Undercuts in plastic injection molding significantly impact both tooling and part cost, often increasing them. Here's why:

Impact on Tooling Cost:

• Complexity: Undercuts require additional features in the mold, such as slides, cores, or collapsible mechanisms, to allow part ejection. These features increase the machining time and complexity, significantly raising tooling costs.
• Number of slides/cores: Multiple undercuts necessitate multiple slides/cores, further escalating tooling complexity and cost.
• Material selection: Certain materials might require stronger or specific slide/core materials due to undercut geometry, adding to the cost.
• Maintenance: Complex tooling with slides/cores requires more frequent maintenance, increasing overall costs.

Impact on Part Cost:

• Cycle time: Ejecting parts with undercuts takes longer due to slide/core movements, slowing down the production cycle and increasing per-unit cost.
• Material waste: Material trapped in slides/cores might need to be reground or discarded, contributing to material waste and cost.
• Secondary operations: Parts with undercuts might require additional finishing or assembly steps to remove flash or imperfections caused by slides/cores, adding to the cost.

Additionally:

• Scrap rate: Complex tooling with undercuts is more prone to malfunctions or misalignments, potentially leading to higher scrap rates and wasted parts.
• Design limitations: Undercuts can restrict design freedom as they might not be feasible with certain mold configurations.

Minimizing the Impact:

• Design for manufacturability: Evaluate if undercuts are truly necessary and explore alternative designs to eliminate or minimize them.
• Simple undercuts: If essential, opt for simple undercuts requiring fewer slides/cores to reduce complexity.
• Standardized inserts: Utilize standardized inserts for common undercut shapes to optimize cost and lead time.
• Prototyping and simulation: Prototype the design and use simulation software to evaluate feasibility and optimize undercut implementation.

Remember: Consulting with experienced plastic injection molding professionals can help you weigh the benefits of undercuts against the cost implications and suggest alternative solutions for optimal results