first of all: my english isn't perfect because I grew up in a country far far away so some of my words might not be understandable by some people. If so, please tell me.

My problem is a problem many (new) players might have: How can I control the inserters so they don't spam all belts?
I've played the game for about 10-15h now and have (beside other things) researched all kinds of inserters. The thing is, that if you need two or more parts for a production (e.g. green electronic circuits - 1x iron plate and 3x copper cables) you might come to the point that you have only iron plates and no copper cables or the other way round. In my production logic, all production stuff has it's own belts (4x4 factories, surrounded by belts where on the inner side the factories get their goods from and on the outer side deliver it). The final (sub)product (like copper cables) is then grabbed by filter inserters and transported to the next stage (e.g. the 4x4 factories for green electr. circuits). When for any reason you run short of copper plates or iron plates the whole production stopps. Then the belt is full of copper cables and no place for iron plates.
So long story short: Is there a way to say the inserter: "You only place so many iron plates on the belt that there are a maximum of 30 plates on the belt"? Then there would be enough space to place copper cables etc.
Thx for your help
Philip