Shenzhen Alu Rapid Prototype Precision Co., Ltd.

Understanding CNC Machining Time Estimation

Estimating CNC machining time is crucial for quoting jobs, scheduling production, and optimizing efficiency. It helps predict cycle times (the duration of active machining) and total lead times (including setup). The process involves calculating based on tool paths, speeds, feeds, and additional overheads. While software like CAM programs (e.g., Fusion 360) can automate this, manual estimation uses straightforward formulas and factors.

Basic Formula for Machining

 TimeThe core equation for a single cut or operation is:

Machining Time (minutes) = Length of Cut (inches or mm) / Feed Rate (IPM or mm/min)

This applies to linear motions like milling or turning. For rotational operations (e.g., lathes), adjust for circumference: Time = (π × Diameter × Number of Passes) / Feed Rate.For full programs with multiple operations:

Total Cycle Time (minutes) = Σ (Machining Time per Operation) + Tool Change Time + Rapid Traverse Time + Air Cuts

Add non-cutting times like setup (e.g., 10-30 minutes) for overall lead time.Key Factors Influencing TimeSeveral variables affect accuracy. Here's a summary:

Step-by-Step Guide to Estimate Time

1.Review the Part Program/G-Code: Break it into operations (e.g., roughing, finishing). Use simulation software if available to extract lengths and rates.

2.Determine Speeds and Feeds: Use manufacturer charts or apps. For example: RPM = (SFM × 3.82) / Tool Diameter; Feed Rate = RPM × Chip Load × Flutes.

3.Calculate Per Operation: For a milling pocket: Measure total tool path length (e.g., 50 inches), divide by feed rate (e.g., 20 IPM) = 2.5 minutes. Add rapids (non-cutting moves) at machine's rapid speed.

4. for Tool Changes: Estimate 0.5-1 minute per change; multiply by number of tools (e.g., 5 tools = 3-5 minutes total).

5.Add Setup and Non-Machining Time: Include fixturing (5-15 min), programming verification (variable), and inspection.

6.Sum and Validate: Total = Cycle Time + Setup. Run a dry test or use CAM simulation for real-world tweaks.