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How to read the specification of the PCB prototyping machine
In purchasing the PCB prototyping machine, you may make your decision merely by looking at specifications comparisons. Generally, the better specification it is, the higher in price it becomes too. However, the machine with the good specification may not necessarily process the circuit as you may have expected.
Chances are, you might end up making an undesirable circuit with the high specification machine.
The rotation speed of the spindle motor
The rotation speed of the spindle motor should not necessarily be high. Higher rotation speed of the spindle motor tends to cause the large degree of runout.
The below figure represents the correlation between the rotation speed of the small size spindle motor.
(Max speed 100000 rpm) and its runout.
The Correlation between the rotation speed of the small size spindle motor and its runout
(Measuring instrument; MITS NANOMETRIC SENSOR MODEL 211)
In this figure, degree of the runout sharply increases from the point over 75,000 rpm.
Causing a lot of burs on the circuits. Thin end mills become even more fragile.
There is the optimum rotating speed for the tools
The optimum rotating speed and the optimum processing speed vary depending on the tools and the substrate board. The finishes of the processing is better when the rotating speed is lower than higher depending on the processing material as reported by the case example by The University Of Tokyo.
Sample from the institute of solid state physics, The University Of Tokyo, Model: FP-21T Precision. The high rotation speed of the spindle motor necessarily make a clear track. This shows that the lower rotation speed of the spindle motor could achieve a cleaner track.