The compression molding process can be divided into charging, clamping, exhaust, curing, demoulding and mold cleaning and so on several stages.
In the forming of plastic with embedded parts machining parts, preheating of the insert before loading location in the mould.
General insert injection tooling manufacturer manually placed, special insert need special tools placed, request when placed correctly and smoothly, so as not to waste or damage the mould.
Refers to the mold cavity of feeding, join the required amount of plastic raw materials.
Join mould of plastic raw materials should be according to the plastic parts requirement within the cavity flows and reasonable pile up.
, like using powder or granular materials, should be piled up into a slightly higher among form, in order to facilitate the discharge of air.
the time required to complete an injection process is called the injection molding cycle.
Injection time including mold filling time, holding time and cooling time, which combined the holding time and cooling time for the overall cooling time.
Mold filling time is directly on the mold filling rate, 3 - in the production
The holding time is for plastic compaction time, larger proportion in the whole injection time, for 20 -
Cooling time in order to make sure the melt ejection when not cause deformation for the principle, general is 30 -
In the production of injection time is commonly 0.
Big up to 5-2 min, thick
before moulding sometimes need to heat plastic raw materials.
Its purpose is to remove moisture and volatile matter other raw materials, the second is to improve the material temperature, enhance the curing uniformity of parts, easy to shorten compression molding cycle.
Preheating method mainly has the heating plate, heating heating, infrared heating, high frequency electric heating, etc.
Compression molding process is to add after prefabrication of thermosetting plastics raw materials directly to the open mold cavity feeding, and clamping heating, melting and pressure under the action of the melt flow and fills the cavity, and exhaust pressure molecular crosslinking reaction gradually hardening, plastic molding, stripping out parts.
Finally clean up mold, into the next cycle.
the auxiliary time includes open mold, mold release, besmear demoulding agent, put insert, such as closing time.
Directly affect the forming period of labor productivity and improve equipment utilization, therefore, on the premise of guarantee the quality of parts, production should try to shorten the molding cycle time at each stage.
Among them, the injection time and cooling time plays a decisive role on the quality of the product, should be reasonable choice according to the practical situation.
injection molding is a kind of important method of plastic moulding, has been widely used in the production.
Injection molding cycle is short, can be a forming complex shape, size precision, with metal or nonmetal insert parts.
Strong adaptability to all kinds of plastic molding.
At present, in addition to the fluorine plastic, nearly all thermoplastics forming, this method is available in some thermosetting plastic injection molding may be adopted, and injection molding production efficiency is high, easy to realize automatic production.
Injection molding equipment is expensive, the die structure is more complex, the manufacturing cost is high, so the injection molding is especially suitable for mass production.
if injection and compaction pressure equal, the shrinkage rate to decrease the size of, often can make the product less volatile, but will cause the release of residual stress is larger, the molding cycle is too long.
But for crystalline plastics such as pom, compacting pressure can improve the melting point of plastic, the demoulding ahead of time, thus forming period does not necessarily increase.
Such as compaction pressure is less than the injection pressure, injection molding processing parts performance and demoulding contrary to the above situation.
also called compression molding, molding, compression molding is processing manufacturer of plastic injection molding processing of the transfer process, at present is mainly used for thermosetting plastics processing.
The preparation before compression molding divided into two parts, preheat and prepressing.
Preloading only commonly used for thermosetting plastics, preheating is thermosetting and thermoplastic plastics are used.
At room temperature will loose powder or fibrous thermosetting plastic on the special YaDing pressed into a certain quality, well-shaped close-grained parison, the process is called the preloading.
Preloading parison is wafer more, also have long strips.
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