gefran VDA-M User manual

INSTRUCTION MANUAL
Two or three channels amplifier
VDA-M
code: 80043
80043_VDA-M_12-2020_ENG

80043_VDA-M_12-2020_ENG 1
Index ...................................................................................................................................................................... 1
Introduction........................................................................................................................................................... 2
Device Data ....................................................................................................................................................................................................2
Warnings and Safety ......................................................................................................................................................................................2
Disposal 2
Disclaimer.......................................................................................................................................................................................................2
Copyright........................................................................................................................................................................................................2
1. General Description ..................................................................................................................................... 3
1.1. Profile ...................................................................................................................................................................................................3
1.2. VDA-M..................................................................................................................................................................................................4
1.2.1. Dimensions...................................................................................................................................................................................4
2. Installation .................................................................................................................................................... 5
2.1. Mounting the Amplifier.........................................................................................................................................................................5
2.1.1. General installation rules ..............................................................................................................................................................5
2.1.1.1. Protection against infiltration of dust and water.................................................................................................................5
2.1.1.2. Minimum space for ventilation ...........................................................................................................................................5
2.1.2. Positioning....................................................................................................................................................................................5
2.2. Connections.........................................................................................................................................................................................5
2.2.1. General rules for connections ......................................................................................................................................................5
2.2.2. Connectors...................................................................................................................................................................................5
2.3. Connection Diagrams ..........................................................................................................................................................................6
2.3.1. Electrical Connection Sensor Side...............................................................................................................................................6
2.3.2. Electrical Connection PLC Side ...................................................................................................................................................6
3. Operation ...................................................................................................................................................... 7
3.1. Power-on..............................................................................................................................................................................................7
3.2. Calibration............................................................................................................................................................................................7
3.2.1. Calibration of clamping force .......................................................................................................................................................7
3.2.2. Calibration of mold protection......................................................................................................................................................7
3.2.3. Calibration of cavity pressure profile............................................................................................................................................7
3.3. Control During Molding Operations .....................................................................................................................................................7
3.4. Molding Cycle ......................................................................................................................................................................................8
3.5. Reset ....................................................................................................................................................................................................8
4. Technical Data .............................................................................................................................................. 9
4.1. VDA-M..................................................................................................................................................................................................9
5. Order Methods............................................................................................................................................ 10
5.1. Digital Strain-gauge Amplifier ............................................................................................................................................................10
5.2. Sensors ..............................................................................................................................................................................................10
5.3. Accessories........................................................................................................................................................................................10
6. Operating Principles .................................................................................................................................. 11
6.1. Strain Forces......................................................................................................................................................................................11
6.2. Different Amplifications ......................................................................................................................................................................11
6.3. Ideal Molding Cycle ...........................................................................................................................................................................12
6.4. How to Control Colding .....................................................................................................................................................................12
INDEX
INDEX

80043_VDA-M_12-2020_ENG2
INTRODUCTION
INTRODUCTION
Device Data
Warnings and Safety
In the space below, write the order code and other plate data
shown on the label attached to the outside of the amplifier.
If you need technical assistance, this information must be
given to Gefran Customer Service.
Make sure that you always have the latest version of this
manual, downloadable at no cost from Gefran’s website
(www.gefran.com).
The devices described in this manual must be installed
by trained personnel in conformity to current laws and
regulations, following all of the instructions in this manual.
VDA-M
Serial No.
Description
Installers and/or maintenance personnel MUST read this
manual and scrupulously follow all of the instructions
contained herein and in the attachments.
Gefran will not be liable for any damage/harm caused to
persons and/or property, or to the device itself, if all of such
instructions are not followed.
Disclaimer
Copyright
Although all of the information in this manual has been
carefully checked, Gefran S.p.A. assumes no liability
regarding the presence of any errors or regarding damage to
property and/or harm to individuals due to any improper use
of this manual.
Gefran S.p.A. also reserves the right to change the contents
and form of this manual, as well as the characteristics of the
devices described herein, at any time and without notice.
The technical data and performance levels specified in this
manual are to be considered a guide for the user in order to
determine the device’s suitability for a defined use, and do
not constitute a guarantee.
They may be the result of test conditions at Gefran S.p.A.,
and the user must compare them to his/her real application
requirements.
Under no circumstances will Gefran S.p.A. be liable for
any damage to property and/or harm to individuals due to
tampering, incorrect or improper use, or use not conforming
to the characteristics of the amplifier to the instructions
contained in this manual.
This manual and its attachments may be freely reproduced
provided its contents are not changed in any way and
provided every copy includes the above Disclaimer and the
statement of ownership of Gefran S.p.A.
Gefran and Sensormate are registered trademarks of Gefran
S.p.A.
This manual may make reference to or reproduce trademarks
and logos of third parties. Gefran S.p.A. acknowledges such
parties’ ownership of these trademarks and logos.
Disposal
The amplifier VDA-M must be disposed of in conformity to current laws and regulations.
If not correctly disposed of, some of the components used in the devices may harm the environment.

80043_VDA-M_12-2020_ENG 3
1. GENERAL DESCRIPTION
1. GENERAL DESCRIPTION
1.1. Profile
The variable digital amplifier, with PLC and strain sensor,
checks the correct functioning of molding machines with
toggle clamping to protect the machine and the mold.
The model VDA-M monitors the cavity pressure profile,
optimizing the injection cycle and therefore the molded
product.
By means of a single strain sensor, the amplifier generates
three independent signals for three molding process
parameters.
The sensor generates the signals based on the different
strains on the machine during the molding cycle.
The signals are amplified with different factors to give the
PLC the maximum signal level to be processed at all times.
The amplifier manages the following molding cycle
parameters:
• Clamping force, i.e., the force exerted by the machine
to close the two mold halves. If a deviation from the
reference clamping force is detected, there is a problem
with clamping the mold.
• Mold protection. Measuring strain while the mold is
being closed and comparing it to the reference strain
level can signal possible foreign bodies between the
mold halves, with risk of damage to the mold.
• Cavity pressure profile. By comparing the cavity pressure
profile generated during injection and molding with the
reference profile, the PLC, in case of strain, can warn
the operator that the molded product does not satisfy
expected quality criteria. The cavity pressure profile can
be measured only if the sensor is attached to one of the
molding machine tie bars.
The amplifier is powered directly by the PLC, which can be
positioned up to 30 meters from the amplifier.
The amplifier is intended mainly for molding machine
manufacturers because the correct settings must be
guaranteed in the PLC.
PLC
VDA-M
max 30 m
System architecture
Molding machine
Strain
sensor

80043_VDA-M_12-2020_ENG4
1. GENERAL DESCRIPTION
1.2. VDA-M
Main features
• Solution for:
– Clamping Force measurement
– Mold Protection
– Cavity Pressure Profile monitoring
• Only one sensor mounted either on the tie-bar or on the
toggle
• Usable on injection molding machines with toggle lever
1.2.1. Dimensions
16.5
18.5
16.5
37
30

18.5
5.5
R7
92 16
23 37
7
7 110
124
Dimensions in mm

80043_VDA-M_12-2020_ENG 5
2. INSTALLATION
2. INSTALLATION
Attention! The devices described in this manual must be installed by trained personnel in conformity to current laws
and regulations, following all of the instructions in this manual.
Before installing, check that the amplifier is in perfect condition and was not damaged in shipment. Make sure that
the package contains all of the accessories listed on the accompanying document.
Check that the order code matches the configuration required for the intended application (supply voltage, number
and type of inputs and outputs). See Chapter ”5. Order Methods” on page 10 to check the configuration
corresponding to each order code.
Attention! If even one of the requirements mentioned above (trained technician in, device in perfect condition,
correct configuration) is not satisfied, interrupt the installation and contact your Gefran dealer or Gefran Customer
Service.
2.1. Mounting the Amplifier
2.1.1. General installation rules
The amplifier is designed for permanent indoor installation.
2.1.1.1. Protection against infiltration of dust and water
The amplifier has an IP65 protection index, so the device can
be installed without problems in rooms that are very dusty or
subject to splashing water.
2.1.1.2. Minimum space for ventilation
The temperature in the housing containing the amplifier must
NEVER exceed 85 °C.
Advice. The lower the temperature in which the
device works, the longer the life of its electronic
components.
2.1.2. Positioning
Fasten the amplifier to a sufficiently rigid and robust support.
Use the four through holes on the amplifier and M5 screws
or bolts.
2.2. Connections
Attention! Failure to follow the instructions in this
section may cause problems in electrical safety and
electromagnetic compatibility, in addition to voiding
the warranty.
2.2.1. General rules for connections
1. Connected external circuits must have double isolation.
2. Use twisted and shielded cables for connections.
3. The shield of the shielded cables must be grounded at a
single point (amplifier connector side).
4. Do not connect unused terminals.
5. Secure the cables so that mechanical forces are not
exerted only on the connectors.
6. 24 VDC models must be powered by a class II or
low-voltage limited-energy source. The power supply
must use a line separated from the one used for
electromechanical power devices, and low-voltage
power cables must run along a path separated from the
system or machine power cables.
7. Make sure the ground connection is efficient. Absent or
inefficient grounding can make the device unstable due
to excessive noise.
8. To prevent noise, the sensors cables must be kept away
from the power cables (high voltages or high currents).
9. The amplifier cables and the power cables must not be
placed parallel to one another.
2.2.2. Connectors
The Gefran catalog offers cables pre-fit with the M12
connector. See table ”5.3. Accessories” on page 10 for
order codes.

80043_VDA-M_12-2020_ENG6
2. INSTALLATION
2.3. Connection Diagrams
2.3.1. Electrical Connection Sensor Side
2.3.2. Electrical Connection PLC Side
5
4
1
2
6
3
Sensor 4/4 bridge M16 6-pin
PLC M12 8-pin
PLC M12 12-pin
Excitation +
Signal +
Excitation -
Signal -
MP : Mold Protection
CF : Clamping Force
CPP : Cavity Pressure Profile
The cable (between amplifier and control system) must be shielded, the maximum length must be 30 meters and the
shield must be connected on connector side only (floating on control side)
Connector
PIN Function
1 Excitation +
2 Excitation +
3 Excitation -
4 Signal +
5 Signal -
6 Excitation -
Connector
PIN Function
1 Power 12...36 VDC
2 CF Signal -
3 Power GND
4 CF Signal +
5 Reset CF signal
6 MP or CPP signal -
7 MP or CPP signal +
8 Reset MP or CPP Signal
Connector
PIN Function
1 Power 12...36 VDC
2 CF Signal -
3 Power GND
4 CF Signal +
5 Reset CF signal
6 MP signal -
7 MP signal +
8 Reset MP signal
9 CPP signal -
10 CPP signal +
11 Reset CPP signal
12
6
2
3
1
4
5
8
7
6
2
3
1
12
10
11 4
5
8
7
9

80043_VDA-M_12-2020_ENG 7
3. OPERATION
3. OPERATION
3.1. Power-on
Power is supplied by the PLC to which the amplifier is
connected; therefore, the amplifier is powered on and off
simultaneously with the PLC.
The amplifier is completely operative 0.5 seconds after
power-on.
3.2. Calibration
3.3. Control During Molding Operations
The data stored during calibration are used as a reference to
detect any problems during molding operations.
With regard to the amplifier, a molding cycle starts at mold
opening and ends at re-opening of the mold after another
molding.
The PLC has to perform the following operations:
• Activation of the reset signal for clamping force (Reset
CF) from mold opening to the start mold clamping
(closing of the two mold halves).
• Comparison of the strain curve generated during closing
with the reference curve stored during calibration.
If measured values exceed the set tolerance band, you
must stop the machine immediately to protect the mold.
During the transition from “closed mold” to “clamped
mold” the reset signal is activated to protect the mold
(Reset MP).
• Measurement of injection cycle signal, from
which the “mechanical relaxation” signal stored
during calibration is subtracted. The resulting
signal is the cavity pressure signal generated
by the mold opening force caused by injection.
This lets you check correct mold filling (attention: this
does not measure absolute cavity pressure value, but
compares the measured profile to the ideal injection
profile).
Before working, you have to calibrate the following signals:
• clamping force;
• mold protection;
• cavity pressure profile.
Run about a dozen of dry molding cycles (without injection),
measure the data, and calculate the average to obtain
reference values for calibration.
3.2.1. Calibration of clamping force
Clamp the mold by applying the clamping force and measure
the strain either on the tie bars (with the GE1029 sensor) or
on the platen on toggle (with the SB46 sensor).
The measured value, which typically differs from the sensor’s
full-scale value, will be set on the PLC as a value equal to
100% of the mold clamping force.
You can convert from μεto tons / kN with the Gefran QE1008
measurement system.
3.2.2. Calibration of mold protection
Run a dry molding cycle (without injection) and store the
values during mold closing.
Using this strain curve as average value, set a tolerance
band on the PLC (depending on the mechanical noise of the
molding machine), which will be the allowed tolerance during
molding operations.
3.2.3. Calibration of cavity pressure profile
We measure actually the mold-breathing or mold opening
caused by the cavity pressure (F = area multiplied by the
pressure in the cavity). This leads to a – very small – stretching
of the tie bars. This stretching is proportional to the cavity
pressure, thus we can gain the cavity pressure profile.
But this signal is superimposed to the relaxation signal of the
machine after the machines is locked.
Clamp the mold and store the decreasing signal deriving
from the reduction of clamping force.
The relaxation takes always place and is 0.5 to 1.5% of full
locking force and is different with softer or stiffer molds.
In order to separate these 2 signals:
1) Lock the machine and reset the CPP signal.
2) Wait 10 seconds (this is NOT used during manufacturing,
just set-up).
3) Reset again (signal is now zero and stable).
4) Now start Injecting: the cavity pressure profile is
displayed.

80043_VDA-M_12-2020_ENG8
3. OPERATION
3.4. Molding Cycle
3.5. Reset
To run a Reset, supply voltage from 12 and 36 V for at least
the reset time selected in the order code (see datasheet,
there are no limits to longer durations) to the Reset input of
the function in question.
For normal function operation, there have to be 0 V (open
contact) at the input.
10
0
12
36
V
t
20
30
ON
Reset CF
Reset MP
Reset CP
OFF
ON
1 2 3 4
OFF
ON
t
OFF
Attention! The duration of the various cycle steps is off-scale.
Closing Mold protection Mold clamping Injection Opening
1) Deactivate Reset CF before mold closing.
2) Deactivate Reset MP just before the mold is clamped.
3) Deactivate Reset CP after the mold is completely clamped and before starting injection.
4) Activate Reset CF, Reset MP and Reset CP during mold opening.
Operative OperativeReset

80043_VDA-M_12-2020_ENG 9
4. TECHNICAL DATA
4. TECHNICAL DATA
4.1. VDA-M
Clamping force output
(CF)
Mold protection output
(MP)
Cavity pressure profile
output (CPP)
Linearity < ± 0.02% FS < ± 0.02% FS < ± 0.02% FS
Output signal Voltage
Accuracy at room temperature 1< ± 0.2% FS < ± 1% typ. (< ± 2% max.) < ± 1% typ. (< ± 2% max.)
Signal input range (FS) 0.1…3.00 mV/V
(100…3000με)
0.02…0.10 mV/V
(20...100με)
0.02…0.10 mV/V
(20...100με)
Output resolution 16 bit 16 bit 16 bit
Sampling rate 1kHz 1kHz 1kHz
Low-pass filter 100 Hz 100 Hz 100 Hz
Case material Aluminum anodized
Reset time see Order code
Reset voltage 12…36 VDC
Supply voltage 12…36 VDC
Power consumption 0.6 W
Allowed load ≥5 kΩ
Operating temperature range -40…+85 °C
Storage temperature range -40…+100 °C
Temperature effects ± 0.01% FS/°C ± 0.02% FS/°C ± 0.02% FS/°C
Weight ∼165 g
Protection class IP65
Output short circuit protection Yes
Reverse polarity protection Yes
Dielectric strenght 2250 V
EC Conformity A According to Directive 2014/30/EU
1) incl. Non-linearity, Hysteresis, Repeatability, Zero-offset and Span-offset
2) Uses 50 V 2J Voltage suppressor
The three output ranges are from 0 up to ±12 V.
The amplifier has an integrated sensor cable breakage detection. In the event of an interruption in one or more sensor lines,
the output voltage increases or decreases to a value ±11.5 V ... ±12 V.
In order to properly use the cable breakage detection it is suggested to use the amplifier only in the range ±10.0 V and to
make sure that the amplifier is reset after every machine cycle.

80043_VDA-M_12-2020_ENG10
5. ORDER METHODS
5.1. Digital Strain-gauge Amplifier
5.2. Sensors
5.3. Accessories
Code F Model Clamping force Mold Protection Cavity profile
F085238 VDA-M-H-L-D-4-0500-0020-0000-H1-HR14-O  
F085239 VDA-M-H-L-N-4-0500-0030-0000-H2-HR11-O  
F085240 VDA-M-H-L-N-4-0500-0050-0000-H2-HR11-O  
F085241 VDA-M-H-L-N-4-0500-0000-0050-H2-HR11-O  
F085243 VDA-M-H-S-N-4-0500-0020-0050-H2-HR11-O 
GE1029
Code F Model Full Bridge Cable length
(m)
Cable and
connector
F075851 GE1029-4-005-C 0,5 
F066943 GE1029-4-030-C 3
F071301 GE1029-4-050-C 5
F066913 GE1029-4-100-C 10 
SB46
Codice F Model Connettor Full Bridge Lunghezza
cavo (m)
Cavo e
connettore
F069688 SB46-A1-4-030-X 90° 3
F071298 SB46-A1-4-050-C straight 5
The sensors are special versions of the GE1029 (bar strain sensor) and SB46 (press-on strain sensor).
The SB46 sensor is applicable only on the toggle, and therefore does not measure the cavity pressure profile.
Please contact Gefran for information on compatibility with other sensors.
Code Description
TE-E-0591_00 Female connector M12 8-pin
F085191 2 meter cable with female connector M12 8-pin
F085192 5 meter cable with female connector M12 8-pin
F085193 10 meter cable with female connector M12 8-pin
F085232 15 meter cable with female connector M12 8-pin
TE-E-0590_00 Female connector M12 12-pin
F085233 2 meter cable with female connector M12 12-pin
F085234 5 meter cable with female connector M12 12-pin
F085236 10 meter cable with female connector M12 12-pin
F085237 15 meter cable with female connector M12 12-pin
5. ORDER METHODS

80043_VDA-M_12-2020_ENG 11
6. OPERATING PRINCIPLES
6. OPERATING PRINCIPLES
During the cycle, the molding machine clamping system
exerts a variable force to clamp the mold halves and keep
them clamped during injection.
This force, applied by reaction to the machine structure,
causes strain on some of its parts.
The strains are instantaneously proportional to the force
exerted.
6.1. Strain Forces
6.2. Different Amplifications
The molding machine is subject to limited absolute strains
even if very high forces are exerted.
By measuring strain in με(microstrain), which is a
dimensionless unit of measure corresponding to a change in
length of 1 μm per meter, it is clear that this value changes
considerably during the various steps of the molding cycle.
Approximately, by setting the strain (and thus the force
needed to clamp the mold) to 1, the mold clamping force is
over 50 and the injection force is about 5.
This means that the very small signal generated by the strain
sensor has to be amplified with different factors to have
significant full-scales for correct measurement of strains.
Therefore, by measuring the strains, you can calculate the
force exerted by the clamping system.
This force measurement criterion can be applied only to
machines with toggle clamping system.
On machines with hydraulic piston clamping, the elasticity of
the hydraulic fluid prevents the force/strain correlation.
Therefore, the technical solution adopted so far involves
differentiated sensors and amplifiers for the various steps of
the molding cycle.
Instead, the Gefran solution employs a single sensor whose
signal is amplified by a variable amplifier to satisfy the various
steps of the molding cycle.
Time/strain diagram of a complete molding cycle
t
με
Closing
Protection of mold
during closing
Optimization of
injection cycle
Monitoring of
clamping force
The graph uses different strain scales (με) to better describe the various profiles.
The graph in the small box shows the same profiles using a single strain scale.
Clamping Injection

80043_VDA-M_12-2020_ENG12
6. OPERATING PRINCIPLES
For every molding machine and every type of production, the
molding cycle can be represented as a continuous variation
of the force applied to the mold as a function of time.
By running a dry molding cycle with precise control of all
operating conditions, you can create a time/force profile
representing the ideal molding cycle, i.e., one that guarantees
best product quality and longest machine life.
Ideally, during production, each molding cycle must be
identical to the previous one to ensure constant results.
In reality, each cycle is slightly different from the others in
terms of applied force and time taken.
These slight differences between one cycle and another do
not affect the final product or machine life provided they
remain within allowed limits of tolerance.
During the molding cycle, by comparing strain sensor data
with the stored sample cycle data you can immediately note
any problems, indicated as the exceeding of tolerance limits.
The PLC performs this check in real time, and therefore can
also stop the machine immediately (before any damage is
done) or promptly warn the operator that the produced piece
does not meet the required quality standards.
In both cases, the company saves money.
During mold closing, a force exceeding allowed limits may
mean either that there is a foreign body between the mold
halves (excess force) or that the two mold halves are not
perfectly closed (insufficient force).
The following graph shows the typical trend of strains
recorded with allowed tolerances during closing of the mold
halves.
During clamping, you can check that the force exerted on
the mold halves does not exceed the level needed for correct
molding.
Avoiding excess force extends mold and machine life.
The following graph shows the typical trend of strains
recorded during clamping.
6.3. Ideal Molding Cycle
6.4. How to Control Colding
This profile is the sum of the profiles of all the steps needed
to complete the molding cycle.
This sample cycle is used to calibrate the strain sensor reads
during the various molding steps, setting the full-scale for
each and recording the related time/force profile
During injection, a deviation from the ideal profile may
indicate problems with filling the mold (or other problems)
that will produce a defective molded piece, even if not
immediately apparent.
The following graph shows the typical trend of strains
recorded during injection, with indication of possible
deviations and their effect on the quality of the molded piece.
με
με
με
Tolerance band
Ideal profile
Excess strain caused by
foreign body between
mold halves
Overshootting
(with leakage of flash)
Too early injection
release (sink marks)
Filling under
holding pressure
Decrease of clamping force due
to relaxation
t
t
t

GEFRAN spa
via Sebina, 74
25050 Provaglio d’Iseo (BS) Italy
Tel. [phone]
Fax [phone]
[email protected]
http://www.gefran.com