3.Machining and processing HPL
HPL-Compact sheets have to be handled with a slower feed speed than HPL composite sheets. On HPL-Compact sheets with decorative surfaces on both sides, tearing of the lower decorative layer can be effectively prevented by changing the exit angle. This can be achieved by varying the height adjustment of the saw blade. With increasing projection, the upper cutting edge is improved and the lower cutting edge is poorer, and vice versa. Good results can also be achieved by placing plywood, chipboard or HPL underneath. Best possible cutting quality of the lower edge is achieved by pre-scoring the underside of the sheet with a small circular saw blade. This prevents tearing on the underside of the sheet because the scoring has already produced a clean cut in the decorative layer on the underside. The scoring saw usually runs in forward direction, regardless of whether the following saw blade runs in forward or reverse direction.
The feed speed has a crucial influence on the cutting quality for HPL-Compact.
A feed per tooth between 0.03 and 0.05 mm has proven successfully.
The feed is calculated with the following formulas, whereby the speed of the machine is usually set for maintaining the ideal cutting speed.
Feed per tooth: Sz = S / (n × Z) [mm/tooth]
transposed to feed rate S = Sz × n × Z [mm/min]
transposed to number of teeth Z = S / (n × Sz)
Where:
Sz = feed per tooth in mm per tooth
S = feed in mm/min
n = rpm
Z = number of teeth
Example:
Number of teeth Z = 52, rpm n = 3500, feed per tooth Sz = 0.04 mm
Substituted into the formula S = Sz × n × Z this yields a feed of
0.04 × 52 × 3500 = 7280 mm/min = 7.28 m/min
