainty. International Journal of Production Research, 1(13).

• Reyner, A., & Fleming, K. (2004). Heijunka Product & Production Leveling. MIT Leaders for Manufacturing Program (LFM).

• Marksberry, P. (2012). The Modern Theory of the Toyota Production System: A Systems Inquiry of the World’s Most Emulated and Profitable Management System. CRC Press

• Hau L Lee, V Padmanabhan, and Seungjin Whang (1997). The Bullwhip Effect In Supply Chains. Sloan Management Review, Volume 38, Issue 3, pp. 93-102

• Emiliani, Bob; Stec, David; Grasso, Lawrence; Stodder, James (2007). Better thinking, better results: case study and analysis of an enterprise-wide lean transformation (2nd ed.). Kensington, Conn: Center for Lean Business Management.

• Coleman, J., and Vaghefi, R. (1994).Heijunka: A key to the Toyota production system. Production and Inventory Management Journal. 35(4), 31-36.

• Van Aartsengel, A., Kurtoglu, S., (2013). Handbook on Continuous Improvement Transformation: The Lean Six Sigma Framework and Systematic Methodology for Implementation. Springer Science & Business Media.

http://theleanthinker.com/2008/03/03/the-importance-of-heijunka/

http://www.villanovau.com/resources/six-sigma/heijunka/#.VPvUqjqrD8E

• Phillip Marksberry, Fazleena Badurdeen, M.A. Maginnis, (2011) “An investigation of Toyota’s social-technical systems in production leveling”, Journal of Manufacturing Technology Management, Vol. 22 Iss: 5, pp.604 – 620

• Katayama, H., & Bennett, D. (1996). Lean production in a changing competitive world: A Japanese perspective. International Journal of Operations & Production Management, 16(2), 8.

• Lima, P., Lobo, C., & Fumagali, A. (n.d.). Comparison of the implementation of lean assembly cells in different production environments. Taktica, Lean Consulting, Brazil.

• Womack, J. and D. Jones (1996). Lean Thinking: Banish Waste and Create Wealth in Your Corporation. New York: Simon & Schuster.

http://www.hoshinkanripro.com/hoshin_kanri_explained.html

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