Temposonics
®
Magnetostrictive, Absolute, Non-contact
Linear-Position Sensors
Load-Frame Monitoring for
Injection-Molding Machines
®
SENSORS
Document No.: 551068
Revision A
Case Study
Injection-molding machine manufactured by Negri & Bossi
Background
Negri & Bossi S.P.A., a leading plastic injection-molding press
manufacturer, discovered an innovative way to measure tonnage
while reducing the amount of costly mechanical and electrical
hardware on its machines. By using a high resolution MTS
Temposonics R-Series sensor, Negri & Bossi can now offer its
customers better performance at a lower cost.
Located in Cologno Monzese, Italy, Negri & Bossi has manufactured injection-molding machines for the plastics industry for more
than 50 years. The plant’s staff of 270 produces an average of 800
injection-molding machines per year. These machines are used to
manufacture general purpose plastics products.
Typically, accessory clamps and strain gauges are used on
injection-molding machines to measure tonnage. Recently, Negri
& Bossi devised an easier, more cost-effective method by using
the high resolution of the R-Series microprocessor-based position
sensors with special embedded software. The sensors measure
tonnage continuously by measuring the stretch of the load frame.
Multi-magnet Output Capability
The Temposonics R-Series sensor, with a CANbus interface, allow
the outputs of four axes to be monitored - the injector, the ejector,
the clamp and the carriage. The sensor monitoring the clamp
has two magnets, one of which is used to save the peak position
reached during each cycle and compare it with the commanded
position. The difference between the two measurements, which
is uploaded to the controller as peak values at the end of each
machine cycle, shows the amount of stretch in the load frame
columns. The press controller then calculates the strain/force,
which is used to adjust the tonnage on successive cycles.
The second magnet monitors ejector position, eliminating the need
for a second sensor. The injector carriage and injector screw are
monitored by a single sensor on the other end of the injectionmolding machine, thus reducing the normal four sensors to two.
This use of the R-Series multiple magnet sensing capability - which
can measure to 15 positions with a single sensor - saves on sensor
costs while providing the benefits of a networked sensor solution.
Engineer Maurilio Meschia, technical manager for Negri & Bossi
was familiar with the high-accuracy positioning of the Temposonics
linear-position sensors. However, it was the new R-Series sensor
performance supported by a CANbus interface that convinced
Engineer Meschia to try the sensor. "By installing the multiple
magnet sensors, we were able to use fewer sensors and eliminate
the use of special strain gauges while still achieving equal or better
data. We tested various other manufactures sensor products and
found only the Temposonics R-Series sensors could give us the
performance and flexibility we needed."
The Temposonics intelligent sensors use special electronics and
software through the CANbus interface to send fast, accurate,
and repeatable measurements. The rapidly updated standard
resolution of 2 microns, the best in the industry, allows the sensors
to measure minute changes in the position of the platen on the
tie bars. CANbus interface consists of multiple microprocessors
distributed in a “Control Area Network” and built around a “bus”
architecture in which several computer components share a digital
communications pathway. MTS Sensors supports both a CAN open
version and a DeviceNet version of CANbus.
All specifications are subject to change. Contact MTS for specifications and
engineering drawings that are critical to your application. Drawings contained
in this document are for reference only. Go to http://www.mtssensors.com for
the latest support documentation and related media.
Non-Contacting Technology
Temposonics R-Series sensors feature a magnetostrictive design
which uses a non-contacting technology, which eliminates
maintenance and premature failure problems commonly associated
with other position sensing methods. The waveguide assembly and
electronics are each fully encapsulated, allowing for more durability
in rugged, industrial environments.
Negri & Bossi now specifies Temposonics R-Series sensors with a
CANbus interface on all their new injection-molding machines. The
high resolution and accuracy inherent in the Temposonics design
has allowed Negri & Bossi to offer its customers better quality and
performance at a lower cost.
Both V370 and V480 injection-molding machines, which were the
first Negri & Bossi machines to feature Temposonics sensors,
were first introduced at the Plast ‘97 Show in Milan. In addition to
eliminating the load cell, Negri & Bossi has also opted to replace the
linear potentiometers, used for positioning, with Temposonics position sensors. According to Engineer Maurilio Meschia, the improved
quality and performance of the machines is directly attributable
to the accuracy and resolution of the R-Series sensor. "We have
switched all of our series to the new Temposonics R-Series system
with CANbus interface."
Part Number: 551068 Revision A 12-05, 02-09
MTS and Temposonics are registered trademarks of MTS Systems Corporation.
All other trademarks are the property of their respective owners.
All Temposonics sensors are covered by US patent number 5,545,984. Additional patents are pending.
Printed in USA. Copyright © 2009 MTS Systems Corporation. All Rights Reserved in all media.
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®
SENSORS