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TROUBLESHOOTING MOLDING MACHINE PROCESS.

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Presentation on theme: "TROUBLESHOOTING MOLDING MACHINE PROCESS."— Presentation transcript:

1 TROUBLESHOOTING MOLDING MACHINE PROCESS

2 MOLDING PROBLEMS PREMOLDING MOLDING MATERIAL HADLING AND STORAGE
PROCESSING CONDITION AND MACHINE PERFORMANC

3 COLOR STREAKING CAUSES: SOLVING: (1)THIS TYPE OF PROBLEM IS
PRINCIPALLY CAUSED BY POOR THERMAL STABILITY OF THE COLORING AGENT. FURTHERMORE, IT OCCURS MORE EASILY IN LOCATIONS SUCH AS WELDS, RIBS, AND THE LIKE WHICH ARE LIKELY TO INDUCE SHEAR FLOW. (2)POOR DISTRIBUTION OF COLORING AGENT. (3)CLEANING EFFECT OF PLASTIC DEPOSITED WITHIN THE MOLDING MACHINE (OR CYLINDER. SOLVING: (1)GO FOR HIGH THERMAL STABILITY COLOR. (2)LOWER THE INJECTION SPEED AND BARREL TEMPERATURE. (3)THROUGHTLY CLEAN TO MACHINE. (4)IMPROVE THE COMPOUND QUALITY

4 SILVER STREAKING CAUSES:INSUFFICIENT DRYING SOLVING:
LOW DRYING TEMPERATURE AND TIME LOW VOLUME OF DRIED AIR BLOCK OF AIR FILTER LOW HOPPER CAPACITY FAULT CONTROLLERS SOLVING: (1)REVIEW DRYING CONDITIONS OPTIMIZATION OF DRYING CONDITIONS ADJUSTMENT OF THE WARM AIR VOLUME CLEANING OF THE AIR FILTER OPTIMIZATION OF THE HOPPER CAPACITY CHECK OF THE CONTROLLERS NOTE:OCCURS OVER THE COMPLETE MOLDING IMMEDIATELY AFTER PASSAGE THROUGH THE GATES

5 SILVER STREAKING CAUSES:INCLUSION OF AIR SOLVING:
(1) MOLDNG CONDITIONS HIGH NJECTION SPEED AND PRESSURE INSUFFICOENT BACK PRESSURE EXCESSIVE PULL BACK OR DECOMPRESSION NO COLD SLAG WELL SOLVING: CORRECT THE INJECTION SPEED AND PRESSURE DECREASE DECOMPRESSION INSTALL COLD SLAG WELL ADJUST REGRIND MIXING NOTE:RANDOMLY OCCURRED AT POINT AROUND THE GATE.

6 SILVER STREAKING CAUSES:THERMAL DEGRADATION SOLVING:
HIGH NOZZLE TEMPERATURE, CYLINDER TEMPERATURE, INJECTION SPEED OR SCREW SPEED BAD GATE POSITION SMALL SPRUE, RUNNER, GATE FAULT HEATING BAND SOLVING: OPTIMAL NOZZLE TEMPERATURE, CYLINDER TEMPERATURE, INJECTION SPEED OR SCREW SPEED CORRECT GATE POSITON INCREASE SPRUE,RUNNER,GATE DIMENSION CHECK ANDREPAIR HEATING BAND NOTE: OCCURS OVER THE COMPLETE MOLDING IMMEDIATELY AFTER PASSAGE THROUGH THE GATES

7 SHORT SHOT: CONDITION DRYING THE PELLET UNEVEN THICKNESS;
                                                                                                                    LOCATION ON SURFACE RIBS AND BOSSES CONNERS AND TIPS CAUSE GENERATION OF GAS PLASTIC VISCOSITY THICKNESS AND GAS VOLUME DRYING THE PELLET CHECK VENTING UNEVEN THICKNESS; STANDARDIZE RIBS THICKNESS GAS VENTING IN RIBS SECTION SURFACE SMOOTHNESS OF RIB CHENNEL INCREASE INJECTION SPEED INCREASE SHOT SIZE RAISE MELT TEMPERATURE CHANGE MATERIAL GRADE

8 CHECK POINTS CHECK VENTING UNEVEN THICKNESS; STANDARDIZE RIBS THICKNESS GAS VENTING IN RIBS SECTION SURFACE SMOOTHNESS OF RIB CHENNEL INCREASE INJECTION SPEED INCREASE SHOT SIZE RAISE MELT TEMPERATURE DRYING THE PELLET CHANGE MATERIAL GRADE

9 JETTING: CAUSES: SOLVING: LOW MELTING TEMPERATURE LOW MOLD TEMPERATURE
CAUSING HIGHER VISCOSITY OF THE MELT WHILE FILLING GATE TOO SMALL INCREASE THE INJECTION SPEED LOW INJECTION SPEED HIGH INJECTION SPEED SOLVING: INCREASE BARREL TEMPERATURE INCREASE MOLD REDUCE INJECTION SPEED INCREASE GATE SIZE

10 FLOW MARK:UNEVEN THICKNESS
INJECTON SPEED BARREL TEMPERATURE CAUSES: FLOW DIRECTION FLOW DIRECTION LOW MELTING TEMPERATURE LOW MOLD LOW INJECTION SPEED 240oC LOW 220oC SOLVING: 240oC MEDIUM 240oC INCREASE BARREL TEMPERATURE INCREASE MOLD RAISE INJECTION SPEED ADJUST THICKNESS PROFILE 240oC HIGH 280oC

11 FLOW MARK:RECORD GROOVE
CAUSES: SOLVING: COOLED PLASTIC FILLING IN THE CAVITY AND OCCURS AT HIGH VISCOSITY, CONSEQUENTLY, PLASTIC IN CONTACT WITH THE MOLD SURFACE AND STRIPES PERPENDICULAR TO THE FLOW DIRECTION ARE FORMED. LOWER THE INJECTION SPEED. RAISE THE INJECTION PRESSURE AND HOLD PRESSURE. RAISE THE MOLD TEMPERATURE.

12 FLOW MARK:STAGGERED MARK
CAUSES: SOLVING: THIS TYPE OF FLOW MARK IS CAUSED BY UNSTABLE FLOW AT THE FLOW FRONT. LOWER THE INJECTION SPEED. RAISE THE BARREL TEMPERATURE AND MOLD.

13 WELD LINES MOLD TEMPERATURE =40oC MOLD TEMPERATURE =100oC

14 WELD LINES CAUSES: SOLVING: (1)SHAPE OF MOLDED COMPONENT HOLES
DIFFERENCES IN MATERIAL THICKNESS OR UNEVEN THICKNESS (2)HIGH VISCOSITY MELT (3)MOLD DESIGN LOW MOLD TEMPERATURE INAPPROPRIATE GATE LOCATION INCORRECT GAS VENTS SOLVING: INCREASE MELT TEMPERATURE RAISE MOLD TEMPERATURE INCREASE INJECTION SPEED. INCREASE HOLDING PRESSURE.

15 FLASH(FINS OR SPEW) CAUSES: SOLVING: LOW CLAMPING FORCE
MOLD SURFACE WEAR MELT VISCOSITY TOO LOW SOLVING: INCREASE CLAMPING FORCE IMPROVE MOLD SURFACE LOWER MELT TEMPERATURE OR SWITCH TO HIGH VISCOSITY GRADE(LOW MFI)

16 DELAMINATION CAUSES: SOLVING: POOR COMPATIBILITY(BLENDS)
CONTAMINATION WITH OTHER POLYMER TOO LOW MOLD TEMPERATURE SOLVING: CLEAN HOPPER,BARREL AND DRYER RAISE MELT TEMPERATURE INCREASE MOLD TEMPERATURE

17 SHINK MARKS: SINK MARK BEHAVIOR DEPENDS ON THE VOLUMETRIC SHRINKAGE
OF THE PLASTIC; THE SOTHERMAL PVT CHARACTERISTIC,AND THE CHRONOLOGICAL HISTORY OF ALL LOCATIONS WITHIN THE INJECTION MOLDING PROCESS IS IMPORTANT. ALTERNATIVELY, WHEN THE OUTER LAYER OF THE MOLDED COMPONENT HAS SUFFICIENT STRENGTH TO RESIST THE PULL OF VOLUMETRIC SHRINKAGE, VOIDS WILL BE GENERATED AT THE INTERIOR, AND IN CERTAIN CASES, THIS WILL NOT BE MANIFESTED AS AN APPEARANCE RELATED PROBLEM.

18 WARPAGE OR TWIST: FACTORS INFLUENCING WARPING ARE AS FOLLOWS:
WARPING" IS A TERM USED TO DESCRIBE THE DEFORMATION WHICH OCCURS WHEN THERE ARE DIFFERENCES IN THE DEGREE OF SHRINKAGE AT DIFFERENT LOCATIONS WITHIN THE MOLDED COMPONENT. FACTORS INFLUENCING WARPING ARE AS FOLLOWS: DIFFERENCES IN SHRINKAGE AND COOLING TIME AS DEPENDENT ON THE DIFFERENCES IN BOTH SURFACE CONTRACTION AND COMPONENT THICKNESS WHICH RESULT FROM DIFFERENCES IN DIE TEMPERATURE DISTRIBUTION. RESIDUAL STRESS RESULTING FROM MOLECULAR ORIENTATION. IN FIBER-REINFORCED MATERIALS, THERE ARE LARGE DIFFERENCES IN THE DEGREE OF SHRINKAGE IN THE FLOW DIRECTION AND THE PERPENDICULAR DIRECTION, AND FOR THIS REASON, SPECIAL CONSIDERATION MUST BE GIVEN TO GATE DESIGN; QUANTITY AND LOCATION) AT THE DIE DESIGN STAGE.


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