Wear in Injection Molds: To Float or Not to Float

Wear Minimization Solution

The best solution to the problem of movement causing stress was very simple. If component A is forced against component B thus putting both components under stress, remove the stress. Removing the stress can be accomplished by a revolutionary principle and that is to incorporate designs that allow components to move in the mold.

Specifically, if component A moves due to stresses, allow component B to move with component A. If both move together, stress is reduced or eliminated—depending on the design concepts. Result: when stresses are eliminated, mold wear is substantially reduced.

Float Concept
This concept of allowing components to move or float flies in the face of the mold builder teachings. It is a concept that is foreign to their experience and teachings. The industry generally agrees that the one type of mold that has the most potential for wear is unscrewing molds (i.e., molds designed to make a part with an internal thread). Today, molders that have adopted this concept and incorporate this into their designs are building very successful molds and are seeing substantial savings in repair costs.

Molders that are having their molds built with copper alloys to take advantage of increased mold cooling discovered that copper alloys are easily damaged. When copper alloys are formulated to resist wear, thermal conductivity can be significantly reduced. Molders then were forced to choose between fast cycle times due to increased mold cooling or better wear resistance. Molders that are using copper alloys successfully in molds have learned that float mould components may be the most successful mold design concept to minimize wear. Floating mold components therefore allow the molder to have minimal wear and fast cycle times.

Key to Success

The key issues in floating mold components are to determine which components will be floated and how to actually design them to float. Molders that have successfully determined how to achieve this are seeing faster cycle times and lower mold repair costs.

30 holes egg tray mould use for paper pulp machinery