The past two years have seen the entry of new players and substantial investment in manufacturing operations.

The QH-102 model from Zhejiang Chihoo has a steel leaf and frame 0.6 and 1.4mm-thick, respectively.

In terms of production capability and the size of the supplier base, China's security doors industry is growing at a fast clip, fueled by the construction boom domestically and overseas.

Following the entry of many new suppliers, the number of makers has risen by more than 30 percent to about 400 in the past two years.

Capacity expansion, meanwhile, averaged 20 percent in 2006, with some companies augmenting their manufacturing capability by rather impressive rates. One supplier in this report boosted capacity by more than 400 percent and can now turn out 80,000 security doors monthly.

Utilization in the industry is likewise high as companies respond to strong demand, particularly from North America and Eastern Europe. With many security door makers using between 75 and 100 percent of capacity, annual output in the line reaches 15 to 18 million sets. This represents 50 to 60 percent of the country's total doors production.

Moreover, suppliers are increasing investment in sophisticated technology to improve certain manufacturing processes, including stamping or pressing and surface treatment. Large companies are using an advanced Windows NT-based metal-stamping and folding system that allows all steps prior to welding to be done in a single production line.

Suppliers are also investing in 1,800 to 2,000-ton hydraulic stamping or pressing machines that can form the skins in one operation.

Assa Abloy-Wangli Security Products Co. Ltd has four such machines ranging from 1,500 to 3,000 tons in capacity.

Zhejiang Chuntian Doors Co. Ltd has digital lathes and pressing and punching machines in its 180,000sqm factory. All processes are carried out in the facility and certified to the ISO 9001:2000 standard.

At Zhejiang Fuyuan Industry And Trade Co. Ltd's 45,000sqm factory, there are two manufacturing lines each for the door leaf and frame.

In addition, most of the companies featured in this report have equipped their plants with automatic lines to carry out heat transferring. The process is the most commonly used type of surface treatment in China.

For better aesthetics, a growing number of suppliers are adopting heat transfers with a wood-grain pattern. Models in this design are $5 to $10 more expensive than painted or powder-coated versions.

Mainstream material

Qunsheng uses cold-rolled steel for the QSD-842model. Fittings include a mechanical lockset with five locking points.

Despite the industry's rapid development, material options in China remain largely traditional. Honeycomb paper is still used widely for the core, although some suppliers have also adopted PU and fire-resistant cotton.

Furthermore, most makers continue to choose cold-rolled steel for certain door parts, with the thickness determining the products' market positioning.

Representing 50 percent of China's entire security doors output, midrange models have skins in 0.5 to 0.8mm-thick cold-rolled steel. Versions of the material 1.4 to 1.5mm in thickness are used for the frame.

The B35G and B42G models from Zhejiang Xingyue Door Industry Co. Ltd adopt 0.7mm cold-rolled steel for the skin. The frames are made of the 1.5mm-thick type. The company subjects doors to testing for fire and corrosion resistance.

Zhejiang Chihoo Machinery Mfg Co. Ltd offers security doors with 0.6mm-thick cold-rolled steel skins. The thickness of the material used for the frame is about 1.4mm. The supplier can turn out 60,000 sets monthly.

Qunsheng Group Co. Ltd adopts 0.5 and 1.5mm-thick cold-rolled steel for the skin and frame, respectively. The company is capable of producing 150,000 sets in a month.

The other 50 percent of China's security door output is split almost evenly between low- and high-end models. The former have skins and frames made of 0.4 to 0.5mm and 1.2 to 1.5mm-thick cold-rolled steel.

Upscale versions, including those from China Buyang Group Co. Ltd and Zhejiang Dali Industry & Trade Co. Ltd, naturally adopt better-quality materials. The thickness of the cold-rolled steel used ranges from 0.8 to 1mm for the skin and 1.5 to 2mm for the frame.

Some suppliers are boosting security by introducing features that provide better soundproofing. Qunsheng, for example, has added a two-layer magnetic seal strip to its QSD-842 and QSD-805 models.

Most China-made products, however, use three or four reinforced hinges, multiple locking points, a mechanical anti-theft lockset, a handle and more than 10 bolts.

These security doors are rated usually as A-level models, meaning they can resist attempts to pry them open using basic handheld tools for as long as 15 minutes. The entire selection of Tian Xing Group Co. Ltd consists of such products. Doors with a higher rating are also available, including C-level models from Zhejiang Dali.