FASTENERS & SEALINGSECTION TITLE
screw by incorporating a special thread forming zone which makes it suitable for use with thermoset plastics too. Te thread geometry was optimised through a well-balanced ratio of the highest possible pre-tensioning force and small contact pressure on the plastic to ensure DELTA PT would offer a secure joint, even under difficult conditions and in challenging designs. Further innovation came in the way
EJOT supported engineers to deploy the DELTA PT. As technology was playing a more significant role at concept stage, EJOT created the DELTA CALC prognosis program which would give designers the parameters for the screw’s applications according to the material and pre-hole dimension. It was a tool
that immediately helped customers to save valuable time during the design phase.
Whilst the PT and DELTA PT continue to provide effective jointing solutions to customer challenges across the world, the performance bar continues to be raised. For this reason, fastener evolution has continued in parallel. And with fastener costs amounting to only around 20% of the total joint cost, meaning that the system costs make up
The three different stages of insertion for the DELTA PT
the remaining 80%, there is significant scope for further development of
screw design. Hence the latest generation of
The EVO PT is the latest generation of the PT screw
the PT, the EVO PT. Tis enables system costs to be reduced with the benefits of higher efficiency and greater productivity. It is a fastening solution which successfully integrates manufacturing and application knowledge
with new methods based on computer simulations into the development process. Te result of this cross-disciplinary approach is a screw with excellent
connection properties. EVO PT features a forming thread
that creates a torque curve during the installation phase, almost independently of the screw-in depth. As a result, a uniform tightening torque can be used in the production at different screw lengths. A special lead-in feature of the screw creates a uniform load on the thread flanks when completely fastened, thanks to its automatic centring in the pilot hole during the installation.
SUPPORTED BY SOFTWARE Like the DELTA PT, EVO PT is supported by a digital calculation service in the form of EJOT EVO CALC. With this software tool, EJOT is able to offer a prediction of the torques and preload forces according to component requirements, aided by individual FEM- supported component optimisation, which can result in valuable time and cost savings in the design phase. All three generations of the PT screw continue to offer design engineers a solution for thermoplastics that is supporting product and process innovation in many industries around the world. It is an excellent example of how important fastener innovation has been in enabling change, and the next generation of the PT, as well as other advanced screw designs, will undoubtedly play a key role in overcoming as yet unknown design challenges.
The DELTA CALC software supports designers at the earliest stages of new assembly concepts
Dan Lunn is an Application Engineer at Ejot UK.
www.ejot.co.uk
www.engineerlive.com 35
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