pellet ring die
See the picture on the left for actual positioning on the cross-section of a ring die
D = Hole Diameter: Typical hole diameters for feed can range from around 1.6mm up to 8-10mm
L = Effective Length: The effective length is the ring die thickness that actually performs work on the feed.
T = Total Thickness: Total thickness is the overall thickness of the ring die. Overall thickness provides the necessary ring die material to avoid breakage. Of the ring die
R = 'Relief' (or also known as (X) Counterbore Depth): 'Relief' or Counterbore depth measures the relief provided in the ring die as the pellet exits the ring die hole. Enlarged holes are counterbored into the ring die to reduce its effective thickness and provide the proper L/D ratio while maintaining the total thickness needed to prevent breakage of the ring die. Specific rows of ring die holes, such as the two inner and outside rows, also sometimes are counterbored to greater depths to encourage feed flow through these outer rows of holes to help ring dies wear more evenly, this is referred to as (VR) variable relief. More examples of various ring die relief patterns can be seen in this diagram: Pellet ring die reliefs
Pellet ring die specifications:
See the picture on the right for actual positioning on a ring die.
I.D. = Inner Diameter of the ring die: The inside diameter is the most common identifying dimension of a ring die and is always specified during ring die selection.
O = Overall Width of the ring die: The overall width of a ring die may vary. Often, there is more than one width available for each ring die diameter.
W = Working Width: ring die working width is measured between the two inside edges of the ring die grooves.
Ring die working area is the area inside of the two ring die grooves. As the pellet ring dies' width and diameter so to does the working area. The ring die working area is very important as different feed ingredients and feeds require a specific time inside the ring die holes, known as ring die retention time, in order to be able to bind together and form pellets. With larger working areas on ring dies there is greater retention time to form pellets, which in turn reduces power consumption per tonne of feed pelleted and helps to improve production efficiency.
ring die cross-section
L/D Ratio: The L/D ratio is the effective length (L) divided by the hole diameter (D). High L/d ratios provide high pellet ring die resistance as feed moves through the hole. Low L/d ratios provide less resistance.
Each material has an L/D ratio requirement to form the material into a pellet.
pellet ring die
I=Cube inlet diameter: The diameter of the inlet where the feed enters the compression area of the pellet ring die. Different configurations of the inlet (countersinks, tapered inlets, well inlets, etc) can be used to achieve extra compression if needed for particular materials.
N=Inlet (well) depth: The depth of the inlet into the pellet ring die.
C=Degree of taper (Choke): The degree of taper, also refer to as the choke. This degree is important as it determines the force to which the feed material is pushed into the pellet compression area.
F=Total depth of well and choke: This measurement is the difference of the effective length and the total thickness of the ring die. It is the depth of the feed travel in the inlet to reach the effective pellet compression area.
Holes in ring dies typically are drilled in three different patterns.
- Close-hole pattern spacing provides more open ring die area and more retention time. The open area of ring dies with close-hole patterns is about 43 percent.
- Wide-hole pattern spacing provides less open ring die area and greater ring die strength. Wide-hole pattern spacing provides about 32 percent open ring die area.
- Standard- or medium-hole pattern spacing provides a compromise between ring die open area and ring die strength.
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