Plastics & Rubber World - September/October 2019 - 38

case study

Kistler supports premium
quality at Husqvarna
robotic lawnmower
manufacturer improves
plastic part finishing
using Kistler systems

Robotic lawnmower from Husqvarna

Photo: Husqvarna UK

Photo: IPR

Remote monitoring of machine
performance

usqvarna Group is a leading global producer of outdoor power
equipment. In the UK, the facility in
Newton Aycliffe, County Durham, focuses
on robotic lawnmowers. One unit is produced every 30 seconds for UK and international distribution.
Designed to be completely weatherproof, the robotic lawnmowers are primarily assembled from injection moulded parts, with motors, circuit boards and
batteries housed in sealed plastic modules. This means the in-house injection
moulding facility must keep pace with the
assembly line.
Large mouldings, such as the main
body, are technical structural parts which
must also maintain a high cosmetic finish.
In 2015, reject rates were higher than desired, requiring a review of the production
process.
Having looked at a series of solutions,
the injection moulding team elected to
use Como Injection, a cavity pressure system from Kistler Instruments. Trials on a

Injection moulding machine fitted with Kistler ComoNovo system

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Sandretto 820T machine virtually eliminated overpacking and mould damage,
resulting in a less than 1% rejection rate.
The Como Injection system further
produced 137 consecutive parts from a
cold start without a single reject, which led
to the system being installed on a further
seven machines.
When Kistler launched ComoNovo, a
new version of its cavity pressure monitoring system, Gary Blenkinsopp, technical and tooling manager, found that unlike
Como Injection, the new system could
self-optimise the machine changeover
position after just a few cycles. It could
also compensate automatically for small
variations in ambient temperatures and
material consistency.
But with Husqvarna's demand for dimensional stability and cosmetic quality,
it was the active feedback supporting ideal timing for the switchover from speed
to pressure control in response to cavity
pressure which was of the greatest interest. The automatic switchover control SLP
(Switch Level Process) provided automated setup and optimisation from cycle to
cycle.
"I was sceptical it would actually work,"
said Blenkinsopp. "But when we switched
it on for the first time it automatically optimised and set up the switch over. Shot-toshot variation was medical standard."
On the back of this performance, five
more ComoNeo systems were ordered,
with ROI forecast over months, instead of
years.
Data from the ComoNeo-equipped machines is networked to a single PC, where
tooling and process technicians can remotely monitor machine performance.
Both new and older machines benefit from
the control provided by ComoNeo, helping to deliver a reliable supply of premium
products to the assembly line, while ensuing the injection moulding machines are
operating at peak efficiency.

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Plastics & Rubber World - September/October 2019

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