Hot Runner Injection

The Purging Process in Hot Runner Injection Molding Machines
1
Preparation

At this stage, the granule loader and the dryer are separated from the feeding unit so that the purging mixture can be fed directly to the screw.

Preparing the Machine
2

All injection screw temperatures are reduced below the current temperatures by 20°C -30°C.

See TEMPERATURE/RATIO table for purging screw temperatures.

Hot runner and nozzle temperatures are increased to 50°C above their current temperatures.

3
Preparation of the Purging Mixture

Shake the CLEANAAX® or CLEANAAX®GF bottle well before use.

3%-4% CLEANAAX® or CLEANAAX®GF is mixed well into the new granules that you will feed into the machine. See the SCREW DIAMETER/MIXING AMOUNT table for the amount of mixture.

Purging
4

It is checked that the screw temperatures have dropped by 20°C-30°C. It is checked that the hot runner and nozzle temperatures increase by 50°C.

The screw material intake speed is reduced by 50% or slightly less. The prepared mixture is fed into the machine from the feeding unit.

The back pressure is slightly increased.

The main injection pressure is used for the purging process.

During the purging process, if necessary, the reduced screw temperatures can be brought back to normal values so that the purging mixture can exit from the nozzle more smoothly.

The mold can be left open and this mixture can be injected into the hot runner and cleaned in the hot runner if desired.

5
Rinse and Check

The granules that you will feed into the machine are passed through the machine in a pure form with a minimum of 30% of the purging mixture.

If the raw material that comes out is clean, the operation is finished and new molding is started. If there is still any residue, steps 2-5 are repeated.

Finish
6

Check if there is any purging mixture left in the feeding unit.

The injection screw temperatures, the hot runner and nozzle temperatures, the back pressure, and the screw revolution are adjusted according to the new material.

The machine is ready for new molding.

Video Explanation

 
Processing Temperature (°C)Purging Screw Temperature (°C)Amount of CLEANAAX® and CLEANAAX®GF in the Purging Mixture
(%gr/1 kg)
Acrylnitrile-butadienes styrene ABS 200-220 170-190 3-4 30-40
Styrene-acrylonitrile SAN 200-220 170-190 3-4 30-40
Thermopasticpolyurethane TPU 200-220 180-200 3-4 30-40
Polyethylene HDPE/LDPE 180-220 150-190 3-4 30-40
Polypropylene PP 180-220 150-190 3-4 30-40
Polycarbonate PC 240-280 210-250 3-4 30-40
Polyethyleneterephatalate PET 180-220 150-190 3-4 30-40
Polybuthyleneterephatalate PBT 230-270 200-240 3-4 30-40
Polyvinylchloride PVC 160-180 - 4 40
Polystyrene PS 200-220 170-190 3-4 30-40
Polyoxymethylene POM 170-210 140-180 3-4 30-40
Polyamide 6 PA6 220-260 200-230 3-4 30-40
Polyamide 6-6 PA66 260-290 230-260 3-4 30-40
Polymethyl methacrylate PMMA 200-230 170-200 3-4 30-40
Styrene-butadiene-styrene SBS 170-180 140-150 3-4 30-40
Styrene-ethylene-butadiene SEBS 180-200 150-170 3-4 30-40
Cellulose-acetate CA 230-260 200-230 3-4 30-40
Polyphenylenesulfide PPS 310-340 280-310 3-4 30-40
Polyether ether ketone PEEK 350-380 320-350 3-4 30-40
Polysulfone PSU 350-370 320-340 3-4 30-40
Polyphtalamide PPA 310-330 280-300 3-4 30-40
Ethylene vinil acetate EVA 200-220 180-200 3-4 30-40
Polyether sulfone PESU 350-380 320-350 3-4 30-40
Polyetherimide PEI 350-380 320-350 3-4 30-40
Polyketone PK 240-260 220-230 3-4 30-40
Screw Diameter
(mm)		 20-40 40-50 50-60 60-80 80-100 100-120 120-150 150-175 175-200
Amount of carrier plastic raw material, kg 0,5-1 kg 1-3 kg 3-5 kg 5-10 kg 10-25 kg 25-35 kg 35-70 kg 70-90 kg 90-150 kg
Amount of CLEANAAX® and CLEANAAX®GF , gr. 3-4% of the total carrier polymer, gr. 15-40 gr 30-120 gr 90-200 gr 150-400 gr 300-1000 gr 750-1400 gr 1050-2080 gr 2100-3600 gr 2700-6000 gr
  • The recommended approximate values depend on screw configuration and the level of contamination.
  • CLEANAAX® and CLEANAAX®GF is compatible with all known commercial polymers and processing temperatures up to 400°C.
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