Padlocks: Mature line gets reliability boost

Monday, 18 January 2010 10:05

Material, surface treatment and QC upgrades are yielding models with greater wear, corrosion and drill resistance.

China suppliers are taking padlock performance up a notch to satisfy tightening security requirements in the high end.

Under this thrust, most makers are investing in QC and material upgrades for traditional cylinder-operated designs.


	Make's MK614 model has a brass body and a 12mm-diameter boron steel shackle.

More companies, for one, are now conducting wear resistance testing to build buyer confidence. The procedure measures the number of consecutive locking and unlocking cycles that finished products can sustain without malfunctioning and losing resistance to unauthorized attempts to pry them open.

For optimum results, several of these enterprises are starting to tap CuNi in cylinder production, where zinc and aluminum alloy and brass have been the predominant material choices.

Owing to the addition of nickel, the copper alloy can better protect against corrosion and retain strength at elevated temperatures. It also has a higher hardness rating, typically above 60HRC.

Models with CuNi cylinders, as such, are able to withstand more than 30,000 opening cycles.

Those that use brass versions have a shorter service life of 20,000 to 30,000 operations. Designs employing zinc and aluminum alloy types can be unlocked and locked between 5,000 and 10,000 times.

Despite being more expensive, suppliers expect CuNi to become mainstream by 2011, along with brass. Zinc and aluminum alloy, on the other hand, will be gradually phased out.

For other critical padlock parts, manufacturers are shifting to carburized steel. Heat-treated with carbon, such variants have a harder outer surface, and greater tensile strength and fatigue resistance.

The use of carburized manganese steel for keyholes can push up hardness ratings by more than 20 percent. Security is consequently improved, with the component able to deter drilling attempts twice longer.

Electroplating advancements, meanwhile, have been paving the way for enhanced rust protection.

Companies, which normally subcontract this surface treatment process, are laying stricter standards on the formulations used by partner factories. This is in response to the higher level of expertise domestic electroplating specialists have achieved following the rise in demand from various sectors.

Thanks to the latest electroplating upgrades, most China-made padlocks can now endure 96 hours or more of salt spray before exhibiting any evidence of deterioration. Previously, the average testing period in the line was at 72 hours.

Although not as widespread, the industry is also seeing some design-based initiatives.

A number of suppliers, for instance, are reworking the structure and layout of inner components, including the cylinder and spring. Such modifications are geared toward reducing the probability that the padlock can be opened using a false key.

Developments in terms of exterior constructions include larger and heavier shackles.

Laminated bodies are also gaining ground. While standard versions are molded in one piece, this kind is formed from multiple flat metal strips that have been riveted together. The plates feature similar contours and include holes for inserting the lock mechanism and the ends of the shackle.

Based on its capability to resist forced entry attempts done using an unauthorized key, this structure boosts anti-theft performance by more than 20 percent.

Appearance upgrades are being introduced as well to stir market interest. Padlocks targeting the children's segment, for example, are being coated in bright colors.

Makers are also moving beyond the basic rectangular or square silhouette by developing rhombus-shaped and round bodies.
Products & prices
Industry overview

Products & prices

China offers three major types of padlocks.

Two of the categories rely similarly on a cylinder lock mechanism and a spring-operated latch, but differ in terms of structure. The traditional kinds have a U-shaped shackle and a keyhole at the base.

Shutter versions are fitted with a straight horizontal shackle and a side keyhole.

The last group are combination models, which open by turning one or more dials according to a predetermined number sequence.

Most China-made padlocks provide resistance to physical attacks such as cutting, drilling, hammering and pulling. Anti-tamper and all-weather designs are also available. Some styles even feature a shackle protector.

The lock bodies usually come in zinc or steel alloy, stainless steel, cast iron and brass.

Metal alloys with high hardness ratings are preferred in the production of shackles. Boron and manganese steel are among the common choices, with both capable of sustaining up to 10,200kg of cutting and pulling force.

Hardening can be conducted to strengthen the bodies and shackles further. Electroplated surfaces undergo salt-spray testing for 72 to 100 hours or longer.

Prices in the line differ based largely on the body and shackle materials, maximum number of unlocking and locking cycles and duration of salt-spray testing. Low-end models go for below $0.30. Upscale counterparts are $0.50 and above.

Industry overview

Accounting for more than one-third of global supply, China is the world's largest manufacturer of padlocks. The country's annual output in the line is estimated at 2.3 billion pieces worth at least $900 million.

Although 10 percent smaller due to the economic crisis, the domestic supplier base remains strong with over 1,000 companies currently engaged in production.

Almost all enterprises are locally owned, with only a few backed by outside financing, often from Taiwan or Hong Kong. Operations are usually based in the provinces of Zhejiang, Guangdong and Shandong.

While there are some businesses that specialize in the line, most offer various mechanical locks, including those for cabinets, computers and vending machines.

When classified according to capability, small companies with annual revenue of below $1 million represent more than 45 percent of the industry.

Suppliers operating at this scale employ fewer than 50 personnel, with only one or two each responsible for R&D and QC. Factories occupy an area of less than 1,000sqm. The manufacture of molds is usually subcontracted.

Half of enterprises are considered midsize. Generating up to $8 million each year, such businesses run 1,000 to 8,000sqm plants with between 50 and 300 workers. Ten technicians at most perform quality inspection and testing. A similarly sized group develops new products based on original or buyer-specified designs. Some operations include mold-making facilities.

Suppliers with larger factories and workforces earn more than $8 million annually. They assign at least 10 personnel to carry out quality management. There are also over 10 R&D engineers who draw up models entirely on their own or in collaboration with clients. The molds for these are manufactured in-house.

This article "Padlocks: Mature line gets reliability boost" is originally posted in Global Sources.

Note: All price quotes in this report are in US dollars unless otherwise specified. FOB prices were provided by the companies interviewed only as reference prices at the time of interview and may have changed.

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