in a printer

abrasive filament

You probably are using an abrasive filament. The most loss on abrasive filament happens when the nozzle runs over the printed material as it extrudes and less from the bore itself. As a result, the nozzles get ground up from the tip.

To reduce the wear of the nozzle, one can swap to such from harder material, for example, stainless steel, which then needs to get replaced less often but the nozzle costs more.

The only way to get virtually no nozzle grind-up from printing abrasive material - especially PC filled - would be to go for a ruby nozzle.

mechanical damage

In case you have misleveled your bed and print too close, you might also ram your nozzle into the bed to a point that the mechanical impact dulls your nozzle. Make sure your bed is leveled properly.

in a 3D-pen

3D pens often come with really soft nozzles and mishandling - as in pushing against a surface - can grind their tips faster than a normal printer would. The other things still apply.

in a printer

abrasive filament

You probably are using an abrasive filament. The most loss on abrasive filament happens when the nozzle runs over the printed material as it extrudes and less from the bore itself. As a result, the nozzles get ground up from the tip. How carbon-fiber filled PLA grinds away nozzles can be seen on this page of the Olsson Ruby webpage (no affiliation), where they printed circles till the nozzles were ground away half a millimeter: it took just 300 grams for brass, a kilo for stainless steel and 4 kg for hardened steel.

To reduce the wear of the nozzle, one can swap to such from harder material (as seen above), for example, stainless steel or hardened steel, which then needs to get replaced less often. On the flipside, the machining of these materials is harder and thus the nozzle costs more.

The only way to get virtually no nozzle grind-up from printing abrasive material - especially PC filled - would be to go for a ruby nozzle.

mechanical damage

In case you have misleveled your bed and print too close, you might also ram your nozzle into the bed to a point that the mechanical impact dulls your nozzle. Make sure your bed is leveled properly.

in a 3D-pen

3D pens often come with really soft nozzles and mishandling - as in pushing against a surface - can grind their tips faster than a normal printer would. The other things still apply.

in a printer

You probably are using an abrasive filament. The most loss on abrasive filament happens when the nozzle runs over the printed material as it extrudes and less from the bore itself. As a result, the nozzles get ground up from the tip.

To reduce the wear of the nozzle, one can swap to such from harder material, for example, stainless steel, which then needs to get replaced less often but the nozzle costs more.

The only way to get virtually no nozzle grind-up from printing abrasive material - especially PC filled - would be to go for a ruby nozzle.

in a 3D-pen

3D pens often come with really soft nozzles and mishandling - as in pushing against a surface - can grind their tips faster than a normal printer would. The other things still apply.

in a printer

abrasive filament

You probably are using an abrasive filament. The most loss on abrasive filament happens when the nozzle runs over the printed material as it extrudes and less from the bore itself. As a result, the nozzles get ground up from the tip.

To reduce the wear of the nozzle, one can swap to such from harder material, for example, stainless steel, which then needs to get replaced less often but the nozzle costs more.

The only way to get virtually no nozzle grind-up from printing abrasive material - especially PC filled - would be to go for a ruby nozzle.

mechanical damage

In case you have misleveled your bed and print too close, you might also ram your nozzle into the bed to a point that the mechanical impact dulls your nozzle. Make sure your bed is leveled properly.

in a 3D-pen

3D pens often come with really soft nozzles and mishandling - as in pushing against a surface - can grind their tips faster than a normal printer would. The other things still apply.