Modular component testing system for automotive parts suppliers
New products, shorter product life cycles, further developments, modifications and additional models are burdening project managers in the automotive supply industry with an ever-increasing number of responsibilities. The means of production need to be modified, retooled, redesigned or even newly procured. The same is true of the accompanying test equipment that is used repeatedly to put the product to the "acid test" at various stages throughout the manufacturing process.
Testing pressed screens again and again
Pressed screens encased with injection moulded plastic and then integrated into housing components perform the task of a printed circuit board and the discrete wiring in components like control assemblies, components carriers, pumps and control systems. The 100% insulation of the conductor strips from one another, as well as the safe passage from the beginning to the end of the current-carrying "metal arteries" is sufficient guarantee that the final product will function faultlessly. Since components like this are usually produced in complex, subdivided production stages, it is advisable to test the components before the next production stage. Any systematic errors, isolated errors or undesirable changes to production tolerances that may occur can thus be detected at an early stage.
High voltage, high current!
In order to meet today's high quality standards, the components need to be tested at maximum rates. Voltages of up to 1200V/DC for testing the insulation and currents of up to 1A per conductor strip for the conductivity test are possible. At each stage of testing, an overall current across all conductor strips of some 30 A is possible. If higher values are necessary, the equipment can be upgraded to meet the customers' individual requirements.
Time is of the essence
In order to keep within the commonly meagre amounts of time allocated for testing, as many tests as possible are carried out in parallel. As the number of possible connections between conductor strips is arbitrary, the test sequence can be adapted to the respective requirements. This is accomplished with the aid of a special modular switching cassette that is optimised to the performance requirements in terms of voltage and current. Switching times and the time required for recording data are kept to a minimum thanks to an ingenious software package. For example: to carry out a complete test on a component with 35 conductor strips, a cycle time of less than 4 seconds can be achieved. At the same time, should a fault occur, it is also possible to provide accurate information about the defective part of the component.
Clear specifications and consistent development have resulted in modular systems that can be upgraded. The switching unit comes in the form of a slide-in cassette. Depending on the customer's requirements, up to 12 of these cassettes can be slotted into the unit. The unit is controlled using the CAN bus, meaning that all that remains to be done is to connect up the item to be tested. No additional hardware is necessary. Each of these cassettes can supply up to 16 conductor strips with two test points each. The standard version of the equipment is capable of testing up to 192 conductor strips. Even the basic version of the software is able to manage the maximum number of test points.
Man and machines alike need to communicate with the test equipment. In order to operate and configure the unit, an easy-to-use software interface with a typical Windows® look is available. The test procedure can be configured simply by selecting and clicking on the test points. The most important data and the system status are displayed and updated continuously. As the equipment is usually integrated into an overall design and must be able to communicate simply with existing SPC controllers, an insulated, digital interface is available via which it is possible to set a configurator as required. This makes it possible to adapt the equipment to changed environmental conditions within a matter of minutes. Each adaptation of the item to be tested is connected directly to the slot-in cassettes in order to avoid potential sources of error caused by too many intermediate terminal connections. The system can be integrated into the company network using customary PC slot cards. Remote maintenance by the equipment manufacturer can either take place by switched line or via the Internet.
Each test carried out is documented individually. This makes it possible to retrace each of the test results. In order to monitor production, a variety of statistical functions have been implemented. The data can of course be exported, enabling you to perform your own evaluation of the data. This makes it possible to adapt the equipment to a wide range of e-business solutions as and when required.
Process safety guaranteed
Using machine operators to monitor the equipment for error-free functioning is not only time-consuming, but it is also unreliable and not always easy to incorporate into automated production processes. This is where the equipment looks after itself. In a user-definable cycle, a self-test is carried out that switches and checks every component and each relay. This test is initiated automatically and is completed in a matter of seconds. In this way, depending on the security level, it is possible to test the equipment at short notice and document the results. Important functions of the equipment are tested whilst the test item is being handled. This means that under normal conditions, the cycle time is not affected.
Mechanical adaptation included
In order to be able to perform the tests in the desired short cycle times, it must also be possible to connect up the test item fully automatically. For this purpose, suitable test-specific adapters are supplied with the equipment. These adapters, frequently custom-made units designed to accommodate the most complex shapes, are designed for millions of strokes. A patented contact module is used to connect to highly sensitive and tightly packed bonded surfaces. With its simple, but well thought-out design, this contact module satisfies all the demands in terms of the technical specifications and the demand for high-quality and undamaged contact surfaces.
Everything from a single source
The interplay between electrical engineering, electronics, software and mechanical engineering is becoming more and more important. Dispensing with interfaces to external locations makes it possible to rule out any potential sources of error from the onset. The system presented here has been developed and implemented by a team of qualified experts. All components come from a single company.
The use of modular test systems in highly automated production areas is indispensable. Only with the aid of a flexible system is it possible to respond rapidly to customer requirements and changed basic conditions.
Author: Volker Grobshäußer
Head of TestSystems
published in the periodical