Here I suggest you two type of fonts, one for more clear printing, one for more fast printing (speed more than 30m/min).
1. TTF font with fill
Video of setting: //youtu.be/dIXtohAdy4k
Pictures of setting:
2. Choose single line font type to print with faster speed
Video of setting: //youtu.be/PuyoMlfSvUQ
Pictures of setting:
PIPE LASER PRINTER, FIBER LASER MARKING MACHINE, LASER ENGRAVING MACHINE, MARKONG ON CABLE, MARKING ON TUBES, LASER PRINTING PIPE, PIPE INKJET PRINTER, PIPE LASER, TUBE LASER, CABLE LASER, PROFILE LASER, PIPE MARKING, PIPE PRINTING, PVC MARKING, PE MARKING, UV LASER, UV LASER PRINTER, UV MARKING, UV LASER PIPE, HDPE MARKING, HDPE PRINTING, HDPE UV, HDPE FIBER, FIBER LASER, PIPE UV