Montblanc

The “500-Hour test” for All Montblanc manufacture watches from Le Locle

This “500-Hour Test” simulates the first years of life which these watches will afterwards actually experience. By subjecting each manufacture watch to a three-week-long test, Montblanc does its best to guarantee that no repairs or other maintenance tasks will be necessary throughout the interval from the moment when the watch is purchased until its first routine servicing.

Montblanc’s “500-Hour Test” is performed on all Montblanc manufacture watches, i.e. all watches encasing movements that have been produced by Montblanc. The COSC’s chronometer test scrutinizes only the movements prior to encasing, but Montblanc’s 500-hour ordeal examines the finished watches with encased movements. Montblanc decided to test the watches with their movements already encased because a watch’s individual functions and its rate behavior can be adversely affected by the mechanical forces that are exerted on the movement during the process of encasing the movement, inserting the dial and installing the hands.

The test consists of several stages, each of which is performed according to methods and monitored by devices that are recognized and approved throughout the watchmaking industry. Montblanc’s examination is unique because it combines individual testing methods and the extreme length of the 500-hour testing interval.

The “500-Hour Test” for all Montblanc manufacture watches is performed as follows:

Test No. 1 – Winding Performance (duration: four hours) Winding the movement and checking the final assembly of the watch

A so-called “Chappuis” machine, which is named after its manufacturer, is used to fully wind mainsprings of self-winding watches which are first inserted into the device and then kept there in constant rotation for four hours. The strong rotary motions, which are much less gentle than that a wristwatch would ordinarily experience on its wearer’s wrist, subject the watches to powerful but not damaging shaking. The vibrations dislodge any dust or other particles which may have found their way into the case. The shocks also further loosen any insufficiently tightened screws, which can then be readily detected and firmly screwed in.

Test No. 2 – Accuracy Test (duration: 80 hours) Continuous checking of the accuracy in all positions

This part of the test occurs inside so-called “FEMTO machines,” which rely on highly sensitive microphones (i.e. an acoustic method) to measure various parameters relevant to a timepiece’s accuracy, e.g. rate, amplitude, etc. The individual mechanical functions of the impulse-pallet, escape-wheel and pallets generate characteristic and unambiguously identifiable sounds; the temporal sequence of these sounds can be acoustically recorded with the utmost precision. Monitoring is undertaken in all positions: i.e. the watch is held vertically and its crown is alternately positioned toward the left, downward, toward the right, and finally upward, as well as with the watch held horizontally and its dial alternately positioned upward and downward.

In order to pass Montblanc’s “500-Hour Test,” a watch’s daily rate must never lose more than six or gain more than four seconds. This range corresponds to the tolerances permitted by the COSC for watches which earn the official chronometer certificate.

Test No. 3 – Cyclotest (duration: 336 hours) Checking the overall function of the movement

During the cyclotest, the watches are smoothly rotated according to a program developed by the Montblanc manufacture. This smooth rotary motion simulates the motions a wristwatch undergoes in real life.

The program simulates phases in which the watch is affixed to its wearer’s wrist, followed by phases when the watch has been taken off and left lying motionlessly.

The test consists of two cycles: the chronograph function is switched on during the first cycle and then switched off during the second phase. The power reserve is tested during each of the two cycles.

Test No. 4 – General Performance Test (duration: 80 hours) Checking the instantaneous rate and the functions in all positions

This test scrutinizes the watch’s overall performance, i.e. its power reserve, the switching of its date display, the accuracy of its rate, and any additional functions. For this purpose, the fully wound watch is placed in a drying oven. The watch remains motionless throughout the entire test, thus assuring the exact monitoring of the power reserve. In accord with a predefined program, the temperature inside the oven varies from +6° to +45° Celsius. This wide spectrum simulates the extreme temperature changes that a watch might experience in ordinary daily use. The test of the timepiece’s resistance to temperature changes exposes the watch to very extreme conditions, similar to those which it might encounter when its wearer travels to different countries and climatic zones. This ordeal is considerably more demanding than the tests administered by the COSC. In addition to the continuous accuracy check performed in test no. 3, a standard PC10 device examines the instantaneous rate at zero hours (i.e. the beginning of the test), 24 hours later, and after 48 hours have elapsed. A special “functiontest” scrutinizes the push-pieces by measuring the amount of force required, and the distance which must be traversed, in order to trigger them. The precision of the chronograph, which measures short intervals, is also measured. The watch is tested in all positions: i.e. the watch is held vertical and its crown is alternately positioned toward the left, down, toward the right and up, as well as with the watch held horizontal and its dial alternately positioned up and down.

Test No. 5 – Watertightness (duration: 2 hours)

To guarantee the case’s ability to resist penetration by water, this test begins with an air-resistance measurement. The next phase is a humidity check: the watch is first warmed on a hotplate heated to 45° Celsius and then droplets of cold water are allowed to fall onto its dial. If fogging appears on the lower surface of the sapphire crystal, the watch is not watertight.

In the final step, the watch is immersed in water to a depth of ten centimeters and the pressure is gradually increased to three bar during a fifteen-minute interval. This simulates immersion to a depth of 30 meters. This test is carried out in accord with the new water-resistance standard (NIHS 92-20, version 2010). 

The quality-assurance team does not release a Montblanc manufacture watch for delivery until after it has successfully passed every phase of the “500-Hour Test,” which guarantees that the timepiece will continue to function properly throughout the coming three to five years, i.e. until the time comes for it to receive its first routine servicing.