FD 146 chair without marking  

Here is a marked one:
http://www.ebay.com/itm/Peter-Hvidt-France-Daverkosen-Solid-Teak-Danish-...
Is it possible the impressed mark got sanded off at some point?
It is teak and oak, by the way.
This design was earlier. Not sure the dates, but I would guess early to mid 50s. If you can find one with a France and Søn mark/medallion its production made it to 1958, but I doubt it.
Note that later this chair's design was updated and it became 147 & 148.

Apologies if this comment is too obvious, but did you look very closely at the inside of the back seat rail. Some of the early FD stamps had thin lines which can be worn away over time.
(Edit: was typing this as leif posted)

As I know in general France and Søn mark their pieces with the medaillon or that branding.
I searched inside but there is nothing and it looks not sanded.
Do you know as well pieces without marking of them?
Cado did not manufactured this chair?

Cado did not manufacture this chair. It is much earlier.
Charles France and Inger Daverkosen started the company, not sure exactly when, but in the early 50s or late 40s. The company's product from back then is not very well known. This chair is one of the notable early successes. Also, an Ole Wanscher designed chair/sofa.
Teak wood is very resinous and oily, with mineral deposits, and was not easy to use on a factory production basis. (It would gum up and dull blades). So not much teak was used in the early Danish factory production, of which this chair is representative.
The early France and Daverkosen marks did _not_ include a medallion. They were a gold foil physical impression. There are a variety of different designs. A bit later France and Daverkosen started using the circle FD logo, and medallions. There evolution of its branding was very iterative.
In the mid 1950s, industrial production with teak had been figured out, and the company started selling chair's like Finn Juhl's Spadestolen, which were all, or mostly all teak. This change drove their entire line to change. And in fact you can see a similar movement with other big factories like Søborg.
In about 1958, Inger Daverkosen left the company, and the name changed to France and Søn, as Charles France incorporated his son into the management of the company. Marks from around this time show a France and Søn medallion with a FD mark. And there are also FF medallions with a graphical treatment similar to the round FD mark.
Around 1960, the logo was changed to the handwritten FF mark with Charles France's signature below it.
On November 15th, 1966, Poul Cadovius purchased France and Søn from the France family. The company was amalgamated with Royal System, which was the name of Poul Cadovius' company that sold wall unit etc. The France and Søn name and branding continued forward unchanged.
On the 20th of August 1970, Poul Cadovius' companies were re-organized with the name 'Cado' introduced as the overall brand name for all of them. Effectively Royal System and France and Søn were subsidiaries of Cado. The branding starts to show the France and Søn 'FF" gold foil stamp with a Cado medallion.
I don't know how much longer the company was around. I suspect it was only a matter of a few years.
Here is a magazine page from the 1953 Decorative Art showing the France and Daverkosen chair. If I had to pick a date for you chair, I would say 1953 is a pretty good educated guess.
Charles France was very reliable about marking his product, so it is surprising that the chair is not marked, but unless there is something incorrect about it which I can't see, it is not a knock-off, and it is almost impossible to believe it would be a forgery, so it must be legitimate. There are a handful of unmarked France and Søn pieces that I know of anecdotally, which is a very, very small percentage of production. So anything is possible.

Hi Leif,
thank you very much for you France and Son compendium.
Such information is really exciting.
Thanks a lot.
Molassekoenig