How to Choose a Door Lock

When choosing a lock, the principle that 'more expensive means better quality' holds true, but not always. In reality, absolutely secure locks do not exist, no matter what manufacturers promise. The difference lies in how long it takes to bypass different lock types: some can be opened in one or two minutes, others may require half an hour of effort using drills, lock picks, and other tools. The best protection, therefore, is a comprehensive approach: a strong door, two reliable locks, a security alarm, and more.

Reliability Criteria

The main criterion when choosing a lock is its secrecy. Simply put, secrecy refers to the number of possible key combinations needed to open the lock. The more difficult it is to find the right key, the higher the secrecy. The number of possible key combinations can range from ten to a million.

Equally important is the material from which the lock mechanism is made. High-strength metal ensures long-term durability of components.

Some modern, unique lock mechanisms have a major drawback: they are vulnerable to rough forced entry (battering, drilling, etc.). Therefore, it's essential to reinforce the lock with steel plates at least 1.5 mm thick.

The most vulnerable part of a lock to a burglar is the keyhole. It's easiest to disable or break the mechanism through the keyhole. Therefore, it's crucial to protect it from unauthorized access. Lock covers, protective plates with secondary locks, and electronic key systems are ideal for defense.

Classification Principles

Door locks are divided into surface-mounted and mortise types based on installation method. Due to installation characteristics, mortise locks reduce the structural strength of the door, making them unsuitable for wooden doors—too high a risk of being kicked in. However, they are ideal for armored doors.

The most universal type is the surface-mounted lock, which is installed on the inside of the door, making the mechanism inaccessible to intruders.

There are several types of locks depending on their internal mechanism:

• cylindrical,
• disc,
• cam,
• electronic.

Cylindrical and Disc Locks

The most widely known type in our region is the so-called English, or cylindrical lock. Its core component is a cylinder with spring-loaded pins. These pins block the cylinder's rotation when an incorrect key is inserted. When the correct key is inserted, the pins align properly, allowing rotation.

Despite being common—some estimates suggest they are installed on 80% of doors in our country—this type is considered the least secure. Older models can be opened with a paperclip, or by drilling or prying.

However, modern versions are made from hardened steel alloys and feature ball bearings that deflect drill bits, preventing them from reaching the pins. Naturally, these are more expensive.

Disc locks were invented at the beginning of the 20th century. Their design includes several disks arranged in a row, each with a hole for the key. This design provides high resistance to picking with lock picks.

But older models can be easily destroyed by drilling. Therefore, it's better to choose a disc lock with an additional freely rotating disc made from a hard alloy—this prevents drilling.

Cam and Electronic Lock Systems

The mechanism of cam locks relies on components called 'cams'—flat plates with notches and protrusions that are pushed by the key’s grooves during opening. Typically, there are about twelve such plates. If any one is not in the correct position, the lock will not open.

Nonetheless, these locks have drawbacks: bulky keys (from which it's easy to make a copy), large keyholes, and vulnerability to picking (on average, a burglar can pick them in about half an hour, or even less). The cam that locks the rotation is often simply drilled out. Despite continuous improvements, the basic methods of breaking into these locks remain unchanged and still very effective.

Electronic locks are gaining market share, mainly used in offices and banks. Recently, they have also become popular for residential doors. To open them, you need to enter a specific code on a keypad. Some models open via electronic key, remote control, fingerprint recognition, and more.

These locks are energy-dependent (usually powered by batteries), sensitive to temperature fluctuations, and not durable under rough forced entry. Overall, they are short-lived. Therefore, they are typically used as an additional layer of protection on a door that already has a different type of lock installed.

Buying Tips

When choosing a lock, first pay attention to the material it’s made from—both the mechanism itself and the mounting plate and housing.

When purchasing, it’s wise to ask the seller for a quality certificate, confirm the lock’s security class (locks of classes 2–4 must be certified). After verifying quality, confirm the warranty period. If the seller refuses to provide a warranty or offers only a two-week return period (as mandated by law), the lock should not be bought—likely a counterfeit.