Tour of Lange Uhren Factory

Part 3

By Peter Chong, May 1999

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Quality Control

After regulation, all the watches are sent to the Quality Control Department, where each watch is subjected to a battery of tests. The machine seen left, actually works like a giant winder but is not used to perform winding duties. For the automatic watches, the rotor is removed to prevent winding during tests. Watches are put on the machines to test their accuracy to positions.

Each watch is regulated to 5 positions:

  1. Dial Up, because typically a watch is placed dial up when not worn.
  2. Dial Down, primarily a diagnostic position rather than a practical one.
  3. Crown Left. This is the position when a watch is worn on the outer wrist of either hand in a horizontal rest position. Typically Crown Right is not regulated, as it is only used by a person wearing the watch on the inside wrist. This position may then be adjusted in the field by a competent watchmaker for this unusual wear position.
  4. Crown Up.
  5. Crown Down. Most important after Dial Up, as in normal wear with the owner’s arms hanging on side.

As discussed in Walt Odet’s excellent article, (definitely required reading for any horology buff), the stability of rate, as expressed in the Stability of Rate in Single Positon, the Stability of Averaged rate in a Single Position, and the Relative Averaged Rate in Different Positions remains the most critical and important criteria. Because only with good stability over time, and between positions, the absolute rate of a watch can be regulated.

It is also interesting to note that in a the mechanical watch, the owner cannot remove himself/herself from the equation of accuracy, which is most often defined to the layman as the absolute rate…the rate over a period of time in reference to a known time standard…as the owners wearing habits directly influence these rates. And when a watch is capable of good stability of the beat over time and between positions, it then becomes a simple matter of a regulation by the watchmaker to cater for the wear patterns. Microscope showing highly magnified image of my watch's escapement...see the video screen left of the microscope. Btw, the microscope is s Nikon SMZ trinocular.

Each movement is examined on a high power microscope. The beating of the escape is carefully examined for regularity of the opening and closing of the coils. Also in this department, all the parts manufactured by outside vendors, like the dial, case, crystal, strap are examined for quality that it meets the manufacture’s high standards. With this field regulation, it can achieve remarkable accuracy…my Lange 1 gains less than 1 second every 24 hours. (as an excercise, work out the error rate).

I also saw a computerized optical machine, which reads the shadow of a plate, after it is cut by the CNC and wire erosion machines, and matches it to the drawing of that part created by the design department. The machine takes about 100 measurements per minute, and makes this comparison.

Tool Time!

True to its own tradition to be independant (Aldoph Lange started to make his own cases when he found that suppliers could not meet his stringent quality demands), Lange Uhren even makes their own tools. This includes the small tools, and jigs to hold the parts of the movement while the watchmaker or goldsmith finishes the component.

This department is located in the basement of the Lange 1 building. And comprises of a typical tool shop, with high speed lathe machines, and other equipment not familiar to me. The Tool Making Department

Wire Erosion Equipment

One of the many CNC controlled Spark Erosion machines in Lange.

We were then led to a Lange 2, the new factory building just across the courtyard from the Lange 1. The first room was the CNC controlled Wire Erosion equipment.

For the unitinated, these machines are capable of making any shape of object from metal plates with greater precision than possible with conventional stamping machines. Lange Uhren has about 8 or 10 of these machines installed.

The reason why many manufactures do not use this method, despite its inate accuracy, is because of the time it takes to cut a plate ranges from 15mins to an hour, depending on the complexity of the design. In Lange Uhren, plates are stacked 6 high, and cut half a dozen a go. But for a manufacture which produces 45,000 watches a year (or even 20,000 watches!), this process is too slow.

Here is how it works: drawings of a component is loaded into the CNC computer. The drawing defines all the straight and curves required, and the computer moves the table to follow the outline against the cutting tool. Cutting is carried out with a wire about the thickness of human hair.

Unlike a sawblade, the wire does not have teeth. The wire is passed from a supply reel to a takeup reel. In between, is the object to be cut. A high frequency eletronic impulse is passed through the wire as it “flies” from the supply reel to the take up reel at a rate of nearly 300 meters per second (that’s 1000 feet per second for our Imperial friends…).

The result is a series of small sparks rise from the wire to the work material, causing the material to vaporise at the vicinity of the wire. When all the wire has passed from the supply to the take up reel, the machine automatically reverses the direction of the wire, and the process continues.

Because of the smallness of the wire, and that cutting can be carried out in any direction, the technique can produce any shape with any required accuracy…with no deflection, and completely true to the design. The resultant cut edge is also remarkably even and has a fine grain matt finish ready for polishing and smoothing (usually by blasting with sand)…though with this technique, very little material needs to be removed to achieve a polished finish.

Uhrmacherschule – The Watchmaking School

Herr Lang, seen with a recently restored example of a Marine Chronometer by Lange.

We next went to the annex building which houses the school. As the entry requirements for a watchmaker to Lange Uhren is extremely stringent, the manufacture is begining to find that the good skilled watchmakers are becoming difficult to find. To remedy this condition, Walter Lange set to follow the footsteps of his ancestors once again by setting up a school.

Currently with an enrolment of about 10 young men and women, this school will begin to bear fruits when they graduate in a couple of years.

Also housed in the school is the Principal: Herr Lang’s workshop and restoration center. Mr. Lang is one of the authorities on repair, restoration and identification of old Lange timepieces. Having been in the employ of the state in the Mathematics and Physics Salon at the Zwinger palace, he has returned to Lange Uhren to serve as principal and restorer.

The school was so inspiring that I too want to become a apprentice!

It was at this school, that our tour of the factory concluded.

Some words to conclude

What struck me most during this visit was the remarkable ingenuity of the people involved in making Lange watches. Their love for high horology, their dedication, attention to detail is second to none in this industry. Many of the staffers are very young, and the management team is extremely well equipped, and very open to customers.

I am extremely impressed with the obsession every single person I met at the manufacture had with quality, with customer service, and with dedication to art and horology.

This was the highlight of my two weeks in Europe which, began with my visit to the Basel Watch and Clock Fair, 1999. Click here for a final surprise!


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