The following three broad types of forming or shaping devices, as described afterward, are used to manufacture the great majority of commercial cookies:
1. Extruders push the dough or batter through a constricting orifice; they are exemplified by deposit machines, bar presses, and wire-cut equipment.
2. Rotary molders shape the dough in die cavities cut into the surface of a metal cylinder.
3. Stamping machines or rotating cutters cut shaped pieces from a continuous sheet of dough.
Extruders. Extruders vary widely in complexity, from simple equipment consisting of a hopper fitted with feed rollers that press the dough through adjustable slits, to complicated devices that extrude deposit-cookie batters through orifices moving in predetermined patterns. The most common type of machine consists of a hopper and one or more feed rollers that force the dough through an array of tubes called die cups. The dies may have orifices of different shapes: square, round, oval, scalloped, and so on. On wire-cut machines, disks are sliced from a continuously extruded cylinder of dough and allowed to drop onto the oven band or transfer belt. Other, more complicated extruder-type machines can extrude multiple doughs or doughs with fillers. Such machines are sometimes called encrusters. A dough casing and filler are coextruded and either sliced by a wire device or pinched closed via a mechanical device. Sometimes, the dough and filler combination is applied directly to the oven band, forming a continuous strip (eg, fruit bar).
Rotary Molders. A simple rotary-molding machine consists of a hopper, a feed roll, a cylindrical die, a knife or scraper, a cloth or woven-plastic belt (also called a web or apron), and a rubber-covered compression roller. There will also be a frame, motors, controls, and so on. Such machines may be permanently affixed to the oven frame or they may be constructed as movable attachments for cutting machine lines.
The curved surface of the metal cylinder is covered with engraved cavities having the shape desired for the dough piece. Alternatively, plastic die cavities may be fastened to the surface. Pressure is exerted on the dough in the hopper. This causes the dough to be forced into the die cavities, as the die roller rotates beneath a slit at the bottom of the hopper. The cylinder rotates past a knife or scraper (which forms the flat bottom on the dough piece), until it contacts the cloth belt passing beneath it. The belt is forced against the die by a rubber-covered roller, which can be adjusted to vary the pressure. As the cylinder lifts off the belt in its continuing rotation, the dough piece adheres to the belt more strongly than it does to the cavity and is, therefore, drawn out of the die. The belt carries the dough piece to the oven band, where transfer is completed by various kinds of simple mechanisms. There are limits to the adjustments that can be made on the machine to achieve these operational essentials, so the physical characteristics of the dough can vary only slightly.
Stamping Machines. In deposit machines, the batter is extruded intermittently through shaped nozzles. Separation into cookie-size portions is achieved by lowering the oven band during the time the extrusion is stopped. This causes the batter on the band to be pulled away and separated from the batter still in the extrusion orifice. Then the band is moved up again toward the nozzle, and extrusion begins again. Such machines are relatively simple, but they are also quite demanding with regard to dough characteristics. In more advanced machines, the nozzles can be moved to form various patterns such as curves, wavy figures, swirls, and circles. A second depositor can be synchronized with the first to put jelly or some other filling on top of the cookie.
A bar-press machine (sometimes called rout presses) extrudes continuous strings or strips of dough directly onto the oven band. Separation of these strips into individual cookie pieces can be made, either before or after baking, by a cutting device. The die plate may be inclined in the direction of the extrusion, so that the dough ribbon is supported for a longer period of time, an arrangement that reduces breaking or thinning of the dough strand caused by gravitational pull. The die orifices are usually slots with a straight lower edge to give a flat bottom to the cookie, and a grooved top edge, to give a ribbed upper surface. Height of the strip can be varied by moving one of the slot edges.
Wire-cut machines represent an advance in complexity over bar-press and deposit machines in that they include a device that cuts off pieces of the extruded dough as it emerges from the die orifice. The cutoff device consists of a wire or blade that is quickly drawn through the dough by a reciprocating harp. The harp is simply a frame or support attached to a mechanism that moves it back and forth beneath the die cups. The dough emerges from the cups in approximately cylindrical form, if round cookies are being made. However, changing the shape of the orifice can modify the cross section of the dough strand. Several of the die cups are held on a bar that fits snugly into a channel at the bottom of the hopper. Wire-cut machines can probably handle more types of dough than any other cookie-forming apparatus, but they do not operate well on elastic, extensible doughs.
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