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TROUBLESHOOTING MOLDING MACHINE PROCESS. MOLDING PROBLEMS a PREMOLDING MATERIAL HADLING AND STORAGE a MOLDING PROCESSING CONDITION AND MACHINE PERFORMANC.

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Presentation on theme: "TROUBLESHOOTING MOLDING MACHINE PROCESS. MOLDING PROBLEMS a PREMOLDING MATERIAL HADLING AND STORAGE a MOLDING PROCESSING CONDITION AND MACHINE PERFORMANC."— Presentation transcript:

1 TROUBLESHOOTING MOLDING MACHINE PROCESS

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

3 COLOR STREAKING CAUSES: (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 (1)INSUFFICIENT DRYING SOLVING: LOW DRYING TEMPERATURE AND TIME LOW VOLUME OF DRIED AIR BLOCK OF AIR FILTER LOW HOPPER CAPACITY FAULT CONTROLLERS (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 (1) MOLDNG CONDITIONS SOLVING: HIGH NJECTION SPEED AND PRESSURE INSUFFICOENT BACK PRESSURE EXCESSIVE PULL BACK OR DECOMPRESSION NO COLD SLAG WELL 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 NOTE: OCCURS OVER THE COMPLETE MOLDING IMMEDIATELY AFTER PASSAGE THROUGH THE GATES CAUSES:THERMAL DEGRADATION SOLVING: HIGH NOZZLE TEMPERATURE, CYLINDER TEMPERATURE, INJECTION SPEED OR SCREW SPEED BAD GATE POSITION SMALL SPRUE, RUNNER, GATE FAULT HEATING BAND OPTIMAL NOZZLE TEMPERATURE, CYLINDER TEMPERATURE, INJECTION SPEED OR SCREW SPEED CORRECT GATE POSITON INCREASE SPRUE,RUNNER,GATE DIMENSION CHECK ANDREPAIR HEATING BAND

7 CONDITION LOCATION CAUSE ON SURFACE RIBS AND BOSSESCONNERS AND TIPS GENERATION OF GAS THICKNESS AND GAS VOLUME PLASTIC VISCOSITY SHORT SHOT: 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 DRYING THE PELLET CHANGE MATERIAL GRADE 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

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

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

11 FLOW MARK: RECORD GROOVE CAUSES: 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. SOLVING: 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 MOLD TEMPERATURE =40 o C MOLD TEMPERATURE =100 o C WELD LINES

14 (1)SHAPE OF MOLDED COMPONENT HOLES DIFFERENCES IN MATERIAL THICKNESS OR UNEVEN THICKNESS CAUSES: (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: 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: 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: 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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