Technical Brief:
Rapid Prototyping for Complex Undercuts
A global OEM needed functional samples for a part with complex undercuts but wanted to avoid expensive, permanent tooling. Manufyn solved this using a split side core injection molding system. This tool used precision-machined segments that move sideways during mold opening to safely release undercuts without damaging the part.
This approach delivered accurate, assembly-ready parts quickly while saving the client from heavy financial risk. It successfully bridged the gap between early testing and mass production for complex designs.
Split Side Core Injection Molding for Complex Undercuts
How Manufyn delivered functional parts for testing through rapid prototyping without high tooling investment
A global OEM approached Manufyn with a plastic component that featured multiple internal and external undercuts. The geometry did not allow straight-pull molding and demanded a tooling approach that could release undercuts without deformation.
Since the customer only needed parts for samples, validation, and functional testing, they did not want to invest in full-scale tooling. Therefore, a rapid prototyping led split side core injection molding solution became the most cost-effective and time-efficient approach.
Key Challenges
The part’s geometry introduced several manufacturing barriers:
- Multiple undercuts located on opposite sides of the component
- Tight tolerance requirement on functional features
- Consistent part ejection without deformation or drag marks
- Need for reliable tool life without heavy maintenance
These challenges ruled out conventional tooling.
Technical Challenge
Traditional lifters or sliders were not feasible due to:
- Limited space for mechanism travel
- Complex undercut orientation
- Ejection path interference
A collapsible core was evaluated, but was eliminated due to part size, operating cost, and the customer’s low-volume requirement.
Core Problem:
Release complex undercuts with dimensional stability, predictable motion, and a manageable cost of ownership.
Manufyn’s Solution
Manufyn developed a split side core injection molding system integrated into the mold base. This allowed the tooling to mechanically withdraw from undercuts during mold opening, clearing the geometry without damaging critical features.
Key Aspects of the Solution
- Split side core divided into precision-machined segments
- Lateral core movement during mold opening to release undercuts
- Hardened tool steel for longevity and wear resistance
- Cam-driven actuation for motion control and repeatability
- Surface integrity preserved even on small feature areas
This tooling approach released complex undercuts without dimensional distortion, scuffing, or forced ejection.
Manufacturing Process
Every step focused on protecting tolerance and reliability:
| Stage | Activity |
|---|---|
| DFM Stage | Mold design with manufacturability validation |
| Tool Build | CNC machining + EDM profiling for core segments |
| Material Performance | Heat treatment & finish prep for long tool life |
| Tooling Trials | Mold assembly, dry runs, and operational setup |
| Verification | T1/T2 optimization to lock cycle time & ejector force |
This ensured the split side core mechanism operated smoothly and consistently under molding conditions.
Results Achieved
The split side core injection molding approach delivered measurable improvements:
- Successful molding of complex undercut features in a single shot
- Zero part deformation or visual damage during ejection
- Dimensional accuracy maintained across multiple production cycles
- Reduced cycle time compared to manual removal or secondary operations
- No post-molding machining or assembly required
Business Impact
This rapid prototyping + split core approach helped the OEM:
- Avoid large tooling investment during early-stage validation
- Reduce time to production readiness
- Improve part quality before scaling
- Build samples for testing, investor demos, and customer trials
- Preserve flexibility for design changes without retooling
Result: A scalable pathway from pilot parts to production — without financial risk.
Why This Matters
For OEMs developing new products with complex undercuts, split side core injection molding:
- Enables low-volume validation before committing to steel tooling
- Eliminates secondary operations or manual corrections
- Combines manufacturability + affordability + engineering integrity
This is where rapid prototyping and industrial tooling intersect.
Need complex undercuts released without high tooling cost?
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