Manufacturing Knowledge

Cost Formula

$$Total = Setup + (Material + Run) \times Quantity$$

• Setup Cost: Fixed cost (~$80.00). 50% discount on reuse.
• Material Cost: Based on Stock Bounding Box volume.
• Run Cost: Machining time based on Removed Volume ($Stock - Part$).

Design Constraints

• Undercuts: Forbidden. All faces must be accessible from +Z.
• Internal Corners: Minimum tool radius is 3.0mm. Use fillet(radius=3.1).

3. Injection Molding (IM)

Best for: High volumes (>1,000 units), plastic parts, low unit cost. Detailed Reference: references/injection_molding.md

Cost Formula

$$Total = Tooling + (Material + Cycle) \times Quantity$$

• Tooling Cost: High fixed cost. Amortized over volume. 90% discount on mold reuse.
• Material Cost: Based on actual part volume.
• Cycle Cost: Driven by Cooling Time ($CoolingTime \propto Thickness^2$).

Design Constraints

• Draft Angles: Mandatory for vertical faces. Minimum 2.0 degrees.
• Wall Thickness: Keep between 1.0mm and 4.0mm. Thick walls exponentially increase cycle cost.
• Undercuts: Faces must be reachable from either +Z or -Z (2-part mold).

4. Economic Strategy

• Quantity < 100: Prefer CNC or 3D Printing.
• Quantity > 1000: Always prefer Injection Molding if geometry allows.
• Method comparison: Compare candidate methods at the requested quantity, not as single-unit quotes. Use setup/tooling cost separately from per-unit variable cost so the chosen process reflects the real production volume.
• Volume Optimization: Reducing part volume directly reduces material cost and run/cycle time.
• Part Reuse: Using multiple instances of the same part ID is significantly cheaper than multiple unique parts due to shared setup/tooling costs (50% discount for CNC setup, 90% discount for IM tooling).
• Weight Exactness: Treat the post-validation weight total as an exact deterministic output from the priced assembly breakdown, not a prose estimate.

5. Technical Design Patterns

Pattern: CNC Fillet Strategy

# Expert Pattern: Automatic filleting of internal vertical edges
internal_edges = part.edges().filter_by(Axis.Z).internal()
part = fillet(internal_edges, radius=3.1) # 3.1mm for 3.0mm tool clearance

Pattern: Injection Molding Shelling

# Expert Pattern: Creating a shelled plastic part
part = shell(part, openings=part.faces().sort_by(Axis.Z).last(), amount=-2.0)

Pattern: Draft for Release

# Expert Pattern: Applying 2-degree draft
part = draft(part, faces=part.faces().filter_by(Axis.Z), angle=2.0, pull_direction=(0,0,1))