After the dough is mixed it is fed to the forming machines. The arrangement of the dough feed system will depend on the type of dough and the type of forming equipment for the particular product.
Mixers may be horizontal or vertical mixers with portable dough tubs. For many mixers, the dough is fed from a portable tub to the dough feed system.
Alternatively many horizontal high speed mixers now have tipping angle of over 100 degrees, which allows them to automatically discharge the dough into a dough feed system on a floor below the mixing room.
For doughs which will be sheeted or laminated on a biscuit cutting machine, a tub lift and tilt unit may be used to tip the bulk dough into the hopper of the sheeter. This is the simplest method of feeding a 3 or 4 roll sheeter on a single floor layout. A disadvantage is the lack of metal detection before the sheeter.
FIG 1: Lift and tilt units to feed the sheeter hopper from a dough tub
Alternatively, for doughs for crackers and semi-sweet biscuits, the bulk dough from the mixer can be tipped into the hopper of a two roll feeder which will meter the bulk dough. It may then be conveyed to the sheeter of the biscuit cutting line or laminator. The conveyor should have a metal detector and reject system to avoid any metal being delivered to the sheeter rolls.
An alternative feed system uses a ‘live bottom bin’. The dough is tipped from the tub into the hopper of the live bottom bin. The base of the hopper is a conveyor which will take the dough forward where it is cut into short pieces by a vertical guillotine. The conveyor operates intermittently to meter the dough as required by the forming line. The dough feed conveyor delivers the dough to the sheeter of the biscuit cutting line or laminator.
Some systems use tines or a ‘chunker’ with rolls in place of the guillotine. These systems divide the dough into separate pieces for conveying to the forming line.
FIG 2: Dough tub tilt unit to feed a live bottom bin
FIG 3: Guillotine on live bottom bin
FIG 4: Live bottom bin arrangement
FIG 5: Automatic dough feed system from Arrow Design Services with options for adjustable dough gate from live bottom feeder, sheeting rolls, kibbler, chunker arrangements
The conveyor from the live bottom bin to the sheeter will have a metal detector with alarm and reject system. The reject system is usually a retractable end nosepiece operated automatically if metal is detected. The rejected dough will fall into a tub below the conveyor.
Rotary moulders must be fed very evenly across their width and at a constant rate to ensure accuracy in the weights of the moulded dough pieces. The bulk dough may be fed from a two roll sheeter or a live bottom bin to the dough feed conveyor. The dough is then kibbled, (broken into small pieces), above the hopper of the rotary moulder and delivered very evenly across the width of the machine. The hopper of the rotary moulder will have level probes and the dough feed system will be automatically controlled to maintain a constant head of dough in the hopper. Vertical guides may be used in the chute to the rotary moulder hopper to ensure an even feed of dough across the width of the machine.
FIG 6: Dough feed to a rotary moulder with metal detector on infeed conveyor
Depositor doughs, (or batters), are relatively fluid and may be pumped to the depositor hopper. Alternatively the batter may be poured from a hopper above the depositor with an adjustable gate to control the flow of batter.
FIG 7: Cake depositor over oven feed end fed with batter from an aerating mixer (on the right) by pump.
From Biscuit, Cookie and Cracker Production, Iain Davidson