A cold wire tears foam and bows badly. The G4 dwell is a short, deliberate pause right after the wire is switched on, before the first cut, that lets the wire reach cutting temperature so the very first move slices cleanly instead of dragging.
Without it, the start of your cut would be rough or the wire would deflect until it warmed up a second or two in. cncfoam.com inserts this pre-heat automatically and you can tune its length in the tool's settings to match how fast your wire heats — thicker wire and longer spans need a touch more. Think of it as letting the wire 'come up to temperature' the way you would preheat any cutting tool.
Without it, the start of your cut would be rough or the wire would deflect until it warmed up a second or two in. cncfoam.com inserts this pre-heat automatically and you can tune its length in the tool's settings to match how fast your wire heats — thicker wire and longer spans need a touch more. Think of it as letting the wire 'come up to temperature' the way you would preheat any cutting tool.