Lean manufacturing measurement: the relationship between lean activities and lean metrics.
| Autor | Manotas Duque, Diego Fernando |
ABSTRACT
Lean Manufacturing was developed by Toyota Motor company to address their specific needs in a restricted market in times of economic trouble. These concepts have been studied and proven to be transferrable and applicable to a wide variety of industries. This paper aims to integrate a set of metrics that have been proposed by different authors in such a way that they are consistent with the different stages and elements of Lean Manufacturing implementations. To achieve this, two frameworks for Lean implementations are presented and then the main factors for success are used as the basis to propose metrics that measure the advance in these factors. A tabular display of the impact of "Lean activities" on the metrics is presented, proposing that many a priori assumptions about the benefits on many different levels of improvement should be accurate. Finally, some ideas for future research and extension of the applications proposed on this paper are presented as closing points.
KEYWORDS
Lean Manufacturing, Performance Metrics. Aleasurement Systems, Lean Activities
RESUMEN
Medición en Lean Manufacturing: Relaciones entre Actividades Lean j, Métricas Lean.
Lean Manufacturing fue desarrollada por Toyota para satisfacer sus necesidades específicas en un mercado restringido y, en tiempos de estrechez económica. Estos conceptos han sido estudiados y, se ha comprobado su aplicabilidad en una amplia variedad de industrias. El objetivo de este artículo es el de integrar un conjunto de métricas que han sido propuestas por diferentes autores, de tal manera que sean consistentes con las etapas y elementos de implementaciones de Lean Manufacturing. Para lograrlo se presentan dos marcos de referencia para implementaciones Lean y los principales factores de éxito se utilizan como base para proponer métricas que identifiquen el avance en estos factores. Posteriormente se propone una tabla que cruza el impacto de las "Actividades Lean' sobre las métricas. postulando que muchos de los supuestos a priori sobre estos impactos deberían ser precisos. Finalmente se proponen algunas ideas para proyectos de investigación hacia el futuro Y posibles extensiones de las aplicaciones propuestas aquí.
PALABRAS CLAVE
Lean manufacturing, indicadores de desempeño, sistemas de medición, actividades Lean.
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INTRODUCTION
This article presents the relationship between the activities that are normally considered part of Lean Manufacturing and the performance metrics that are proposed for Lean environments.
To accomplish this, first a brief historical and conceptual background in Lean Manufacturing is presented, followed by a framework of success factors for Lean implementations.
Then, the dimensions of performance that should be measured in a Lean environment are presented, followed by the development of metrics for each of these dimensions.
Finally, a table is used to relate the activities that are associated with Lean production to the performance indicators previously described.
Avenues for future research are mentioned, in order to suggest possibilites for further exploration in this topic of the effect of Lean Activities in the performance measures.
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BACKGROUND IN LEAN MANUFACTURING
2.1 Historical Development
To provide context for Lean Manufacturing and measurement systems, it is important to understand the historical development of Lean concepts. Should the reader desire to investigate further about the development of Lean Manufactuiring. there is extensive bibliographical material available.
All roots of Lean point first to Henry Ford, who put in place an impressive production system in the Highland Park manufacturing plant, in 1913. There, a set of practices and tools (interchangeable parts, standard work and the assembly flow line) was put in place in such an integrated way that allowed them to turn out products at incredible speeds. with very short flow times and high consistency.
This system was not very flexible, though. The Model T was manufactured virtually unchanged during 19 years under this system, and there was no need for setups or changeovers since there was only one product being processed in that line. Increased demand for shorter product cycles and more variety, as well as the market demands after World War 11, changed the competitive marketplace in such a way that Ford's early "Leanness" was not sustained in they long run.
But, there were good students learning important lessons. Kiicbiro Toyoda (member of the founding family of Toyota) and Taiichi Ohno (Toyota's leading manufacturing engineer) visited Ford factories right after World War II and observed their operation. They were convinced that with some elements from the Ford system, their adaptation to their scale and reality and a lot of ingenuity they could snake Toyota a ccnnpetitive force in the automotive market.
Essentially, they changed the emphasis from machine and workstation optimization to product flow through the total process, implementing some clever and "simple" ideas like dimensioning the manufacturing resources according to actual demand (right-sizing), improving the self-monitoring capabilities of equipment to ensure quality (Jidoka), designing the process layout to facilitate the sequence of the operations (Group Technology), studying and improving quick setups to enable rapid changeovers (SMED) and the use of kanbans to coordinate the production pull from and link one workstation to its predecessors and successors, and also to link the company with its suppliers and enable JIT supply (Womack, 2002).
These processing improvements made possible to offer a wide variety of products in a sequence that reflected more closely the market's demands, reducing lead times and eliminating the need for large volumes of inventory (which, with the space constraints for manufacturing and warehousing facilities in Japan, was critical for the financial success of any business).
Also, a management system was developed to reflect and support all these changes in focus and style, which is now known as the "Toyota Production System" (TPS). It is not the focus of this document to go into great detail about TPS, however some elements will be mentioned, like autonomous work teams, visual controls and information displays, "andon" lights to observe the status of the process, "jidoka" (autonomation) or the ability of equipment to detect out of control processes and stop itself, and the continuous strive to reach one piece flow.
2.2. General Principles
Since this is not a treaty on Lean manufacturing implementation, the reader would find examples and case studies on Lean implementation in different sources in the literature (Thompson and Wallace, 1996; Grutter. Field and Faull, 2002: Sohal, 1996;
It has been said that the two basic concepts in Lean thinking are to eliminate waste and create value (Murman et. al., 2002). Emiliani (1998), based on Womack and Jones (1996) presents a more detailed framework with five basic steps:
* Specify Value: What do customers want? When and how do they want it? What combination of features, capabilities, availability and price will be preferred by them?
* Value Stream Analysis: A Value Stream is the collection of processes and activities required to bring a product to the customer, from beginning to end. The Value Stream is not limited by boundaries between companies; that is the reason to strive to integrate suppliers, manufacturers, distributors and even retailers in the efforts to recognize and analyze the Value Stream. Also, three main categories of activities are distinguished: a). Those that add value; b). Those that do not add value but cannot be currently avoided and c). Those that do not add value and should therefore be eliminated.
* Continuous Flow: Companies should try to make value flow continuously, not in batches. In this paradigm, the term one-piece flow has great appeal and is highly coveted. Also, traditional functional organizations do not, help continuous flow, therefore a focused teams approach (closer to the product) is recommended.
* Customer Pull: A principle made popular by the JIT concepts; it states that companies should not push their products to customers, and rather let them pull "value" (products or services) and link all the production chain...
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