Acoustic Emissions | Sound Immission

Manufacturing News Center - Machine manufacturers and operators assess the effects of reducing noise or acoustic emissions

Synopsis-January 7, 2005-Jobwerx News-

Noise is simply an undesirable sound. It is frequently the cause of disturbances and even illness in the workplace. Despite weighty recommendations and consequent international legislation on the subject, the results are not always completely satisfactory.

To really effectively reduce noise in a facility, there must be shared determination and very close joint-working involving the machine manufacturer and user. Although manufacturers must supply products with the sound emissions in free field conditions over a reflecting plane declared in the machine handbooks - i.e. with no environmental factors - when the machines or lines are installed in industrial buildings, the sound emissions change. In this case the term used in assessing the effects of noise is "acoustic immission". It is the energy sum of:
- noise directly produced by the machine being used
- noise generated by the reverberating components correlated to the type of building the machine is installed in
- background noise, i.e. the noise coming from all the machines generating sound directly and reverberating, except for the machine being investigated.

In short, a serious professional approach to the problem inevitably involves close collaboration between the manufacturer and user in determining the value of the acoustic immission at the operator's work station.

The first steps
Once a company decides to invest in, for instance, a new bottling line or revamping an existing one and does not have the international resources required for correctly assessing the sound propagation conditions, then there are two alternative solutions: Seek the services of outside consultants, or ask support from the line supplier by commissioning a preliminary study on acoustic impact according to the EN ISO 11690-1, EN ISO 11690-2, EN ISO 11690-3 and EN ISO 14257 international standards. These regulations provide a detailed description of the physical parameters required in constructing and then, assessing an "acoustically state-of-the-art" industrial building. Meeting the standards also ensures the building will pass any inspections by regional organizations. Obviously this will only be possible by interacting from the outset of the project with manufacturers offering specific competence in the acoustic field. SIG Simonazzi, of Parma, Italy, rose to this challenge some time ago and is now in a position to offer increasingly advanced technological solutions. SIG Simonazzi manufactures machines and equipment for the beverage industry.

Bottle sounds
Controlling the noise generated by a bottling line is a complex problem and involves applying many techniques to act on the concrete possibility of reducing levels (for example, by applying sound absorbing and/or sound proofing material, the reduction of vibrations and the inclusion of highly evolved mechanical components). A second field of action concerns electrical equipment, control techniques, and related branded software packages, designing ventilation systems, and liquid flows in various types of piping. In theory, the application of these methods produces an ideal environment, provided the facility and all its basic components and production layout are careful designed by correlating the number of sources, their sound power levels, the volumetric distribution of the building and the absorption characteristics of the materials employed.

Designing good acoustics in the building-plant system involves using acoustic simulation systems based on experimental noise data acquired in successful projects in long years of experience.
Running simulations mean being able prevent or reduce to a minimum noise in lines at the engineering stage. By intervening in existing situations, the effects of soundproofing can be predicted.

Thus although it is not easy to build an acoustically state-of-the-art facility, a great deal can be done, as demonstrated by recent SIG Simonazzi experience. For years SIG Simonazzi has collaborated with research groups in Italian and foreign universities such as the MIT, Massachusetts Institute of Technology, Boston, Department of Industrial Engineering at the University of Parma, and the University of Ferrara, to study sound propagation in large low industrial environments, the typical structures housing bottling lines.

The aim is not only to meet the requirements of the Machinery Directive, but also to offer SIG customers a well-documented fast consulting service for industrial acoustics. SIG Simonazzi is so committed to noise problems that it has even promoted an information campaign with the UNI ISO and CEN bodies concerned with the standardization so that its own studies and experimental evidence will be taken into account in the new regulations called 'Determination of Sound Emission Values for Packaging Machinery'.

Over the years, the university researchers and SIG Simonazzi technicians have aimed to go beyond the algorithmic limits of the environment correction (K) factor, established by the EN ISO 3746 and EN 11204 standards, thanks to a simple change in the traditional formulas for semi-reverberating sound fields. In other words, a simplified empirical formula was devised to assess the correct K figure in vast low environments, respecting the original approach of the standards. All of this has meant that the noisiest areas can be identified - and therefore the position of operators analyzed in advance - and various adjustments can be made to minimize sound emissions, also taking into account the economic implications. Through sophisticated data-acquisition techniques and computerized acoustic simulation, machines (sources) can be described acoustically and directly modified whenever necessary to meet the required standards. Lastly, a number of certified suppliers have been identified and provided with technical acoustic specifications so that SIG Simonazzi's sub-contracted components always meet the established standards.

At times controlling the sound source cannot be effected without interfering with the machine and its hygiene. In these circumstances, therefore, the focus must be shifted to other methods of control: by adopting for example, protective measures for the operators, such as soundproof cabins and protective ear-muffs with active control and intercoms, enabling groups of operators to communicate and work at distances.

One of the most critical points in terms of noise is the container transport system. In this case, the approach is organized into various actions, such as establishing the right size for accumulation areas the careful choice of lubricants, and the use of ergonomically valid effective covers. All of this is "spiced up" with plenty of advanced software to control on-line the parameters which notably condition the noise levels of bottle conveyors.

Recent developments
SIG Simonazzi is currently committed on various fronts as regards studies on noise.

The first, mentioned above, involves promoting standard regulations currently in a draft version for the CEN.

The second concerns operator protection. SIG Simonazzi is researching a new system for the active control of noise. In other words, the development of an electronic device made up of a series of loud-speakers and receivers (array technology) laced at a short distance from the sources which emit a sound with waves in the opposite phase from the source waves. Like the limits in high frequency demonstrated so far, this technique is well known.

SIG Simonazzi will soon be able to present the new positive application developments through the use of the "wave filed synthesis", offering more silent machines at low-costs for the market. Similarly, it will be possible to establish noise-free areas and the line called "Silent Bubbles", in which operators will be able to "acoustically recover" from their working day.

SIG Simonazzi has also joined the LAV (Laboratory of Acoustics and Vibrations) network promoted by the Emila Romagna Region through HI Mech (a district for high-mechanical technology) coordinated by the Universities of Parma-Ferrara and Bologna.

Conclusions
The commitment, energy and resources continually invested by SIG Simonazzi to reduce sound emissions in its own lines, clearly reveal the company's overall objective to be an all-around system integrator: a partner in a position to offer reliable and complete solutions, supported by the company know-how acquired in major national and international collaboration projects. Significantly, the research aimed at the active control of sound levels, and wave field synthesis in particular, has also seen the involvement of MIT, Boston and the ISVR, Southampton.

Contact George Fornari at SIG Simonazzi - Phone +39 0521 0994969

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: SIG Simonazzi

SIG Simonazzi designs, manufactures, and sells machines, complete lines, and turnkey systems for preparing, filling, and packaging beverages (beer, soft drinks, mineral water, isotonics, neutraceuticals, juices, milk and milk-based beverages, wines, and spirits) in plastic/glass bottles and cans.

As a supplier of complete systems, the company integrates its lines with machines produced by other SIG companies operating in the sector: labelers (Alfa), seamers (Comaco), blow-molders (Corpoplast), mixing and sterilizing systems (Manzini), end-of-line robot and logistics systems (Elettric 80).

Sig Simonazzi is based in Parma, Italy with other facilities in Italy, Brazil, Mexico, and China, the company has sales offices worldwide.

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