Arsip Blog

Diberdayakan oleh Blogger.

Senin, 30 Januari 2017

The Plastic Injection Molding Process

By Ann Foster


Fundamentally, injection molding refers to manufacturing processes in which plastic granules are heated to melt and forced through some mold cavity. The process is commonly utilized in producing plastic parts. In addition, plastic injection molding enables the production of various products. Such products usually differ in size, application and complexity. The process nevertheless needs raw plastic materials, machines as well as molds.

Normally, the raw plastic materials are first converted into molten states by the machine before being infused into the mold for cooling and solidification. In Cobourg, ON, the technique produces plastic parts that are thin-walled and are put to different uses such as plastic cases. The cases are usually used to seal various products including household appliances, consumer electronics, power tools and automotive dashboards. Other products that are also produced include open containers such as buckets.

The injection molding cycle is usually very short lasting between 2 seconds to 2 minutes, and the cycle consists of four stages. The first stage is known as clamping. Before injecting the material into a mold, you must close the two halves securely using a clamping unit.

During the injection stage, every half is attached to the machine and one half is made to slide. The clamping unit is normally hydraulically powered and pushes these mold halves together while exerting enough force to ensure the mold is closed securely while injecting the material.

The second phase is the injection stage where raw plastics usually in pellet forms are constantly inserted into molding machines before being advanced to a foam unit. The materials are usually made to melt at this stage through heat and pressure. The molten materials are quickly infused to the molds where the build-up of pressure compacts and holds them. The amount of infused material is normally called a shot. The duration taken at this stage remains tricky to determine. Nevertheless, an estimate may be arrived at using the quantity of shot, the injecting power and injecting pressure.

The other phase is the cooling phase. Here melted materials enclosed in the casts are cooled when they adhere to the interior cast surfaces. They become solid and take up the shape a part is determined to take. However, shrinkages may happen as cooling occurs, even though material packing at this phase allows some additional materials to get into the casts hence lessening the extent of shrinks.

Ejection is the final stage normally happening after adequate time passes to allow the cooled portions to be ejected. The ejection is done by an ejection system. Once a mold is unfastened, the parts are taken off the mold. Force is usually applied to eject parts because they may shrink and stick during cooling. To enable ejection, molds release agents are also utilized by spraying on mold-cavity shells prior to material injection.

When the cycle is completed, post-processing is normally done. This is since the materials contained in molds channels normally solidify as they cool and remain stuck attached on these parts. Nevertheless, the extra material and any flash that may have occurred needs to be trimmed off.




About the Author:



Tidak ada komentar:

Posting Komentar

Followers

Copyright 2012 AUTO BLOG | Designed By Kang Mis.