As a test program manager, it's important to understand how to design and build a test system that will last an entire product lifecycle. But what factors most affect the longevity of a test system? And what components of a test system are most at risk for obsolescence or part failure?
Before designing a system, engineers must understand what factors affect longevity, how to approach system design (considering both hardware and software), what industry or application specifics matter most, and how to find a test partner capable of specific system needs.
What factors most affect longevity for a test system?
New innovations drive new demands for test, and when creating a test system, there are many factors that can affect the longevity of a test system. The three most important are power requirements, testing volume, and component quality.
Power Requirements
Depending on the application, power requirements have a great impact on longevity of a test system. With high-power testing, significant amounts of energy travel through the system, causing strain and leading parts to wear out quickly. Systems require careful design to ensure that the switching relays do not get welded, and cables do not overheat. On the other end of the spectrum, low-power applications like Flex-Ray, Ethernet, or RF testing for cell phone handsets cause almost no power strain.
Test Volume
Sheer volume of units under test significantly affects longevity of a system. Some systems test thousands of data points at high speed, this high-volume testing can lead to fixtures wearing out more quickly.
Aerospace testing is typically low volume. These systems often test 1-2 units per day and testers last more than 20 years. Cars and related components are medium volume, testing thousands of units per day, and systems should be expected to last 10-20 years. In semiconductor manufacturing, however, test systems might test 20-30 million parts per day. Not only do these systems last less than 10 years, but test engineering managers also need to have spare components or a plan for keeping production moving when parts fail.
Mean time between failure (MTBF) measures reliability – the higher the MTBF, the more reliable the component – engineers can use these measurements to generally predict component life. This measurement can be applied to connectors, test probes and switching as they are mostly mechanical and are prone to wear.
Component Quality
The quality of the components used in a test system is one of the most important factors affecting its longevity. Poor quality components are more likely to fail, which can lead to expensive repairs or even replacement of the entire system. To ensure long-lasting performance, it is essential to use high-quality components that have been designed for durability and reliability. For example, standard connectors used in electronics may be useable for only several hundred insertions, while connectors used in mass interconnect systems in test systems are rated for thousands of insertions. If your test setup requires manual insertion of connectors to the device under test, keep this limit in mind and source components from providers who have a decades-long track record of customer success.
Approaching Test System Design with Longevity in Mind
When designing a system for longevity, engineers must evaluate specificity and cost, understand points of failure, and take into consideration software compliance.
System Specificity and Cost of Failure 
System specificity demands must be evaluated to create an accurate system that doesn’t also exceed budget requirements.
It’s easy to overcomplicate a test system by designing it to test every possible scenario – for example, a handheld consumer product with a 1–2-year lifespan and no life-critical application, doesn’t require a test system so extensively (and expensively) elaborate to test for absolutely every corner case possible – instead, engineers can use a more streamlined validation test. However, an aircraft with an extremely high cost of failure demands a nuanced test system during the verification process that will specifically test a magnitude of variables, including failure modes.
Points of Failure
When it comes to the longevity of a test system, there are several components that are most at risk for obsolescence or failure. The probability of failure increases as more components are included in the system. The simpler a system is designed, the less points of failure are available, but the greater the impact of a single failure as it comprises more of the system.
Engineers who design test systems for longevity must maintain a plan for spare or replacement parts, as well as create a preventative maintenance schedule. Test partners can manage this process for organizations to ensure if a part fails, a spare is available.
Software Considerations
Software is another area where obsolescence can affect longevity of a system. As new software versions are released, older versions may no longer be compatible with the latest test systems. This can make it difficult to keep your test system up to date and running smoothly over decades.
Some considerations engineers must remember when evaluating software:
- Undocumented changes in test system software are often the root of software issues
- Old operating systems may require special drivers when new components are incorporated into the system
- Switching software is separate from the overall test manager, so working within it to control the test system can help improve overall test speed
- Well-written software can be reused from the product validation to verification, further saving time and costs
- Test solution providers can recommend reputable software developers to bridge gaps between new components and old operating systems, saving time and resources
How do longevity requirements vary across industry applications?
Longevity requirements for test systems vary depending on the industry application. For example, in the automotive industry, a typical test system may need to last for the duration of a car's warranty period, which is typically four years or 40,000 miles. In contrast, in the aerospace industry, a test system may need to last for the lifetime of an aircraft, which is typically 20-30 years or more. There are several factors that contribute to these different longevity requirements, including historical knowledge, regulatory requirements, and security concerns.
Historical Knowledge
Your test system design should take some account of testing in various stages of product design, integration into production, as well as potential future changes in the product roadmap. Industries like automotive have been conducting HIL testing for engine emission control and safety for decades – the best practices learned in this industry can significantly cut down the design process for automotive production test systems. New advances in automotive, like electric vehicles, require extensive battery management and testing. By using historically flexible solutions like the modular PXI platform, engineers can swap in more capable modules when testing shifts from 400V to 800V battery systems.
Regulatory Requirements
Regulatory requirements can also impact the longevity of a test system. For example, in some industries such as medical devices, there may be regulations that require testing equipment to be calibrated on a regular basis. As a result, these industries typically require more durable and reliable testing equipment that can withstand frequent calibration cycles. Calibration can also affect system downtime if spares are not available to keep the test system operation while the instrument is calibrated offline.
Using a test provider that participates in standards bodies like PXISA and the LXI Consortium helps organizations remain ahead of what new specifications are coming and can translate these regulations into new test requirements.
Security Concerns
Platform choice is important when an application has security requirements, especially in network security and modifications to test programs. LXI is a quick and flexible platform, programmed with more modern programming languages using Ethernet and executed via networked PCs and laptops – but this approach can open a system to security risks without careful advance planning. PXI is more rigid in form factor and constrained to programming via a local PC. But if the PC is connected to the company Ethernet network, the issues of network security still apply. Some security requirements may demand local data storage, making the platform decision straightforward for a user. For a flexible option, Pickering Interfaces offers an LXI interface for PXI.
How do you best select a test partner to work with?
There are a few key factors to consider when choosing a test partner to work with to ensure the longevity of your test system – look for a partner who is experienced, connected, has a long term obsolescence policy, and can support an application for its entire product lifecycle.
Pickering Interfaces has provided switching and simulation solutions for decades – with experience across industries and applications from aerospace to battery management to semiconductor test.
In addition to our tools (including the cable design tool, product selector and simulation tools that let engineers begin evaluating components today), we have a wide network of partners around the world who integrate our test hardware solutions with software.
Lastly, Pickering Interfaces commits to supporting its more than 2000 modules – if a part becomes obsolete, we can replace it with a modern one that accomplishes the same form, fit, and function. We also work with customers in the design phase if a specific module isn’t available to modify an existing one or create a new one to meet the demands of a test system.
Read more about how to effectively sustain your automated test system.
