Metal detectors: Suppliers emphasize anti-interference

	Shenzhen Aoyadi¡¯s VO-8000 walkthrough model can detect a clip-sized piece of metal and automatically record the number of alarm times and people who passed through.

Many are set up during sports activities, art gallery events and prestigious occasions.

A growing number of commercial establishments and schools also require metal detectors due to security concerns. Targeting these sectors, China manufacturers are rolling out sturdy models that can withstand various operating environments. External appearance is likewise an R&D priority as designs should complement the interiors of contemporary buildings.

Demand is particularly high for walk-through units but handheld and desktop types are also offered. Most are terrestrial versions but some are for underwater use.

Upscale products intelligently discern metal from a power flux, radio frequency and other disturbance.

Some can actually suppress and filter these through control mechanisms, including adjustable operating frequencies.

Mainstream models, although not as fine-tuned, have a multizone range, light-and-sound alarm and photoelectric bars that show the location of the metal object.

Walk-through units, which make up the bulk of supply in China, usually have modifiable sensitivity, the maximum level of which can sense items as small as a pin or a paper clip.

In high-end versions, the weight, volume, size and location of metals can be preset to avoid false alarms caused by keys, jewelry and belt buckles.

The VO-8000 model from Shenzhen Aoyadi Electronic Equipment Co. Ltd is an example. Aside from a remote control and an LCD, it has eight high-precision area detection levels that can be set independently from zero to 99.

The capability to recognize both ferrous and nonferrous metals is one that suppliers are incorporating into their releases.

Entry-level products can identify up to 150g of copper, aluminum and zinc but are unable to distinguish uncommon types. Some units, however, sound off when a predetermined weight of manganese is present.

Zhangzhou Eastern Intelligent Meter Co. Ltd¡¯s model TS1260 walk-through equipment, for instance, has a composite circuit design and infrared sensors that can track even stainless steel, iron and alloys. It also features strong immunity against disturbance.

Targeting a low false alarm rate, companies are adopting DSP chipsets capable of high-tech filtering. The IC can be programmed to discern the characteristics of copper within a magnetic field. This enables the machine to detect similar objects that pass through its sensors.

Most companies only have the signatures of common metals, making it difficult to pinpoint alloys and complex materials. China suppliers are currently addressing this issue by beefing up their technical know-how.

Industry composition

More than 150 suppliers in China specialize in metal detectors, the majority being tier 1 and 2 manufacturers. Hosting roughly 90 percent of the companies, Guangdong province is regarded as the major supply center.

Large makers, which comprise 5 percent of the total, have production facilities covering about 5,000sqm and at least 500 employees. They churn out all kinds of metal detectors, with output running up to several thousands monthly.

PCB assembly and much of the manufacturing process are done in-house. Aftersales service is usually offered.

Those classified as tier 2 represent about 20 percent of the industry. These companies typically have 2,000sqm factories, more than 100 workers and an average turnout of 500 units per month.

The majority offers walk-through and handheld units mostly in terrestrial version.

The rest are small enterprises and trading companies that subcontract all but the final assembly because production is essentially complex and labor intensive.

To achieve the desired level of reliability and anti-interference property, for example, each module undergoes a three-day aging test, the longest for all electronics.

Manufacturers are confident that overhead will lessen as the industry matures. Many components and materials can now be sourced locally.

The supply chain is expected to grow in the next few years, especially since significant cost fluctuation is unlikely in the short term.