Unger Meat Grinder

Fig. 19: Schematic drawing of grinder

A meat grinder is a machine used to force meat or meat trimmings by means of a feeding worm (auger) under pressure through a horizontally mounted cylinder (barrel). At the end of the barrel there is a cutting system consisting of star-shaped knives rotating with the feeding worm and stationary perforated discs (grinding plates). The perforations of the grinding plates normally range from 1 to 13mm. The meat is compressed by the rotating feeding auger, pushed through the cutting system and extrudes through the holes in the grinding plates after being cut by the revolving star knives. Simple equipment has only one star knife and grinder plate, but normally a series of plates and rotary knives is used. The degree of mincing is determined by the size of the holes in the last grinding plate. If frozen meat and meat rich in connective tissue is to be minced to small particles, it should be minced first through a coarse disc followed by a second operation to the desired size. Two different types of cutting systems are available, the “Enterprise System” and the “Unger System”:

Fig. 20: Grinder: Worm feed (feeding worm/auger) and cutting set with plates and knives (system "Unger")

• • The “Enterprise System” (Fig. 19) is mainly used in smaller meat grinders with orifice diameters up to 98 mm and consists of one star knife, sharpened only on the side facing the disc, and one grinder plate. Hole diameters can vary from 13 to 5 mm.

  • The “Unger System” (Fig. 20) is used in meat grinders with orifice diameters up to 440 mm and consists of the kidney plate, one or two star knives sharpened on both edges and one or two grinder plates. For a final particle size above 8 mm the recommended setting is kidney plate – star knife – grinder plate. For a final particle size <8 mm the recommended setting is kidney plate – star knife – grinder plate (13 mm) – star knife – grinder plate (6 to 1 mm) (Fig. 21).

Fig. 21: Grinder plates of different hole size, star knives and spacer rings for tightening of cutting assembly