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Glossary of Terms

The amplitude of a balance wheel, expressed in degrees [deg], is the angle formed from its equilibrium state up to the maximum rotation.

When the movement is fully winded, the amplitude values are generally located between 260° and 310°, depending on the gravity, the frequency, the aging of the oils, etc.

The computation of the amplitude always remains an estimation and the result must be used carefully. Indeed, in order to calculate the amplitude, the time between the first and the third pulse of the beat noise is measured. Between these two pulses, the balance wheel rotates a certain angle: the lift angle which is determined by the construction of the movement.

The beat error is the time difference between the “ticks” and the “tocks” and is expressed in milliseconds [ms]. It indicates an asymmetry in the balance wheel’s vibrations. The beat error should remain between 0.0 and 0.8ms. Above, it can reduce the amplitude, degrade the accuracy and increase the time needed for a watch movement to start.

The frequency is the number of oscillations the balance wheel does over time. The ONEOF App expresses the frequency in Hertz [Hz] which is the number of oscillations per second. Watchmakers also commonly use the number of beats, or vibrations, per hour [b/h].

The ONEOF App automatically detects the most common beat frequencies from 2Hz (14’400b/h) to 10Hz (72’000b/h).

Due to phenomenons related to the acoustic physics, the rate accuracy must be averaged over a period called the integration time, expressed in seconds [s].

The different integration time values are: 2s, 10s, 20s, 30s or 60s.

The lower the time integration, the less stable the measurement. However, a low integration time allows the measurement to show more detailed fluctuations.

Basically, you would use a long integration time (30 or 60s) for inaccurate vintage watches or if you use the ONEOF Accuracy2 in a noisy environnement.

If the watch is stable, accurate, and you are doing the measurement in a calm environnement, you can use a lower integration time.

The integration time can be changed in the App settings in expert mode only, before or during a measurement.

The lift angle is the angle in degrees [deg] covered by the balance wheel between the first and the third peak of the escapement signal.

It is a geometric feature, determined by construction and given by the manufacturer.

In the watchmaking industry, the lift angle is known to be inaccurate: between 2 movements of the same production, a variation of +/- 3° of the lift angle is not rare. As a 1° change equates to about 7° change of the amplitude value, that is the reason why the acoustic measurement of the amplitude remains an estimation (manufacturers always use more precise laser measurement).

For the most of the standard watch movements the lift angle is about 51°.

The rate accuracy is an instantaneous indication of the deviation of the balance wheel beating frequency and is expressed in seconds per day [s/d].

A watch can run faster or lower and its accuracy changes over time as a result of a wide variety of perturbations: internal imperfections in the gear train, aging of the oils, gravity and vibrations, temperature variations, magnetization of the hairspring, etc.

A watch is “accurate” when its daily variation is within the range determined by the brand. For example:

  • Rolex: -2…+2s/d
  • Omega, Master Chronometer certification: 0…+5s/d
  • COSC certified movement: -4…+6s/d
  • Or any other ranges: -10…+10s/d, -15…15s/d, etc.

Please note that as the watch accuracy is constantly changing over time, the instantaneous rate accuracy can be out of the specs while the average daily rate is still within the brand’s range.

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  • Acrotec Group
Acrotec Logo

The Acrotec Group is a team of entrepreneurs and talents with a single ambition: to continuously push the boundaries of precision micromechanics and everything associated with it. Acrotecs objective is to better serve its customers, to gain their trust and to earn their loyalty.

  • Watch & Jewelry
  • MedTech
  • Precision High-Tech
Watch & Jewelry
Acrotec is the leading independent supplier of mechanical movement components to the Swiss watch industry. The products offered by the Acrotec Group include most of the key components of a watch movement, including shock absorbers, oscillating weights and barrel springs, and also escapements, barrels, the index-assembly, and many other components and assembled parts. Acrotec also offers automated machining, tools, and all specific treatments and finishings.
MedTech
Acrotec is one of the leading contract manufacturers in the MedTech sector in Europe. The group is active in the manufacture of complex components and subassemblies for medical devices, as well as precision pumps used in dialysis and diagnostics. In addition, it is a trusted partner in the production of spinal, extremity, maxillofacial, cardiovascular and dental implants, as well as in most instruments used in surgical procedures.
Precision High-Tech
With its large production capacity and mastery of production processes in accordance with ISO9001, IATF and EN9100 certifications, Acrotec supplies a wide range of demanding industrial sectors. The groups strong technical expertise combined with the vertical integration of many production processes offers a qualitative and competitive service to our partners.
Visit Acrotec website
Acrotec Logo

The Acrotec Group is a team of entrepreneurs and talents with a single ambition: to continuously push the boundaries of precision micromechanics and everything associated with it. Acrotecs objective is to better serve its customers, to gain their trust and to earn their loyalty.

  • Watch & Jewelry
    • Butech : Specialised wire for watchmaking stones
    • Décovi : Precision turning for complex components ( oscillating weights )
    • Générale Ressorts : Specialist in barrel springs and energy modules
    • easyDec : Specialised in the high precision turning of micro components
    • H2i : Innovative, high-performance, accurate measuring tools including ONEOF products
    • KIF Parechoc : High precision watch components
    • mu-DEC : Micro-turning of components with complex geometries
    • Mimotec : UV-LIGA technology, CLR-LIGA, anti-counterfeiting
    • Precipro : Precious metal machining
    • Petitpierre : Complex assembly machines and high end tools
    • Pierhor-Gasser : Stones for watchmaking
    • STS : Surface treatment on all components of the watch movement
    • WatchDec : Turning of micro-components
  • MedTech
    • AFT MicroMécanique : Specialised for more than 20 years in the manufacturing of spin implantable devices, orthopaedics and instrumentation
    • Butech : Industrial applications requiring a very fine wire and absolute precision
    • Décovi : Precision turning of equipment components for medical applications
    • Diener Precision Machining : Producer of high-quality mechanical components such as implants, instruments and specialised subassemblies for medical devices
    • Diener Precision Pumps : Provides custom precision pump solutions for OEM customers in the medical market : diagnostic, dialysis, sterilization, cooling
    • easyDec : High precision screw-cutting on complex micro parts
    • Microweld : Laser welding and laser marking in the medical sector / Microwelding and laser microcutting for implants and instruments
    • Pierhor-Gasser : Rubies and sapphires for medical applications as isolator of pacemaker isolators, bearings for endoscopy
    • PoliTrempe (only in French) : Micro-welding and laser micro-cutting covering a wide range of applications
    • Tectri : Specialised in precision machining of implants and medical devices
    • WatchDec : Turning of micro-components for Medtech applications
  • Precision High-Tech
    • Butech: Industrial applications requiring a very fine wire and absolute precision
    • Décovi : CNC turning and milling for electronics and all industries
    • Diener Precision Machining : Precision machining a wide range of industrial applications
    • Diener Precision Pumps : Production of precision pumps for the printing and food industries
    • DJC : Bar turning of parts in large series for the automotive and electronics industries
    • easyDec : High precision screw-cutting on complex micro parts
    • Générale Ressorts : fiber optics
    • Petitpierre : Machining of prototypes and small series for the microtechnology, automotive and space industries. Realization of complex assembly machines of microcomponents
    • PoliTrempe (only in French) : Micro-welding and laser micro-cutting covering a wide range of applications
    • Roch Mécanique de précision : Machining of small and medium series focused on the aeronautics industry
    • Tectri : CNC turning for the micromotor sector
    • Vardeco : High-speed bar turning of electronic components
Visit Acrotec website