in plastic injection molding industrial, it refers to part features that prevent straight ejection at the parting line, which cause much mold complexity and lead to higher mold construction and maintenance costs. Whenever it’s possible, redesign the part to avoid undercuts. Minor part design changes can often eliminate undercuts in the mold. For example, adding through holes can give access to the underside of features that would otherwise be undercuts, simple modifications enable the mold to form a hole in the sidewall rather than with a side-action mechanism.

  • Side-action moulds are available with our standard manufacturing time of 5 working  days only. we always give customer most quickly service than any other company in china, actually more quickly than US, or Europe injection molds maker.
  • Side Action Support for Simple Undercuts or complicate undercut with difference manufacturing way.

At Cnmoulding  any number of undercuts we have the capability to produce your custom parts design. Our precision mold making technologies allows us to provide you the highest quality service , it will delivers the most complex plastic injection molded parts in the industry.


  • Injection Molding Undercuts ,the features is we don’t make it on the parting line area, it will cost much high fee and not easy to finish ejector part out.
  • Undercuts typically lead to increased whole injection molds complexity , it can lead to higher invest a mold construction costs as well.
  • The use of the most simple product design, do not add too much ribs, you can save the cost of the mold, so as to better design of plastic parts and more efficient molding process

Either an internal undercut or external undercut construct, when mold design it  requires an extra a slider or lifter structure to capture the detail of it. When an undercut feature cannot be removed from the part design, the tooling will most likely require for example hydraulic cylinder mechanisms  or gas assistant mechanisms to help facilitate the ejection out.