Optimizing Manufacturing Test Stations

Your existing test station operates just fine but you’re thinking that maybe you can wring out a little more juice from all that hardware and software. Maybe you want to:

1. increase production volume
2. or make it easier for operators to use the station
3. or maybe you think you can contribute more value to your production line operations.

As part of an overall manufacturing test strategy, optimizing existing manufacturing test stations provides better manufacturing results without having to start from scratch.

Helping the operators use the test station

Many test stations need some interaction by a person (if your test station is fully automated, you can skip this section).

One optimization goal is aimed at reducing the effort by an operator to perform a test. Optimizations can include:

• Switching the order of the tests to increase the operator’s efficiency.
• Adding some incremental hardware to automate one or more steps.
• Replacing the computer monitor with a larger screen to ease eye strain during tests that use visual feedback on the monitor.
• Reworking the display to make things easier to read.
• Reorganizing the test station layout to simplify access to any tools and/or parts used during assembly, the mouse and/or keyboard, or other components.

Of course you should also ask your operator for suggestions since they likely would know best.

Another useful optimization is including or enhancing electronic information about the test procedure. For example:

• If your test procedure is written on paper, convert to electronic work instruction documentation. Electronic work instructions can be presented automatically to the operator step by step.
• Consider having two modes for electronic work instructions: one for a beginner and one for an expert. The beginner mode could include more explanatory detail, possibly via videos or images with annotations.
• If your test station is using a test executive, consider measuring the amount of time each step takes for each operator. With this timing information, step-focused training opportunities are found, where the most effective operator(s) can help collaborate with those struggling with one or more steps.

Software version upgrades

Over time the application software running on the test station falls behind the latest available versions. This could be the test app software itself, i.e., the test executive and/or test steps, or the OS upon which they run.

Keeping up with versions should be considered a part of a tech refresh plan, mainly because delaying will eventually result in a painful leap. By waiting a long time before addressing an upgrade, the upgrade path might need to be multi-step from the version you are using now to an intermediate version (or several versions) to the latest version. Making a single large leap can require application rewriting or incorporating new hardware driver because the OS no longer supports the original device driver model.

Of course, doing an incremental upgrade also addresses hardware obsolescence issues proactively rather than having to find spare parts on eBay under pressure when a piece of hardware fails.

These optimization recommendations are not the same as a full-on obsolescence upgrade. Instead consider these recommendations like replacing your HVAC filters. The system runs better afterwards. In contrast, forgetting to change those filters will eventually result in failure of one or more subcomponents. If you’re interested in addressing obsolescence, here’s a tech refresh plan checklist.

Incremental upgrades can help improve manufacturing test stations in the following ways:

• OS robustness increases with OS updates (usually).
• Cyber security improves with OS updates (certainly).
• Connectivity options increase with OS updates (what’s going to come after Bluetooth and Wi-Fi?).
• Support for latest measurement HW alleviates worries about unavailable components.
• Adding new features to the test app is often easier.

Increasing automation

Even with some minor changes in equipment and parts handling, a test stand can be further automated. Here are a few ideas:

• Replace old meters and instruments with new automatable versions. Rather than have the operators transcribe measurements from a device’s display, modify either the test executive or the test step software to read the value automatically.
• Update data analysis. People often underestimate the time wasted in creating reports for internal use or for review by their customers. Automating the report generation step can shorten hours (or even days!) of work into seconds. This optimization often pays for itself in less than a month.
• Part handling with a robot or cobot (collaborative robot). Consider using a robot or cobot to help load or unload a part into the test station or interact with it during a test. This hand-freeing method gives more time to the operator to perform important tasks in parallel with the robot/cobot.

Test parallelization

If your test system is being used 100% of available time, you can increase production volume by making the test station an N-up tester (as opposed to building a duplicate test station), able to test N parts in parallel (or at least partly parallel).

Pure duplication of the test station is straightforward (but maybe nontrivial) but it has the added burden of consuming at least twice the manufacturing floor space and doubling the cost to build another station.

Instead, consider converting your existing test station to an N-up tester by adding just enough additional hardware coupled with modified test executive software to enable reuse of existing hardware for testing more parts.

For example, consider the time saved in part testing if, while one unit is being tested, the operator is unloading the previous UUT and loading the next UUT. The test station equipment has a bunch of switches that ping-pongs the test hardware first to one UUT “part nest” and then a second. Production line volume increases because the operator’s time spent with part handling is being optimized. See Improving Manufacturing Test Stations to Support Production Volume Demand Increases for details.

Manufacturing 4.0 integration

Manufacturing 4.0 (which is akin to Industry 4.0) initiatives have driven many companies to wrap digital methodologies around their processes and procedures. In the production test domain, M4.0 is driving some manufacturers to augment their monitoring of manufacturing operations with data from test results produced by the test system. Operational information from the assembly and test steps reveals insights like:

• The most prevalent out-of-tolerance features
• Which operators that are most efficient in both quality and timing
• Which test steps takes the most time
• The models that have the most failures

Once these operational test results are aggregated, analyzed, and ranked, across part models, operators, test stations, and so on, manufacturing and design engineers find clarity on which problems to tackle first to bring the largest benefit to production quality and cost. See here for more detail.

Practical tips to optimize your manufacturing production processes

Consider deployment tools

If you’ve got duplicate test stations, consider ways to deploy test sequence or test app upgrades via a deployment tool such as the NI TestStand Deployment tool, NI SystemLink, tools from GitHub, or create your own. Also consider ways to make one test station run tests in parallel, say while the operator is in an unload/load cycle.

Use databases and develop reports

Save test data into a searchable datastore, such as a SQL database like Microsoft SQL Server (or the free “Express” version), MySQL, or perhaps a non-relational database like Mongo.

Develop reports by scanning these datasets to look for information on each assembly and test execution that shows the test step with the most failures for each test sequence, the sequences with largest and smallest execution time variability, and the test results that correlate with product warranty returns.

Pull in other departments / teams

Engage test developers, product design engineers, and product managers in discussions regarding testing of any new product. Develop a test plan that offers enough coverage and is cost-effective. This team should comprise one from each role regardless of the people being internal or external to the manufacturer.

Similarly, for test station upgrades or obsolescence replacements, involve at least the test developers and the product managers for that test plan creation. Design engineers will have insight to any potential design changes to be aware of since the test system will often still be in use when a new design appears.

Start monitoring the test stations

Add monitoring sensors and usage metrics to the test station to help manage system maintenance. Be cognizant of ROI. Typical usages are to monitor the equipment used on the test station such as motors, pumps, filters, or other equipment where their failure halts production or reduced product quality.

Run failure analyses

Run an analysis of failures to decide where upstream corrections to process or materials can effectively increase quality and reduce waste. A common example happens when a subassembly or part within the assembly has been sourced from a different vendor, where that item does not perform as well as before the switch. Another example might be a new operator building and testing the subassembly being rolled up at the test station showing the increased faults.

Additional product testing strategy insights

Check out Hardware Product Testing Strategy – for complex or mission-critical parts & systems for more product testing strategy insights.

Next Steps

Which optimizations are best for you? And in which order should you implement?

Take some time to think about the benefit of each potential optimization, whether cost reduction, increased production capacity, higher first pass yield, or something else, and balance that benefit against the cost and time to implement.

Follow that optimization with the next best optimization. And revisit these recommendations every couple of years to continue to improve.

If you’d like help optimizing your test station or discussing options, feel free to reach out.