Cutting by irradiation or by contact

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Cutting by irradiation or by contact

Some brief notes about 2 different way to cut foam:

By contact

In this way the hot wire touches the foam and melts it by contact. This is the usual way applied when you cut the foam by hand.
Pro:
- you can have faster cutting speed
- the kerf is little, can also be as short as the wire diameter
Cons:
- the hot wire bends and cannot follow well the desired path. This is usually negligible when you cut smooth surfaces, but can create big problems on sharp corner. In this case the direction change is applied when the hot wire haven't still reached the right position, so a big deformation can occur. To improve this my last application devWing Foam offer the option to automatically add stop pauses at sharp corners, in this way the hot wire can reach the right position before the direction change is applied
- you must use strong tension to keep the hot wire as straight as possible. This often requires an external bow, or the CNC frame can be over stressed

By irradiation

In this case the foam is melted by the heat irradiated by the hot wire, and the hot wire never touches the foam
Pro:
- the cut is much more precise, as the hot wire doesn't bend but stays straight
- you can use a lower tension to keep the hot wire straight, so you can also use an automatic rewind system, that works well also for strong tapered cuts
Cons:
- you have a slower cutting speed
- the kerf is wider, so you must set it with more accuracy.