Energy Value-Stream Mapping - A Method to Optimize Value-Streams in Respect of Time and Energy Consumption

Abstract

In the industry, Lean Production Systems have been successfully used for years to reduce inventories and lead times. The Value-Stream Mapping Method (VSM) has proven itself to be the best practice tool for this purpose. With this method process steps can easily be divided into value-adding and non value-adding ones. However, the VSM does not provide any information about the process energy consumption and, as a consequence, it does not give any hint at how much of the energy used actually serves value-adding purposes. Would it be known how much energy is used for value-adding and for non value-adding process steps, then it would be possible to optimize value-streams in a holistic way, simultaneously considering time and energy consumption. This paper describes how the VSM can be extended to an Energy ValueStream Mapping Method (EVSM) while maintaining its original character and its inner logic. Keywords:Energy Value-Stream Mapping; Energy efficient production and logistics; Lean and Green Manufacturing INTRODUCTIONWhile the manufacturing industry is one of the main energy consumers, it is at the same time also the key factor for our prosperity. Considering the continuously rising energy cost and an increasing public awareness of the need for a sustainable economic activity, many branches of industry have in the meantime declared energy efficiency their strategic business objective.During the second half of the last century, labour productivity has increased almost fourfold, while energy productivity has not even doubled during the same period of time [1]. In the past, the industry's rationalizing efforts have focused on increasing the degrees of automation while simultaneously cutting down the cycle times.When in the nineties of the last century the methods of the Toyota Production System (TPS) came to be known in the Western world, numerous companies tried to adopt them for their own use. At that time the TPS was considered, and today still is, a benchmark for designing highly efficient value-streams and very often it is also described as a lean production system. THE TOYOTA PRODUCTION SYSTEMTaiichi Ohno, who is one of the TPS's architects, describes its essence as follows: ‚All we are doing is looking at the time line from the moment the customer gives us an order to the moment when we collect the cash. And we are reducing that time line by removing the non value-added wastes' [2]. So, the point in the TPS is to keep the time interval between the placement of an order and the payment of the product as short as possible. Therefore, the creation of value should be as efficient as possible, in other words it should be achieved while avoiding waste. To accomplish this, non valueadding processes (waste) should be eliminated wherever possible. If complete elimination is not possible waste should be at least reduced to a minimum. To identify non value-adding processes systematically, Ohno classified the types of waste as follows [2]:• Waste of overproduction• Waste of time on hand (waiting)• Waste in transport...

Real-Time Operation Management of CHP System in Manufacturing Industry

“…Moreover, this step can be linked to the forecast system, in which potential energy demand of the next CTH is simulated (Herrmann, Thiede, Kara, & Hesselbach, n.d.;Müller, Stock, & Schillig, 2014). This should be achieved by taking into account a set of updated production schedules, which determines updated energy demand profiles.…”

Energy Value-Stream Mapping a Method to Visualize Waste of Time and Energy

“…The value-adding efficiency of the process in terms of energy, as well as in terms of time, can now be defined as η Eva and η tva , equation 1, 2. Therefore the value adding energy is divided by the total energy consumption of the process [1,6,14]. (2) The use of dual signatures allows evaluating the production process in respect to the efficient usage of time and energy.…”

“…When time is wasted and during this time energy is consumed, this amount of energy necessarily also has to be regarded as waste, too. Up to now the authors have analysed several production processes like milling, casting, welding, injection moulding, handling, robotic and laser applications [1,6,17,18]. For all of them a dualistic approach can be made.…”

“…The analysis of the manufacturing process by means of dual energy signatures allows it to extend the VSM to an EVSM while maintaining the inner logic of the VSM [1]. The results of the investigated milling process are embedded into the EVSM, Figure 6.…”

“…While the manufacturing industry is one of the main energy consumers, it is at the same time also the key factor for our prosperity. Considering the continuously rising energy cost and an increasing public awareness of the need for a sustainable economic activity, many branches of industry have declared energy efficiency their strategic business objective [1].…”