AV4: The Turning Point Against the Thermal Expansion of Doors

Are you or your customers frustrated with doors that are difficult to operate and unlock? Are you making costly site visits to address issues caused by thermal expansion? If you want to eliminate unnecessary service calls for sticky locks, keeps and hinge adjustments while saving time and money, as well as boosting your sales and brand reputation, then AV4 is the solution to smooth operation in the face of thermal expansion.

A known industry issue, thermal expansion is a natural phenomenon where materials expand when they are heated, and contract when they cool down. This occurs because heat causes the atoms in the material to vibrate more vigorously, which in turn makes them occupy more space. Thermal expansion can have practical implications on the functionality of all door materials, affecting fit, operation and durability over time.

Winkhaus UK, a pioneering force in the door hardware market, has a solution. The newest innovation in autoLocking solutions, AV4, has been designed to directly address these challenges, whilst remaining easy to operate for the widest range of users.

Adapting to misalignment

As a door naturally moves, more force is required to engage the locking mechanism, as the parts no longer align. This means that extra pressure needs to be applied to turn the key, effecting use and functionality for the doorset and triggering call outs for the installer to investigate. However, AV4 has been designed to address these challenges. With wider installation tolerances built into the lock, AV4 requires up to 70% lower force to operate than competitor auto locks and auto-engaging locking solutions.

George Smith, Technical Manager for Winkhaus UK, explains how AV4 is tested, the results, and the benefits this has for the fenestration industry.

George said: “The force required to retract a locking mechanism can be affected by many factors including the quality of installation, alignment of keeps and door maintenance, temperature and building structure. As these factors fluctuate, so does the potential deviation of a door, necessitating meticulous testing against a stepped increase in tolerance to simulate real-world conditions.”

“This imperative assessment aligns with PAS24, the robust security standard governing doorsets and windows, drawing its testing methodology from BS6375-2. Mandating a maximum force of 2Nm for retracting the locking mechanism, with lower force indicating smoother operation, underscores the commitment to fortified security and reliability."

Testing against real world conditions

Winkhaus wanted to measure the real-world impact that AV4 can have on a doors ease of use, and invited end-users to test how it operated under thermal expansion compared to other locks on the market.

When it comes to thermal expansion, the industry standard tolerance for doors is up to 5mm with a tolerance of +or-2mm being commonplace. To simulate deviation, packers were inserted in 2mm increments with initial measurements being take from zero deviation. The doors used were from the same fabricator and were formed on the same date and batch of manufacture.

For the testing we benchmarked AV4 against the AV2, the current market leading autoLocking solution and a range of competitors products.

To start the test, we measured the force required to operate without any packers installed, so zero deviation in the doors used. We expected to see little difference but found that not to be the case with AV4 requiring under 70% less force to operate.

All the locking solutions tested met the PAS24 requirement, operating under the required 2Nm force to operate with 4mm packers installed at the top and the bottom of the door. AV4 at this stage required between 36% and 47% less force to operate than the other products tested. Above this point there was a high failure rate with the competitor products tested, and we did not continue testing if locks required more than 2Nm force to operate. AV4 at this point of the testing was only requiring 0.75Nm force, so we continued to increase the number of packers, and therefore deviation of the door.

Beyond 4mm deviation only AV2 and AV4 still operated below 2Nm in the sample of products we tested. At 6mm AV4 continued to operate, and again with 8mm of packers installed – double the industry standard and tolerance for door manufacturers. At 8mm AV4 required only 1.54Nm of force to operate, lower than any other lock we have tested, whilst remaining easy to operate from either key or thumbturn.

Enhanced user experience

AV4 offers significant advantages for fabricators and installers, as it is able to work in situations where other locks might not perform due to its low force to operate. Not only does this reliable locking solution reduce the need for costly replacements over time, but it also minimises the lost time and expense associated with frequent maintenance visits, enhancing the reputation and profitability of fabricators and installers within the industry.

For homeowners, the AV4 offers user-friendly operation, ensuring ease of use for individuals of all ages and abilities. Its low force to operate allows accessibility to everyone, including those with disabilities that affect their ability to grip or apply force to other locking solutions. Additionally, the longevity and reliability of AV4 means that occupants can enjoy the convenience of a single, dependable locking solution throughout their tenure - from children to grandparents - promoting a sense of continuity and supporting the requirements of the future home's initiative.