Automotive NVH Series: Part 4 by M. French and M. Jay

AUTOMOTIVE TESTING - LAB OPERATIONS

his is the last in a four-article series on automo- tive NVH testing. The first article' described the T larger environment of automotive NVH testing,

why it is of such importance now and how the industry is balancing the requirements for improved NVH perfor- mance and for decreased testing costs. The second ar- ticle2 described some of the details of NVH testing in- cluding the types of tests and the facilities built around them. The third article" focused on instrumentation and data processing requirements.

Perhaps the easiest thing to overlook in automotive NVH testing is how the lab runs day to day. Operations is not an easily quantifiable topic like an equipment specifica- tion or a floorplan, but it is a critical aspect of getting the most out of the investment. Readers well know that the current business environment is very demanding and return on capital investments (like a test lab) must meet strict corporate standards. Public corporations must meet analyst's expectations each quarter or suffer as fund managers shift large stock holdings quickly in search of larger returns. As a result, test labs are under severe pressure to be efficient and to have no more equipment or facilities than necessary. How well the lab is run may well be the most important factor in the long term suc- cess of a test lab. It is probably the most important as- pect of keeping customers, staff and upper management happy.

LAB0 RATORY FUNDING One sticky subject is how people get access to the lab and who pays for it. Two popular ways of funding a lab are charging for testing and charging a flat fee. These two methods are analogous to paying the doctor for ev- ery office visit or joining an HMO, and they involve many of the same financial considerations. The fee for service approach requires that a test requestor pay for every test or test series separately. Typically, a test will not be run unless there is a purchase order in place. If the lab is funded through a flat fee on its customers, they are typically assessed a charge regardless of how much they use the lab. The fee may be assessed once during the year or spread out to be paid on a monthly basis. There is no consensus on the best way to fund a lab and there are good arguments for both methods.

Some numbers may help make the arguments clearer. Running a routine modal test may only take a few days

M. French (SEM Member) is Manager of Testing and Tech- nology Development - Vibration and Acoustics, and M. Jay (SEM Member) is Senior Engineer, at Lear Corporation, Southfield, MI.

Editor's Note: This is the fourth in a series of Feature ar- ticles prepared by Mark French, Chair of SEMs Modal Analy- sis/Dynamic Systems Technical Division. Please contact SEM i f you have any questions or comments regarding this, or any other, ET article. PB

and a seemingly small amount of equipment, but the reality is quite different. A good multi-channel data ac- quisition system may cost $75,000. Add $50,000 for good software and another $15,000 for sensors and there is $140,000 in equipment being used. If a laser vibrometer is required, add somewhere between $20,000 and $100,000 to the capital investment. Of course, trained people are required to run the test, perform any post- test analysis and write the test report. Also, don't forget that maintenance costs on the equipment and software are usually 10%-15% of the purchase cost every year. At this writing, the charge for a routine modal test (50 or so degrees of freedom) can easily exceed $3,000.

At $3,000 per test, it would take about 47 tests just to recoup the equipment costs. I t would take 5-7 more ev- ery year to recover the maintenance costs of the equip- ment and another two or three to recover training costs. If an engineer is dedicated to modal work, the salary with overhead costs (insurance, unemployment, Social Security, etc.) is another 20 or so tests per year. There are other costs as well. Running 50 tests per year would probably clear a profit, but if that profit is less than about 15%, the corporation might be better off putting the money in a good mutual fund and reassigning the staff. A well-run lab will have the people and equipment in place when the customers need them, will have tests scheduled to make the most use of the equipment and will meet budget targets reliably.

Labs that charge directly for testing generally do it on a per-test or project basis. This approach passes along the costs of running a lab to its customers so that the cost to the organization of lab operations is not hidden. Ideally, the effect is for those customers to exercise restraint in requesting lab services and, the assumption goes, use those services efficiently. Of course, another effect is to limit exploratory and developmental testing. Schedul- ing personnel must also be willing to turn away custom- ers who need testing but cannot pay for it. This can be a major cause of friction between departments. Finally, this funding approach provides a very useful tool to pro- gram managers who are trying to control development costs. High lab charges tend to show up on expense bud- gets on a monthly basis and can point to problems in the development process that may not be apparent other- wise.

The alternative is to fund lab operations through a sur- charge or tax on its customers. To continue the example used above, a test lab may choose to charge its custom- ers a flat fee of $150,000 per year for modal testing, no matter how many tests are actually run. This is, of course possible only when customers are internal. One advan- tage to this approach is that the administrative over- head is greatly reduced and there is little need for lab personnel to act as gatekeepers or to police organiza- tional billing policies. Another advantage is that some- one pursuing a new or innovative project has less need to get funding in order to try that idea in a lab. Imagine

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the situation that would be created if graduate students had to seek funding for every test they wanted to run.

The disadvantage of the flat fee system is that testing appears free to the customers after the yearly charge is recouped and the incentive is to test as much as pos- sible. In our example, the incentive for customers is to run a t least 50 tests as these have already been paid for. Internal organizations can even see themselves compet- ing to use the most lab resources since any testing be- yond what is covered by the charge to one’s own organi- zation appears to be paid for by other organizations. In such a situation, the lab can be running a t capacity whether the company’s activity justifies it or not - if test- ing appears to be free, people will want more of it. It is then difficult to tell whether there is too much test ca- pacity since i t can be difficult to tell how much of the testing is really adding value.

TEST CAPACITY The issue of test capacity is another topic of continuous fascination among corporate financial officers. While there is no universal definition of test capacity, it is es- sentially the amount of testing a facility is capable of doing over a period of time. For example, if a road simu- lation test on a shaker table takes two weeks and a lab has two shaker tables, it has a maximum capacity of 52 tests per year. That assumes that customers ask for tests to be run every two weeks - a near impossibility. If three tests come in at once, there is temporarily not enough test capacity and one test must either be delayed or sent to an outsource lab. If there is a three-week lag between test requests and the equipment sits idle for a week, there is temporarily too much test capacity.

Test facilities are very expensive and there are many commercial facilities available to perform testing on an outsource basis. Thus, all organizations must find a bal- ance between operating their own labs and relying on outsource facilities. Internal labs have the advantage of being flexible and responsive to the needs of the organi- zation. They are also much preferred if the test speci- men is confidential in any way; it is much easier to main- tain security of a new design if it never has to leave the company to be tested. However, test labs incur large fured costs and can be considerable financial burdens if they are underused.

Outsource labs only charge for tests performed, so there is no fixed overhead in the event of a decrease in busi- ness. However, your organization is likely to be only one of many customers who have queued up a t the outsource facility and there is no assurance that outsource capac- ity will be there when it is needed or that unusual or non-standard equipment will be available.

Many companies avoid building enough lab capacity to handle all testing requirements. Internal labs are de- signed with capacity to handle say 75% of the projected needs. They should then run pretty much a t capacity all the time, maximizing the return on the capital invest- ment while additional work (usually the most routine testing) is outsourced. Thus, in the event of a business

slowdown, the internal lab can still run a t capacity as outsourcing is reduced.

DESIGN CONSIDERATIONS The physical layout of the laboratory and its location must also be given careful consideration; a poorly de- signed facility will have a lower capacity than another with the same staff and equipment, but a more efficient layout. For instance, test areas that may produce noise or vibration must be physically isolated from spaces in which acoustic measurements are to be made; seldom is the converse a problem. In general the solution is to use a combination of reaction masses, absorptive boundaries, isolated floors, and even treated air-handling systems to help minimize bleed and cross-talk between test cells. Otherwise, acoustics and vibration tests must be sched- uled so as not to run a t the same time and test capacity is decreased.

At this writing, lab space costs $100-$150 per square foot to build, not including equipment, and renovating a n existing building may not be much cheaper. There must always be a compromise to stay within the budget. The matter becomes still more difficult to solve in envi- ronments such as Europe andAsia where land is signifi- cantly more expensive and in many cases, simply non- existent or inappropriate for a laboratory. If the lab will be surrounded by neighboring facilities that generate intrusive levels of noise or vibration, these concerns must be addressed adding to cost and complexity of the de- sign.

Floor space is expensive, so reserving areas for storage and for moving equipment through the facility is always a hard decision. A good layout and strict management of test specimens and equipment scheduling can greatly reduce the amount of this non-productive space that is required. As a simple example, placing a test area that requires access by a full vehicle far from a door requires that space be set aside for a large aisle. There are lim- its, though. Customers with proprietary or sensitive test specimens will insist on their test being isolated from the rest of the lab. Also, customers never seem to de- liver test specimens when you want them to; there should be well-organized storage areas for a modest backlog of materials. Most of the storage space will be filled most of the time, no matter how much space you have. Build- ing too much can be just as bad as building less than enough.

Electrical isolation must also be addressed. This can be accomplished by ensuring that all instrumentation lines between each control room and test cell are housed in electromagnetically permeable conduit and isolated from ground references tha t exist in a test cell. Failure to address these issues usually results in ground loops, a phenomenon caused by current flowing between grounds of differing potentials. At best this results in AC mains components, either fundamental or harmonic (i.e. 60 as well as a t 120, 180, 240 Hz. etc.), superimposed on data lines corrupting the data. Very small signals such as those from strain gages etc., can be completely swamped, leaving the data worthless and the technicians little

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choice but to run redundant signals lines - a costly and avoidable fix.

STAFF IN G Of course, the best lab facilities are worthless without a qualified and motivated staff. Running a test lab pre- sents some unique challenges for the management team. From their standpoint, a key measure ofefficiency is the number of tests performed each month or perhaps the monthly billing totals. These must be compared to the operating expenses and the capital depreciation of the building and equipment. Thus, routine, procedural tests are attractive; they offer a steady and dependable source of income and can often be run by relatively junior (and inexpensive) employees. The obvious problem, though, is that keeping good people is difficult if the lab’s work is limited to just grinding out routine tests.

There must be a regular flow of high technical content testing and perhaps analysis work to provide develop- mental opportunities for the staff. While junior staff may be cost-effective in the narrowest sense, no lab can func- tion for long without the technical foundation provided by well-trained and experienced engineers and techni- cians. Without them, even minor problems can stop op- erations. Worse, problems may go unnoticed and bad data may be sent to customers.

A less obvious problem with focusing too much on rou- tine testing is that it changes the nature of the lab’s prod- uct. Rather than selling valuable solutions to technical problems, the lab is reduced to pushing a commodity (test data) that is available from many different sources and is indistinguishable from that produced by the competi- tion. Then, the only way for a lab to distinguish itself is with lower prices. This is a very tenuous position for an internal lab that must compete with outsource facilities.

As an example of a routine test, consider a component sound measurement. It is common for automotive prod- ucts to have both absolute sound level requirements and sound quality requirements, so measuring the sound produced by a component like electric motors is very rou- tine. If the only product of a lab is the data representing sound levels as the motor is run up, the lab is trying to sell a commodity. If the lab is able to suggest improve- ments to the motor, to develop improvements to the test procedure, to help their customers refine the design re- quirements, so what they ask for is really what they want and to act as a partner in the product development pro- cess, the lab is selling a valuable service that is far from being a commodity.

We feel strongly that developmental work is necessary for the long term health of the test facility. However, it can be a tough sell. It is often difficult to define the tan- gible benefits of such work and intangible arguments are necessarily weak ones. In addition, the people most likely to successfully conclude a development project are the

. most capable and typically the most expensive. That * doesn’t mean the returns aren’t real. After the initial . payback on time invested, test costs can be reduced due . to compressed procedures, or alternately, data generated . by the newly-modifiedprocedure that can be shared with . other groups.

THE LABORATORY AS A CUSTOMER Universities face a unique challenge in selling research projects to test organizations. Many test organizations do not have resources to devote to long term develop- ment projects, so there are opportunities for research organizations to sell improvements in procedures and equipment. It is important that the payoffbe quick. The researcher proposing a n extended effort with no guaran- tee of success has a pretty tough job. The ideal from the buyer’s point of view is a researcher who is selling a prod- uct for which the development is already complete. That product may be a new test method that improves results or reduces test time or a new piece of equipment such as a n improved accelerometer. The problem is, of course, that research has traditionally been funded based on expenses rather than results. By definition, the outcome of a research project is not certain and businessmen don’t like uncertainty. They want to buy a product, not a pro- posal.

. CONCLUSION

. We strongly hold the opinion that running a test lab well

. is critical to its overall success. The quality of opera- ’ tions is probably more important than the quality of the ‘ test equipment available and is very closely linked with : the quality of the people who staff the facility, and the . quality of the work produced. Well-implemented opera- . t ional procedures c a n maximize r e t u r n on t h e . organization’s investment in a number of ways: they can . create a rewarding work environment that attracts and ‘ retains skilled staff; high operating efficiency minimizes . the investment required to satisfy testing needs; and the . facility and staff can become a valuable part of the prod- . uct development process by contributing more than just . test results.

, References

. 1. French, M., and Jay, M., “Introduction toAutomo- - tive NVH Testing,” EXPERIMENTAL TECHNIQUES, * 22(4), 32-33 (July/August 1998).

2. French, M., and Jay, M., “Automotive Test Meth- . ods,” EXPERIMENTAL TECHNIQUES, 22(5), 39-42 . (SeptemberlOctober 1998).

’ 3. French, M., and Jay, M., “Instrumentation and ‘ Data Processing for Automotive NVH Testing,” EXF’ERI- . MENTAL TECHNIQUES,22(6), 43-44 (NovemberIDe- . cember 1998)..

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