When a sub-assembly supplier to a global car manufacturer needed a new type
of fastener they knew to turn to the experts at JET PRESS. Their outline
requirements appeared straight-forward at first: attach fasteners into a
sub-assembly so that this sub-assembly then fitted easily, with those fasteners,
directly onto the vehicle. However, it soon became clear that due to specific
fitting-force, ease-of-use and cost considerations, there was nothing in the
vast range of standard fasteners from JET PRESS that would quite fit the
bill; our technical team would design a bespoke product.
Each fastener needed to be held securely in the panel hole of the
sub-assembly during transport to the vehicle assembly plant. The sub-assembly,
complete with the fasteners attached, would then be positioned to the underside
of the vehicle where the final fitting needed to be quick and easy. One-hand
operation of the fixing was required with no more than 30N of force to secure
the fastener in place. Once in place the fastener had to withstand forces of at
least 200N, at a temperature that would at times reach as high as 130° C.
“The specifications were quite precise and for the volumes involved, we were
able to create an entirely original design.” explained Martin Belcher, JET PRESS
Technical Manager. “Other
two-stage rivet fasteners generally have to be pre-assembled from two
components and this significantly adds to their in-place cost. Our solution was
a singly-moulded drive rivet with a double-detent positioning feature. It is
manufactured from impact-modified, heat-stabilised material that gives rigidity
and temperature stability in excess of the specification.
Another design consideration resulted in a recess under the head of the
fastener's drive-pin and this facilitates the release of the fixing using a
screwdriver; this is important for maintenance and for recycling at the end of
the vehicle’s life.”
The fastener is first fitted on the bench at the sub-assembly manufacturer’s
plant. The rivet is placed in the hole of the sub-assembly and the drive pin is
pushed to the first stop position. This breaks the moulding seal between the
rivet body and pin, and holds the fastener securely in the sub-assembly. The
first detent positioning device prevents the pin from accidentally being driven
fully into its final position during transport.
On the vehicle, the sub-assembly can be held in place with one hand. The
operator then simply uses their free hand to drive the pin fully home in the
rivet where the second detent positioning device holds the pin in place. This
final push locks the pin in the closed position and prevents it from coming
loose due to gravity or vibration forces.
“It was very satisfying for us and for the customer in designing such an
effective and low-cost unique fastener.” concluded Martin.
Find out today about how JET PRESS expertise
can help you find or develop the best fastening solutions in your business.