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Six Sigma was developed by Motorola in the 1980s as an enhancement of their Total Quality Management (TQM) approach focusing on quality improvement. Companies such as General Electric (GE) developed the concept even further and extended the application of Six Sigma tools to their entire business, including the development of new products, with a focus on both financial gain and customer satisfaction. Six Sigma, however, also offers a rigorous, data-driven procedure for process and product improvement and for the development of new products and processes using proven methods and tools taken from the Quality Management and Quality Engineering toolbox. Integration into the existing engineering culture and the application of these tools and concepts to a typical application at a leading global exhaust system supplier are outlined in this paper. The procedure which is used for measuring the surface radiated noise is analyzed in detail by the principles of Six Sigma.

Steel prices soared in the past years due to the increased demand on the Asian market. Due to difficult economic conditions of the automotive industry it is not possible to transfer expenses to the final customer. Reduction of steel is therefore required to compensate for higher steel prices. Whereas the underbody design space decreases in European vehicles, requirements are getting higher in terms of tailpipe noise and backpressure reduction. This leads to flat structures for mufflers which are integrated into the underbody to achieve as much inner volume for tailpipe noise damping as possible. That requires larger surfaces and results in a rise in costs, weight and radiated noise over surfaces. Additionally, original equipment manufacturers (OEM) require lightweight designs to meet carbon dioxide and consumption targets. Especially for Diesel applications the weight of exhaust systems is penalized by heavy Diesel particle filters.

The emitted noise of an exhaust system is divided into three different kinds of noise: Tailpipe noise, noise transmitted through the hanger into the cabin and surface radiated noise. This paper deals with the surface radiated noise which becomes more and more unmasked as the radiated sound power of other sources, e.g. of the tailpipe, decreases. Noise sources, the transfer path and the radiation of a structure are presented. A method for calculating and optimizing a structure with FEA (finite element analysis) is also part of this paper. An exhaust system is a complex dynamical system. Global eigenfrequencies of a whole exhaust system are below 200 Hz. A muffler moves then in rigid body motion and the radiated sound power is subjective not relevant. The main sound power is transferred through the hanger to the underbody. At higher frequencies the acoustical effects appear more local and are more effective in noise radiation.

Up to now Six Sigma has mainly been used for manufacturing. A Six Sigma approach was introduced in 2004 at Tenneco for transactional business This paper illustrates 2 examples where Six Sigma was successfully applied to improve the service quality. One first case is the improvement of a measurement system analysis [1]. In the exhaust system domain the acoustic performance of an exhaust system must meet the requirements in terms of drive-by noise of a vehicle and in terms of subjective sound. Therefore it is vital to measure the so-called “tailpipe noise” of an exhaust system with precision and reliability. Otherwise some iterations take place to confirm the data, or - more critical - an exhaust system design can be rejected when in reality it is just meeting the target curves and inversely, this could be accepted when the targets are not met.

A experimental method has been developed to assess the flow noise in tailpipe noise through measurements on an acoustic flow bench with cold air. To set up this procedure, measurements were made on flow bench, engine dynamometer and chassis dynamometer. The Mach number seems to be the appropriate parameter to correlate the overall level of the radiated flow noise. If mass flow and temperature under running conditions are known, the noise level can be extrapolated for real conditions. The Strouhal or Helmholtz numbers are appropriate parameters for getting details of spectra contents.

The lean implementation method is crucial for successful results. Tenneco's early lean experience showed that project execution took too much time, resulting in the risk of de-motivating people and reducing the credibility of the company's lean strategy. An experienced team from finance and sales & engineering worked to understand the root causes and find a new way of: identifying preparing executing tracking and closing the lean projects. This paper describes the lessons learned and how Tenneco improved its lean methodology.

Several factors influence a company working culture including its industry, its geographical region, as well as the cultural and the educational background of its employees. Despite these, Japanese companies have successfully transferred a company’s working culture from Japan to other countries [2], so that only minor regional differences in productivity remain. Such transfer is possible with a strong process oriented mind set and working style. This paper examines the change in a working culture associated with the prototyping of exhaust systems in India. That change required a shift from a reactive “firefighting” mode of working to a structured, projectable and reliable working environment. The goal was to achieve increased in-time delivery, higher quality, greater flexibility, more innovation and reduced cost. The same process approach may be transferred from India to other parts of the world, while allowing for country-specific influences on a company’s working culture.

The Rybnik Eng Center was reactivated at the beginning of 2008. One of the objectives of this new center is to develop the lean spirit and to directly apply it to the new center. Two years have now passed and these 2 papers give the opportunity to review the current status and to reflect on the lessons learned so far on our lean journey. The 2 papers are structured around people, processes and tools. The first paper focuses on the people, the second one on the processes and the tools. Some great progress has been made in the different areas of application including: - Processes: Some key engineering processes in Testing, CAD, CAE and prototype shop were thoroughly investigated and improved. Especially the quality of the outputs and significant reductions in lead times have been achieved. - Tools and Technologies: Tenneco worked on both aspects, the soft and hard tools. Soft tools are covering visual management which allows a better alignment.

Rybnik Engineering Center (REC) is the new R&D center developed by Tenneco in Poland. One of the key ideas behind the REC is to develop it based on the lean engineering principles. In a first step a white paper was established and agreed upon with senior management. This white paper consisted of: a vision a set of objectives derived from this vision and a road map to reach this vision The creation of REC has been articulated around 3 major themes: 1. PERSONNEL - It is about how to identify and hire people that will fit into our lean culture. A further challenge is to then train and mentor the people. A similar model known as the inverse-T at Toyota was implemented. Lastly, a network of partners has been established and integrated in the Tenneco development processes. 2. PROCESSES - Both engineering and cross functional processes have been systematically reviewed or new ones developed.

[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12] This paper describes the implementation of lean in the Human Resources department at Tenneco Europe. In the past, the implementation of lean transactional was mainly focused on Sales & Engineering and Finance. Our experience shows that the lean approach can be applied in a similar way as in Finance or Sales & Engineering. This paper illustrates some examples of critical processes related to Human Resources which have been improved. These include the “on-board” or integration process the management of employee flextime accounts process to create and manage a resignation certificate absenteeism reduction in one Tenneco plant For these three last processes, the key workshop deliverables are: project charter.

After having successfully implemented lean manufacturing in the 1990ies and lean engineering since 2004, Tenneco Europe expanded lean to its administrative organizations in October 2009. The implementation approach was directly derived from lean engineering previously implemented in Tenneco Europe as this was considered closer to administration processes than manufacturing processes were. A first SAE paper on lean transactional was presented in 2011. This paper covered a vision, a road map and a process to roll out the lean Spirit in the Administrative world. This paper and the papers listed in the reference list provide in detail the lean tools and principles used in lean transactional and engineering. This new paper is focussed on some concrete applications where the lean mindset has been implemented mainly by the finance team supported by sales, project management, marketing, manufacturing and engineering.

Tenneco first implemented the lean transactional process ten years ago. One of the key success factors was to ensure that the lean system was sustained within an organization as part of a philosophy of continuous improvement. This has probably been the most challenging part of implementing lean in Tenneco. During the early years of implementation, lean was managed as a top down approach which consisted of: identifying executing and tracking lean projects by the management, a small number of additional people and lean experts. This approach had the advantage of building up critical mass and helped to instill a lean change culture in a reasonable timeframe. But the Tenneco experience showed that even if early results were encouraging, the implementation was not consistent enough to sustain a mindset of continuous improvement. This top down approach needed to be reinforced by a much stronger bottom up approach which consisted of group leaders acting as change agents.

More and more automobile manufacturers are requiring a typical sound pattern for a car or a platform, even the unique „brand sound” for a whole brand, on the top of their specification. By this image factor sound design becomes increasingly important for the exhaust system development. The whole sound pattern, especially the tailpipe noise of the exhaust system, plays an important role at the subjective impression of the car [1, 2]. There are two sound classifications: the limousines with an harmonic, quiet and discrete sound whereas for sports cars a more rough and powerful sound is requested. Compared with the gasoline engine the diesel engine has, based on inner power driven processes, a minor sound spectrum because its harmonics and main orders are hardly audible and mostly attenuated by a turbo charger. For turbo charged engines special concepts have been worked out in order to achieve a sporty sound.