Underquoting kills shops; overquoting loses jobs. These methods give estimates within ±15% on most parts.
Method 1: MRR-Based Estimate (Roughing-Heavy Parts)
Cycle time = (Material removed in cm³) ÷ (MRR in cm³/min)
MRR by material (steel, carbide tooling):
- 1018 mild steel: 30-60 cm³/min
- 1045 carbon steel: 25-50 cm³/min
- 4140 alloy: 20-40 cm³/min
- 304 stainless: 15-30 cm³/min
- 6061 aluminum: 100-300 cm³/min (HSM)
- Inconel 718: 5-15 cm³/min
- Titanium Ti-6Al-4V: 10-25 cm³/min
Add 30-50% for setup, finishing passes, tool changes.
Method 2: Time-Per-Feature Estimate
For mixed-feature parts, sum time per feature:
| Feature | Time (steel) |
|---|---|
| Drill hole 6mm × 25mm deep | 4 sec |
| Drill hole 12mm × 50mm deep | 15 sec |
| Tap M8 × 1.25 × 20mm | 8 sec |
| Bore hole 20mm × 30mm deep | 12 sec |
| Mill 25×25mm pocket × 5mm deep | 30 sec |
| Face 100×100mm × 1mm | 20 sec |
| Tool change | 5-10 sec |
| Spindle on/off + warmup | 5 sec each |
Method 3: Per-Class Multiplier
For repeating part families, develop multipliers:
- Simple part (1-2 ops): 5-15 min cycle
- Medium (3-5 ops, fixturing): 15-45 min
- Complex (multi-side, tight tol): 45-120 min
- Very complex (5-axis, mold): 2-8 hours
Cost Components
Total cost = Material + Tooling + Machine time + Labor + Margin
| Component | Calculation |
|---|---|
| Material | Stock weight × cost/kg + waste 15% |
| Tooling | (Tool cost ÷ tool life) × tool count |
| Machine time | Cycle time × shop rate ($75-200/hr) |
| Labor | Setup time × operator rate ($40-80/hr) |
| Margin | 15-40% (quoting) or 10-20% (production) |
Quote Mistakes to Avoid
- Forgetting tool changes (each 5-10 sec adds up over 50-tool job)
- Underestimating setup (often 30-90 min for prototype)
- Not pricing surface finish requirements (Ra 0.4 µm needs 2× the time of Ra 1.6)
- Forgetting inspection/QC time
- Not adding for material certifications (aerospace/medical adds 5-15%)
Use ML/Software
- MachiningCloud — Tool selection + estimating
- HSMAdvisor — Speeds/feeds + cycle estimate
- Quotefactory — Web-based quoting
- Paperless Parts — Quote automation for shops
For tool selection that improves estimates, browse our catalog.
Shop Related Products at HOOGUU
