The mobility transition begins in manufacturing

Sustainable mobility does not begin on the road, but right from the manufacturing stage. Electric motors, connectors, fuel injection systems, fuel cells and battery cells can only operate efficiently and safely in the long term if the relevant geometries are rigidly controlled. Any deviation detected at an early stage prevents rejects, rework and unsafe process conditions. Metrology thus makes a direct contribution to the conservation of resources, a long service life and reliable operation. This article uses five applications to demonstrate how coordinate measuring machines from Werth Messtechnik, utilising optics, probes, computed tomography and multi-sensor systems, combine short measurement times, high resolution, high accuracy and system availability.

Four requirements, one common sample

Thin electrical steel sheets, delicate contacts, internal nozzle geometries, large-area embossed plates and safety-critical cells differ considerably in terms of material, geometry and production volume. Nevertheless, the requirements for metrology follow a common pattern. Short measurement times ensure the throughput of series production; high resolution makes fine structures and incipient defects visible; high accuracy maintains the usable manufacturing tolerance; and readily available systems prevent downtime close to production. With regard to accuracy, the rule of thumb known from test process suitability applies: the measurement uncertainty should be a factor of 10 smaller than the tolerance. The greater the measurement uncertainty, the narrower the usable manufacturing tolerance becomes and the more workpieces that are close to the limits must be discarded according to the decision rules of ISO 14253-1 as a precautionary measure. More accurate measuring machines, on the other hand, preserve the manufacturing tolerance, as the tolerance band remains available to the production machinery and is not eroded by metrology. They thus reduce scrap and inspection costs, even if they are more expensive to purchase. However, the greatest reduction in costs comes from rigid, controlled processes. Those who recognise trends before workpieces fall outside the tolerance range reduce scrap and rework at source.

Rotor and stator laminations for electric motors

High production volumes for rotor and stator laminations involve delicate, thin workpieces. An electrical lamination for traction motors is typically only 0.2 mm to 0.35 mm thick, and the trend towards thinner laminations reduces eddy current losses and increases efficiency. Burrs on the punched edges are more than just a cosmetic issue. They can penetrate the insulating coating of adjacent laminations and cause layer short-circuits, leading to overheating and a loss of efficiency. At the same time, burr formation is an early indicator of wear on the punching tool. By monitoring trends in this regard, tools can be maintained on a condition-based basis rather than rigidly according to fixed intervals. Many recurring geometries need to be tested within a short timeframe, and because probing forces can cause deformation of the thin sheets, webs, burrs, flatness and warpage must be captured non-contact and at high resolution. The ScopeCheck® FB DZ coordinate measuring machine from Werth Messtechnik is designed for this type of series inspection using HD raster scanning. With raster scanning, the image-processing sensor captures the workpiece during axial movement in many overlapping single images, which are combined to form an overall image with up to 20,000 megapixels. This method is available across the range, from the highly accurate VideoCheck® series to the production-oriented ScopeCheck® machines. This allows the entire sheet metal part to be captured without re-clamping, and process variations become apparent at an early stage, before they cause scrap or unstable downstream processes.

Connectors and fine pin geometries

Connectors represent a typical inspection task in the field of electrification. With 800 V on-board electrical systems, charging infrastructure and an increasing number of sensors, the number of contacts per vehicle is rising, as are the demands placed on each individual contact. Deviations in pin position increase insertion forces and contact resistance, which can lead to unacceptable heating in high-voltage connectors and, in the case of signal contacts, to failures in driver assistance and charging functions. Structural resolutions of 20 µm or better are required for the fine pin geometries. HD raster scanning captures large workpieces with numerous features in seconds and is 50 times faster than conventional image processing. Many contacts are also overmoulded or, once assembled, no longer accessible from the outside. This is where Werth’s computed tomography provides a non-destructive view of the entire workpiece volume. To achieve this, the workpiece is irradiated with X-rays from multiple orientations whilst mounted on a rotary table, and the software reconstructs a three-dimensional volume model from the projections, incorporating all external and internal geometries. Werth’s TomoScope® machines measure 10 times faster than comparable CT systems. The WinWerth® software visualises results such as pin positions or installation orientations in a way that allows them to be used directly for process control.

Injection nozzles for petrol, diesel and hydrogen

Injection nozzles remain relevant for various propulsion concepts, ranging from optimised internal combustion engines to hydrogen propulsion. The critical features are often found on the inside. The orifice diameters of modern injectors are often just 100 µm to 200 µm, and the mold and edge rounding of the bores determine the spray pattern, fuel consumption and emissions – factors that are becoming increasingly important as exhaust emission standards become stricter. In hydrogen propulsion, leak-tightness and new material combinations are additional considerations, as the dry gas, unlike liquid fuels, does not act as a lubricant. Burrs and tolerances in the range of a few micrometres are decisive for flow rate and long-term durability. A purely external inspection is not sufficient for this. Werth’s computed tomography captures external and internal geometries – such as blind holes and needle seats – non-destructively and in their entirety. Burrs are not only detected, but also measured and objectively assessed. For particularly small, highly accurate tactile measurement tasks, including Roughness, the Werth Fiber Probe® WFP complements the range. This micro-probe, which has been established for around 30 years and features a 20 µm ball, operates with low probing forces and can access features that are virtually inaccessible to conventional styluses.

Bipolar plates for fuel cells

Fuel cells convert hydrogen and oxygen directly into electrical energy, with water as the sole reaction product. Bipolar plates are key functional components in this process. They separate the individual cells of the stack from one another, distribute the gases evenly across the active surface via fine channel structures, conduct the electrical current from cell to cell and dissipate the reaction heat via cooling ducts. For metrology, this involves the surface inspection of large, finely structured workpieces. Metallic bipolar plates are embossed or hydroformed from foils, some of which are less than 0.1 mm thick. The channel structures are measured to just a few hundred micrometres. As a stack consists of several hundred plates, flatness and thickness deviations accumulate across the stack and affect contact pressure, contact resistance and hydrogen tightness. Embossing depths, sealing surfaces and tool misalignment also have a direct impact on function and reliability. At the same time, the measurement must not mechanically affect the sensitive surfaces. Werth’s multi-sensor systems combine fast optical methods with non-contact distance sensors for this purpose. Raster Scanning HD tests the large plate surfaces in a short time, whilst the highly accurate Werth CFP (Chromatic Focus Point) chromatic distance sensor measures embossing depths, flatness and warpage without causing any mechanical disturbance. With the infinitely adjustable WRT rotary/tilt head, it can be aligned perpendicular to inclined surfaces. This helps to speed up series production approvals, reduce scrap rates and obtain process data for mold corrections and rigid production windows, particularly during the start-up of series production when stamping dies are corrected iteratively.

Battery cells and 100% inspection

The requirements are most concentrated in the case of battery cells. Terminals, overhangs, jelly-roll geometry, delaminations and particles must be tested within seconds and at high resolution. The anode overhang is a safety-critical size in this context. If the anode does not reliably protrude beyond the cathode, there is a risk of lithium plating, leading to a loss of capacity and the danger of a short circuit. Metallic particles and delamination inside the cell can trigger internal short circuits, potentially leading to thermal runaway. According to assembly, computed tomography is the only method that can visualise and perform non-destructive measurement of such internal features. 100% inspection thus becomes a key aspect of the manufacturing process. Werth TomoScope® systems, featuring the Werth HighResLonglife X-ray source and AI-supported automatic defect detection, are designed to tackle this challenge. Defects as small as a few micrometres are detected up to 35 times faster and on a quarter of the footprint of solutions with comparable levels of comparability. The high-resolution Werth X-ray sources, operating at 130 kV to 230 kV, enable measurements five times faster than conventional reflection sources whilst maintaining the same resolution. Their twelve-month maintenance cycle coincides with regular equipment maintenance. The parallel operation of two machines in a test station halves the cycle time – for example, from 30 seconds to 15 seconds – whilst also providing redundancy in the event of maintenance or malfunctions. Further regulatory impetus is provided by the EU Battery Regulation (EU 2023/1542), which requires comprehensive documentation and traceability through the battery passport and CO₂ footprint declaration.

Traceable measurement, capable testing

Across all applications, the automotive industry requires, according to IATF 16949, verifiably suitable testing processes, the suitability of which is usually assessed according to VDA Volume 5. Coordinate measuring machines with computed tomography are specified and approved according to VDI 2617 Part 13 and ISO 10360 Part 11. In addition, Werth offers CT coordinate measuring machines calibrated according to the specifications of the German Accreditation Body (DAkkS), which has been mandatory in the automotive industry for several years. Traceable measurement across the entire workpiece volume is thus based on the same standards as traditional tactile and optical coordinate metrology.

Controlled processes as a shared benefit

The examples show that sustainable mobility does not require an individual measurement technology, but rather the right combination of sensors, speed, evaluation and availability. Optics, probes, computed tomography and multi-sensor systems complement one another when external contours, internal geometries, micro-structures and sensitive surfaces need to be assessed close to the production line. For those responsible for manufacturing, however, there is more at stake than mere precision in the laboratory. What is crucial is reliable approval, reduced scrap rates, available systems and measured data that contribute directly to process control. Metrology thus becomes a building block of economical, safe and resource-efficient manufacturing, and therefore a cornerstone of the mobility transformation.