Understand seven systems of plastic molds in one article

Time:2021-04-09 15:05:26 / Popularity: / Source:

First system: gating system

It refers to part of runner before plastic enters cavity from nozzle, including main runner, cold slug well, runner, gate, pull pin, etc.
plastic molds 

Second system: temperature control system

Temperature control system: In order to meet mold temperature requirements of injection process, a temperature control system is required to adjust temperature of mold. For injection molds for thermoplastics, cooling system is mainly designed to cool mold (mold can also be heated). Common method of mold cooling is to open a cooling water channel in mold, and use circulating cooling water to take away heat of mold. In addition to using cooling water to pass hot water or hot oil, heating of mold can also install electric heating elements inside and around mold.
plastic molds 

Third system: forming parts system

Forming parts system: refers to combination of various parts that constitute shape of product, including movable mold cores, movable mold inserts, fixed mold cores, fixed mold inserts, etc.
Under normal condition of fixed mould, outer surface of formed product, and under normal condition of movable mould, inner surface of formed product.
Fixed and movable mold cores are combined to form a cavity, and then injection system will flow plastic into cavity. After cooling, fixed and movable mold cores can be opened.
plastic molds 

Fourth System: Institutional System

Mechanism system: It means that product's undercut is inconsistent with normal demolding direction, and it needs to do a mechanism for core pulling to meet normal demolding of product.
Normal mechanism on mold is basically divided into two kinds, one is external side core pulling (such as outer slider), and the other is internal side core pulling (such as inclined top, inner slider).
plastic molds 

Fifth system: Guiding positioning system

Guiding system: refers to various sliding systems on mold, such as mold base guide posts and guide sleeves; zero-degree positioning blocks on mold base; back pins and EGP guide posts on ejector plate; and mold plates on mold.
plastic molds 

Sixth system: ejection system

Ejection system: It means that product needs to come out of movable mold core, so it needs an ejection system. Ejector system basically includes ejector ejection, push block ejection, push plate ejection, hydraulic cylinder ejection, pneumatic ejection, etc.
ejection system 

Seventh system: exhaust system

Exhaust system: refers to melt will replace gas in cavity during injection molding process. If gas is not discharged in time, it will be difficult to fill melt, resulting in insufficient injection volume and unable to fill cavity, partial scorching of product or obvious bonding lines, and area where product is bonded is not easy to fill.
There are many types of exhaust: conventional method is to make an exhaust groove on parting surface of mother mold core, or you can make an exhaust groove on parting side of mold, an exhaust sheet on male mold side, insert exhaust, ejector exhaust, and exhaust steel exhaust, etc.!
exhaust system 

Product has complex buckles and undercuts, how do we design mold structure?

In some consumer products, in order to meet needs of product functions, some buckles and undercuts are often designed on product. Some products not only have undercuts on the outside and inside, but also have some special undercuts and deep reinforcing ribs inside product. Front mold cavity is also very deep, external structure of product is complex and there are many undercuts. How do we design mold structure when encountering such a product? Today I will share with you a set of car mold structure, hoping to give you some inspiration.
exhaust system 

Product glue feeding method:

There are many ways to feed product, including bottoming, diving, direct gating, horn feeding, dispensing, etc. This product has strict appearance requirements and high efficiency requirements. This set of molds uses a large nozzle to directly feed glue, as shown in figure below.
mold structure 
Through slope analysis, there are deep reinforcement ribs in the front mold of polished product, and there is a column with a depth of 80mm. In order to prevent product from sticking to front mold, column of front mold should be designed as a front mold insert. Because front mold ribs are very deep, consider designing ejection structure in front mold. this product has a round shape, product has undercuts all around, and some undercut directions are not exactly same, as shown in figure below.
mold structure 

Analysis of front mold structure:

Because product has a deep cavity in front mold, there are deep bone and column inside product. Column is designed as a front mold insert, and deep cavity is considered to be a front mold insert. To prevent product from sticking to front mold, we use button mechanism to design ejection mechanism on front mold when the mold is opened, as shown in figure below.
mold structure 
Product has five undercuts in back mold, only one of which is normal ejection position, and other four positions are oblique. Because first slider is very long, cylinder core is used here. Structure design is shown in figure below.
mold structure 
Sliders at second and fifth positions of rear mold are same. When designing, pay attention to: first slider is next to second slider. Due to limited space, bead of second sliding block is only designed with one-sided guide, and thickness of A plate is very thick, so inclined guide posts of two small inclined sliders are fixed with pressure blocks, as shown in figure below.
mold structure 
Third part of product is an oblique slider in rear mold. When designing this slider, you should pay attention to: slider has a long core-pulling stroke. This slider uses a cylinder core-pulling structure, but there is a long core inside slider. Child needs to be inlaid separately, as shown in figure below:
mold structure 
Fifth part of product is an oblique slider in rear mold. When designing this slider, please pay attention to: slider has a long core-pulling stroke. This slider uses a cylinder core-pulling structure, but there is a long core inside slider. It needs to be assembled separately. Connection method of oil cylinder,connection of oil cylinder and slider insert are as shown in figure below.
Analysis of front mold structure 

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