Level sensors at the conveyor ’ s inlet and discharge are linked to the sachet filler ’ s controls , enabling both units to operate in sync .
He learned that the operation would improve if the powder could free fall into the metal detector in a steady stream . One possible solution would be to add a rotary valve under the surge hopper , but lack of headspace made that impossible , Phua says . Instead , Flexicon recommended offsetting and raising the metal detector , allowing room to add a new flexible screw conveyor to feed powder to the metal detector in a steady , controlled flow . Flexicon Singapore provided the new conveyor to accommodate spatial constraints and throughput requirements .
The conveyor is 1.5 m ( 59 in .) long and includes a spiral enclosed in a 90 mm ( 3.5 in .) diameter outer tube made of ultrahigh-molecular-weight polyethylene . The screw — the only moving part that contacts the product — ensures that the powder does not pack , cake or separate .
The conveyor includes a 150 mm ( 5.9 in .) diameter inlet flange and charging adapter that connects under the surge hopper ’ s butterfly valve . From there , the powder is transported at a 41-degree angle and discharges into the metal detector through a 150 mm ( 5.9 in .) diameter downspout . The conveyor ’ s 2.2 kW ( 1.3 hp ) drive turns at a constant speed to transport about 720 kg ( 1,587 lb ) of powder per hour for 20 hours a day . Level sensors at the conveyor ’ s inlet and discharge are linked to the sachet filler ’ s controls , enabling both units to operate in sync .
Above , contaminant-free powder gravity feeds from the raised metal detector ( top right ) and is transported by the flexible screw conveyor to the sachet filler .
Above , The conveyor screw is driven beyond the point of material discharge , preventing MILO drink mix powder from contacting seals or bearings . Left , Nestlé Singapore packages 720 kg / hour ( 1587 lb / hour ) of healthful MILO drink mix powder .
Regulated flow improves detection , cuts downtime
According to Phua , the new flexible screw conveyor has streamlined the operation . “ All strikes are rejected before the powder enters the original flexible screw conveyor to the sachet filler ,” he says , “ eliminating false rejections and manual clearing of powder from the conveyor .” His colleagues in the quality-assurance department welcome the improvement . “ Because we have more positive rejection from the metal detector , quality assurance people have less worry about contaminants not being rejected .”
More reliable rejection boosts productivity by increasing sachet filler uptime and reducing incident reporting , while conserving product . “ Previously , large chunks were being rejected . Now as a freefall , less powder is flowing , which reduces product loss by a good amount ,” he concludes .
Flexicon ( Europe ) Ltd . + 44 1227 374710 | sales @ flexicon . co . uk www . flexicon . co . uk
FDPP - www . fdpp . co . uk 7