By Liz White, UTI editor
Budapest -- Quality fundamentalists in automotive seating have decided that flexible polyurethane foam, a cellular material, full of air bubbles, should have no pinholes in its surface.
But until now it also "not proved possible to produce moulded flexible foam parts in high serial volumes without a single pinhole or void," stressed Raphael Thienpont, president and ceo of seat foam maker Proseat GmbH & Co. KG.
In an 8 June presentation at the Europur meeting in Budapest, titled "Quality -- a balancing act between common sense and fundamentalism," Thienpont, noted a similarity between this type of "grotesque justification on appearance," and the EU's 'straight bananas' fiasco.
The stone-age fundamentalists of the auto industry say, "We have no voids or pin-holes in drawings, so we will not accept them in products," Thienpont commented.
Meanwhile, some apologists accept a certain number of pinholes but on the 'B' side, the underside of the cushion. Thienpont characterised this concession as, "as stupid as stone age fundamentalism -- only it sounds better."
Foam seat parts are completely wrapped in textile or leather. "They have a 100-percent functional role to play," the Proseat executive said.
They have to provide the occupant good comfort, give him ergonomic support and "dampen the vibration provoked by the car suspension whilst driving," Thienpont said.
Quality fundamentalism starts when a purely functional part is judged on its appearance and then very grotesque arguments are found to justify it, he continued.
Looking at the A side of seat pad, the top surface, Thienpont said the foam backings of the seat covers have been made so thin that every surface irregularity on the foam gives a problem. And this leads to high sensitivity to any A surface defects. "More and more this is considered as a sacred surface so we cannot even think of repairing some small defects," he added.
But the situation is completely different once the foam part has left the foamer and is at the seat assembler, Thienpont said.
Once there the foam changes from "a carefully engineered complex component which has to be handled with care to a problem solver for poorly conceived seat covers and assembly concepts."
"All of a sudden nobody is offended at all," when self adhesive tapes are glued on the sacred surfaces in order to keep the covers in place, or a lot of twisting and tearing is done to adapt the foam cushions to the misfits of other seat components.
This also explains the easy life of in-house foamers at Tier l seat makers. No one sees their foam," Thienpont pointed out.
Thienpont also commented that "mechanical engineers who must hate chemistry," have another issue with seat foam: pads commonly have a comfort zone in the middle and support zones at the side, achieved by pouring two different foam systems in the same mould -- not simultaneously but one shortly after the other, he explained.
Of course these two systems have different rise profiles, Thienpont said, "When one pours two different liquids into the same cavity it is only natural that one liquid penetrates the other to a certain extent." There are indeed engineers who do not like that phenomenon as a principle, he said (referring yet again to the banana problem).
Thienpont noted that foamers have to admit some fault here in provoking a reaction. "Some or all of us produced and supplied parts where the hard foam did penetrate the soft foam so far that it directly influenced the hardness measurements in the center of the comfort zone."
Thienpont's apocryphal mechanical engineer, on the other hand, wants the system to work as the neat separate layers in a tequila sunrise cocktail. But foam does not work like that.
"So we must not be too surprised that the reaction was heavy," Thienpont said: first came the demand that the different hardnesses have different colours and second, that the 'marriage zone' of the two hardnesses is limited to 20mm.
Thienpont said "even a 30mm zone would be challenging, but technically common sense. Although it would not make any difference to the function of the part," he emphasised. "We have to cope with an arbitrary decision," which does not create added value.
A second effect is the claim for hardness measurements based on narrowed tolerances all over the surface of the comfort zone. Knowing that there is a pouring time of four "seconds" and foam starts rising from the first second the mixture is poured, this new claim becomes technologically interesting.
Seats use different foams with different rise profile, to give different foam hardness/density for various parts of the cushion. That brings us again to quality aspects that "have become a little crazy," Thienpont said.
The two different hardness foams become different colours, and the specifiers "want to define a 20mm width of interaction of two systems," he said, noting that not even the most sensitive could feel such a distinction.
This is "technically a challenge: we could manage 30mm," Thienpont said.
Such academic fundamentalism results in cost issues, he continued, adding that the amount of testing involved has led him to feel that Proseat is "a testing company using a lot of foam."
Thienpont said there are many other examples of such fundamentalism, including an evergreen example, about hysteresis and foam.
But the story is that there is "no added value for the end customer," in such stipulations.
Thienpont concluded by stressing that he has no intention of questioning the aim for quality.
"On the contrary, it is because quality is so important that we should together help to implement the notion of lean management and avoid waste also in quality matters," he said.