Cutting Path Optimizer

How Is Cutting Path Optimization Performed?

Cutting path optimization minimizes the total non-cutting (rapid traverse) distance and time when processing nested parts on sheet material using laser, plasma, or waterjet cutting. After parts are nested, the sequence and direction of cuts significantly affect cycle time — an optimized path can reduce total processing time by 10-30% compared to a naive sequence.

Key optimization goals: minimize rapid traverse distance between cuts (traveling salesman problem), order interior features before exterior contours (interior holes cut first, preventing part shift), control lead-in/lead-out placement to avoid thermal damage, and manage cutting direction (CW for exterior contours, CCW for interior in most machines) to maintain kerf compensation accuracy.

The total processing time includes cutting time (cut length / cut speed), rapid traverse time (rapid distance / rapid speed), and pierce time (number of pierces × pierce delay). Cutting speed varies by material and thickness: mild steel at 6 mm — laser ~3 m/min, plasma ~2.5 m/min, waterjet ~0.5 m/min. Rapid speed is typically 30-60 m/min.

Formula: Total Cut Time = Cut Length / Cut Speed Total Rapid Time = Rapid Distance / Rapid Speed Total Time = Cut Time + Rapid Time + (Pierces × Pierce Delay) Cutting Efficiency = Cut Time / Total Time × 100%

Example Calculation

20 parts with total cut length 15,000 mm, rapid distance 3,500 mm, 45 pierces. Cut speed 2,500 mm/min, rapid speed 40,000 mm/min, pierce delay 0.5 s. Cut time = 15000/2500 = 6.0 min. Rapid time = 3500/40000 = 0.088 min. Pierce time = 45 × 0.5/60 = 0.375 min. Total = 6.46 min. Efficiency = 6.0/6.46 = 92.9%.

When to Use This Calculator

• Programming a laser/plasma/waterjet CNC cutting machine and wanting to minimize cycle time by optimizing the travel path between cuts
• Estimating total cutting time for a production batch to plan machine scheduling and operator assignments
• Comparing different nesting arrangements not just by utilization but by total processing time including rapid traverses
• Optimizing pierce count and sequence to reduce consumable usage (nozzles, electrodes) and thermal distortion on the sheet

Common Mistakes to Avoid

• Cutting exterior contours before interior features — this causes parts to separate and shift, making interior hole locations inaccurate
• Not accounting for kerf compensation direction — exterior contours require outward offset, interior features require inward offset; reversing this makes all features wrong by the full kerf width
• Ignoring lead-in/lead-out placement — piercing directly on the part contour leaves a witness mark; always use a lead-in approach from waste material
• Using uniform cut speed for all features — small holes and tight radii require speed reduction to maintain kerf quality; the machine cannot physically follow sharp corners at full speed

How to Interpret Results

• Cutting efficiency > 90%: Excellent — minimal time wasted on rapid traverses and piercing
• Cutting efficiency 80-90%: Good — typical for well-optimized multi-part sheets
• Cutting efficiency < 70%: Poor — too much rapid traverse time; re-sequence the cutting order or group nearby features
• High pierce count relative to part count: Indicates many interior features — consider common-line cutting for adjacent parts to reduce pierces

Related Standards & References

• ISO 9013 — Thermal cutting — Classification of thermal cuts — Geometrical product specification and quality tolerances
• ISO 17659 — Welding — Multilingual terms for welded joints (thermal cutting terminology)
• AWS C7.1 — Recommended practices for electron beam welding and cutting
• EN 12584 — Imperfections in oxyfuel flame cuts, laser beam cuts and plasma cuts

Frequently Asked Questions

Why should interior features be cut before exterior contours?

When the exterior contour is cut first, the part separates from the sheet and can shift or tilt on the cutting table. Subsequent interior cuts (holes, slots) would then be misaligned. By cutting interior features first while the part is still fixed to the sheet skeleton, all features maintain their positional accuracy. This is a universal rule for thermal cutting processes.

How does kerf width affect the cutting path?

Kerf width (material removed by the cutting beam/jet) must be compensated in the toolpath. For exterior contours, the beam center is offset outward by half the kerf width. For interior features, it is offset inward. Typical kerf widths: laser 0.1-0.3 mm, plasma 1.5-3.0 mm, waterjet 0.8-1.2 mm. Incorrect kerf compensation causes all features to be undersized or oversized by the kerf radius.