There’s a lot of talk about automation these days, not just in manufacturing circles but also the news in general. As the demands of modern manufacturing grow more complex, and manufacturing industries continue their digital transformation—with automation playing an ever-expanding role—where does this leave traditional, manually operated metrology tools like portable measuring arms?

Because the right inspection method will always be based on the specific needs and context of the application, this article explores why portable arms, far from being obsolete, continue to be an essential part of the quality tool kit in advanced manufacturing environments throughout the value chain.

Automation = Quality at scale

Automation is an essential driver of quality in advanced manufacturing. Automated processes are crucial to a manufacturer’s ability to scale while boosting quality and efficiency; its numerous advantages are bringing it to the very center of manufacturing.

Automated systems

Automated systems require no human input during their measurement cycles, which makes them perfect for measuring “on-line,” right next to a production line that could be hazardous for people.

Automating quality inspection removes the potential for human error, especially in mundane, repetitive tasks, and those where an operation is attempting to increase output. It delivers consistency and reliability, enhancing overall quality.

Automated systems don’t get tired, so they can work as many hours as needed, guaranteeing maximum efficiency. They don’t require food, breaks, or even light to work.

Their throughput (parts measured per hour) could never be matched by even the most skilled manual operator.

They can be integrated in real time into the whole manufacturing system, so corrections can be implemented upstream at the first sign of “drift” in measurement results.

Continuing role for manual measurement

Against this incoming wave of increasingly automated metrology, what does the future look like for manually operated portable measuring arms?

In the rush to the new, it’s too easy to underestimate the continuing value of known, established tools. We perhaps sometimes forget that the best inspection method will always depend on the measurement application requirements.

It’s especially important to dispel the notion that because a portable measuring arm is a manual device, it therefore has little to offer in smart manufacturing environments.

It’s especially important to dispel the notion that because a portable measuring arm is a manual device, it therefore has little to offer in smart manufacturing environments.

Manual inspection need not mean unreliable, incomplete, siloed, or disconnected data. High-quality measurement data from portable arms can be harnessed throughout the manufacturing value chain to support quality and innovation in design, manufacturing, and inspection phases.

A long-standing example comes from the tube industry, where arms have been used for decades to check tube components, calculate any production errors, and send the necessary corrections back to the CNC bending machine that made them.

Not all measurements can or should be automated; certain tasks will always be best with manual inspections. Beyond inspecting high-volume batches of the same part coming down a production line, within industry there are plenty of other measurement applications where manual (and portable) metrology equipment still has a fundamental role to play. Obvious examples are one-off or unique parts, short runs, or custom components.

Design, analysis, and iteration

Long before parts reach mass production, they will have gone through design, analysis, and iteration phases that all require accurate 3D measurement.

But those phases require small quantities of parts to be made, and those parts could even be distributed across various locations and suppliers. Programming a robot or CMM to measure these parts would be slow and create a bottleneck. So would taking the parts to where the robots (or stationary CMMs) are installed. Portable instruments that can be taken to where the parts are—even if they’re with a supplier in a different city—offer an easier solution while staying affordable and maintaining accuracy.

Let’s take the common measurement application of inspecting a sheet-metal fixture. A portable arm or laser tracker is clearly a better fit than an industrial robot.

First, if you’re checking a fixture, you’re obviously in the development phase—not yet the manufacturing phase—of building a new product, so there will inherently be a lot of design iteration. You might measure that fixture and find issues with it that require adjustment. Once the fixture has been adjusted, it must be measured again to check whether the adjustments were correct and that no new problems have crept in during the interim. And so the process continues.

Having a manual instrument means you can go back even a day later and add data without any need for reprogramming the system.

Second, the beauty of manual metrology is that you can go back later and measure more if you need more information from the part. Perhaps you’ve sent a measurement report to the manager, who spotted something that wasn’t noticed on the shop floor. Having a manual instrument means you can go back even a day later and add data without any need for reprogramming the system. It’s totally intuitive—almost point and shoot.

Quality control shifts left

Using a portable arm in this way allows quality control to play a strong role during the development phases of a product, not just during manufacturing, as part of the accelerating “shift left” approach in manufacturing. Shift left emphasises detecting and resolving potential quality and manufacturability issues as early as possible in the product life cycle. Portable measuring arms and arm-mounted laser scanners will continue to play an indispensable role here, particularly in the early phases of developing a new product.

Metrology-informed simulation

One exciting and fruitful example of shift left is the integration of real-world measurements into digital design and simulation models that enable manufacturers to validate designs and improve production processes using virtual prototypes that more accurately predict and prevent quality issues.

Here, metrology data are imported to improve and validate process resimulations to accurately evaluate part design and the aggregate results of the manufacturing process to check their effect on quality.

This enables manufacturers to improve design for manufacturability and production processes, and to predict potential quality issues before physical manufacturing begins.

Notable current applications using portable arms and laser scanners are virtual fixture and virtual assembly solutions, where real-world scan data are used to morph CAD-based geometries to align with reality, and to get to the right fit and function faster in reality.

First article inspection

Another good example of portable manual equipment use is in FAI (first article inspection), which is a large part of Hexagon’s business globally, especially in industries that enforce rigorous standards, such as aerospace and automotive.

When a supplier delivers parts to a customer, FAI is required to certify that the parts are good so the supplier will get paid. The customer will randomly take one of those newly delivered parts to check against their CAD data. Programming a robot or CMM to do this would be wastefully time-consuming—a case of using a sledgehammer to crack a walnut. But with a portable measuring arm, that part can be scanned and analyzed in 20 minutes.

And more

Other examples where portable solutions excel include maintenance, repair, and overhaul (MRO) in the aerospace sector, where single existing working parts must be checked to ensure the aircraft is safe. Also, in reverse engineering, you’re perhaps making aftermarket parts for an existing vehicle, or replacement parts that are no longer in production for a jet engine.

Accuracy and consistency of portable measurement

In the era of smart manufacturing, data quality is crucial. It’s the foundation for effective quality management. The most vocal objection to manual measurement techniques is that they are prone to human error and can be inconsistent.

One vital requirement to establish data integrity is to ensure full adherence to recognized global industry standards. That’s why all Absolute Arm systems are ISO-certified (10360-8, 10360-12, 17025, and the optional 10360-2 for our smallest system), ensuring reliable, traceable accuracy that’s verified by certified artifacts.

Absolute Arm compact machine tool application. Image: Hexagon

More than this, to ensure data quality and enhance productivity, we’ve focused on simplifying complexity everywhere we can to reduce operator variability. Hexagon’s latest measuring arms and laser scanners have a host of features and capabilities that make precision measurement reliable and user friendly, regardless of an operator’s experience, so that they can just walk up, take the arm, and inspect the part. These include:
• IP54-rated protection against dust and fluids that ensures the arm is robust enough to work in harsh environments
• Precise measurements in temperatures from 5°C to 45°C
• Environmental sensors and collaborative feedback alert users to vibrations, displacement, and shifts in ambient temperature that could compromise measurements, enabling users to address instability without breaking their workflow, and consequently producing more dependable results
• A zero-G counterbalance makes the arm feel almost weightless during use, allowing operators to use the arm for longer periods while maintaining precision and ensuring reliable results
• SHINE technology in the Absolute Scanner series of laser scanners automatically optimizes settings for different surfaces, making high-precision measurements easier and more efficient

Absolute Arm with AS1 at work in a foundry. Image: Hexagon

Conclusion

The future of metrology in manufacturing isn't about choosing between automation and manual measurement. It’s about recognizing when each delivers optimal value. As manufacturing continues its digital transformation, the smartest environments are those that leverage the strengths of both.

Manual systems can’t match the productivity of automated systems in high-volume, repetitive production. But for anything outside that routine, automation can become challenging to manage.

Manual tools such as portable measuring arms bring flexibility and responsiveness that automated systems can’t match, especially during early-stage design validation, prototyping, and in situations requiring on-the-spot inspections or handling of unique, low-volume, or bespoke components.

Portable measuring arms and other advanced portable devices continue to evolve, effectively addressing concerns about accuracy and consistency through rigorous certification and user-centric innovation.

In an increasingly automated world, portable arms aren’t vestiges of a bygone era; rather, they remain indispensable assets in the push for smarter, more agile manufacturing. They ensure that quality remains achievable and cost-effective across every phase of manufacturing, proving that the human touch guided by precision technology still has an essential role to play.