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Unraveling the Mystery of Splay in Plastic Injection Molding

What is Splay in Plastic Injection Molding

Splay, a cosmetic defect in plastic injection molding, manifests as silver or white streaks on the surfaces of molded parts, as showcased in the accompanying image. Identifying splay can be challenging, as its appearance may resemble other defects such as surface scratches, scuffs, flow lines, contamination-related delamination, or flaking, all of which will be explored in future posts.

How Does Splay in Plastics Happen?

Determining the root cause of splay involves a comprehensive troubleshooting approach across key injection molding areas: the molding process, the mold itself, the press, and material. If splay consistently appears in specific locations, the mold is likely the culprit; if it occurs randomly or throughout the part, the issue typically originates from molding material or the process. Over-lubrication, moisture in the material, or excessive heat during molding are potential contributors, along with a cracked mold.

what splay looks like in plastic manufacturing

Addressing splay requires strategic measures:

  • Ensure material dryness.
  • Scrutinize the mold for damage.
  • Verify the melting temperature.
  • Increase mold temperature.
  • Decrease nozzle temperature.
  • Review gate size.

Delivering flawless parts is imperative, and our team at JATCO Incorporated, a California-based plastic injection molding company, excels in detecting and remedying the specific causes of splay.  Quality analysis is key for in making sure that our clients get their parts on time and on budget, and that we do not produce excessive plastic parts that will have no use due to any defects.

Rely on our expertise to guide you in product design and material selection, preventing defects before they impact your final product. Contact Steven Ames, Director of Sales, at for the information you need to make informed decisions on your next molding project.