Test instrument used on high-speed spindle motors

Non-contact bearing systems offer significant advantages over other low-friction devices. Air Bearings Ltd (ABL) excels in the design and application of these bearings in high-speed spindle motors. Their output is mainly directed to the PCB drilling industry, worldwide. The boards typically end up in mobile phones, cameras and miniaturised communications equipment. The drills can operate at speeds of up to 350,000 rpm, driving a 0.1mm diameter drill bit.

With total volumes reaching 1500 units per month, made up of a wide variety of sizes, the need for a vigorous testing programme is essential.

Each unit progresses through a number of build stages with appropriate quality assurance approvals, with the motor and stator being tested individually before assembly and the complete unit tested again after assembly by a Baker AWA 2.2 Winding Analyser.

The AWA winding analysers are designed to test the insulation system of electric motors, with tests including a winding resistance test, a meg-ohm test, a PI test, a DC step voltage test and, finally, a surge test.

The surge test is the most important test, as it is able to detect weak insulation between turns, coils and phases prior to the motor displaying any symptoms of a fault. The non-destructive nature of the surge tests are an important factor.

Whitelegg Machines says that the well known 'Megger' test is widely used for testing motors but, most importantly, Megger and other typical testers cannot detect weak insulation turn-to-turn (copper-to-copper).

The choice of the AWA by ABL rested on, among other aspects, the AWA offering automatic testing with PC-control, with comprehensive database software and being very easy to use. Colour test reports can be created quickly via the unit, or on an office PC using the desktop software supplied with the test unit.