The Know-How To Be Your Best
in resin casting and impregnation for higher quality
and cost-effectiveness in the casting of electrical and electronic parts.
We shall be pleased to send you further additional information on:
Electrical industry
Electronics industry
Electronics industry/Electrical industry
Vacuum mixing and
metering systems
Vacuum mixing and
metering systems
• Multi-component vacuum casting
systems
• Systems with single casting valve
• Systems with multiple casting valves
• High performance degassing units
• Multi-component atmospheric casting
systems
• Multi-component vacuum casting
systems
• Systems with single casting valve
• Systems with multiple casting valves
• High performance degassing units
Vacuum compounding
and material
preparation systems
Brochure No. 8
Brochure No. 5
Electronics industry/
Electrical industry
Electronics industry/Electrical industry
Electrical industry
Impregnation systems
• Atmospheric impregnation systems
Vacuum impregnation systems
• Vacuum-pressure impregnation (VPI)
systems
• Vacuum drying and impregnation
systems
Brochure No. 3
Automatic pressure
gelation (APG)
• Vacuum mixing and metering
systems with direct injection
• Single casting valve
• Multiple casting valves
Brochure No. 6
Electronics industry/electrical industry/
chemical industry/plastics industry/
special applications
Electrical industry
Laboratory and
special systems
APG clamping
machines and moulds
Brochure No. 4
Drying and curing
systems
• Batch ovens, compartment dryers
• Serpentine conveyor ovens
• Inline-conveyor ovens
• Multiple layer elevator ovens
• Pressure-curing ovens
• Special ovens
Brochure No. 9
Electrical industry
Mixing and metering
system COMPACT
Brochure No. 7
VERFAHRENSTECHNIK HÜBERS GMBH
Bernhard-Otte-Str. 1 • D-46395 Bocholt Postbox 1552 • D-46365 Bocholt
Telephone **49 / 28 71 / 28 1-0 Fax **49 / 28 71 / 28 11 50 http://www.huebers.de
Brochure No. 10
03/99
Brochure No. 2
• Silo and conveyor systems for
components in solid and liquid form
• Dryers for fillers
• Mixer and premixer groups
• High performance degassing units
• Metering and weighing systems
Brochure No . 5
Vacuum mixing and metering systems
for the electronics industry
The Know-How To Be Your Best
in resin casting and impregnation
Verfahrenstechnik Hübers: Innovative technology
for higher quality and cost-effectiveness in the casting of electroni
VTH. The specialist in resin casting technology.
The Know-How To Be Your Best.
Throughout the world where electrical parts
have to be cast and impregnated VTH is
rated one of the leading names. With many
patented developments, VTH is known as
the innovative pacesetter in the field. Its name
stands for outstanding precision and high
economic efficiency in resin casting
technology. VTH's know-how has made the
company a partner with industry whose
competence can be relied upon. VTH
provides engineering support, systems and
system components tailor-made to customers'
needs. Improvements in product quality and
productivity are VTH's objectives.
The result: greater competitiveness for VTH
customers.
Competence and capability for the customer.
VTH experts are respected partners of the
industry and the casting material suppliers in developing new processes and products.
Prior to an order: Soundly based processengineering support to find the best technical solution
with the best economic result.
A convincing success story: 12 patents have
been applied for in the last 15 years.
Made by VTH: All system components specific for
the particular process are manufactured in-house at
VTH. Like the outsourced components, they are
subjected to the strictest quality checks.
VTH offers all the processes: Casting and
impregnating, single and multi-component systems,
atmospheric pressure, vacuum, vacuum-pressure
and pressure-gelation.
Single modules or complete systems: Storage
and conveyor systems, compounding and preparation systems, mixing and metering systems, units
for generating vacuum, overpressure and temperatures, casting chambers, moulds and clamping
machines, dryers and curing systems.
VTH. Facts and figures.
• Founded in 1937
• Headquarters: at Bocholt in Germany's
state of North Rhine-Westphalia on the edge
of the Ruhr industrial heartland and 70 km
north of the international airport at Düsseldorf.
• 80 employees
• Between 1968 and 1998 more than 65
patents and registered designs have been
applied for.
• More than 20 agencies world-wide
• Since 1963 VTH has built and installed over
1400 systems throughout the world.
VTH. International benchmark for higher
quality and cost-effectiveness in resin
casting and impregnation.
2
Of every size: From laboratory systems to
systems for large-volume manufacturing with
programmable logic controls and on-line monitoring
of quality.
Replacement parts are supplied rapidly and
flexibly thanks to the great depth of in-house
manufacturing at VTH.
Controls and programming by VTH. VTH's controls,
customized to specific process requirements, offer
many advantages. Electrical installation and
programming are carried out by VTH specialists.
Prior to shipment: Every system is completely
assembled and the process is tested with the customer's
own raw material.
Personal responsibility: The VTH team that builds
a system also installs it at the user's factory, commissions
it and remains personally available for the system user
by phone.
ic parts.
VTH. High performance resin casting systems for the electronics industry.
VTH customers place the very highest
requirements on resin casting.
To fulfill their function over long periods
of time parts must be free of pores, have
a homogeneous structure, the undercut
edges must be filled completely, the
impregnating of windings must be reliable
and surfaces must be smooth.
Homogeneous preparation and mixing of
the casting material and exact metering
are required in order to achieve the very
best electrical properties. In addition today
the complete process must serve the
economic criteria for just-in-time
production. This in turn requires clean
casting, high system availability, the ability
to change over to other casting materials
easily, exact reproduction of process
parameters, reliable programming and online monitoring of the process.
VTH's special technology meets this
challenge.
VTH resin casting systems are unparalleled in terms of their many patented details:
• component preparation, mixing and
metering technics,
• component degassing and preparation
processes,
• devices for controlling and regulating
the process,
• modular structure requiring little
maintenance.
Assurance of outstanding electrical
properties. Maintenance of the tightest
manufacturing tolerances, high and
constant product quality.
Process parameters such as mix ratio,
casting volumes, pressures, temperatures
and casting times are kept reliably constant and are reproducible. They are
easily changed when required.
On-line quality assurance of
production processes.
Easily realized system options to
permit the use of other resin systems
with different viscosities, filler loadings and
material formulations and allow use of the
products of the majority of manufacturers
including local ones.
Environmentally friendly production
processes which allow users to dispense
with solvents almost entirely.
Low sensitivity to
operational disruptions
and high system
availability.
Security and flexibility
for the future. The system
can be converted for other
processes, used for other
products, expanded easily
and retooled rapidly.
Cost reductions in
raw materials, power,
labour and retooling.
Time savings in
operating, cleaning,
maintenance and service.
Automatic casting units from VTH stand for
highest casting quality and productivity.
For this reason nearly 100 % of all ignition coils
produced in Germany in large volume are cast on
VTH systems. This 3-chamber automatic casting
unit represents the core of a system for casting
up to 1,000 ignition coils per hour with programcontrolled precision. (View from position A. See
horizontal projection of system on page 5.)
Contents
Page
Examples of VTH systems
...used to produce
• ignition coils
6/9
• fly-back
transformers
9
...providing innovative
solutions for special
problems
11
The Know-How To Be Your Best.
VTH-systems technology
-an example
4/5
VTH metering-mixers
VTH metering pumps
6/7
VTH static mixers
VTH casting systems
8/9
Automation and
further advantages
10
Production range
and literature
12
3
Vacuum mixing and metering systems from VTH
The know-how for total system engineering. Including oven system
High output vacuum mixing and metering system for 3-chamber vacuum casting, im
Productivity and quality made by VTH.
Fully automatic system for the precision
casting under vacuum and at atmospheric
pressure of up to 1,000 ignition coils per
hour. The system was planned and built by
VTH to customer's specification and includes
ovens, vacuum and pressure systems,
conveyor systems and VTH control.
With automatic pallet recognition: the
required casting parameters are selected
for each individual ignition coil type without
any interruption in production. This enables
the system to be charged with different
ignition coil types. VTH process and plant
technology ensures high plant availability
under continuous operation conditions.
1
Preheating oven
2
2.1
2.2
2.3
2.4
Vacuum mixing and metering system, vacuum casting
Resin premixer with high performance degassing
Hardener premixer with high performance degassing
Metering-mixer / metering pumps, resin
Metering-mixer / metering pumps, hardener
3
3-chamber casting automat
3.1 Loading chamber
3.2 Casting chamber with static mixer and 4-nozzle casting
head.
3.3 Unloading chamber
4
Impregnating in pressure chamber
5
Mixing and metering system, postcasting
5.1 Metering-mixer, resin
5.2 Metering-mixer, hardener
Atmospheric postcasting station with 2-nozzle casting
head
The Know-How To Be Your Best.
Multi-component mixing technology from VTH.
6
7
Gelation oven with pallet lift
VTH vacuum metering-mixers.
VTH static mixers.
8
Full curing oven
Large surface to give optimum preparation
of the material.
Are able to be used even with a very wide
range of mix ratios and viscosities.
9
Cooling section
Homogeneous, gentle mixing.
Optimum degassing - even without the high
performance degassing unit.
Casting resin components are uniformly
evacuated and uniformly prepared - whatever
their viscosity.
VTH metering pumps.
Metering takes place from evacuated vessels.
Even highly filled materials can be metered
precisely.
Maintenance-free and wear-resistant; no
pressure losses even when longer supply lines
are required to reach a number of casting valves.
The delivery of the pumps is not affected by
gravity so that the systems can be floor-mounted
if necessary.
Long service life even with highly abrasive
materials.
VTH metering pump drives.
The synchronized running of the two metering
pumps guarantees exact maintenance of the
selected mix ratio.
Long cleaning intervals, easy to maintain,
long service lives.
Can be flushed out with just the resin
component - no solvent required.
10 Pallet conveying sections
10.1 Pallet lift
11 Product tray conveying sections
11.1 Separation station, pallet / product tray
11.2 Loading station, product tray / pallett
12 Switch cabinets, control, process data printer
VTH casting systems.
Material passes directly from the static mixer
and casting valve into the mould. There are no
hoses.
Front view
8
Absolutely bubblefree and dripless casting;
no contamination of the part or casting chamber.
Small amount of reactive mix - just that
required for casting, uniform temperatures,
higher quality and precision of casting - even
with multiple casting and very small casting
quantities.
7
VTH on-line process control.
Quality-assuring, automatic, programmable
operation for high volume production.
9
11.1
10
10.1
VTH process and plant technology meet the highest
requirements in terms of precision and cost-effectiveness.
• Pressure station for accelerating the vacuum-pressure
impregnation process and ensuring that even the smallest
cavities are reliably filled.
• Postcasting station provides filling to a precise level.
(View from position B).
4
m s and conveyor technology for maximum productivity.
mp regnating under pressure and postcasting at atmospheric pressure.
Platform
8
Cycle time: 3 min per pallet.
7
9
11
11.1
10
10.1
Ground floor
12
12
5.1
2.1
2.3
5.2
2.2
2.4
7
5
2
1
3
1
2.1
6
4
3.3
3.2
B
10.1
3.1
A
11.2 11
10
• The ignition coils arranged on product trays are
conveyed on pallets through the
preheating
oven and are brought up to process temperature.
• In the
first or loading chamber of the
3-chamber casting automat the parts are
evacuated. Then casting is carried out in the
middle chamber under vacuum.
• The components are homogenized, degassed
and dried under vacuum in premixers and are
then
pumped to their particular vacuum
metering-mixer. From here and in accordance
with the amount of material required in the casting
chamber,
the synchronized metering pumps
deliver the components continuously and with
the exact mix ratio to the
VTH static mixer.
Here, directly above the casting head, the
components are brought together for the first
time whereby just that quantity of each required
for the particular casting operation to be carried
out is metered in.
In the static mixer and still
under the influence of the stroke of the metering
pumps, the components are mixed together
intimately and rapidly to give the reactive mix.
With its viscosity still constant, the required
quantity is metered out precisely via 4 casting
valves under vacuum into the moulds. The
casting valves (together with the static mixer)
can be moved horizontally in the X-direction
with the aid of the vacuumtight slider plate (VTH
patent). Since the pallet can be moved in the Y
direction, this means that every point on a pallet
can be reached for casting.
• In the
third (unloading) chamber the
vacuum is released. Then in the
pressure
chamber pressure is applied to accelerate the
impregnation process.
• The above process causes the level of the cast
material to fall.
Topping off is now carried out
in the postcasting station at atmospheric pressure
to bring the level precisely back to the upper
edge of the mould . The
postcasting station
is supplied from its own pair of metering mixers
with metering pumps via a static mixer with 2nozzle casting head.
• In the
gelation oven the reaction resin
gels. The pallets leave the gelation oven at the
platform level.
• After this the parts are allowed to cure in the
curing oven.
• On leaving the oven the product trays are
separated from the hot pallets and
are
cooled down in the cooling section on
the platform.
• In order to save energy,
the pallets are
conveyed to the lower level while still warm where
they are loaded with freshly charged product
trays prior to entering the
preheating oven
again.
• This microprocessor-controlled system is
equipped with on-line control of all process
data while its superordinated instrumentation
and control system includes a pallet recognition
system. With the aid of the latter, the process
parameters required for the particular parts to
be cast are selected from programs stored in
the PLC.
5
Examples of VTH systems
used to produce ignition coils.
397
Like all VTH ignition coil casting systems, this one too
has been optimized so that the high voltage coils produced
on it will have uniformly excellent electrical properties.
• Achievement of consistently homogeneous mix quality even
with highly filled material.
• Uniform impregnation of the fine-wire winding that reliably
reaches every last cavity.
• Highest metering precision to ensure exact filling to the
required level and clean contacts.
• At each program change the process parameters - casting
volume, casting speed, positioning of the casting nozzles as
well as vacuum, temperature and pressure data - are reliably
reproduced.
• Automatic changing of the casting program via pallet
recognition when the parts to be cast change.
The system with its multifunctional single-chamber casting
automat is designed for the fully automatic manufacturing of
up to 300 ignition coils per hour.
On the right in the photo: preheating oven; in the middle:
gelation oven; on the left: curing oven. Each of the ovens is
of the serpentine conveyor type.
Multifunctional single-chamber casting automat of the system
shown above for the exact metering of different shot sizes.
The casting chamber, which is tight to both vacuum and pressure, has
• 4 casting nozzles
• for 3 functions:
1. Precise, dripless vacuum casting,
2. Accelerated impregnating under pressure,
3. Postcasting at atmospheric pressure to give the precise filling height.
• All casting functions are supplied from one mixing and metering
system.
• As with all VTH systems, the parts of the system coming into contact
with the reactive mass can be cleaned by flushing with the resin
component without the use of solvent.
VTH can also provide
economic solutions for
small and medium-sized
production units.
• Single-chamber casting
automat combined with
batch preheating and batch
curing oven. The ovens are
loaded and unloaded
manually.
• Here too the mixing and
metering system which can
be seen in the background
and the VTH control ensure
uniformly high product
quality and reproducibility of
the casting parameters.
6
VTH material preparation, VTH metering.
The Know-How To Be Your Best.
VTH metering-mixers.
VTH metering pumps.
VTH metering pump drives.
The know-how ...
The know-how...
The know-how ...
Each vessel is characterized by its large diameter
and low height.
The special shape of the slow running stirrer is
optimally matched to the shape of the vessel.
The gap between the lower edge of the stirrer
and the base of the vessel is less than 1 mm.
The double-jacket vessels can be heated, chilled
or kept at a constant temperature as required and
ensure uniform temperature distribution throughout
the complete vessel.
The vacuum is retained reliably during the
complete production period.
Pneumatic lid-lifting device.
Piston-type metering pumps with no pressure
loss.
Driven from above through the stirrer axis.
6-fold vacuum sealing that does not come into
contact with the casting resin.
Quickly changed insert modules to permit
different quantities of casting resin.
Option: patented, fully ceramic metering pumps
of silicon carbide for highly abrasive casting resins.
Externally mounted metering pumps working synchronously in pairs for automated multi-shift operation
with the desired number of clamping machines.
The metering pumps can be driven alternatively
either via (1) Pneumatic central drive with infinitely
variable lever arm system driven from a centrally
positioned cylinder.
Or (2) Electronically controlled servomotor
drives with brushless servomotors, controlled and
monitored by microprocessor (VTH patent).
... for exact metering:
... for optimum material preparation:
Homogeneous and gentle mixing.
Short material preparation times.
Optimum degassing even without a high performance degassing unit.
Uniform degassing capability regardless of the
viscosity of the material and the proportion of filler
it contains.
Sedimentation cannot take place at any point in
the vessel.
Constant evacuation and thereby uniform homogenization.
No phases in which air is introduced into the
vessel and hence no contamination of the material
with air or atmospheric humidity.
Exact maintenance of the temperature.
Metering from the evacuated vessel.
Even highly filled materials can be metered
precisely and reliably.
No pressure losses even where there are long
lines to a number of casting valves.
Maintenance-free and wear-resistant, reliably
vacuumtight.
Function independently of gravity, i.e. they can
be floor-mounted.
Long service life even with highly abrasive
materials.
VTH high performance
degassing unit.
...for the exact mix ratio required:
Synchronized running of the two metering pumps.
The mix ratio can be set precisely and then
remains absolutely constant.
(1) Simple and cost-favourable version.
(2) High flexibility in selection of the casting
parameters: the quantities of each component
which should be metered to the static mixer and
the speeds at which this should be carried out are
freely programmable.
(2) Electronic metering control is possible when
pressure sensors and a pressure monitoring system
are fitted.
Electronic VTH metering pumps mean that three
or more components can be metered synchronously
if desired.
Simple to maintain and quick to clean:
VTH metering-mixers with the pneumatic
lid-raising device are freely accessible.
The know-how...
Only needed when further shortening of the
material preparation time is required.
The material is transported through the unit by
an externally located conveyor screw driven
independently of the stirrer.
... for acceleration
of the preparation phase:
Minimizing of the material preparation time.
Optimal matching of the circulation speed to the
viscosity of the material.
The mix ratio can be set
precisely and changed
easily with this pair of
metering pumps which are
driven in tandem from a
central pneumatic cylinder.
To change the ratio, you only
have to adjust the fulcrum
point on the lever arms.
Mix ratios, casting quantities and casting
speeds can be freely programmed with
this pair of electronically regulated VTH
metering pumps.
7
VTH static mixers, VTH casting systems.
The Know-How To Be Your Best.
VTH static mixers.
... for the homogeneous mixing of the components:
The Know-How...
A VTH static mixer consists of 10 or more metal
segments. Each segment has 4 angled bores.
The segments stand on top of one another as
a column in a tube, into which they fit exactly. The
diameter is just a few centimetres.
The two components in liquid form, which are
pressed in separately at the top of the column, are
mixed together fourfold on passing through each
segment. After passing through 10 segments they
have been mixed together over 2 million times.
1
3
2
3
Low volume
Vacuumtight
No dead space
Not sensitive to
temperature
Low generation of heat
Made of metal
Double jacket version
Simple structure
4
1
4
No moving parts
Favourable flow
2
Gentle on the material
Can be used even with extreme mix ratios and
large differences in viscosity of the individual
components
Contains only a small quantity of the reactive mix
Quality is assured
Cleaning can be carried out without any solvent
by flushing out with the resin component
Work can be carried out as required at both low
and high temperatures
Advantageous with sensitive casting resins
Can be heated electrically (standard version)
Can be heated, chilled or kept at constant temperature
Service-friendly, easy to clean, low procurement
and operating costs, maintenance-free, long service
life
One segment
of a VTH static mixer
VTH casting chamber systems.
8
The know-how…
... for precise casting and short cycle times:
Casting is carried out automatically; depending
on the particular system type, it is carried out at
atmospheric pressure, under vacuum or under
vacuum followed by application of pressure.
Static mixer and casting resin valves can be
moved horizontally (X-direction) and vertically in
a vacuum-tight manner (VTH patent).
Moving of the casting mould in the Y-direction
in combination with the movement of the casting
nozzles means that every point in the casting
chamber can be reached for casting without hoses
being required.
The special design of the VTH outlet valves
means that dripping is prevented even with multiple
casting.
Different versions of casting chambers are
available to match the particular application.
Equipped with viewing windows and frequently
with doors in the front.
Optional: multiple mixing and metering head
system (VTH patent). VTH static mixer and multiple
metering head are combined with plunger pumps
which have no dead spaces. The latter draw in the
precise amount of mix required for the meteringout operation which takes place simultaneously.
The plunger pumps are driven via a common drive
and meter the mix exactly and simultaneously
through the casting valves into the parts.
Optional: 3-chamber vacuum casting system
with loading and unloading chambers.
Short path from the static mixer to the outlet valve. This means that only a small quantity of reactive
mix has been prepared at any one time.
High and uniform metering precision. Bubblefree and dripless casting under vacuum or at atmospheric
pressure with single or multiple casting heads.
Higher quality of casting thanks to constancy of temperatures and other processing parameters during
the short processing time.
No contamination of the parts or casting chamber by dripping nozzles.
Rapid, easy cleaning of the small part of the system carrying the reactive mix by flushing out with the
resin component. No solvents required.
Less cleaning work and shorter downtimes increase output.
Each point in the casting chamber can be reached by the outlet valve giving higher system productivity.
Easy changeover from casting at atmospheric pressure to vacuum casting and vice-versa.
Multiple mixing and metering head system:
Simultaneous and highly precise metering out of the very smallest quantities under vacuum.
Increases the capacity and productivity of the system
• through simultaneous casting of a number of parts
• through ability to reproduce casting quantities even over extended periods of time,
• through process control and quality assurance via active electronically controlled nonreturn valves,
• through a metering-monitoring system developed by VTH especially for this purpose (VTH patent)
• through high metering precision, long service life of the multiple mixing and metering head and low
amount of cleaning required.
The same system can also be used for casting at atmospheric pressure.
3-chamber vacuum casting system:
Shortening of the process time through elimination of evacuation and vacuum-release times.
Increasing of the capacity and productivity of the system through
• shorter cycle times,
• longer service life of the mixing and metering head as a result of shorter waiting times when filled
with reactive mix,
• additional quality assurance through pre-evacuation in the first chamber.
Examples of VTH systems for the casting
of fly-back-transformers and ignition coils.
The know-how for high system productivity - examined here in detail:
Casting chamber of a high output system for the production of fly-back transformers.
With bypass line to prevent filler sedimentation.
The following points can be seen:
1. The design with its compact 5-nozzle casting head with VTH static mixer, 5 plunger
metering pumps and 5 casting valves ensures that the amount of reactive mix prepared
at any one time is kept to the absolute minimum. The result: long service life, less
cleaning effort.
2. The casting valves under the vacuumtight slider which permit each casting point in
the chamber to be reached exactly. The result: clean casting without splashes or drips.
3. The resin bypass line, which can be fitted easily with the aid of its quick-fastening
system, enables the resin component to be circulated under vacuum and constant
temperature during periods when there is no production (blank shift, weekends, public
holidays). Result: no sedimentation, long maintenance intervals.
High performance casting chamber for the world's largest consumer
of ignition coils.
• Ultra-compact VTH vacuum casting chamber with 16-nozzle casting
head.
• Each casting valve has its own VTH metering plunger.
• The pallet with the parts is pushed in at the side, positioned exactly
with a pusher and - following casting - pushed out without any vibration.
• The head can be moved along the Y-axis and the pallet positioned
along the X-axis. The 16-nozzle casting head casts all 16 coils
simultaneously.
The advantages
• The pallet conveyor system does not pass through the casting chamber.
This means that the size of the casting chamber can be reduced and this
in turn means that evacuation is faster and the process more cost-favourable.
• Extremely fast casting process.
• Short dwell time of the parts in the chamber. Each part has the same
history. Highest possible uniformity of the casting quality with the reactive
mix being produced just in time.
FP Seite 15
The qualitative characteristics of this
production system for up to 800 fly-back
transformers per hour:
• absolute homogenization at mixing and
preparation of the material,
• reproducible process parameters,
• highly precise metering,
• casting without drips or splashes.
Fully automatic system with predrying oven
and cascade-regulated secondary drying
oven with four temperature zones and one
cooling zone.
The serpentine conveyor system in the ovens
• saves space and
• reduces power costs.
9
Automation, system engineering.
The Know-How To Be Your Best.
Monitoring and control.
The know-how…
Mixing and metering monitoring: 3 options with
modular characteristics.
1. Manual monitoring by taking of samples at
the 3-way valve.
2. On-line monitoring with metering control
device. The pressure curves of each metering
stroke of each metering pump are recorded, compared and logged.
3. Direct fully electronic monitoring and control
of the metering quantity and mix ratio by command/actual comparisons via the electronic metering
pump drives.
The sum of the individual
technical details maximize
the overall benefit of VTH
systems: For example VTH
non-return valves with quickchange system. Maintenance can be carried out
while the vessels are full.
Easy-to-maintain
system structure.
The know-how…
Two of many examples:
Lid-raising device for premixers and VTH
metering-mixers.
VTH non-return valves.
…for high system availability:
Long servicing intervals.
Low expenditure for service.
Lid-raising device (see photo on page 7).
Gives easy accessibility to primary system parts.
Enables important system parts to be maintained
without the vessel having to be emptied.
Allows the vessel to be cleaned rapidly and
easily when changing the material.
Enables large quantities to be put into the vessel
easily.
Fully automatic process monitoring.
In addition to the process control processes, all
the process parameters can be monitored and
compared with the permissible limit values set for
them.
If the values measured leave the permissible
range, optical and acoustic alarm signals are given
and an error message is displayed on the monitor
in clear text.
If a fault arises at metering, the system is stopped
immediately. The cause is also displayed on the
monitor and logged.
VTH non-return valves (see photo on left)
Can be supplied in passive or active version.
Flow-favourable design gives long service life.
Can be maintained and serviced even when the
vessel is full.
Quick-change system permits easy replacement.
Programmable logic control.
Modular
system structure.
Where fully automatic, microprocessor-controlled
systems are required, VTH uses programmable
logic controls which have proven themselves in
the area of casting resin metering.
Initial programming is carried out by VTH
specialists who are also trained in process
engineering.
The variables required for different process
sequences are freely programmable and can be
stored in subroutines.
Programming is carried out and operator
guidance provided on a video terminal with easily
understood menus.
Superordinated instrumentation and control or
process visualization systems are available as
options.
... for increased productivity:
Fully automatic, disruptionfree production
process.
Utilization of the full capacity of the system,
minimal downtimes, high system availability.
Ability to change over the production process
rapidly and without problems to other products,
other raw materials or other processes.
High flexibility permitting small quantities to be
manufactured economically for just-in-time delivery.
Enhancement of competitiveness on the market.
Rapid amortization of invested capital.
10
The know-how…
Existing system parts can continue to be used
even following expansion of capacity.
Systems can also be used for other products.
The process carried out by a system (e.g. vacuum
casting, atmospheric casting, pressure gelation
and vacuum pressure gelation) can be changed
easily.
Ability to add additional casting stations supplied
in parallel from a central material preparation,
mixing and metering system.
Fully automatic, disruptionfree production speeds up
amortization of the capital
invested and increases competitiveness. This is what the
Know-How To Be Your Best
means.
…for greater flexibility
on the market:
VTH has cost-favourable systems to permit low
initial investment costs. These systems can be
expanded subsequently - again in a cost-favourable
manner.
Output can be increased and production costs
reduced as the market and sales grow.
Ability to react flexibly to new opportunities as
they arise on the market.
Examples of VTH systems
providing innovative solutions for special problems.
Absolutely bubblefree casting at atmospheric pressure with heavily filled epoxy
resin and an extreme resin/hardener mix ratio of 100 : 10 parts by weight.
• This system is used to cast semiconductors containing ceramic components and
this in turn means that casting cannot be carried out under vacuum.
To produce parts able to withstand high thermal loading, a fully homogeneous structure
must be achieved with a filled material.
• The components are prepared and mixed under vacuum.
• Casting is carried out at atmospheric pressure fully automatically, without drips and
with high precision in terms of the quantity metered out and the point of casting.
• The photo shows the complete system with metering-mixer, casting table and switch
cabinet with monitor and process data printer.
Finding a solution for every problem is an area where VTH is constantly making
use of its know-how and experience.
• Here a resin system curing at room temperature had to be selected for casting
the pressuretight and seawater-resistant jacketing of underwater pumps.
• Using a highly reactive PUR system with a potlife of just 4 minutes, this system
carries out casting under vacuum and with absolutely no bubbles.
• Following casting the casting chamber is returned to atmospheric pressure in just
a few seconds. The pressure difference of ∆p = 1 bar presses the mix into the
spaces to be sealed or impregnated.
• To increase the production capacity, the system uses 2 pallets to supply the 2
casting chambers arranged in parallel.
Reducing the curing time pays.
The graphic on the right shows the influence of pressure on the speed and degree of impregnation.
VTH offers three alternative solutions for reducing the impregnating or curing time.
1. Pressure chamber downstream of the vacuum casting chamber - see system example
on pages 4/5.
2. Application of pressure in the casting chamber following casting under vacuum (vacuumpressure chamber) - see system example on page 6.
3. Pressure curing in a pressure curing oven - see example below on this page.
The know-how to be your best: VTH is the master of all the relevant system technologies for
the processing of highly reactive material and the shortening of impregnating and curing times.
Use of a new, rapid-curing cationic resin material for the large volume production
of line transformers.
• Instead of requiring 120 °C for 6.5 h, the material saves energy by curing at 75 °C
in just a few minutes. At 20 °C the reactive mixture has a latency of over 20 h and
remains stable during this time.
• The very fast cross-linking reaction starts at 65 °C. A pressure difference of ∆p = 1
bar between vacuum casting and application of atmospheric pressure would not be
sufficient to give good impregnating of fine-wire windings.
• For the new resin material, VTH developed and built the appropriate mixing and
metering system in co-operation with the resin manufacturer and system user.
• The line transformers, which have been cast under vacuum, are impregnated and
cured in the pressure curing oven with ∆p = 6 bar in just a few minutes.
• Compared with conventional materials for diode split transformers, the material
shown here reduces the manufacturing time by 87%, the investment costs by
20%, the spare part and stockholding costs by 75% and the space requirement
by 65%.
• In addition to the time savings and improvements in productivity, there are also
improved product properties such as lower shrinkage and higher moisture resistance.
The system requires no solvents or cleaning agents and there is almost no wastage
of resin at the start and end of the production process.
Degree of impregnation as a function
of pressure and time
Degree of impregnation (%)
∆p = 6 bar
∆p =1 bar
Time
11