Customising electric power steering (EPS) systems to meet OEM requirements

　　According to chief product engineer Europe, Paul Poirel, the technology that EPS systems feature has implications not just for their own manufacture but also for the assembly operations carried out at the OEM's plant. He points out that EPS exists in three basic formats depending on where the essential EPS hardware is located. These are:

　　• Column assist where the EPS functionality is located high up the steering column just behind the dashboard within the passenger compartment

　　• Pinion assist where the hardware is positioned on the steering gear pinion shaft, an arrangement that can offer OEMs enhanced packaging flexibility

　　• Rack assist where the location is even lower down to enable the handling of higher front axles loads

　　Poirel explains that in terms of output capability column and pinion systems are more or less equivalent. Another difference between these and a rack system, he notes, is that the column and pinion systems involve a metal to plastic contact for transmitting the essential guidance from the steering wheel to the system whereas in the rack system it is metal-to-metal contact. In use that tends to mean that a rack system would be most appropriate in more powerful, heavier, higher-end vehicle applications; upmarket SUVs being a good example.

The company’s products are manufactured to the specific requirements of an individual OEM

　　Meeting specific demands

　　In the case of Nexteer's own product development operations, Poirel says that what the company regards as core engineering (which “defines the building blocks”) takes place in the US, but applications engineering in which those ‘blocks’ are combined to meet the specifications of a particular OEM, is more distributed.

　　The company's products, Poirel emphasises, are specific to the demands of an individual OEM – or at least they are in mature markets such as Europe and the US. Elsewhere (he mentions China as an example) some OEMs may invert that situation and look to fit an existing product to a new vehicle. “They do sometimes ask 'have you got a product for us',” he confirms.

　　In the majority of the company's markets customisation, as Poirel confirms, takes place at the level of individual vehicle models. Indeed the relative ease with which it is possible to customise the company's products to meet specific OEM requirements is one of their key attributes.

　　Assembly benefits for OEMs

　　But, as Poirel explains, this is where the assembly implications for the OEMs start to kick in. For a start it provides the vehicle manufacturers with the opportunity to standardise elements of the steering systems involved across different vehicle models. Electrical and mechanical interfaces are the first examples he cites. Nevertheless it is, he cautions, “impossible to configure a single system that will fit any vehicle.”

　　There are further benefits when it comes to the actual fitting of EPS systems into vehicle assemblies. Irrespective of the particular product configuration involved there will, he says, be “just a few mounting points with fasteners.” In addition there will be a requirement for “just one electrical connection” for the power required to drive the system and one for communications, though it is sometimes possible to combine the two.

The company says it has to ensure that the functionality of each control unit is proven

　　The benefits that capability brings are brought into sharp relief when the assembly procedures involved are compared with those required by hydraulic steering systems. According to Poirel that can often mean draining fluid that has previously been used to fill the hydraulic system and then carrying out a refilling exercise – a set of operations that can require a sequence of “several stations”. A purely hydraulic system, he adds, will also require the installation of additional components such as pumps, drive pulleys, mounting brackets, etc.

　　As for the company's own assembly operations those at Tychy involve a mix of mainly manual assembly procedures with an emphasis on highly automated test routines. Ensuring the functionality of the electronic systems is fundamental to the capability of the complete system. As Poirel puts it the company has to ensure that each control unit is proven “before we tighten the screws on the cover.”

　　Close inspection

　　For example all soldered joints on printed circuit boards are subjected to an automated visual test routine in an in-line 'dark chamber'. In addition, the company also has a number of specially trained staff who are certified competent to carry out visual inspections of such joints and if necessary to overrule the automated system. Their skills are particularly vital, Poirel adds, at the final stage where the control unit is mated with its associated sensors.

　　At a more strategic level the company tries to ensure that both shopfloor equipment and procedures are, as far as possible, identical across all its plants worldwide. Appropriate quality metrics are then gathered and subjected to a global comparative analysis on a monthly basis.

　　A flexible approach

　　So how are the company's manufacturing operations likely to develop from here?

　　That is one of the issues that concern Guilherme Pizzato, regional director Europe for the company and also director for global supply management. Pizzato says that a starting point is recognising just what are the company's necessary core competences. On that count he focuses on “our ability to develop our own electronic architectures.” The company has extensive software and hardware capabilities, he says, and the combination is vital to ensuring it has the “flexibility” to meet changing customer demands.

　　Most of the relevant work is carried out in the US, he confirms, but can be devolved regionally if need be. That is the case, for instance, for a column EPS system with a brush rather than brushless motor that the company has developed for the Chinese market. Pizzato explains that the brush format is less sophisticated but also less expensive than its brushless counterpart and has been developed specifically to meet a market requirement. “It meets a demand and is acceptable to the customer,” he observes.

　　Pizzato concedes that in automotive industry terms EPS systems are still a relatively new type of product though he adds that even though Nexteer only began to make them 16 years ago it already regards itself as making their “fourth generation”. As far as the company's own manufacturing procedures are concerned he says that one of its most important features – the generally high level of inspection in involved – will continue to be the case.

　　Nevertheless Pizzato does not believe there is anything intrinsic to the manufacturing of EPS systems that has a particular need to be inspection-intensive. Instead he says that, as with any other manufacturing operation, the company does not want to pass faults up the line and that in common with general industry practice, inspection levels will tend to be more extensive for newer products with a gradual reduction following on as the procedures involved become more established. He points out that operations at Tychy currently include the production of a latest generation product for a premium segment German car maker and so involve more inspection than might otherwise be the case.

　　Training and continuous improvement

　　Nexteer also brings its own twist to another common industry practice – that of continuous improvement to achieve 'lean' manufacturing procedures. In this instance the company allows a number selected employees to receive tuition, training and general experience elsewhere. In addition to on-site activities a small number – two to three at a time – will be released for a 12-month period to undergo further development at company facilities in the US. Pizzato says that the individuals concerned will have been identified as “high-potential” and might typically be “senior engineers” or “supervisors with ambitions to take up management positions.”

　　At a more strategic level the company tries to ensure that both shopfloor equipment and procedures are identical across all its plants worldwide

　　Pizzato says that while there is obviously “always room for further improvement” he is still generally satisfied with the company's levels of lean manufacturing efficiency. “I think we are doing very well,” he confirms. Some confirmation of his assessment is provided, for instance, by the fact that recent OEM acknowledgements include a 2014 GM Europe SQ Excellence Award for Gliwice and a 2015 PSA Best Plant Award for Tychy.

　　Integrating suppliers

　　As a Tier 1 supplier Nexteer obviously forms the focal point for its own logistical chain of Tier 2 companies. Pizzato says that in general terms the company plans supply activities at a global level though there are separate teams for operations in Europe, North America and China. So there is a tendency for the same suppliers to be used at different plants across the world. There may also be some use of purely local suppliers on a plant-by-plant basis. The ideal would be a facility operated by a global Tier 2 company that was relatively local to the relevant Nexteer facility. Around 150 component suppliers serve the Tychy plant.

　　For the future, Pizzato adds, Nexteer is looking to “integrate some of our particularly key suppliers more closely into our development processes.” He mentions electronic components, electric motors and castings as amongst the areas the company is targeting. That is, he explains, very much what the company's own customers are doing with Nexteer, so in that sense the objective is simply to pass the benefits of such close inter-company working further down the logistical chain.

　　The main advantage, Pizzato observes, would be that of having “more time” to develop optimal solutions. That would be particularly beneficial, he explains, since there is no foreseeable prospect of any significant reduction in the requirement for EPS systems to be developed for specific vehicles; they are not going to become standardised products.

Nexteer’s assembly operations at Tychy involve a mix of manual assembly procedures and automated test routines

　　Rapid market growth

　　The attractiveness of EPS systems to OEMs is reflected in the rapid advance of EPS into the mainstream market, with this technology is expected to take a 90% share of the European car, pick-up and LCV markets in the next five years. As for those areas where EPS has yet to make in-roads Poirel indicates that there is probably a performance extreme involving very large vehicles where the technology is unlikely to make much impression in the immediate future.

　　He also says that it has probably not yet made as great an impression as it might in the light commercial vehicle field simply because the long lifespan of such vehicles means that there are still a large number on the roads whose origins pre-date the widespread adoption of the technology. Intriguingly, though, Poirel adds that he expects that situation to begin to change quite markedly before the present decade is over.

　　EPS systems themselves, he says, will continue to develop and he highlights increased energy efficiency – in basic terms drawing less power from the vehicle's battery to achieve equal or even enhanced performance – as a major target for Nexteer.

　　About Nexteer

　　Since 1999 the company has made 30m electric power steering systems and now employs 11,000 people worldwide in their manufacture at sites in Europe, the US, China, Mexico and Brazil. The company has two manufacturing sites in the south west of Poland at Tychy and Gliwice employing around 850 and 350 people respectively. The plants have received €80m investment since 2010.