Plastic411: Plastic Injection Testing

Welcome to the Plastic411  Processing Assessment. Upon completion, this test is designed to identify plastic injection skill level. Skill range is from material handler to process engineer. This 100 question quiz is available in printable form including the test keys for $110.00. Great tool for interviewing applicants.

You can pay with PayPal, Debit or credit Card. The tests with answer keys will be sent via email.

Thanks for using this platform, and feel free to contact me for help with training development onsite at your facility. Plastic411 training is floor intensive, taught only on the floor using your presses, equipment, materials, processes.


Congratulations! You are a Plastic 411 processing guru! If you scored less than 80%,  Plastic 411 CORE Processor Training  would be your best option. Above 80%, the Scientific Molding Training would best fit your needs.  For class information and scheduling, contact me via the methods listed below:

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Scientific Molding Training- Click HERE


Phone: 404-793-9834

Unfortunately, you did not pass the Processing Course. Additional training is your best option! For class information and scheduling, contact me via the methods listed below:

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Processing I Course Information- Click HERE

Or, contact:


PHONE: 404-793-9834

#1. The purpose of Process Monitoring is:

#2. A press uses 85 pounds of material per hour, producing 170 parts. How much material will be used in 5 hours, and how many parts will be produced? How much does 1 part weigh?

#3. When is it important to close a mold in set-up mode?

#4. When installing clamps, the bolts should be torqued to:


#5. The typical peak pressure for nylon is:


#6. When setting a mold, clamps should be attached:

#7. Polypropylene regrind can be used over and over, with little effect on process control.

#8. You are trying to acheive 95-98% fill with no hold pressure. You are currently at 80%. What adjustments can be made to achieve 95-98%?

#9. The glass transition temperature (Tg) is:


#10. The flash pictured needs to be corrected using process changes. Choose answers below to correct condition.

#11. This part has signs of heavy splay at end of fill. Which of the following changes may improve the condition, or identify the cause?

#12. T or F: When changing a hot runner mold, hot runner can be heated to temperature 30 minutes prior to changing mold to reduce mold change time.

#13. When changing from nylon to polypropylene during a mold change:

#14. When making changes to back pressure, how long does it take for those changes to take effect?

#15. Molds that have valve gates set up properly require a gate seal study once a process has been established.


#16. Peak pressure is:

#17. Color swirls can be caused by:

#18. Based on this gate seal chart, Hold time for this process should be:


#19. When making a change to back pressure, how long does it take for barrel temperature to stabilize?

#20. True or false: Size and shape of material from grinder does not affect how it mixes with virgin material or the production process.

#21. Flash that is feather-like in appearance:


#22. Material with a high relative viscosity:

#23. What steps are taken to develop a decoupled molding process?

#24. Melt temperature is measured by:

#25. Gassing is common with many materials, such as nylon. How often should a mold be cleaned and checked for proper greasing?

#26. This burn defect is on every shot. The burn is occurring half way through the injection. If the part has a 10″ inch shot size, how should the injection be profiled?

#27. After confirming that melt temperature is in the middle of the melt window, what happens to material viscosity and fill time when heats are raised?

#28. The material manufacturer recommends a melt window of 500-550 F, and the melt temperature checks at 546. What result might you get if you increase back pressure?

#29. Splay at end of fill happens when:

#30. Best practice for shutting down a clear Polycarbonate hot runner tool would be:

#31. A gate seal study is performed to:

#32. Shear heat from the screw rotation and back pressure supplies 70-90% of the total heat in the screw. Heater bands supply the rest and help prevent fluctuations.

#33. A burn at the flow front’s end of fill can be a sign of:

#34. True or False: A pressure drop study is best utilized when injection pressures are close to or at maximum pressure at middle to end of fill within the molding process

#35. What is the normal drying time and temperature for unfilled nylon?

#36. Parts you are producing are too small according to print. What changes might you make to increase their dimensions?

#37. A mold that has details the flow front must pass around at 50 % fill might require:

#38. Dispersion discs can be used for:


#39. A dryer that is working properly, should:

#40. The orifice of a nozzle tip should be ________________ the sprue bushing orifice

#41. What reasons below might lead to an erratic and inconsistent cushion?


#42. If this part was pulled from the mold with the side marked “warp” being the stationary half, what adjustment would you make to get rid of the warp (after you checked to make sure mold set up was correct)?

#43. What is the drying time and temperature for Polypropylene?


#44. T or F: A part that is short (not completely filled) and has flash should be checked for signs of tool damage or wear at the parting line.


#45. When a parting line is being checked for damage:

#46. Measuring the flex of a tool within the platen configuration can identify:

#47. A material that is hydroscopic is prone to drawing in moisture and must be dried at the temperature and time determined by the material manufacturer

#48. If a material ratio is identified at 25:1, or 4%.. the correct mixture would be:

#49. A press keeps alarming because the metering zone temperature is higher than normal. The monitoring is set at 25 degrees above the setpoint. What reasons below could be causing it

#50. Where in the screw does the majority of plastic melting occur?

#51. What conditions lead to bubble (void) defects in a part?

#52. When making a change from injection to hold pressure (cut-off), how long does it take for the change to take effect in the process?

#53. Valve gate delay timers:

#54. Which Screw/ Barrel measurements best identify cause for inconsistent cushion?

#55. Which of the following shows an example of a submarine gate?

#56. When venting a mold, what percentage of the cavity parameter should be vented and at what spacing?


#57. Runner size should be ____________ the wall thickness dimension of a part.

#58. If bar x is moved to the right, what direction will the gears move the bottom bar?

#59. What is the purpose of a nylon tip?

#60. Which is the best method of ejector set up?

#61. Nylon regrind can be used over and over, with little effect on process control


#62. Which material used for purging doesn’t belong?

#63. When having issues with color swirl, you should:

#64. T or F: When picking a nozzle tip, it should have the same size orifice as the sprue bushing

#65. T or F: Low Pressure close should be set to the minimum pressure required to achieve lock up pressure.


#66. When having problems with contamination with a hot runner tool, you may need to:

#67. Glass transition temperature refures to:

#68. When making temperature changes to a hot runner, manifold temperatures:

#69. If the actual temperature of a thermolator reads much lower than the set point, it is likely that:

#70. When having problems removing a part from a mold with a robot, you should:


#71. T or F: Material that is hot to the touch has been dried and is ready for use

#72. Support pillars in a mold:

#73. Vented Pins:

#74. When changing material from Nylon to clear polycarbonate, you should:

#75. When changing materials during a mold change, nylon to polypropylene should be:


#76. When setting Decompression after rotate, you should:

#77. Poor knits that lead to cracking weaknesses or visual defects are generally signs of:

#78. If part color is light, but color set point and equipment operation is correct:

#79. When shutting a press down for the weekend:

#80. The correct pressure to torque bolts into a platen is:


#81. Splay is caused by:

#82. You are running a 4 cavity hot runner tool. One part has a burn at end of fill, and higher part weight than another that is short and has a low part weight. You should:

#83. A tool you are running has a valve gate that isn’t firing. You should:

#84. When mold temperature is causing warp, you should:

#85. A mold you are running has a shine appearance that is occuring on a textured surface. You should:


#86. Lamination (flaking) is caused by:

#87. Water pressure measured going into a mold measures at 14 GPM, The pressure coming out is at 11 GPM. This condition should be:

#88. At start up, there is a problem at the feed throat that is causing a Polycarbonate material to load poorly. Potential fixes to the problem might be:

#89. When setting process monitoring for fill time, the +/- set point should be:

#90. A process has been validated when:


#91. T or F: If adding back pressure to a process does not result in a temperature increase, the result may lead to material degradation and poor material properties,

#92. During mold changes, if a material change requires changing from PCABS to polypropylene, you should:

#93. If a thin-walled part tends to stick on the stationary side of the mold, you may need to:

#94. Jetting (Worming) is caused by:

#95. If the size of a gate is to small, it could lead to the following defects:


#96. If an ejection pin is too small, it can cause the following conditions:

#97. The following conditions can cause problems that can affect process control consistency:

#98. T or F: When heating a press from cold state, a front, metered or feed zone temperature that rises at a different rate could be a sign of bad heater bands,

#99. T or F: Hot runner temperatures are generally used as an extension of nozzle temperature into the hot runner manifold. As such, nozzle temperature and manifold temperatures are usually the same.

#100. T or F: Raising barrel and mold temperatures leads to increased peak pressure and viscosity.


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