dnfsdd8aaa35
New Member
Posts: 10
Status: Offline
Joined:
pm | | China Automotive Plastic Mold factory (1st Feb 23 at 7:15am UTC) | | China Automotive Plastic Mold factory Cold runner mold
A cold runner mold usually consists of two or three plates that are held inside the mold base. The molten thermoplastic is first injected into the mold through a gate from a nozzle that fills a network of runners leading to the mold cavity. In this system, the runners are unheated and act as a delivery system to distribute the molten plastic to the individual mold cavities. The cold runner system then cools the gates, runners and sprues together with the molded part.
In a two-platen mold, the gate and runner system remains connected to the final product. An ejection system is then used to separate the molded part from the core of the mold. For those who have assembled model cars in their youth, the runners and parts are not separated. The child who assembles the model is responsible for the final part of the process.
In a three-plate mold, the stripper plate contains the gates that deliver the molten thermoplastic into a network of runners in separate cavity plates. The final molded part is formed and cooled on a core half-plate without any runner or gate connections. The three-plate mold system automatically separates the runners from the part when the mold is opened. In both two- and three-plate mold systems, runners can be reground and recycled, thereby reducing plastic scrap.
Hot Runner Molds
A hot runner mold consists of two plates that are heated with a manifold system. The manifold helps maintain a stable temperature by keeping the molten thermoplastic in the runner at the same temperature as the heated cylinder. The heated runners convey the molten plastic to the nozzles that fill the core mold to form the final part.
The heated runner system is housed on a separate plate. The plate remains stationary for the duration of the molding cycle. The core mold plate then opens to reveal the final molded part without any runner connections.
There are several types of hot runner systems. In general, however, they fall into two main categories: externally heated and internally heated. Externally heated systems are well suited for polymers that are sensitive to thermal changes. Internally heated systems provide better flow control.
Hot runner processes eliminate the runner completely, so recycling and regrinding (which can only be done with virgin plastics) do not affect cycle times. A variation of this system is called an insulated runner. Insulation, rather than heat, keeps the plastic in a molten state. This system can only accommodate a few types of plastics, especially semi-crystalline polymers, which tend to have very low thermal conductivity.China Automotive Plastic Mold factory
website:http://www.b-fmould.com/automotive-plastic-mold/ | |
|
