During the compression molding process, plastic raw materials in powder or ingot form is placed in the heating of the metal in the mold cavity. Because the parting surface is horizontal, vertical downward. After the closing of the mold, molding pressure heating effect for a period of time. The pressure is 2 ~ 3t / in and Fahrenheit temperatures 350 under, is a partially liquid filled plastic, die cavity. Although in recent years the development of phenolic resin in 25S plasticized plastic, but usually needs 1 ~ 15min plastics. Finally out of plastic parts mold. If the part containing a metal insert, should be in the injected plastic front, said insert into the cavity positioned Kong Zhong. Ingot in a mold cavity prior to preheating out gas, liquidity, so full of mold and shorter plasticizing time. Dielectric heating of heating billet convenient method.Because the plastic is directly into the mold cavity, so the compression mold than other molding process mold is simple, does not need the runner and gate, can save raw materials, for cleaning the runner and gate, the thermosetting plastic is a great waste of resources. For compression molding press is usually a vertical hydraulic machine. Larger press requires the operator to be absorbed in operation; however, an operator can operate simultaneously in several small press, the press should be reasonable so that the operator can conveniently placed you from one to another operation, the operator must ensure that when he again bypass specific press when, just ready to die mold.Thermosetting plastics in pressurized and heated under the action of curing, the characteristics decide the suitable for compression molding and transfer mold. Because the compression mold to alternate heating and cooling, so the thermoplastic plastic is not actually used in compression molding. In order to make the thermoplastics hardening and from the cavity of the ejector, requires the use of plastic cooling.The compression mould type. For the compression mold can be divided into four basic types, respectively is: do not overflow type compression molding, retaining ring does not overflow type compression molding, overflow type compression molding and semi-positive mold. In the overflow type compression mold, plunger type punch with the die into the die cavity forming, because the lower die without retaining ring or limiting device, a plunger type punch continued down to all the pressure is applied to the plastic, so that to produce a good electric performance and the physical properties of dense plastic parts. Join the mold cavity plastic dose to be precise measurement, think its impact parts wall thickness. Retaining ring does not overflow type compression molding and not overflow type compression molding is similar, only at a predetermined point increases the retaining ring, so that the plunger type die at a predetermined point to stop the movement, in the mold of retaining ring absorption of the original action on the part of the partial pressure of. This compression mold can be accurately controlled parts of the wall thickness of plastic parts, but the density change is quite big. In the overflow type compression mold, overflow material will increase the upper and lower die size. When the upper mold of plastic when pressure, excess plastic from the parting surface of overflow. On the overflow material further pressure, he hardened finally in the upper die forming flash. Production of dense plastic parts generally requires the use of computation is slightly more raw materials to increase the pressure. This type of mold is in the production of widely used, because it wanted to relatively easy to manufacture, and can control the thickness and density of plastic parts, making it closer to the requirements. The semi-positive mold is overflow type compression molding and not overflow type compression mould combination type, in addition to fly outside edge, the baffle ring can limit the upper die mobile.The importance of injection mold1 plastic has small density, light weight, strength, good insulation, low dielectric loss, strong chemical stability, molding with high productivity and low cost advantages, in the national economy and people’s daily life in various fields have been increasingly wide range of applications, in the early nineteen ninties early, the annual production of plastics by volume of steel and more than the sum of non-ferrous metal production. In the mechanical and electrical ( such as the so-called black appliances ), instrumentation, chemical, automotive and aerospace and other fields, has become a good substitution of metal plastic materials metal materials plastic, appeared the trend of.2 to the automobile industry as the example, the automobile lightweight, low energy requirements for the development, auto parts material produced apparent plastic steel to change, at present our country auto plastics for automobile weight of 5% to 6%, while the foreign already amounted to 13%, according to the experts, plastic car bike consumption also will to further increase. In modern cars, either outside the decorative pieces, decorative pieces, or function and structure, can be made of plastic material, decorative pieces of a bumper, fender, wheel covers, guide plate; decorative pieces in a dashboard, door panels, side panels, glove box cover, seat, after retaining plate; the function and structure of a fuel tank, radiator water chamber, the air filter cover, fan blades. According to statistics, China’s 2000 car output of about 2000000 cars, car uses plastic amounted to 1380000 tons. From the domestic and foreign auto plastics application situation, automotive plastic consumption has become a measure of the level of production technology of automobile.3 as the plastic parts the most effective method of molding injection molding the molding can be a complex structure, size precision and with embedded metal parts products, and the molding cycle is short, can be multi cavity, high productivity, large quantities of production of low cost, easy to realize automation production, so in the plastic processing industry in China a very important position. According to statistics, plastic mold accounted for about all ( including mold metal mold plastic products ) 38.2%, the total weight of about 32% is used for injection molding, more than 80% of the engineering plastic products are produced by injection molding method.4 according to customs statistics, China imported a total of $977000000 in 2000 in which the mold, plastic mold a total of US $550000000, accounting for 56.3% of total imports of US $1112000000 in 2001, mold, wherein the plastic mold a total of US $616000000, accounting for 55.4% of. From a variety of speaking, import volume is the largest plastic mold.
When the design, manufacturing and injection moulding,and there is much more to consider guidelines. To create the mold easier, faster turnaround time, increased speed, your products will be on consumers. Here more than 10 design guidelines to be followed in the design and manufacture of:Avoid holes. Holes may be too complex to die. This will also increase the risk of cutting tool breakage. The two sides will drive the cost.If you die holes, through holes are preferred. This will make the mold is more effective at separating, and ensure that the holes are in even diameter.Please check with your firm to install or fixture positioning function of the manufacturer. Experience counts in this regard, you want a part of you, is a hardy. Usually the thread component can be obtained by simple male-female mating portion is replaced. Simple, like other things, is the key here.In the actual use of unified screw size. Think in the design process the final user. Off the shelf assembly. Unified screw size and the use of” your design will be easier to let more people.Angle or surface consistency, there is often a kind of variation. This will depend on the material used. Often because of his differences are not apparent to the human eye has little effect. However, if your design requires a precise surface or the angle of specified materials, such as hot-rolled low carbon steel plate, will hold its form.Flatness should also apply to units and reasonable overall form tolerance. This will prevent sudden surface changes in a relatively small area within the function.Size tolerance. Offset machining tool, allowing the size tolerance. ” Tool compensation” allow tooling tool size.Consideration of matching parts stacked tolerance. When creating the mating parts, both the male and female part considered separate tolerance. If the tolerance is not considered another may lead to parts not mating, causing costly redesign.When the design requires a specific direction, provides a design elements, to make this point clear. If you cannot explicitly instructed to its design and construction, it should be a part of the whole design, you should consider to design.Maintaining part. Each additional component design, multiplied by the risk of trouble. . and keep part of simple design, it is important to keep as we present an overall design as simple as possible. The key here is to create a design, will maximize the process of injection molding.
