Structure of Conventional Process

The master pattern for tire molds has long been based on machining processes. CNC machining is performed based on design data, followed by manual insertion of steel blades. The process is fragmented, with CAM design, machining, and assembly operating as separate tasks.

This structure depends on the following conditions.

・Machining accuracy is a composite of equipment and craftsmanship
・More complex geometries increase machining time and cost
・Design changes require reconfiguration of the machining process

As a result, lead time tends to be fixed at 2 to 4 weeks, and flexibility for product variation is low. Especially as tread designs become more segmented, this process structure itself appears as a constraint.

Meaning of Introducing 3D Printing

SLA-based 3D printing fabricates the master pattern as a single integrated structure. The base and blades are not separated, and geometry is generated directly from data. The key point here is not “replacement of machining” but “integration of process.”

The comparison with the conventional process is as follows.

Conventional
・Fragmented processes
・Machining plus assembly
・Human-dependent optimization

3D Printing
・Integrated process
・Direct linkage to data
・Algorithm-driven optimization

Lead time is reduced to 2 to 4 days, and process reconfiguration becomes unnecessary. Design changes converge to data updates, with limited impact on physical processes. This change is not merely time reduction, but closer to a discontinuity in process structure.

Conditions for Feasibility and Constraints

There are clear conditions required for this approach to be viable.

Quality Requirements

・Surface roughness: Ra ≤ 3.5 μm
・Roundness: 0.03 mm
・Tread accuracy: ±0.08 mm

These are minimum conditions for functioning as a casting master pattern, representing not a prototype level but a pre-mass-production standard.

Operational Conditions

・Material stability of dedicated resin
・Continuous operation of equipment (24/7 assumption)
・Automatic layout and hollowing by AI software

The role of software is particularly significant. By automatically generating layout, support structures, and internal structures, operator dependency is eliminated. The locus of skill shifts from humans to systems.

Economic Conditions

・Cost reduction: approx. 45 to 50 percent
・Process reduction: up to 80 percent
・Material usage: 2 to 2.5 kg per segment

The cost reduction here does not stem from lower machining costs alone, but from changes in the fixed cost structure through process reduction.

Supplementary Notes

・In this application, the final product is a metal mold, and the resin is an intermediate
・Reuse is possible, but in practice single use is common
・The scope of application is not prototyping, but evaluation and pre-mass-production stages

Summary

The introduction of 3D printing is not a substitution of manufacturing method, but a reorganization of process structure.
Fragmented processes are integrated, and both the time axis and the structure of skill change.
The key to feasibility lies not in the equipment, but in an integrated system including materials and software.

Sources and References

・UnionTech Webinar “Redefine Patterns on Wheels” presentation content