Try these steps to fix injection molding problems.
For each problem in the left column, try adjusting the variables listed across the top row in the order suggested by the numbers in the color-coded icons. Try adjusting the variable up or down as the point of the triangle indicates. In some cases (marked by diamond-shaped icons), there is no general rule about whether to raise or lower the value of the variable. So you will have to experiment.
The two right-hand columns point out two different sorts of factors that should be checked: Are nozzle heaters functioning properly? Is resin contamination occurring?
An 8.5 x 11 in. version of this chart with a protective plastic covering, suitable for posting by the molding machine, is available for free from Teknor Color.
By Joe Allbritton
Teknor Color Co.
Joe Allbritten is senior technical service engineer at Teknor Color Co.'s compounding plant in Jacksonville, Texas, which makes color and additive concentrates and precolored compounds. Allbritton has been with Teknor for 25 years as a color matcher, QC technician, laboratory manager, and in sales and technical service. He may be reached at (903) 586-0583, or e-mail firstname.lastname@example.org.
INJECTION MOLDING TROUBLESHOOTING REFERENCE GUIDE Variahles to Adjust Injection Cycle Injection Sprue/Runner PROBLEMS Pressure Time Hold-Time Gate Size Blush at Gate 4A 5A Brittleness Color Streaks 8A Flash 1B 8B Jetting Delamination 7B Poor Dimens. Stability 3A 2A 6A Poor Surface Finish 1A Short Shots 2A 7A Sink Marks 2A 3A 5A Sprue Sticking 6B 3A 2B 4A Sticking in Cavity 1B 3A 2B 6A Warpage 5B 3A 7A Wave Marks 4A 3A Weak Weld 4A 7A 6A Weld Burns 8B 7A Variahles to Adjust Gate Land Nozzle Adjust Clamp PROBLEMS Length Opening Feed Pressure Blush at Gate Brittleness Color Streaks 9B Flash 2A Jetting 5B Delamination 6B Poor Dimens. Stability 4A Poor Surface Finish 5A Short Shots 8B 1C Sink Marks 8B 1C Sprue Sticking Sticking in Cavity 4C Warpage Wave Marks 1C Weak Weld Weld Burns 5A Variahles to Adjust Stock Mold Injection Screw PROBLEMS Temp. Temp Speed RPM Blush at Gate 3C 1A 2B Brittleness 1B 3A 7B 4B Color Streaks 2C 3A 1B 5B Flash 4B 5B 3B 7B Jetting 2C 3A 1B Delamination 3A 2A 4B Poor Dimens. Stability 1C 4C Poor Surface Finish 2B 3A Short Shots 4A 5A 3A Sink Marks 4B 5B Sprue Sticking 1B Sticking in Cavity 6B 5B Warpage 2B 1B 4B Wave Marks 5B 2B Weak Weld 3A 1A 2A Weld Burns 2C 1B 3B Variahles to Adjust Back Gas Nozzle Contamination PROBLEMS Pressure Vents Heating Band Blush at Gate Brittleness 5B 6A 2D Color Streaks 6A 7D 4D Flash 6B Jetting 7D Delamination 1D Poor Dimens. Stability Poor Surface Finish Short Shots Sink Marks 9A 6A Sprue Sticking 4D 5D Sticking in Cavity Warpage 6B Wave Marks 6A Weak Weld 5A Weld Burns 4B 6A Check the key variables in the order indicated by the numbers. A Increase B Decrease C Adjust up or down D Check
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|Title Annotation:||INJECTION MOLDING: Troubleshooter|
|Date:||Dec 1, 2006|
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