Die-parting line

Pipe and Tubing. A typical die for extmding tubular products is shown in Figure 4. It is an in-line design, ie, the center of the extmded pipe is concentric with the extmder barrel. The extmdate is formed into a tube by the male and female die parts. The male die part is supported in the center by a spider mandrel. Melt flows around legs of the mandrel and meets on the downstream side. The position of the female die part can be adjusted with bolts adjustment is requited to obtain a tube with a uniform wall thickness. 

Fig. 4. Pipe or tubing die for in-line extmsion A, die body B, mandrel, pin, and male die part C, die, die bushing, and female part D, die-retaining ring E, die-retaining bolt F, die-centered bolt G, spider leg H, air hole I, seat for breaker plate J, ring for attachment to extmder and K, die land (15).

Basically the BM lines have an extruder with a die or an injection machine with a mold to form the parison or preform, respectively. In turn the hot parison or preform is located in a mold. Air pressure through a tubular pin-type device located usually at the parting line of the mold will expand the parison or preform to fit snugly inside their respective mold... 

Die casting Reusable metal mold Copper or low-melting-point alloys Good dimensional tolerances, thinnest cast sections possible, quick cycle time High die cost makes it impractical for low volume, limited alloys, need draft/parting lines, size/weight limit Small intricate parts, housings, valves, heat sinks, toys... 

For cheese extracts this method is not suitable due to the interference of the matrix. However, it works well if a part of the spectrum at higher wavelengths is used for the calculation. This alternative base-line method uses the straight line between the absorbance at 311 and 329 nm as die base line. The net absorbance may be taken from the UV spectrum as the difference between the absorbance at the maximum at 317 nm and the base-line (Figure 4-B). It may also be calculated from ... 

Endeavor to keep the parting line in one plane since this will result in simpler and lower-cost dies. 

Parting Line. Large extrusion dies must be able to separate at the melt flow line for easier fabrication and maintenance. Smaller extrusion dies may not have a parting area, because they can be constructed in one piece. 

Venting at the parting line is no problem therefore, a surface ending there caa always be well vented using simple methods well known to die mold designer. (Unfortunately, the me cannot be said about venting for ribs, hubs, etc. this will be covered later.)... 

Flash—Excess material which forms at the parting line of a mould or die, or which is extruded from a closed mould. 

Stack dies (Fig. 3.7) separate the flow gaps between vertically stacked plates instead of between nested mandrels. Theoretically, any number of plates can be stacked to add one layer for each parting line between plates. This technique yields some potential advantages. Because the various extruders can be located in a fan around the... 

Dies can be manufactured with removable lower lips. Their primary advantage is to make the die more versatile. The thickness of the final product being produced is related to the thickness of the material exiting the die. A removable lower lip increases the lip opening range of a die. The disadvantage of a removable lip is the parting line in the flow surface. 

A Fast-Gap system (trade mark of Extrusion Dies, Inc.) on a die extends the adjustment range, and eliminates the parting line of a removable lower lip. This device provides an additional 5 mm of adjustment ( 2.5 mm), by simply turning a hex headed power screw on the end of the die. The operator can now also flex open the lip to clean it, and then close it back to the run position, saving time and reducing scrap. 

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