Key Takeaways
- Conformal cooling channels follow the mould cavity shape.
- Printed in H13 tool steel by DMLS — impossible to drill conventionally.
- Faster cycle times and more even cooling.
- Improves moulded part quality and tool life.
Injection mould cycle time is directly tied to cooling time. A typical mould cycle for a 3 mm wall polypropylene part is 25–35 seconds — of which 15–22 seconds is cooling. The geometry of the part determines the ideal cooling circuit layout; straight drilled channels cannot follow that geometry. Conformal cooling channels can — and they are only manufacturable through additive manufacturing.
The Problem with Conventional Drilled Cooling
Conventional mould cooling uses straight drilled channels — circular cross-section, straight path, typically 8–12 mm diameter. Drilling is the constraint. You can only drill in straight lines from the mould exterior, which means cooling channels are always some distance from the part surface. In a complex core or cavity with tight radii, the nearest a drilled channel can reach is 15–25 mm from the surface. Heat must conduct through that 15–25 mm of H13 steel before reaching the coolant — and that thermal resistance is the limiting factor in cycle time.
What Conformal Cooling Achieves
A conformal cooling channel follows the part surface at a uniform 6–10 mm depth, regardless of geometry. For a core with a 15 mm radius, the cooling channel spirals around it at 6 mm depth — impossible to drill, printable in DMLS in a single build. The uniform proximity means uniform heat extraction, which means uniform part temperature, which means shorter cooling time and less warpage from differential thermal contraction.
Results from Layer X conformal cooling projects:
- Automotive glove box insert: conventional 28s cycle → conformal 19s cycle (−32%)
- Medical device housing: conventional 22s cycle → conformal 16s cycle (−27%)
- Consumer electronics back cover: warp reduced from 0.8 mm to 0.2 mm with unchanged cycle time
The DMLS H13 Process for Mould Inserts
H13 tool steel is the standard material for injection mould cores and cavities. DMLS H13 achieves hardness of 44–48 HRC as-built, rising to 52–56 HRC after double tempering at 550 °C. This is within the specification range for mould inserts used in PP, PE, ABS, and glass-filled nylons.
Layer X prints mould inserts in H13 with conformal cooling channels as small as 4 mm diameter, maintaining channel-to-surface distance of 5–8 mm. The inserts arrive with bead-blasted external surfaces ready for cavity EDM or CNC finishing of the part-forming surfaces. The cooling inlet/outlet ports are CNC-finished to standard O-ring groove dimensions for standard mould hardware compatibility.
Cost vs Benefit
A DMLS H13 mould insert is 3–5× the cost of a machined H13 insert of equivalent size. The business case rests on cycle time savings. At ₹1,500/hour for a two-cavity press running 20 hours/day, a 30% cycle reduction saves ₹900/hour × 20 hours × 300 days = ₹54 lakh per year. A ₹3 lakh DMLS insert premium pays back in under 2 days of production. For any mould running sustained production, conformal cooling is the correct engineering decision.
Contact team@layerx3d.in with your existing mould CAD or part drawing to receive a conformal cooling feasibility assessment and quote.