Understanding Three Plate Molds and Hot runner System

BY NAIK DEVANG

MOLDS TYPES

Two plates moldThree plates moldStripper plate moldsStack moldCam action moldHot runner mold

THREE PLATE MOLD

Refers to mold that have top gate

Two opening between three plates

Difference between stripper plate and three plate

THREE PLATE MOLD

THREE PLATE MOLD

MOLD COMPONENT OF THREE

PLATESucker pin to degate the runnerRunner stripper plateStripper & bolts uses to

sequence opening of three plates

WHAT IS HOT RUNNER?

Hot runner is nothing other than “EXTENDED NOZZLE”,ITS SOLE PURPOSE IS TO DELIVER THE MATERIAL TO EACH DROP EQUALLY. The most efficient way to accomplish this is to have a balance manifold with equal flow length and channel sizes from the point of injection to each cavity.

WHAT IS HOT RUNNER ?In plastics you need to heat the manifold as

the plastic is a solid granule.Here also you need a manifold to take the

molten material to the multy cavity.In air, water & hydraulic you put washer or

Teflon to stop the leakage.Here also you put copper washer to prevent

the leakage. So both are in average similar character

you needn’t fear about the hot runner system.

HOT RUNNER STARTING PROCEDURE .

Keep controller in front of the m/cThe control system must be located to

allow free movement of air and limited exposure to heat, dust, dirt, moisture, and corrosive vapors.

You must be able to easily access the front panel and the rear panel of the temperature controller.

Check all the connections thoroughly.

HOT RUNNER STARTING PROCEDURE

Connections of main plug pin :- Use plug socket & pin only. Not loose wire& runner.

Ensure neutral is connected to the machine neutral only.( not in earthling plug)

Connections of the connecters (8 pin, 16 pin etc ;) must be connected firmly, Should not leave loose connected. Use connecter clamps for firm contact.

EX:- {3 coil heaters and 2 cartridge heaters fail due to this simple basic reasons only}.

switch on the control panel , if any abnormality is found during the staring, switch off the controller & check following points.

Check all the connections once again. Check fuse on the controller. Check MCB switch on the controller

If the above points are found OK, then check Next following points.

CHECK POINTS

Check T/C with multi meter. Ensure T/C is in good condition.

Check heaters continuity with the multi meter. If found OK, re connect it to the connector.

Start the controller again. Module screen shows the temperature increasing.

If any of the display shows reverse temperature that means the T/C connection is reverse. Change the T/C wire connection

Start again, now the temperature will start increasing.First set the value to 100 c.Once it is achieved, and then increase the value step by step

to the desired temperature.The set value & the actual temperature should not more or

less than the tolerance allowed If any of the display shows hi temperature then it may be the

fault of the modular, better change the modular or change the total controller it self. Inform tool room persons.

Following list shows the connection of heater and T/C diagram which are standardized in all our moulds and controllers.

T/C

HETEAR

M

M

F

F

F

M

MALE CONECTOR.

MALE CONECTOR.

LEAKAGE AND PREVENTIVE MAINTENANCE

Most common location for leakage is seal off between the nozzle and manifold.

Hot runner is accidentally overheated.Detect a leak

Plastic can be seen coming out through electrical connectors.

Sudden loss of random cavities or parts that are not packed properly.

DesignManufacturingTraining

PREVENT LEAKS

CHECK POINTS DURING PRODUCITON

DON’T RUN PRODUCITON WITH CAVITY BLOCK THROUGH LESS TEMP IN ONE ZONE.

CHECK AND ENSURE MATERIAL LEAKAGE FROM MANIFOLD AT EVERY TWO HRS.

IF SHOT PIECES IS OBSERVED CHECK FOLLOWINGS

TEMP,LEAKAGENOZZLE BLOCKRE-GRINDING MATERIAL IS NOT ALLOWED.

CHECK POINTS FOR MOULD LOADING AND UNLOADING.

CONNECTOR HOOD SURFACEWATER CONNETIONWHILE MOLD GREACING HOT

RUNNER NOZZLE TEMP.MUST CHECK.

THANKS