Structural foam molding

Structural foam molding is a modified version injection where conventional molding plastic products consist of a dense outer surface of the skin that surrounds the inside (foam). This process is suitable for large-scale production, the product is relatively thick. Foam cores are produced from this process is suitable for bending applications. If the skin has the highest tensile strength and compressive stress, then the neutral axis of the work on the weaker parts of the inner foam. This process offers several advantages from the manufacturing process because it is able to produce products that are complex and have a low voltage so that the tendency for reduced bending or distorted. Then the clamping force is required of this process is lower than conventional injection molding process. This process is widely used for the production of large-sized plastic such as engine housings, chassis, computer housings, bin-bin storage, pallets and others. Polymers are often used for this process is the HOPE, PP, ABS and PC. Resins used in the Low Pressure is applied to this process consists of a small amount of blowing or foaming agent, this type of Chemical Blowing Agent (CBA) decomposition temperatures approaching the temperature of the resin. During the CBA process is decomposed in a large volume of gas as the beginning of a foaming process. Then injected into the cavity short shot. The skin is formed when the gas pressure near the surface of the collapse due to the mold surface. Furthermore, the gas spreads pressing short shot to complete filling cavity. After filling the gas continued to press with the uniform in all directions, pressing the dense skin on the mold surface, effectively also eliminate sink marks. Compared with the conventional injection process, voltage and much reduced shrinkage due to pressure on the cavity is relatively uniform. Before the ejection process must be ensured that the product starts cold and dense. Besides the advantages mentioned above there are a number of disadvantages when compared with conventional injection molding process, namely because the thickness of the walls are made then the cycle time achieved the longer, the consumption of the material also becomes more and more. For this type of process better position the gate at the thinnest part, is to facilitate filling the cavity thick sections. Unlike in conventional injection molding process on the premature solidification of a thin section of a thicker section and the gate does not occur. (Bid / multiple sources)

Isometric projection

In isometric projection, the projection plane forms three equal angles with the co-ordinate axis. Thus, considering the isometric cube in Figure 2.4, the three cube axes are foreshortened to the same amount, i.e. AB = AC = AD. Two things result from this, firstly, the angles a = b = 30 ~ and secondly, the rear (hidden) corner of the cube is coincident with the upper corner (corner D). Thus, if the hidden edges of the cube had been shown, there would be dotted lines going from D to F, D to C and D to B. The foreshortening in the three axes is such that AB = AC = AD = (2/3) o.5 = 0.816. Since isometric projections are pictorial projections and dimensions are not normally taken from them, size is not really important. Hence, it is easier to ignore the foreshortening and just draw the object full size. This makes the drawing less complicated but it does have the effect of apparently enlarging the object by a factor 1.22 (1 + 0.816). Bearing this in mind and the fact that both angles are 30 ~ it is not surprising that isometric projection is the most commonly used of the three types of axonometric projection. The method of constructing isometric projections is shown in the diagrams in Figures 2.5 and 2.6. An object is translated into isometric projection by employing enclosing shapes (typically squares and rectangles) around important features and along the three axes. Considering the isometric cube in Figure 2.4, the three sides are three squares that are 'distorted' into parallelograms, aligned with the three isometric axes. Internal features can be projected from these three parallelograms. The method of constructing an isometric projection of a flanged bearing block is shown in Figure 2.5. The left-hand drawing shows the construction details and the right-hand side shows the 'cleaned up' final isometric projection. An enclosing rectangular cube could be placed around the whole bearing block but this enclosing rectangular cube is not shown on the construction details diagram because of the complexity. Rather, the back face rectangle CDEF and the bottom face ABCF are shown. Based on these two rectangles, the construction method is as follows. Two shapes are drawn on the isometric back plane CDEE These are the base plate rectangle CPQF and the isometric circles within the enclosing square LMNO. Two circles are placed within this enclosing square. They represent the outer and inner diameters of the bearing at the back face. The method of constructing an isometric circle is shown in the example in Figure 2.6. Here a circle of diameter ab is enclosed by the square abcd. This isometric square is then translated onto each face of the isometric cube. The square abcd thus becomes a parallelogram abcd. The method of constructing the isometric circles within these squares is as follows. The isometric square is broken down further into a series of convenient shapes, in this case five small long-thin rectangles in each quadrant. These small rectangles are then translated on to the isometric cube. The intersection heights ef, gh, ij and kl are then projected onto the equivalent rectangles on the isometric projection. The dots corresponding to the points fhjl are the points on the isometric circles. These points can be then joined to produce isometric circles. The isometric circles can either be produced freehand or by using matching ellipses. Returning to the isometric bearing plate in Figure 2.5, the isometric circles representing the bearing outside and inside diameters are constructed within the isometric square LMNO. Two angled lines PR are drawn connecting the isometric circles to the base CPQE The rear shape of the bearing bracket is now complete within the enclosing rectangle CDEE Returning to the isometric projection drawing of the flanged bearing block in Figure 2.5. The inside and outside bearing diameters in the isometric form are now projected forward and parallel to the axis BC such that two new sets of isometric circles are constructed as shown. The isometric rectangle CPQF is then projected forward, parallel to BC that produces rectangle ABST, thus completing the bottom plate of the bracket. Finally, the web front face UVWX is constructed. This completes the various constructions of the isometric bearing bracket and the final isometric drawing on the right-hand side can be constructed and hidden detail removed. Any object can be constructed as an isometric drawing provided the above rules of enclosing rectangles and squares are followed which are then projected onto the three isometric planes. 

Engineering Drawing for Manufacture by Brian Griffiths 

Publisher: Elsevier Science & 

Technology Books

The raw material for plastic products

The raw material for plastic products, petroleum, natural gas and coal as a carbon source. The starting material is now part of the pyrolysis recycling plants are used: The name of the plastic is a generic term for synthetic or natural product produced by the conversion of macromolecular materials. These macromolecules consist of individual, chemically linked to each other building blocks of molecules, called monomers. With a series of monomers are called polymers. In this case, a single polymer chain is formed of thousands of monomers. Plastics can be composed of linear molecules, branched or cross-linked. Linear and branched macromolecules that no network should be moved by using heat. The molecules can slide to one another, that is material to flow and form. Therefore, the polymer material known as thermoplastic. The longer the molecular chain of plastic material, the higher is its strength properties. Thermoplastic properties ranging from soft to hard, difficult or hard and brittle. For elastomers, the macromolecule is a weak network. They are at room temperature before the chain due to their high mobility in the rubber state. Elastomers are not meltable and insoluble. Plastic with a strong spatial cross-linked chains of molecules known as thermosets. They act hard and brittle at room temperature. They are insoluble and infusible, and elastomers. There's also called a thermoplastic elastomer (TPE), the rubber-like material that can melt, however. They are made of thermoplastic materials such as thread-like molecule. In the thermoplastic elastomer, a molecule such as a thread but has segments of individual molecules, which have a strong attraction for one another that they act like a network. There is one main difference between thermoplastics and thermosets and elastomers associated with the process. Thermoplastic melts, processed, and then cooled. Thermosets and elastomers are processed cold and then heated, resulting in (heal) crosslinking of plastic. When Duromerverarbeitung should always be reworked, because the parts can not be formed without form. In the case of thermoplastics, the difference is still between the thermoplastic amorphous and semi-crystalline. This refers to how the thread-like molecules that are stored after cooling. If they are present in the network is completely random, they are called amorphous thermoplastics. The properties of amorphous thermoplastics • can form regular structures because they do not close the packaging. • If you are in a condition such as wipes or cotton balls • in the state of transparent colorless • lower shrinkage than semi-crystalline thermoplastics. translate fr: KraussMaffei Kunstsofftechnick

Types of drawings

There are a number of different types of engineering drawings, each of which meets a particular purpose. There are typically nine types of drawing in common use, these are: 1. A design layout drawing (or design scheme) which represents in broad principles feasible solutions which meet the design requirements. 2. A detail drawing (or single part drawing) shows details of a single artefact and includes all the necessary information required for its manufacture, e.g. the form, dimensions, tolerances, material, finishes and treatments. 3. A tabular drawing shows an artefact or assembly typical of a series of similar things having a common family form but variable characteristics all of which can be presented in tabular form, e.g. a family of bolts. 4. An assembly drawing shows how the individual parts or subassemblies of an artefact are combined together to make the assembly. An item list should be included or referred to. An assembly drawing should not provide any manufacturing details but merely give details of how the individual parts are to be assembled together. 5. A combined drawing is a combination of detail drawings, assembly drawings and an item list. It represents the constituent details of the artefact parts, how they are manufactured, etc., as well as an assembly drawing and an accompanying item list. 6. An arrangement drawing can be with respect to a finished product or equipment. It shows the arrangement of assemblies and parts. It will include important functional as well as performance requirements features. An installation drawing is a particular variation of an arrangement drawing which provides the necessary details to affect installation of typically chemical equipment. 7. A diagram is a drawing depicting the function of a system, typically electrical, electronic, hydraulic or pneumatic that uses symbology. 8. An item list, sometimes called a parts list, is a list of the component parts required for an assembly. An item list will either be included on an assembly drawing or a separate drawing which the assembly drawing refers to. 9. A drawing list is used when a variety of parts make up an assembly and each separate part or artefact is detailed on a separate drawing. All the drawings and item lists will be crossreference on a drawing list. Figures 1.11 and 1.12 show an assembly drawing and a detailed drawing of a small hand vice. The assembly drawing is in orthographic third-angle projection. It shows the layout of the individual parts constituting the assembly. There are actually 14 individual parts in the assembly but several of these are common, such as the four insert screws and two-off hardened inserts such that the number of identifiable separate components numbers 10. On the drawing each of the 10 parts is numbered by a balloon reference system. The accompanying item list shows the part number, the number required and its description. Separate detailed drawings would have to be provided for non-standard parts. One such detailed drawing is shown in Figure 1.12, which is the detailed drawing of the movable jaw. This is shown in third-angle orthographic projection with all the dimensions sufficient for it to be manufactured. Tolerances have been left off for convenience. Engineering Drawing for Manufacture by Brian Griffiths Publisher: Elsevier Science & Technology Books