Injection Molding Defects Quiz

Quiz by: How Does High Injection Pressure Cause Defects in Products? โ€” Refer to this article for more details.

What defect is characterized by wavy-like traces on the surface of plastic products due to excessive injection pressure?

Stream marks and silver streaks occur when excessive injection pressure causes the melt to flow too quickly, leading to unstable melt fronts. This creates wavy-like traces on the product surface. Flying edge and burn marks are caused by different issues related to mold parting and temperature, respectively.

What appearance defect is caused by excessive injection pressure, resulting in plastic melt overflowing from the mold parting surface?

Flying edge occurs when the injection pressure is too high, causing the melt to overflow from the mold's parting surface, forming fringes. Stream marks are wavy lines due to fast melt flow, and burn marks result from high frictional heat, not pressure overflow.

Which defect results from rapid melt flow involving air, creating a mottled surface appearance?

Silver streaks form when rapid melt flow involves air, creating a mottled appearance on the surface. Burn marks are from excessive heat, flying edge is from overflow, and internal stress relates to internal structural issues.

What appearance defect is characterized by localized high temperatures causing discoloration and odor?

Burn marks occur when excessive frictional heat causes discoloration and odor. Stream marks are wavy lines from unstable flow, flying edge is overflow from the mold, and internal cavities are voids inside the product.

What is a primary cause of flying edges in injection molded products?

Flying edges are primarily caused by high injection pressure, which forces the melt to overflow from the mold's parting line, creating unwanted fringes. Low mold temperatures and slow cooling rates do not directly cause flying edges. Excessive mold clamping force also does not cause this defect.

How can silver streaks appear on the surface of an injection molded product?

Silver streaks occur when the melt flows too quickly and involves air, leading to air entrapment. This causes the appearance of streaks on the product surface. Neither excessive cooling time nor low injection pressure causes silver streaks. Inadequate clamping force is unrelated to this defect.

Which defect is caused by excessive internal stress in injection molded products?

Excessive internal stress can lead to deformation and cracking as the material cannot withstand external forces. Burn marks arise from high temperatures, weld lines from meeting flow fronts, and color variations from inconsistent material or processes, not from internal stress.

What causes flying edge defects in injection molding?

Flying edge defects occur when the injection pressure is too high, causing the plastic melt to overflow from the mold parting surface, resulting in unwanted fringes. This defect requires additional trimming, increasing production costs.

Which of the following is a result of excessive injection pressure during molding?

Excessive injection pressure can lead to stream marks and silver streaks due to unstable melt flow and air entrapment. These appearance defects compromise the visual quality of high-gloss or transparent products.

Which factor is most likely to cause burn marks during the injection molding process?

Burn marks are primarily caused by excessive injection pressure, which generates frictional heat as the melt flows through narrow areas. This localized heat can scorch the plastic, resulting in burn marks. Other factors like slow injection speed or improper cooling time typically lead to different types of defects.

What can cause silver streaks or flow marks on the surface of an injection molded plastic product?

Silver streaks and flow marks occur due to excessive injection pressure. This high pressure causes the melt to flow too quickly, leading to an unstable melt front. As air gets involved, it creates streaks on the product's surface, affecting its appearance quality.