there are as many as dozens of thermoforming molding method, each with his characteristics and adaptability of the double thermoforming has distinguishing feature very much, he is between the upper and lower two pieces of wood in two and a half mould is heated, this approach can be forming two layers of shape, color and function of different parts of the hollow or arms. This process is the deficiency of the traction than is restricted, general control under 2:1. Also known as rotational molding, roll forming is a kind of can be used to make all kinds of size and shape, wall thickness is uniform, almost non-existent hollow seamless products processing method of internal stress.
when foam plastic molding for raw materials adaptability is strong, thermoplastic or thermosetting plastic processing and shaping can be through the appropriate process route for plastic foam, but currently use morer is polystyrene, polyethylene, PVC, and polypropylene and other thermoplastic and thermosetting plastic phenolic resin, epoxy, polyurethane, etc. Moulding foaming, through mold machine molding for a certain shape requirements of the moulded parts, or moulded into large pieces of material, then cut slices, small pieces or processed into the user to specify the shape of the product. This kind of product is often used for shockproof buffer material.
the limitations of thermoforming technology, as a result of the hot forming temperature range, the flow of the plastic deformation is limited, thus forming some shapes only relatively simple products, and thickness uniformity is not good enough, but as a result of thermoforming have simpler equipment, less investment, can realize the automation of mass production, high production efficiency, etc. The thermoforming products has continued in the application of the demand and extension. Roll forming process is that the resin powder or liquid resin into the mold, the heating mould and make the continuous biaxial to around, gradually heated molten resin in the mould, the mould wall form a thin layer of molten layer, continue rotation mold, the melt can be evenly coated on the surface the whole mold, then cooling, demoulding, take out the products.
roll forming are mainly used for processing the molding process and molding process in large and medium-sized or large products, such as a large container, mailboxes, litter bin, yacht, etc. , the thickness of the products can be in more than 10 mm, maximum volume to thousand liters. Products can be a single solid layer, can also be processed into foam layer, multicolor and multi-layer composite of composite products, as well as with embedded parts of products, short fiber reinforced products. Commonly used material is polyethylene, PVC, pp, nylon, polycarbonate, ABS also developed in recent years, such as engineering plastics, to expand the application range.
thermoforming commonly used raw materials by the impact resistance of styrene, ABS, polyethylene, polypropylene, polyvinyl chloride (PVC), organic glass and engineering plastics such as nylon, polycarbonate sheet can be used in the single sheet, it can also be multiple injection molding processing varieties of composite sheet, multi-layer sheet or glass fiber reinforced plastic sheets and foam sheet. Products include tray, tray, blister packaging, such as food packaging materials, large products such as decorative, refrigerator liner, bath crock, surfboard and auto parts, etc. Hot molding products can be a single, usually large exposure of the products, also can be a forming, at the same time by dozens more used for small packing of parts.
foam plastics is a kind of internal formed from the tiny bubbles and uniform pore structure of foam plastic products. The generation of gas source mainly comes from the three conditions: 1. Raw material composition of the foaming agent is added in the processing of thermal decomposition under the conditions of gas. 2. The gas under high pressure from external into molten resin. 3. Formed by the interaction of polymer components of gas produced. In either case, as the premise, foaming must make when the viscosity of the resin in a liquid or a certain scope.
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