Molded edge

Mold edge nodes (c). These nodes have less than 4 neighbors. A neighbor that is missing on one side implies no flow across that edge, taking care of the dp/dn = 0 boundary condition (natural or Neumann boundary condition). 

Panel- A thin flat piece of wood, plywood, or similar material, framed by stiles and rails as in a door (or cabinet door), or fitted into grooves of thicker material with molded edges for decorative wall treatment. 

No outflow along an impermeable mold edge with an outward unit normal vector, n... 

Figure 1 shows a typical pentagon design. The thickness was standardized on 2.54 mm, and the finished molded edges were to be exactly 2.54 mm. The problem occurred when students became over creative with what they wanted inside the pentagon. They did not realize how complicated it would be to machine lion heads, palm tress, and other novelty shapes. They quickly revised their design so that it could be made with simple... 

A small amount of particleboard is made with a fire-retardant treatment for use in locations where codes require this material, as in some offices and elevators. Particleboards receive overlay and finishing treatments with ease. Wood veneers, melamine overlays, printed paper overlays, vinyl overlays, foils, and direct grain printing can all be done quite simply. A small amount of particleboard is also made in the form of shaped, molded articles such as furniture parts, paper roU plugs, bmsh bases, and even toilet seats. There is another small increment of particleboard made by the extmsion process. These products are made in small captive operations owned by furniture manufacturers which consume all of this production in their furniture. The extmsion process differs from conventional flat-pressed particleboard in that the wood furnish is forced between two stationary heated surfaces. The mats are formed from one edge and this edge is alternately formed and pushed between the heated platens, which are maintained at a distance equal to the thickness of board produced. This is an old, slow, small-scale process, but is stiU in use in at least one location. 

Gel coats are typicaHy used to provide a part with a finished surface directly from the mold. Various inserts, stiffeners, and mechanical attachments can be incorporated in the mol ding step, thereby further reducing secondary operations. Final edge trimming is accompHshed with a variety of tools such as... 

Fourth, molded-in metal should be avoided whenever alternate methods will accomplish the desired objective. If it is essential to incorporate such inserts, they should be shaped so that they will present no sharp inside comers to the plastic. The effect of the sharp edges of a metal insert would be the same as explained in the first point above, namely, brittleness and stress concentration can occur. The cross-section that surrounds a metal insert should be heavy enough that it will not crack upon cooling. A method of minimizing cracking around the insert is to heat the... 

Parting line PLs on the surface of a molded product, which are produced by the parting line of the mold, when required can often be concealed on a thin, inconspicuous edge of the product. Doing so preserves the good appearance of the molding and in most cases eliminates the need for any finishing. 

Molded-in insert If metal inserts are to be molded into a plastic product consideration should be given to wall thickness around the insert (Table 3-18) and their shape. The shape should present no sharp edges to the plastic, since the effect of the edges would be similar to that of a notch. A knurled insert... 

Fig. 8-21 Effect of edge (a) or center gating (b) a mold showing (c) edge performed but center foiled (view on right side).

Mold construction FRP spray metal, cast aluminum gusket seal, air vents, self-sealing injection port FRP FRP, spray metal, cast aluminum, pinch (land) Metal, shear edge High grade steel shear edge... 

Part trim equipment Generally expected mold life (parts) 3,000 Yes 1,000 3,000 With optimum shear edges, minor trimining only 150.000+ 150.000+ ... 

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