Heißkanaldüsen Typ SLT/-DLT Customer information

Heißkanaldüsen Customer information Typ SLT/-DLT
Nozzle design for injection moulding on tandem tools
50% of cycle time can be saved by switching from
standard injection moulding production to tandem
technology. A precondition here is the ideal adaptation of
the melt flow path and the nozzles to suit the altered
process. To produce glass-fibre reinforced polyamide
covers, GÜNTHER Hot-Runner Engineering developed
within a very short time a nozzle construction that offered
the advantages of low costs, reliable heat management
and easy installation.
Objectives which even in normal economic circumstances
would rank among the most important for a new
process are of particular significance in times of crisis.
These are to manufacture components in as short a time
as possible and at costs as low as possible. The fact that
tandem technology in injection moulding can reduce
cycle time by up to 50% induced a major German
manufacturer of motor tools to change over to this technology
for the production of glass-fibre reinforced
polyamide covers for work tools. Tandem technology
makes use of the unproductive cooling time in injection
moulding. Ideally this doubles the output from a standard
machine. The process runs as follows: after closing the
first parting level of the mould and injecting the melt, the
second parting level opens during the cooling process,
the parts fall out of the mould, the parting level closes and
the melt is injected. While the components are cooling in
the second level, work can be continued in the first level.
The advantages for the process of this overlapping are
shorter time requirements and lower costs.
Fig. Mould with tandem technology: One challenge is the melt flow
path from the first to the second parting level.
www.guenther-hotrunner.com
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Before the process changed over to this technology the
assembly, which consisted of two differently-sized
components, was produced on two injection moulding
machines in two different moulds. In tandem technology
the production of the assembly could be combined in one
mould so that there was no longer any need for a second
machine.
Keeping mould costs low
To implement the technology, the injection moulder got in
touch with T/Mould GmbH & CO KG, Bad Salzuflen, the
sole supplier of tandem technology, at the beginning of
2008. “A major challenge presented by such a project is
to keep tool costs as low as possible”, explains Daniel
Gersmann, who is the supplier's Project Consultant.
“In the current project the main challenges were the
design of the nozzle and melt flow path. The tandem
technology side of the project did not present any great
problems because the component geometry is relatively
simple.”
To find the best solution, injection moulders and suppliers
of tandem technology drew on the know-how of Günther
Heisskanaltechnik GmbH in Frankenberg (Eder). The
hot-runner specialist developed a system for the
application in which the functionality of the complete 2+2cavity
mould could be produced with two nozzles. The
alternative to this would have been a more complex hotrunner
system with main manifold and sub-runners for
injection for both components. The simple layout
reduced the costs of the nozzle construction by more
than half compared to the redirection system.
Combination of hot-runner and cold-runner technology
“Looking back, we actually built the system twice”,
remembers Carlo Rasi, sales representative for the
Frankenberg hot-runner specialist. “The first solution
comprised a large hot-runner system with which the melt
was conducted through main manifolds and sub-runners
to the hot-runner nozzles; the transfer nozzle was
constructed as a valve gate nozzle.” The original idea
was that in addition to the nozzle in the first level, two
nozzles with their heads lying against each other would
be used in the second level. “However, this solution not
only required a larger mould but also a larger injection
moulding machine and would accordingly have
increased costs. Furthermore”, continues Rasi “such a
solution would not have been ideal because of the heat
loss.”
For any questions, please contact our Application Engineering department at + 49 (0) 6451 5008-31 or -63.
The information is given in accordance with our present-day knowledge and is meant to provide technical background.
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