Abstract
Short changeover times have always been critical in manufacturing and are a necessity nowadays in all types of industries, due every wasted minute means inefficiency. Single Minute Exchange of Dies (SMED) is a methodology developed by Shigeo Shingo in 1985, which seeks to reduce the setup time of a machine to less than ten minutes (Shingo, 1985). It provides a rapid and efficient way of converting a manufacturing process from a current product that is been running in the production process, to the next product (Tharisheneprem, 2008), aimed always to decrease the setup time in industrial machinery, given flexibility in product and their characteristics. Through this research, we found that we can achieve some benefits through the implementation of the SMED methodology such as: the reduction of changeover time up to 90% with moderate investments (Cakmakci, 2009), reduce waste and increase quality, it makes low cost flexible operations possible.
Top1. Introduction
The concept of lean manufacturing was developed for maximizing the resource utilization through minimization of waste, later on lean was formulated in response to the fluctuating and competitive business environment (R. Sundar, A.N. Balaji, & R.M. Satheesh Kumar, 2014). The process of waste elimination is achieved through the application of lean tools and techniques (Vinodh & Ben Ruben, 2015). Lean manufacturing has its roots in automotive industry and it is derived from the Toyota Production System, the management philosophy that had been developed through decades by Toyota after the Second World War (Haragovics & Mizsey, 2014). Lean system aims to improve value addition by means of removal of non-value added activities, making the value stream smooth, and converting push production to pull production and perfection by continuous improvement (Vinodh & Ben Ruben, 2015). Lean Manufacturing is a multidimensional approach that embraces a wide variety of management practices in a unified system. These practices comprise just-in-time, quality systems, cellular manufacturing, work teams, and supplier management, among others (García-Alcaraz, Maldonado-Macías, & Cortes-Robles, 2014), and Figure 1 illustrates a theoretical structure for Lean Manufacturing in industries.
Figure 1. Basic lean manufacturing tools (Vinodh & Ben Ruben, 2015)
As competition among companies increases, firms have been trying to find ways of having the competitive advantage in the market place (Cakmakci & Karasu, 2007), and due to the intricacy of market order and competitiveness, many manufacturing organizations are under pressure to produce and dispatch products in shorter delivery times (Rahul.R.Joshi & Prof.G.R.Naik, 2012), hence to compete effectively short lead times are essential to provide customer satisfaction (Alad & A.Deshpande, 2014), having materials flow along the production process, and long set-up times are an obstacle to the flexible use of production resources and are therefore a core production organization issue (Herr, 2014).
Another important issue in this matter is to gain flexibility, that defined as the ability of a system to perform proactive and reactive adaptations of its configuration in order to cope with internal and external uncertainties in production process that affect the materials flow (Winkler, 2009). A key enabler for achieving flexibility and implementing lean production is the reduction of set-up times (Fritsche, 2011), defined as the time running from the last good part of the previous lot until the first good part of the follow-up lot, that is the aggregate period with the manufacturing equipment not producing good parts (Fritsche, 2011), the representation of change over time is shown in Figure 2.
Figure 2. Representation of change over time (Ulutas, 2011)
Hence, the setup time reduction is an important challenge to setup time reduction resulting in a lean production system. In such a context, lean manufacturing systems have the ability to achieve responsive, small batch manufacture so that they can meet rapidly changing market, especially when it comes to realizing the ability to serve high-mix, low-volume markets (Herr, 2014). However, producing more products at smaller batch sizes, results in more changeovers. Thus, a rapid changeover capability is critical for being able to produce small quantities of a large diversity of products, the basis of a pull production (Ferradás & Salonitis, 2013).
A methodology that helps for setup time reduction is single minute Exchange of die (SMED), it was developed by Shigeo Shingo in 1985 at Toyota specifically for the purpose of better responsiveness to the market with a wider variety of styles and options (Henry, 2013). The term refers to a theory and techniques for performing setup operations in under ten minutes, i.e., in a number of minutes expressed in a single digit. Although not every setup can literally be completed in single-digit minutes, this is the goal of the system described here, and it can be met in a surprisingly high percentage of cases (Shingo, 1985).
Key Terms in this Chapter
Waste: Any activity that consumes resources but creates no value for the customer. (Marchwinski et al., 2008).
Internal Setup: That part of the setup which must be done while the machine is shut down, for example, removing or attaching dies, Rubrich & Watson, 2004 cited by (Dave & Sohani, 2012).
Downtime: Production time lost due to planned or unplanned stoppages. Planned downtime includes scheduled stoppages for activities such as beginning-of-the-shift production meetings, changeovers to produce other products, and scheduled maintenance. Unplanned downtime includes stoppages for breakdowns, machine adjustments, materials shortages, and absenteeism (Marchwinski et al., 2008).
Setup Reduction: The process of reducing the amount of time needed to changeover a process from the last part for the previous product, to the first good part for the next product. (Marchwinski et al., 2008)
Setup Waste, External: Activities such as searching, locating or moving jis, tools, bolts, clamps, fasteners, gauges or instructions in the setup area Rubrich & Watson, 2004 cited by (Dave & Sohani, 2012).
Die Set: This is a tooling that is removed and replaced in a punch press during a changeover. A die set consists of a set of male punches and female dies which, when pressed together either creates a hole in the work piece or forms the work piece creating features desired by the customer ( Dave & Sohani, 2012 ).
Changeover: The process of switching from the production of one product or part number to another in a machine (e.g., a stamping press or molding machine) or a series of linked machines (e.g., an assembly line or cell) by changing parts, dies, molds, fixtures, etc. (Also called a setup.) Changeover time is measured as the time elapsed between the last piece in the run just completed and the first good piece from the process after the changeover (Marchwinski, Shook, & Schroeder, 2008).
Value Added Activities: The time spent on activities that add value to an item from the customer’s perspective. These activities that effectively change the form and function of a raw material into a good or service that the customer is willing to pay for Marchwinski & Shook, 2003 cited by (Dave & Sohani, 2012).
Non-Value Added Activities: Time spent on activities that add costs but no value to an item from the customer’s perspective. These are activities that the customer is generally not willing to pay for Marchwinski & Shook, 2003 cited by (Dave & Sohani, 2012).
Lean Production: A business system for organizing and managing product development, operations, suppliers, and customer relations that requires less human effort, less space, less capital, less material, and less time to make products with fewer defects to precise customer desires, compared with the previous system of mass production. (Marchwinski et al., 2008).
Setup Waste, Internal: Alignment activities required to remove and install tools, for example, the time associated with using a fork truck to maneuver the old tool out and the new tool in while setting up a press, Rubrich & Watson, 2004 cited by (Dave & Sohani, 2012).
Punch Press: A machine tool used to work materials (typically steel) by changing the shape of the raw material. Material shape is changed through application of direct pressure which forces the material to change shape. The function of the punch press is to hold the die set and apply the motion and pressure required to perform value added operations to raw materials ( Dave & Sohani, 2012 ).
External Setup: That part of the setup which can be done while the machine is still running, for example, preparing a die to be uses for the next run, Rubrich & Watson, 2004 cited by (Dave & Sohani, 2012).