Astemo has installed the principal manufacturing equipment for its £100 million electric vehicle inverter expansion in Bolton, keeping the project on course for volume production to begin in April 2027.
Two production lines are being developed at the company’s Horwich site, with one handling the main inverter assembly process and the other incorporating surface mount technology for printed circuit boards used within the power electronics system. The first line has been commissioned and has already completed initial pre-production builds for the customer vehicle programme.
More than 80% of the wider redevelopment has now been completed, including the installation of a controlled cleanroom environment across a substantial part of the manufacturing floor. Once both lines reach planned output, the Bolton plant is expected to have annual capacity for more than one million inverters.
The investment is expected to create 125 positions and protect around 100 existing roles, strengthening a site that already supports automotive electronics and powertrain production. Rather than adding a conventional mechanical component line, the project introduces a manufacturing system in which semiconductor handling, printed circuit board assembly, thermal management, software configuration, and electrical testing must operate together.
Inverters convert direct current from an electric vehicle’s traction battery into alternating current for the motor, while also controlling speed, torque, regenerative braking, and energy flow. Their performance affects vehicle efficiency, thermal loading, range, acceleration, and long-term powertrain reliability.
Producing them at automotive scale requires more than assembling enclosed electronic units. Surface mount production must control component storage, solder paste deposition, placement accuracy, reflow profiles, automated optical inspection, traceability, and the handling of moisture-sensitive parts whose commercial lifecycles may be shorter than the vehicles they support.
Power semiconductor modules and control electronics must then be integrated with cooling systems, busbars, connectors, housings, insulation, and embedded software. Each stage introduces opportunities for faults that may not become visible until the completed inverter is operated under high voltage, temperature, and load.
Automotive qualification therefore places heavy emphasis on repeatable process data. Equipment settings, component lots, inspection results, torque values, firmware versions, and end-of-line test records must be associated with individual assemblies and retained throughout the product lifecycle.
That traceability becomes especially important when a failure appears after vehicles have entered service. Investigators must be able to distinguish an isolated component defect from a process drift, material issue, software problem, or wider design weakness without recalling unaffected production.
The Bolton expansion also creates a domestic manufacturing route for a component category that has often been imported as British vehicle plants have moved from combustion powertrains towards battery electric and hybrid platforms. Local production can shorten the feedback loop between component engineers and vehicle manufacturers during launch, validation, and later design changes.
Although the UK automotive sector continues to contend with uneven production volumes, capital spending is increasingly concentrated around electrification, energy systems, software, and advanced electronics. Vehicle and component manufacturers must commit to new processes before demand has fully stabilised, while simultaneously managing the declining volumes and fixed costs attached to established combustion programmes.
Factory investment is extending beyond the production line itself. Higher renewable electricity generation across UK automotive plants is accompanying changes to plant energy systems, process efficiency, carbon reporting, and resilience against volatile electricity prices.
Astemo’s manufacturing ramp will now depend on converting installed equipment into a stable serial process. Pre-production builds allow engineers to test tooling, cycle times, material flow, quality controls, operator routines, and software integration before customer volumes increase.
Problems found during this stage can still be corrected without disrupting full-rate production, but the available time narrows as vehicle launch dates approach. Supplier approvals, production part approval processes, capability studies, and durability evidence must all be completed while equipment and workforce performance continue to mature.
The cleanroom and surface mount line will require disciplined material control, particularly where semiconductor allocation, electronic component obsolescence, and supplier changes affect approved bill-of-material configurations. A replacement component may be electrically similar while still requiring renewed software, thermal, electromagnetic compatibility, or reliability assessment.
Capacity exceeding one million units gives Bolton sufficient scale to support a major vehicle programme, although utilisation will ultimately follow customer schedules and the pace of electric vehicle demand. Automotive suppliers have to install enough capacity to meet launch forecasts without allowing fixed costs to overwhelm margins when model volumes move more slowly than expected.
By April 2027, the plant must demonstrate that its electronics, mechanical assembly, software, inspection, and testing systems can deliver as a single automotive process. The equipment is largely in place; the remaining work lies in proving consistent output, controlled quality, and the cost discipline required for sustained series production.
