Acoustic Testing of Automotive Exhaust Systems
ASMET was founded by Andrzej Szarski in 1989. Located in the Polish city of Czersk, some 250 km north-west of Warsaw, the company has grown rapidly from its origins as an automotive spare parts supplier to become a major European manufacturer of high quality automotive exhaust systems. ASMET has a production capacity of up to 250000 complete exhaust systems per year and remains privately owned. The noise performance of its exhaust systems has always been a focus area for ASMET. In 1999, the company purchased a complete Brüel & Kjær solution to measure and analyse the acoustic parameters of its products.

With changes in its political structure, the late 1980s saw a boom in the importation of used cars into Poland. Spare parts from European manufacturers were expensive. To satisfy this growing demand, Andrzej Szarski founded ASMET in 1989.  The company’s vision was established at its birth. To design, develop and manufacture automotive spare parts with quality, durability and performance that are equal or superior to the OEM equipment from automotive manufacturers. After a short time, ASMET decided to concentrate its focus 100% on the production of exhaust systems, and its success over the last 15 years is a testament to Andrzej Szarski’s decision.

The product range is wide with exhaust systems for over 600 different models in current production. These comprise more than 1000 different components. All design and development is in house, including the   manufacture of production jigs.  The flexible production lines enable both large and small batches of products to be easily and efficiently integrated together. About 250.000 complete exhaust systems are produced each year and there are facilities to manufacture up to 25.000 units per months at times of peak demand. ASMET employs nearly 90 people. The company is accredited to ISO 9001.

 

Miroslaw Bruski is ASMETs Managing Director.  He has a Masters Degree in Engineering and joined the company in 2000.  Miroslaw says, every month we add about ten new models to our product range, although there is still a demand for exhaust systems for older cars and we keep many in stock. Others can be produced on demand with short production runs from as few as 20 pieces. He continues, every year we receive a report from the SAMAR company that monitors the automotive market in Poland. The report provides us with information on which new cars are sold each year, and those that increase or reduce.  From these figures, we analyse the market and decide for which models we should manufacture exhaust systems.

ASMET currently has about 20% of the market for replacement exhaust systems for cars and vans in Poland - more than any single competitor.  Some 15% of the company’s production is exported and ASMET is keen to expand this area of its business. For the last ten years, ASMET has exhibited at the automotive fair held annually in Poznan.  In  2003, the company showed its products at Equip Auto in Paris and at Frankfurt in 2004. New EU rules require that replacement exhaust systems sold in Europe must be tested. Of ASMETs large production range, some 250 have been tested and a further 200 are in progress.

 

During its 15-year history, ASMET has acquired great expertise in manufacturing exhaust systems. Miroslaw says, our policy is to purchase original equipment exhaust systems and to then thoroughly test and measure them before starting the design and development of our replacement. The common opinion from our customers is that our exhaust systems have a very precise shape and fit easily, and this saves the repair workshops a huge amount of time and trouble.

 

Many vehicles now use catalysers to reduce emissions.  We buy these components from a specialist manufacturer, add them to our complete exhaust systems, and sell the complete unit as a branded ASMET product.  But it also works the opposite way and catalyser manufacturers often buy our components and then sell the complete unit as their own product.

 

To improve the durability, heat resistance, noise level and sound quality of its products, ASMET uses Owens Cornings  Silentex. Muffler Filling System and glass fiber based  Advantex® Muffler Roving, For some applications, polyethylene bags filled with continuous filament fibre glass wool are used.

 

To design and develop an exhaust system, ASMET buys at least two complete units from the original equipment manufacturer. The units are carefully measured and CAD drawings produced. The aim is to achieve as close a shape to the original as possible.  The next step is that acoustic measurements are made in the anechoic room. The unit with the best noise parameters is cut to reveal its construction and the interior dimensions are again measured and CAD drawings made.

Prototypes of the new design are made and these are thoroughly tested, both for their physical dimensions but also their acoustic properties. Subject to these being within the specified limits, the new model is released for production.

Miroslaw adds, But we can also develop our own designs based upon our years of experience. For instance, with one well-known and popular truck, we developed a new design of exhaust that gave a 6 dB reduction in cabin noise. To ensure consistent overall product quality and durability, the steel sheet and tube used by ASMET is imported. Manufacturers in Germany are the main sources.

 

Testing Acoustic Performance
Miroslaw says, we have always regarded the acoustic performance of our products as a critical factor. Our goal is to make our exhaust systems highly durable but also quieter than the original component, and this is reflected strongly in our marketing policy. The measured spectra of our products must be equal or better than those of the original part. Exhaust noise is becoming an ever-increasing issue in Poland and the acoustic performance of our exhaust systems is a key market differentiator. We always aim for the best possible noise performance. Every three months, each model of exhaust system is taken from the production line and batch tested for dimensional accuracy and its acoustic parameters. If high volumes of a particular model are ordered, batch testing is made at more frequent intervals. Miroslaw continues, Of course, many people, especially younger drivers, want their cars to sound right. So although we aim to manufacture exhaust systems with the lowest noise level, we also pay attention to the overall quality of the sound. We have a simple philosophy. Each and every customer must be 100% satisfied. We accept all complaints and offer a replacement exhaust without question. If the noise performance is the reason for a complaint, it is vitally important to fully investigate it, and compare the performance both to the OEM part and also other units taken from the production line.

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