Capacitor Inspection System, sorting 5 lac pieces a day.

1. Background & Requirement

DEKI Electronics, Noida is a leading manufacturer of Miller, Box Type & Metallic Capacitors. Inspection of capacitors for various defects after completion of the production process was, historically, done manually by naked-eye inspection — a process that does not scale cleanly with production volume and is subject to operator fatigue and inconsistency.

DEKI wished to automate this inspection process. For this purpose, Neometrix engineers thoroughly studied the production line, the various defects that occur, and their classifications, to arrive at a System Requirement Study (SRS). The SRS captured the initial understanding of the specifications required, along with a preliminary cost estimate and an outline of the proposed solution.

2. Inspection Process

The resulting Capacitor Inspection System is designed for an inspection rate of approximately 5 lac (500,000) pieces per day — roughly 17 bar-type capacitor holder strips per minute moving through the line. Capacitors are carried on bar-type holder strips along a conveyor whose motor and drives allow variable timing of the belt, so line speed can be tuned to the production rate upstream.

As each strip passes the vision station, a machine-vision camera mounted on dedicated fixtures inspects the capacitors against a settable tolerance — principally drop rejection, related to the shape of the resin coating on top of the capacitor.

3. Sorting & Rejection

The system has the ability to remove defective capacitors from the line as well as inspect them. All faulty (NG) capacitors are diverted by a bending mechanism into a single reject bin, keeping rejected units fully segregated. A separate mechanism removes the capacitors that pass inspection, so the two streams never intermix downstream of the vision station.

4. Vision System

The inspection camera is built around a Sony ICX098BL progressive-scan sensor in 1/4" format, with C/CS-mount lens compatibility. It outputs 640 x 480 video at 30, 15, 7.5 or 3.75 fps (Y/Mono), with a sensitivity of 0.5 lx at 1/30 s and 20 dB gain, a 10-bit ADC with 8-bit output, and an SNR of 9 at 25°C, 0 dB gain. Shutter speed is adjustable from 1/10000 s to 30 s, gain from 0 to 36 dB, and offset from 0 to 511 — giving the vision station a wide operating envelope across lighting and line-speed conditions. The camera and its mounting fixtures are rated for -5°C to 45°C operation, -20°C to 60°C storage, and up to 80% non-condensing humidity.

5. Deployment

The Capacitor Inspection System has supported capacitor manufacturers including INDTECH Capacitors (India) and UCon Capacitor (India), moving their post-production QA from manual naked-eye inspection to a repeatable, settable-tolerance, machine-vision process capable of handling production-line volumes.