The most common causes of plastic leakage in screw barrels are:
- Frequent change of injection molds on one injection moulding machine (IMM);
- Difference in the radii of the injection bushing of the mould and the nozzle of the IMM;
- Knocking down the injection bushing of the mould;
- When injecting with screw withdrawal at each cycle;
- Automatic operation of the machine without human supervision.
Plastic leaage in Hot Runner System(HRS) can occur in:
- Improper manufacture or assembly of the mould in case of:
o Clearance between nozzle centering ring and cavity plate;
o Clearance between the nozzles and the HRS manifold;
- Knocking of a support plate or insert – because of long-term operation of the mould or low hardness of the steel;
- Injection with a non-tempered mould;
- Excessively high injection pressure, relative to the mould.
What causes plastic leakage?
Any one of the above causes:
- filling with plastic the heaters and thermocouples of the screw barrel or HRS, which in most cases is related to their failure;
- long hours to clean up the leaked plastic;
- suspension of production until the accident is resolved.
How can we prevent auger/GKLS flooding and how does the system work?
Introducing the AIRTECT plastic leakage early warning system.
It works by supplying a minimum amount of air (0.001l/min) with a low pressure of 0.2bar through a tube in areas where there is a risk of plastic leakage.
In the event of an uncontrolled flow of plastic, it clogs the tube, the controller reports an increase in pressure and emits a sound and light signal. After a preset time (standard 10s), the system signals the IMM and it stops to prevent flooding of the screw barrel or hot-runner system.
A short video with a demonstration of the working principle can be found here - VIDEO
Depending on whether you need plastic leakage monitoring of the barrel screw only or also the HRS, the following solutions are available:
- LA500/LM2050 controller for plastic leak detection on 1 screw barrel zone
The LA500/LM2050 controllers have one channel to monitor plastic leakage at the nozzle of the IMM. Additionally, it is possible to connect a manifold to it, to monitor up to 32 zones.
- Controller LA502 for leak detection of 1+1 screw barrel zone
The LA502 controller has two channels for simultaneous monitoring of two screw barrels. As with the other models, there is an additional option to include a manifold to monitor up to 32 zones.
- Manifolds for detecting plastic leaks at HRS
If it is necessary to monitor for leaks at HRS, manifolds with 4, 8, 16, 24 zones can be connected to the above controllers.
- ULTIMATE systems for plastic leaks detection at HRS - closed air circuit 1 or 2 loops.
The system has 6, 12 or 20 zones + an additional closed air loop (1 or 2) for monitoring leakage around the hot runner nozzle heads and manifold
The investment in installing a plastic leak monitoring system pays for itself with the first or second detection of a leak, saving money and time and ensuring reliable operation in production.
More information about the different models of controllers and distributors can be found on our website HERE or by contacting us.
Kind regards
KRASCO