Developments in automotive interiors will place increasing demands on polyurethane foam as the world moves towards autonomous cars, smart seats and different automotive ownership models. Simon Robinson spoke to two key thinkers at Adient.
We are moving towards a world of smart seating and enhanced comfort in cars that will increasingly monitor their occupants to keep them safe, and take over business of driving.
In some visions of the future, publicly pooled cars will appear on demand at the click of a smartphone app, take their occupants to their destination while entertaining them on the way. Cars will become semi-public or shared spaces if car clubs and hire-on-demand ownership models become popular.
This is an extreme view, but undoubtedly there will be changes in the way we see cars which mean that automotive interiors are going to be considerably different in the future.
Adient is one of the world’s largest car seat manufacturing and automotive interior design companies. It was spun off from Johnson Controls in October 2016. Brent Hodge, director of foam engineering, and Eric Michalak, chief engineer, work together to design innovative seats and interiors for OEMs.
Key development
Smart seats will be a key component in tomorrow’s cars, Michalak and Hodge said. They will be fitted with biometric sensors to monitor the condition of the driver, and enable cars to alert them if they need a human to take control of the vehicle back, or allow the car to decide that they are incapable and act accordingly.
‘Biometric feedback is an exploding market within automotive seating,’ Michalak explained. ‘There are a lot of opportunities for systems such as heart rate monitors, drunk driving detectors, and sleepiness and drowsiness detectors. There are about 12 different sensors which could be applied to seats. The question is – what do you do with that feedback?’
For example, Michalak said, the drunk driving detector could be set up to stop the car, or prevent it from starting if it detects the driver consumed more alcohol than the law allows.
‘It could also be possible for a seat to monitor and alter the car’s behaviour depending on your heart rate,’ he added.
He cautioned that this still requires some work. ‘For example, if you’re rushing home and your heartbeat is elevated, how will the chair be able to distinguish between that and a heart attack?’ he said. ‘Should the car contact somebody like the hospital, or next of kin? Should the car pull over if it detects irregular or elevated heartbeat?’
Adding sensors to seats will have important consequences for the way the seats are designed, and the foam formulations that will be used for seating. The sensors will take up some of the space currently occupied by foam.
How much space and weight do biometric sensors bring to the seat? ‘Those which touch the skin are likely to weigh a couple of grams and be quite small,’ Michalak said. ‘Heart rate sensors, however could be embedded in the chair itself and will have to be able to send and receive signals. These will have to go through half of the foam, all the seat material, and the occupant’s clothing and body fat. These sensors could weigh approximately half a kilogram each,’ Michalak suggested.
‘We are at the embryonic stage of development. People are trying to pack a lot of things into seats. We don’t know what the correct package is, and we’re not sure which is the right size with the right feedback,’ he added.
Hodge, director of foam engineering at Adient, believes there are a number of factors that will make life more complicated for polyurethane foam manufacturers. ‘The potential for sensors to be located on the surface or just underneath in the body of the foam means that the foam must be of good quality and consistent firmness in the areas of the sensors,’ he said.
‘The sensors we use today to remind occupants to wear their seat belts, are located be between the PU foam and the foam which backs the trim cover,’ Hodge added. These sensors sit directly on top of the moulded polyurethane foam.
‘Typically, the sensors are compliant systems today, and as we move forward towards larger sensors, we don’t know what shape they will be, or how flexible,’ he said. ‘We may have to come up with a unique way to put some padding in the trim cover to minimise effects of the sensor.’
A second conflict that still needs to be resolved concerns seat weight and the amount of foam it contains. There is, Hodge claims, a big drive to reduce mass in seat structures, and the associated mechanisms being used on the seat itself. And he believes this can go too far.
Too little foam = customer dissatisfaction
‘We’ve had instances where customers have reduced an incredible amount of weight from the polyurethane foam, and had nothing but customer dissatisfaction shown in JD Power and Consumer Reports,’ he said. ‘Whether a seat is 25 mm or 50 mm thick, you need a certain mass of foam to support the occupant. From a polyurethane foam technology standpoint, we haven’t found a material from any of the large suppliers that gives you maximum performance and occupant comfort at 35 g/l density.’
Hodge says that MDI permits a slightly greater operating range, and the thinner the seating package, the more MDI is favoured. ‘MDI can be used down to about 50 g/l, but it’s performance is better at 65 to 80 g/l density. TDI is typically use of foams between 45 and 65 g/l density,’ he said.
To enhance occupant comfort, innovations such as bladder-systems are now being used in seats fitted to higher end vehicles, he added. The TPU bladders are placed on the surface of the foam, between the moulded foam and the trim cover. ‘They would definitely help give more function, and more customisation to the occupant,’ he suggested.
The seat is where the occupants come into contact with the car, and so both car and seat makers spend a lot of time thinking about how to improve that experience for the customer.
Michalak said that many people believe that the car seats are merely a cushion and a back, and you simply put it in a vehicle. ‘But we probably have the hardest job, because the vehicle is designed around your H (or hip) point, the point at which the torso and upper leg portions of the body pivot,’ he said.
That H point has to be maintained within 10-12 mm on a complete seat build up. ‘We have to make it comfortable and aesthetically pleasing, and in a crash, your seat must maintain you in that position,’ he explained.
Adient approaches seat design in two ways: it will design a new seat concept itself, or it will produce seats to an OEM’s specification. ‘The customers have a vision, we have a lot of building blocks, and we can work together to develop a seat sample or we will have a revolutionary concept like Vision Seat which we show customers when it is ready,’ Michalak added.
Adient concentrates its efforts developing foam formulations to align with customer requirements and expectations. In terms of seat and foam formulation design, each customer has their own definition of comfort, foam properties, and seat geometry. Regional preferences do exist in terms of foam properties relative to comfort.
He said that Adient sits on a number of regional automotive standards committees. Taking the current automotive emissions standards situation as an example, he said that the SAE committee on VOCs is very active and is trying to reach a norm that can be adopted by the automakers. ‘There are UN and ISO committees working on upgrades/replacement specifications to VDA 276 and 277,’ he said. ‘We know VDA 276 has already been withdrawn, replaced by ISO 12219 series (12219-4 applies for VDA276).’
There are signs of people working together. The biggest thing that is starting to happen now is the focus on individual VOCs. ‘10 years ago the focus was on total volatile organic compounds for Europe. At that time Asian customers were already screening substances), now it is on VOC and substances including aldehyde and ketone emissions,’ said Hodge.
‘A lot of work is being done from the aldehyde perspective to ensure that the moulded foams for seating applications will have minimum contribution to emissions,’ he added. ‘It is clear that a low VOC foam does not mean a low aldehyde foam. It could mean exactly the opposite. There is no correlation between the two.’
Attempts to simply solve the problem of emissions can have unintended consequences, Hodge said. Some non-fugitive additives may contain impurities or contribute to the formation of non-expected aldehyde products during the foam production process. ‘This is impacting emission results when testing a piece of foam,’ he said.
A lot of work is now going on to understand the levels of impurities of additives in formulations, and to ensure they contain no aldehydes at the outset. Cleaning the polyols, which might require additional steps at the polyol manufacturers, is another important contributing factor when making aldehyde-free foam.
‘We pride ourselves on being able to develop our own chemistry,’ Hodge said. ‘We have developed foams internally for performance, such as vibration damping, low VOC or low hysteresis-loss MDI foams over the years.’
The company operates its technology development on a hub-and-spoke system. ‘We have tech centres in all the regions,’ Hodge explained. The Plymouth, Michigan and Strasbourg, France tech centres are our major polyurethane foam chemistry development centres. Adient also has three developing tech centres in China in Shanghai, Changchun and Chongqing.’
Adient employs 10-15 people in foam development. ‘In manufacturing, we have 11 foam plants in North America, eight in Europe, nine in South-east Asia and 24 in China,’ Hodge added. ‘We are one of the world’s largest suppliers of moulded polyurethane foam, and we do see different requirements from the Asian, European and North American automakers regarding foam chemistry and the performance of the foam.’
Sharing developments
Hodge explained that the company’s polyurethane centres of excellence for foam chemistry development take the lead on developing foam formulations for regional customers. ‘For example, the Plymouth tech center would take the lead on developing foam for a Japanese customer and then share it with our colleagues in China and Southeast Asia that have a similar customer,’ he said.
‘The strategy is to develop technology regionally in our centres of excellence and then spread that out to the rest of the world. The plants’ job is to produce consistent foam that meets the properties our formulation will give them.
While declining to specify the kind of machinery Adient prefers, he said that the company has a best business practice for what its machinery needs to look like, and what its delivery systems, chemical storage and mix heads will be.
‘As we install new lines at new plants they are all from the same base architecture, and are sized based on capacity needs,’ he added. ‘They are modular and can be 32,42 or 52 carrier lines. All the hardware, software and mix heads are similar around the world.’
One cultural difference that Hodge has noticed to be changing is that TDI is being introduced into Europe and is now a little more popular for the lower density formulations. ‘Also, MDI is becoming a little more popular in the US, so most of our lines are set up to be able to pour MDI and TDI out of the same mix head, to give full flexibility on the lines,’ he said.
The vision behind the Vision seat
In an attempt to improve driver comfort, Hodge said, there is already a US automotive seat in production in a higher-end Lincoln with 38-way adjustment. Adient has looked at this approach, and decided it is too complex. Its new Vision Seat, launched at the North American International Autoshow in Detroit this January ,is not only lighter and thinner than conventional seats, but adjustments have been made simpler by grouping seat movements together.
‘There are a lot of ways to make a person uncomfortable,’ said Michalak. ‘Because the normal driver doesn’t understand ergonomics, we looked at a 32-way seat, and broke it down to a series of dependent movements.’
These movements take account of the way that the parts of a human body move together.
‘When you sit down, your pelvis rotates and, at the same time, your spine adjusts, your shoulder blades move, your neck rotates, your thigh bones adjust, and finally your fibula and tibia,’ he explained.
His team designed the Vision seat by looking at how those changes would occur in differently sized people occupying a seat in driving and non-driving positions. Adient found that there are a number of more or less comfortable positions.
‘We want to go to those positions in a simple movement,’ Michalak said. This means a simple movement of the seat might alter several parts of the seat at the same time, and also the pedals to maintain driver comfort, he added. It helps to effectively transfer loads between the occupant and the car as it accelerates or slows down.
The Vision Seat is designed to be more like an adjustable office chair than traditional automotive seating.
Existing automotive seat designs will commonly untuck an occupant’s shirt or blouse as the seat reclines because the seats pivot at a point above the seat cushion. The Vision seat has an anthropometric pivot, below the surface of the seat. This means that, as the seat moves, all of the parts of the body that were originally touching the seat remain in contact.
