From:sochi
There are the reasons as follows: The change of feed amount was excessive. The feed rate was too fast. The materials of cover plate were selected improperly. The vacuum degree(air pressure) of fixed drill was not insufficient. The rate of feed withdrawal was inappropriate. The front edge of the cutting chip at the drill point angle was cracked or damaged. The spindle deflected too much. The performance of the chip removal was bad.
Solutions
Maintain the optimum amount of feed.
Adjust the feed speed and rotation rate according to the experience and the reference data in order to match best.
Replace the cover plate materials.
Inspect the vacuum system (air pressure) of the CNC drilling machine and check whether the spindle rotation rate changes or not.
Adjust the rate of feed withdrawal and drill rotation for the best status.
Check the drill usage status or replace it.
Inspect and clean the spindle and drawback chuck.
Improve the performance of chip cutting and removal and check the status of chip removal groove and cutting edge.
The reasons analysis of white circles at the orifice and hole edge (the copper layer at the hole edge was separated from the base material, and the hole was exploded)
There are the reasons as following: The local fragmentation of the base plate was caused by thermal stress and mechanical force in the process of drilling. The thickness of glass cloth and woven yarn was relatively thicker. The substrate material quality (cardboard) was bad. The amount of feed was excessive. The drill tip was loose and can not be fixed tightly. There were too many layers of lamination plate.
Solutions
Check the wear condition of the drill tip, and then replace or regrind it.
Select the glass cloth woven with fine glass yarn.
Replace the substrate material.
Check whether the amount of the set feed is correct or not.
Check the diameter of the drill tip handle and whether the force of the spindle spring clamp are sufficient or not.
Adjust the lamination data according to the process regulation.
The problems above usually occur in the production of PCB mechanical drilling. The measurements and inspections should be made as much as possible in the actual operations. At the same time, the strictly regulated operation is of great benefit to reduce the quality faults in the process of drilling production, improving products quality and increasing production efficiency.
