A visit to La Joux-Perret in La Chaux-de-Fonds
DonCorson
A visit to La Joux-Perret in La Chaux-de-Fonds
La Joux-Perret is one of the well established watch industry suppliers supplying many brands. They can develop and/or supply complete movements as well as components. Their own brand is Arnold and Son.
La Joux-Perret has three different markets in view:
1) Small quantity (100s), high end reserved for their own brand Arnold & Son
2) Medium quantity (1000s), for many brands
3) High quantity (10'000s), as a supplier for movement manufacturers.
As these different markets place differing demands on the production equipment they have a vary large and varied machine park. Many of these machines, such as the Zumbach transfer machines I have rarely seen. As strange as it may seem, mass production requires higher precision and greater production repeatability than production of smaller quantities. The parts must be absolutely perfect and identical so that the assembly, whether automatic or with personnel, can progress without any incidents requiring skilled intervention slowing things down. And the time used for each part must be minimised which makes precision stamping and transfer machines the units of choice.
Of course LJP has the usual pallet of development engineers (who at LJP are all first professional watchmakers who have then gone on to study engineering, the perfect combination) laboratories, prototyping and test equipment. But those kind of things we have often seen, what is fascinating is the equipment for mass production. Most of this is equipment from the '50s and '60s that LJP has refurbished and updated. This is the perfect combination: the absolute precision and vibration-free running of the older heavy cast iron cam-programmed machines along with the flexibility of added computer controlled components.
After this long winded introduction, let's take a look around.
The movement design engineers and their labs with extensive test equipment.
A stock room with finished components.
Bins loaded with movment plates in production. This is mass production. First the plates are stamped out of metal bars. This stamping includes many of the openings in the plate. Then after heat treatment the parts move on to the transfer machines for the precision work. We will see the stamping machines further on.
Some Zumbach transfer machines. Each head on the machine cuts one particular feature with specially made tools. The cutting is done all at the same time for all the heads as the entire upper psrt of the machine moves up and down. The use of special tools for each station makes it expensive to set up the machine, but on the other hand the machining time is much less than with CNC. A Zumbach machine spits out a part every couple of seconds as there is a cutting tool at each station. A CNC machine has only one cutting tool at a time doing all the operations that a Zumbach does all at the same time sequentially.
Some standard CNC machines used for lower quantity production. The big advantage of CNC is the flexibility.
As we can see on these partly finished pieces the metal blanks all have positioning holes so they can be machined with precision in several steps.
More mass production.
We move on to gear production. Not easy to photograph the parts themselves which one can hardly see without a loupe.
A machine for polishing the axles of the pinions.
We are getting close to the stamping area. Here we see stamped blanks in maichort (german silver). The Arnold & Son movements are made entirely in maichort and not brass.
The stamping machine. Metal bars in on side and parts or blanks out the other.
There is, of course, a big stock of stamping tools and, as we see here, raw material.
This long machine is just for cleaning the parts.
Stamping and machining metal induces large stresses in the pieces that can cause deformation. To eliminate this deformation the pieces are heat treated several times during manufacturing. Here we see the heat treatment ovens and some parts awaiting treatment.
What could this machine do? Well it is to remove the metal dust from the machining liquids so that they can be reused in a closed circuit with next to no waste.
Here we see a machine for grinding the pieces to thickness. Because of the formentioned deformation and heat treatments the parts are stamped from stock that is thicker than needed. After stamping and heat treating they are then ground to be perfectly flat, the side parallel and to thickness on this machine.
To deburr the pieces after milling they are treated to a bath of ceramic sticks.
Ball blasting the surfaces.
Some finished plates. These mass production parts are all destined for outside clients.
We have seen how the flat plate and bridges are made, we now move on to round parts coming from the room full of automatic lathes.
Raw material
The next room is full of electro-erosion machines, these are used for cutting intricate flat parts, also in hardened materials. It is a big advantage to cut material that is already hardened because of the problems of warping of irregular parts during hardening.
There a selection of parts cut with electro-erosion.
In this picture we can see the spark that does the material removal, the tiny light spot.
Now we will move on from the machining to the decoration areas. First some examples of decorated movement parts.
Checking the quality of the snailing.
Beveling on the beveling turret.
Some hand engraved bridges.
Let's look over the shoulder of the engraver.
Polishing bevels
Now for some finished watches.
The Time Pyramid in rose gold and steel. The movement of this watch is built along the lines of a typical British table pendulum clock.
The CTB dead beat seconds chronograph, an extremely handsome watch IMHO.
The DTE double tourbillon.
I have found this visit to La Joux-Perret fascinating. I have never seen this combination of mass production precision with small quantity hand finishing under one roof.
Stay tuned for some more pictures of the Arnold and Son collection coming soon.
Don
La Joux-Perret is one of the well established watch industry suppliers supplying many brands. They can develop and/or supply complete movements as well as components. Their own brand is Arnold and Son.
La Joux-Perret has three different markets in view:
1) Small quantity (100s), high end reserved for their own brand Arnold & Son
2) Medium quantity (1000s), for many brands
3) High quantity (10'000s), as a supplier for movement manufacturers.
As these different markets place differing demands on the production equipment they have a vary large and varied machine park. Many of these machines, such as the Zumbach transfer machines I have rarely seen. As strange as it may seem, mass production requires higher precision and greater production repeatability than production of smaller quantities. The parts must be absolutely perfect and identical so that the assembly, whether automatic or with personnel, can progress without any incidents requiring skilled intervention slowing things down. And the time used for each part must be minimised which makes precision stamping and transfer machines the units of choice.
Of course LJP has the usual pallet of development engineers (who at LJP are all first professional watchmakers who have then gone on to study engineering, the perfect combination) laboratories, prototyping and test equipment. But those kind of things we have often seen, what is fascinating is the equipment for mass production. Most of this is equipment from the '50s and '60s that LJP has refurbished and updated. This is the perfect combination: the absolute precision and vibration-free running of the older heavy cast iron cam-programmed machines along with the flexibility of added computer controlled components.
After this long winded introduction, let's take a look around.
The movement design engineers and their labs with extensive test equipment.
A stock room with finished components.
Bins loaded with movment plates in production. This is mass production. First the plates are stamped out of metal bars. This stamping includes many of the openings in the plate. Then after heat treatment the parts move on to the transfer machines for the precision work. We will see the stamping machines further on.
Some Zumbach transfer machines. Each head on the machine cuts one particular feature with specially made tools. The cutting is done all at the same time for all the heads as the entire upper psrt of the machine moves up and down. The use of special tools for each station makes it expensive to set up the machine, but on the other hand the machining time is much less than with CNC. A Zumbach machine spits out a part every couple of seconds as there is a cutting tool at each station. A CNC machine has only one cutting tool at a time doing all the operations that a Zumbach does all at the same time sequentially.
Some standard CNC machines used for lower quantity production. The big advantage of CNC is the flexibility.
As we can see on these partly finished pieces the metal blanks all have positioning holes so they can be machined with precision in several steps.
More mass production.
We move on to gear production. Not easy to photograph the parts themselves which one can hardly see without a loupe.
A machine for polishing the axles of the pinions.
We are getting close to the stamping area. Here we see stamped blanks in maichort (german silver). The Arnold & Son movements are made entirely in maichort and not brass.
The stamping machine. Metal bars in on side and parts or blanks out the other.
There is, of course, a big stock of stamping tools and, as we see here, raw material.
This long machine is just for cleaning the parts.
Stamping and machining metal induces large stresses in the pieces that can cause deformation. To eliminate this deformation the pieces are heat treated several times during manufacturing. Here we see the heat treatment ovens and some parts awaiting treatment.
What could this machine do? Well it is to remove the metal dust from the machining liquids so that they can be reused in a closed circuit with next to no waste.
Here we see a machine for grinding the pieces to thickness. Because of the formentioned deformation and heat treatments the parts are stamped from stock that is thicker than needed. After stamping and heat treating they are then ground to be perfectly flat, the side parallel and to thickness on this machine.
To deburr the pieces after milling they are treated to a bath of ceramic sticks.
Ball blasting the surfaces.
Some finished plates. These mass production parts are all destined for outside clients.
We have seen how the flat plate and bridges are made, we now move on to round parts coming from the room full of automatic lathes.
Raw material
The next room is full of electro-erosion machines, these are used for cutting intricate flat parts, also in hardened materials. It is a big advantage to cut material that is already hardened because of the problems of warping of irregular parts during hardening.
There a selection of parts cut with electro-erosion.
In this picture we can see the spark that does the material removal, the tiny light spot.
Now we will move on from the machining to the decoration areas. First some examples of decorated movement parts.
Checking the quality of the snailing.
Beveling on the beveling turret.
Some hand engraved bridges.
Let's look over the shoulder of the engraver.
Polishing bevels
Now for some finished watches.
The Time Pyramid in rose gold and steel. The movement of this watch is built along the lines of a typical British table pendulum clock.
The CTB dead beat seconds chronograph, an extremely handsome watch IMHO.
The DTE double tourbillon.
I have found this visit to La Joux-Perret fascinating. I have never seen this combination of mass production precision with small quantity hand finishing under one roof.
Stay tuned for some more pictures of the Arnold and Son collection coming soon.
Don
Comments:
111forza July 18th, 2014-14:35
interesting Fantastic report Don thanks for posting very interesting
Ancienne Le Brassus July 18th, 2014-15:38
great report, new appreciation of Arnold & Son watches! Definitely amazing stuff! Thanks for this report, it is very nice and as I said, creates a new appreciation. I'd like to hear a bit more about the company's philosophy behind this work, and something about the direction they're moving in. Will stay tuned to your reports! Thanks S
amanico July 18th, 2014-16:04
Excellent article, Don. I learned a lot! For example, I didn't know that this manufacture was owned by Arnold and Son. I ignored, also, that they had three categories of products. For me, La Joux Perret worked on Chronograph movements. Nwo, I know that their wrok is much wider, and very interest...
Goldenlutin July 18th, 2014-16:21
Little confusion... Nicolas, I think that you meant Arnold & Son and not "Graham and Son " :))) Best, Goldenlutin
amanico July 18th, 2014-20:48
Oooops, yes. I had in mind the Graham Foudroyante Chronograph Whose movement has been made by La Joux Perret, if I am not wrong. ( ETA movement + Chrono module made by La Jous Perret ), a movement used by Graham, Panerai and Girard Perregaux, and myabe a fourth one, but I forgot the name... Hence the confusion. Will...
KIH July 18th, 2014-18:45
Great report.... .. this is the first time I see inside LJP. Very informative. But still makes me scratch my head - what does Citizen think of doing with this...... The seem to have little idea.... Waste and shame! Thanks, Don, for your report! Ken
Dr No July 18th, 2014-19:16
The most remarkable aspect of this article . . . . . . is the ease with with it communicates complex technical information to a lay audience (myself included). Elegant writing, Don, and thoroughly enjoyable reading. Thank you! Art
Echi July 20th, 2014-19:49
+1. Thanks, Don! Very enjoyable read even for a layman :) (nt) ..
hs111 July 19th, 2014-02:12
What a great comprehensive report & pictorial !.. Indeed, learned a lot .. Thx & Best !!
jporos July 19th, 2014-07:03
Thanks Don! Important to think about how mass produced movements need much greater precision than limited edition movements. Gives us different goal posts to measure the achievement in each by.
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Preliminary Announcement: ZENITH PuristS Factory Visit
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Dear Forumners, Zenith Manufacture has kindly invited PuristS to visit their factory in October 2014 when the Swiss watch industry re-opens after the Summer break. The tentative dates are 9th and 10th October. PuristS from around the world will meet up in Geneva for a get-together on the evening before the tour. The programme should include a day-visit to the Zenith Manufacture in Le Locle before a return to Geneva.
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