Is it generally accepted to take months off (unpaid) during a PhD? Currently I am finishing my masters degree program in Life Sciences / Biotechnology by doing an industrial internship. After having obtained my degree, I would definitely like to do a PhD if I can find an interesting project in a location where I would also see myself living for a couple of years. 

Another, non-career related ambition of mine is to go travelling for a couple of months. Now most would say that the time in between obtaining your degree and starting a PhD would be perfect for this, however, at the moment I lack the money to be able to make such a travel. 

One option that came to mind would be to start a paid PhD program, which would me allow to save up some money to start a travel. Now the question is: would it be possible to take months off from my PhD work in the middle of the program? Note, I am not looking to spare up free days and use them all on this travel period, I would intend to take a real period off (and not be paid as a consequence). 

I do realise that if this is possible at all it will be very specific and varying between different programs/supervisors/institutes, but I am looking for the general view in academia on this topic.

Edit: the geographical location where the PhD program would be done, is most probably Europe.
This is almost completely dependent on two things: 


Your departmental policies and program structure
Your advisor


In the US, most programs (all of the ones I'm personally aware of) work on a 9-month academic year schedule, so there's generally 2-3 months a year left over. This is a time that is variously spent on research, conferences, teaching appointments, or internships, so you generally want to be on the same page as your advisor (and department) on your plans.

Not all doctoral programs run this way, though, so if this is important to you, you should ask current students, potential advisors, and administrators in prospective programs how this generally goes.

As to affordability, that's really up to you in how cheap you want to (and are able to) live, choosing programs that are in affordable areas, and availability/pay of internships in your field.