The latest part of Delphi to be sold to a private firm was its Ride Dynamics and Brakes unit, which has become Beijing West Industries (BWI) Group.
Under GM, Delphi was of the world’s largest automotive part manufacturers. After being made a fully-independent company in 1999, the company faced an uncertain future, leading to a filing for Chapter 11 bankruptcy protection in 2005. In an effort to cut costs and refocus on core activities, a series of plant closures followed; in 2006, Delphi closed 21 of its 29 remaining US plants. As part of this restructuring, various non-core parts production businesses were sold off, including battery production (sold to Johnson Controls, 2006), brake hoses (Harco Manufacturing, 2007), and wheel bearings (Kyklos, 2008). These were followed with the March 2009 announcement that the Ride Dynamics and Brakes unit would be sold to China’s BWI Group.
BWI Group is made up of three separate investment entities; Shougang Corporation (51%), Beijing’s Fangshan District (25%) and Bao’an Investment Development (24%). Shougang, one of China’s largest steel producers, is said to view the purchase as route to product diversification, while retaining steel production as its core business. Bao’an Investment is held by Tempo Group, a company which has been providing after-market parts in the US for over a decade.
While Delphi had almost exclusively supplied GM, BWI Group has no such ties to a parent company. Tim Schlangen, MR Mounts Engineering Manager, sees the sale, finalized in November 2009, as an opportunity to market former Delphi products to carmakers of any size and in any region. Of particular interest will be BWI’s magneto rheological (MR) engine mounts, the latest addition to the company’s range of premium car parts that will first feature on the Porsche 911 GT3.
Although there are a range of powertrain mounts, Schlangen says the new product is specifically designed for use as an engine mount: “There could be up to five different types of (powertrain) mounts depending on what type of vehicle it is, the setup, but the ones we are producing now are for the motor.” Delphi was one of the first companies to address the problem of engine mount optimization, and was the first to introduce glycol-filled mounts that could be tuned to control one main vibration frequency. The latest MR mounts have almost completely eliminated the need to compromise mount behaviour, in allowing mount stiffness to be tuned to control powertrain frequencies in real time.
The key element to the MR mounts is the MR fluid. Iron particles suspended in a base liquid are located within a sealed cavity in the rubber body of the mount. When a magnetic field is applied by a coil, the particles become aligned, increasing the sheer stress and resistance to flow. The stronger the magnetic field, the higher the dynamic rate (or stiffness). Further to this, closed loop feedback provides direct measurement of the fluid pressure, ensuring real-time compensation for changing conditions and as the components age. According to Alan Lee, Director of Sales, Marketing and Planning at BWI, the importance of the technology represented by the fluid cannot be understated. “The fluid and its properties, that’s one of the key intellectual property assets that has been developed by BWI.”
Schlangen says that the fluid in the MR mounts has been researched intensively over the past six years, chiefly to ensure that there is a minimal amount of fluid breakdown. “We have virtually eliminated the properties that would cause this to happen, and with the software, if you do something that has changed, you can change the current level and get back to where you need to be.
“We test fluids and compounds offline to make sure they meet performance specification, because once they have been built up, there’s a lot of value in the end part. We try to get stations involved in testing those parts and then we have testing as a sub-assembly, the bottom can (which is a diecast part) and the stamped top part, we crimp that, then run it through our performance sector to make sure it meets customer specification for the specific vehicle.”
Benefits represented by the MR mounts go far beyond that of the standard equivalent, according to Schlangen: “There are two types of passive mounts. A conventional mount uses a metal bracket and a piece of rubber, while a hydraulic mount has fluid in it, in a track, with a rubber main spring. These can be tuned to a vehicle. Then there are active mounts, MR mounts, that we control with the changing of the sheer strength of the fluid, driving the rubber main spring.”
Schlangen continues: “About 1,000 times per second, the system looks at what the vehicle body is doing in terms of roll and pitch, what the wheel is doing, throttle position, brake, gear selection, together with internal and external temperatures. From this data, we can determine what the vehicle is going through, millisecond by millisecond, and calculate precisely what needs to be done using the onboard CPU.”
The rubber main spring is also a critical element to the MR engine mount. Of particular importance is the material’s durability and how it interacts with the fluid. Schlangen says that the on-site lab at the company’s Dayton, Ohio headquarters has carried out extensive research into rubber compounding and formulation, ultimately delivering the best rubber material for the control and isolation of powertrain vibration. A further two suppliers are being used to develop new, ‘outside the box’ formulations. Benefits of the MR mounts include improvements in powertrain isolation, vehicle stability and traction. While sound and vibration can be reduced, the mounts offer brand-specific tuning, with the opportunity to incorporate driver-initiated settings, linked to other active systems such as dampers and a sports exhaust system.
Variations on a theme
Schlangen points out that owing to the variety of engines and powertrain combinations, no two mounts are the same, which leads to individual development costs for each application – costs generally assumed by BWI. “As you change engines and powertrains, they fit into a completely different space. So if I have two different powertrains on the same vehicle, the chassis is probably the same, but the engine side is probably not. So I have a lot of part pieces to make the same base component. Then my end of test changes because the engine specs would be different.”
Carmakers also have difficulties in outlining part specification at the development stage. “(Part) specifications are tough to write, because car manufacturers are not exactly sure what to ask. We keep running into the same situation, where they say ‘We know what that does’, then they put it on the vehicle and realize they have no idea how to specify what you’re able to do.” In order to solve such problems, BWI can take the vehicle in-house to develop a mount solution. This can take place at the Dayton HQ, or at either of the company’s technical centres in France or Poland.
When it comes to part installation, Schlangen says the mounts must be applied on the chassis (a process known as ‘decking’) in preparation for marriage of the powertrain and body. Beyond managing engine vibration, the mounts must also be able to handle the stress of being the point at which the body and powertrain meet. In a sense, the mounts serve the same purpose as cartilage in a human joint.
The magneto rheological development featured in BWI’s engine mounts has also been used in its range of shock absorbers, this in addition to the existing air-levelling shocks and the range of MagnaRide shocks and struts that will feature in the new Ferrari 458 Italia. Tim Schlangen is adamant that replacing standard springs with such technology is not simply reinventing the wheel. “From a damper control standpoint, the difference between an MR shock and a passive shock is astounding. The MR fluid allows us to draw force velocity curves that we just could not do with passive mounts. When (sufficient) pressure is put on any given corner of the car, a spring would not be able to handle the forces involved, there the MR system could easily do this.”
In operation, the stiffness of the dampers is altered by varying the strength of the electric current passing through the liquid; the fluid rearranging itself to stiffen or relax the level of body control. “The current actually changes the effective viscosity of the liquid,” says Schlangen. “We use a DC current measuring between five and 25V. It’s a low-level current, not like a starter.”
In addition to engine mounts and shock absorbers, BWI also produces braking systems for a variety of carmakers. In China alone, the company supplies both national and transplant companies including BYD and GM. Within brakes, there are two well-defined areas of technology, foundation braking systems, which includes production of rotors, callipers, boosters and master cylinders, together with control systems, which covers development and implementation of ABS and electronic stability control systems.
Alan Lee explains that the vast majority of rotors are cast, then finished in a post-cast machining process. “The rotors have to have specific diameters and surface finishes. They also have to be very well balanced or you will feel that throughout the vehicle - even our fine suspension parts will not stop that type of vibration!”
Other cast components used by BWI in its braking systems include the callipers, master cylinder and ABS body – the latter may also be made from aluminium in an extrusion process, this in an effort to reduce overall weight. To provide consistent, reliable braking, cooling of the brake discs is vital. Schlangen says that there are various methods that can be used to keep rotors in peak condition, even under heavy use. “Rotors use some quite complex geometries to assist in cooling. While the rear brakes might be solid (steel), the front rotors will probably be veined, and some of the veined systems are quite complex.” Techniques used to cool rotors can vary, with some companies using veined or crossed rotors, while another technique use body geometry to provide a constant flow of air to the rotor. Says Lee: “Combine the two areas and we can deliver the whole corner unit. Bearing, brake, calliper, damper and spring or strut. Between the two areas, we’re capable of engineering and providing the complete unit.”
In light of this option, how do manufacturers prefer to receive the components, as individual parts or as a completed module? Schlangen: “I think that depends on how a company partitions the work. In areas where labour is more expensive, companies prefer us to supply the subassemblies. In places like China, where labour is relatively inexpensive, they are just as happy to put separate parts together inside the production plant.”
Test for success
This has implications for safety and testing, as Lee explains. “From our standpoint, what we like about delivering modules is that we have complete control over the output of that part. It’s no longer a case of ‘how did it get bolted together’ or ‘does this line up’. When delivering modules we can address any problems in-house, so we do like it for those reasons.
Lee goes on to explain that in the case of ‘pulsation’ braking systems, such as those that feature ABS, it is critical that tolerances are maintained. Like the full corner module, if BWI is producing and assembling the parts, the company can guarantee the tolerances, which is virtually impossible to do if separate companies are supplying individual brake system components.
In the case of the manufacturer assembling parts that have passed BWI’s in-house testing criteria, does the manufacturer assume liability for the failure? “We first test our components in the lab, comparing our results with the manufacturer’s requirements,” says Schlangen. “Then we have a document that outlines our testing and their testing. The car company can then carry out durability tests, after which we receive the parts, together with related feedback, and we can test internally before the parts are put on the vehicle.”
Sounds time consuming – and it is. According to Lee, development of a powertrain mount can be between 18 and 36 months. For dampers it is never less than 12 months, while brake development times can be anywhere from nine months to two years, depending on customer requirements. According to Schlangen, manufacturers include a series of tests on the production line to make sure that the parts are applied to the vehicle correctly, consisting of a roller test, where the wheels are spun up to a certain speed and have to stop using a pre-defined pedal force, testing the traction control and the ABS units. “There are checks at every level and step of production, because being a safety part, there is no room for error.”
Further, each part is marked in inventory, so if there is a problem, it can be traced back through the production process to uncover where the fault occurred in the internal production process.
“Over the past five or ten years, a lot of (part) manufacturers have been introducing traceability that allows you to get back to a time of day, shift and batch. We used to hold this information internally, but now a lot of customers are now asking for that information.” BWI uses a combination of paper labels, laser marking and part stamping to mark each component. Each of the stations in the production process is connected, which allows management of each of the processes and overall finished part quality.
“The electric booster masters, they have labels, while the powertrain mount has a paper label on it,” says Schlangen. “We’ve spent some time on this and it works very well. There’s a check valve on the booster which is marked using a non-contrast barcode, read by a red laser. There’s no contrast to it, so it measures the height of the bars, allowing us to read the part numbers of each check valve. There are four of them together, they’re all the same colour, but when they go through this non-contrast system, we can identify each component. What the customer likes is that they don’t see a label, they’re black. So we have some simple systems, such as standard labels, and some very complex systems, such as this non-contrast bar code.”
Design for Environment
As with most companies producing parts for consumption by automotive manufacturers, BWI must address concerns surrounding the impact its production facilities have on the local environment.
“We’ve done business around the world, while at the same time being conscious of the local environmental requirements,” says Alan Lee. In addition, the company has its own internal standards, which outline how operations must be completed. “We have to go through special treatments of waste water and air quality checks, as well as measuring all other outputs. We’re not doing anything that’s really dirty these days, as we don’t make brake linings or pads any more.”
Tim Schlangen adds: “There’s actually a part of our design process called DFE (Design for Environment). We have a checklist of items, materials, that we look at for recyclability, so the reusability of a part is taken into account before the part goes into production.”