How quality is checked in lamp production

Quality control is more than a look at the finished product. The checks carried out from incoming parts to packing, and what each one measures.

‘Quality checked’ is printed on a lot of packaging, but what lies behind it is rarely explained. In lamp production, inspection is not a single operation at the end of the line. It is a system of steps spread across the whole process, each designed to catch a particular defect as early as possible. The later a fault is found, the harder it is to fix: a wrong chip found before it reaches the line is simply sent back; the same chip found in a finished bulb may mean re-examining an entire batch.

Three main stages

In industry, quality control is usually split into three parts:

• Incoming inspection — checking components and materials as they arrive in the warehouse.
• In-process inspection — checking semi-finished items at various points on the line.
• Final inspection — checking the finished product before it is packed and shipped.

Different plants may name these stages differently, but the logic is the same: catch the problem at the stage where it costs least.

What is checked on arrival

The quality of an LED bulb depends heavily on its parts, so incoming inspection usually looks at:

• the colour and brightness group of the LED chips and whether it matches the order;
• board dimensions, the condition of the layers and the cleanliness of the pads;
• the ratings and appearance of driver components;
• dimensions of housings, domes and caps, and the absence of cracks or bubbles;
• the shelf life of adhesive and solder paste.

Not every item in a delivery is checked, but a sample chosen according to statistical rules. If the sample contains more defects than allowed, the delivery is rejected or sent for full inspection.

Incoming data is also used in dealing with suppliers. If defects keep appearing in deliveries from the same supplier, inspection is tightened; after a long run without problems, the sample size may be reduced. That way inspection effort goes where the risk is highest.

Checks along the line

During production, checks are placed after the key operations. Once chips are soldered to a board, the board is powered up to confirm every chip works. After the driver is assembled, its output current is measured. After the cap is crimped, it is checked for straightness and resistance to twisting.

Operators’ attention matters here too. Excess adhesive, a dome sitting at an angle or a pinched wire are caught more by eye than by instrument. Every defect found is recorded so its cause — machine setting, material or working method — can be investigated.

Burn-in

Assembled bulbs are left running for a period. Some faults in electronic products appear in the first hours of use: a weak solder joint heats up and breaks, a faulty capacitor fails. Burn-in keeps these early failures in the factory instead of letting them reach the customer. Bulbs that go out or start to flicker during the test are set aside and counted; if that count suddenly rises, it is a signal to look for a problem on the line or in a component batch. The duration and conditions of burn-in are set by each manufacturer’s own procedures.

What final inspection measures

Checks on finished bulbs fall into two groups. Some are carried out on every bulb or on most of them: does it light, are power and current within limits, does it look right. Others are done on samples because they take more time and equipment:

1. Measuring luminous flux and colour temperature in a dedicated measuring chamber.

2. High-voltage insulation testing, to make sure no current can reach the housing.

3. Checking power factor and the effect on the supply.

4. Mechanical strength of the dome and cap, including a drop test.

5. Thermal testing — measuring housing temperature during long operation.

Packaging is checked as well: the text on the box must match the bulb inside, and the batch number must be printed correctly.

Traceability

An invisible but very useful part of any quality system is traceability. Each batch gets a number, and that number shows which component batches were used, on which shift and on which equipment. When a complaint comes in, the manufacturer can use the batch number on the box to look for the cause. For the buyer the lesson is simple: keep the box and its batch details, and provide them if a problem arises.

Zaferoğlu Elektrik’s product pages state that Zəfər İşığı bulbs meet international standards and are resistant to impact and humidity. Test details for a specific model can be requested from the company.