🔍 Chip welding (aluminum bits fusing onto the cutter) is usually caused by excessive heat and inadequate chip removal. To avoid it: \n- **Use a proper bit**: A sharp single-flute (O-flute) bit is best for aluminum because it clears chips fast and each chip carries heat away:contentReference[oaicite:79]{index=79}.\n- **Set the right feed & speed**: You want a decent feed rate so that the bit is always cutting a fresh chip (not just rubbing). If you go too slow, the bit stays in contact generating friction which heats up the aluminum and causes it to stick. A rule of thumb for say a 1/4\" carbide end mill in aluminum might be ~18,000 RPM at 60-80 inches per minute with shallow depth per pass, but you should fine-tune for your machine.\n- **Use lubrication or air blast**: Spraying a little WD-40 or a mist of cutting fluid can greatly reduce welding. If you can’t use liquids, an air compressor blowing on the cut helps eject hot chips. SpeTool notes that O-flute bits disperse heat well and stop welding:contentReference[oaicite:80]{index=80}, but combining that with a lubricant is even better.\n- **Shallow passes**: Don’t plow too deep in one go. Shallow passes keep heat generation low and let the chip clear.\nBy doing these things, you keep the aluminum in solid chip form (which flies out) rather than re-melting. The result: your bit stays clean, and the surface finish is better.

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