Some hacks will help you progress faster! We will share some of them.
 
1) Statistics is a wise tool to make your production process effective! To keep the production running smoothly, you need to make the following machine in each milling line work faster than the previous one. You see that the sanding machine works slower than the resawing machine. This makes materials pile up. You need to increase the sanding machine speed.  
 
Slow machine
Pile of materials
 
2) You can build the new machine when you upgrade the income of the previous one to level 25.
 
3) If you buy the ''X2 income forever'' offer and run an X2 ad campaign, you will get the X4 income for 6 hours! Please note that the increased income multiplier won't be displayed in your statistics.
 
X2 ad campaignX2 income forever