Injection Mould Construction

A molding according to the function of each of its parts can be divided into four sections 1. Introductory part of the plastic nozzle into the cavity cavity 2. penunjuang system (support system) 3. demolding system 4. heat transfer system

Mold Base Standard Part

In the manufacture of injection mold, mold base is an integral part, mold maker can make your own mold base or buy a standard mold base, the system of the mold base can be adjusted with the construction standards required, both for the two plate and three plate, stripper plate ejectors, hot runner and mold base for a screw, when the entire standard mold base is not there to meet the new final step is to make a special mold base.

Injection Mould Classification

classification or types of mold injection very depend on what we need to make the plastic parts, because every parts have specific and unique design. when design molds we must see what the influencing factor like geometry, number of cavities, ejection principle, plastic material and shape of part.

Injection Mold Cooling

This section is the most important part of the overall mold cylcle time, because in one cycle time, the process of heat exchange to spend about 70-80% of the total cycle time, thus setting the optimal heat transfer system will greatly affect the quality and cycle time of a product.

Undercut System : Cam, Angular, Lift Cavity, Loose core

cavity and core, and its derivatives when there are undercut on product, design and construction of a good core cavity and in accordance with the requirement could increase the life of tooling itself, reduce material consumption, reduce dependence on maintenance inserts, and can reduce the cost of making the mold so the mold cost per products also declined.

Friday, December 21, 2007

Construction Injection Molds Classification

classification or types of mold injection very depend on what we need to make the plastic parts, because every parts have specific and unique design. when design molds we must see what the influencing factor like geometry, number of cavities, ejection principle, plastic material and shape of parts.

The basic classification of mold based on construction shown on picture below


1. Standard Molds
the standard mold is the most simple design, basically the standard molds is same as two plate molds construction, they divided in two side : cavity side and core side, cavity side is the side that construct to flowing plastic material from nozzle to cavity parts, basically they consist of sprue, runner.

core side construct to make shape for core, demolding system and ejection system, at this side we design ejection system.
standard mold have one parting line, and have one opening direction. this type of mold use in all kinds of plastic parts that doesn't have undercut, inner and outer screw.
Light brown color little and straight in ejection system is shown ejector pin.



2. Slide mold

development from this mold type is the used slider parts in various molds types, basic slide mold is transfer horizontal movement of mold to vertical movement, this types of molds is used to make parts with undercut, you should see more at the post when we need slider for learn more.




3. Three plate molds
basically three plate molds has two parting line, and floating plate, floating plate support by support pin, Since the mold has two parting planes, the runner system can be located on one side of floating plate or make special plate that attach in floating plate, we called runner plate, see post about runner plate. Three plate molds are used because of their flexibility in gating location. this types of molds is flexible even use in multiple cavity.

note : floating plate also called cavity plate or plate number 3, to know more the different between two plate mold and three plate mold see the posting about Basic and Types Molds Construction

4. Split Cavity Mold
basically the split cavity is same as 2 plate standard mold, but the cavity have split block to make undercut product or external threads.


this type of mold use when the slider is not enough to make the undercut or the threads. the disadvantages of this mold is when use for little parts, the construction will difficult.








5. Mold With Screw Device

this mold special to make thread forming, the core can be rotate when demolding process, both internal or external threads can be forming by this type mold.





from those picture we can see that they have gear device, the gear will rotate when form thread.





6. Stripper Ejector Mold
this type of mold have special purpose to make a cup shape without undercut, stripper ejector will make ejection more easy, same movement and power at the product and without a lot of marks in product






Molds with complex and difficult design can be integrated or combined one to the others mold type.

Saturday, December 15, 2007

Introduction to Mold Engineering of Thermoplastic

most electrical, and home appliances made from plastic, one of technology to make plastic product is using mold, specially injection mold of thermoplastic, basically when thermoplastic material heated, they will change of state, thermoplastic material will become soft, melt and flowable, when cooled again, they become solid again.

What is Injection Mold ?

there are some definition of injection mold

is a manufacturing technique for making parts from both thermoplastic and thermosetting plastic materials in production (wikipedia.com)

A manufacturing process for forming objects, as of plastic or metal, by heating the molding material to a fluid state and injecting it into a mold.(www.answer.com)

Herbert Ress, 2002 : an injection mold is arrangement, in one assembly a number of cavity spaces built to shape of the desired product, with the purpose of producing plastic parts in large number

this blog define injection mold is manufacturing process to make plastic product that have cavity spaces to shape the product by heating and injection pressure.

Types of Injection Molds
based on how injection mold would be processed wikipedia.org devide injection mold as 7 types until now, they are
1. Reaction injection molding
2. Liquid injection molding
3. Gas assist injection molding
4. Co-injection molding
5. 2-Shot Injection Molding
6. Fusible core injection molding
7. Rapid injection molding

based on type of opening method and runner system, The DIN ISO standard 12165, "Components for Compression, Injection, and Compression-Injection Molds" classifies molds on the basis of the following criteria:
1. standard molds (two-plate molds)
2. split-cavity molds (split-follower molds) stripper plate molds
3. three-plate molds
4. stack molds
5. hot runner molds

depending on material to be injected classifies as :
1.thermoplastic injection molds
2.elastomer molds
3.thermoset molds
4.structural foam molds

picture below shown 3 plate mold type with cold runner system and ejection system
click the picture to enlarge




closed Condition
picture below shown 3 Plate Molds Types in 3D design, in closed position with support pin, puller bolts, leader pin or positioning pin.


you can also learn more about basic pin construction at post about pin in molds
Opening Condition
then the construction molds of 3 plate type when opening is like picture below

picture below is shown three plate condition when open


we also can learning more about ppening Sequence, why and how the molds open, and explaining each molds opening step or sequence at post about opening construction

those opening sequence is just for 3 plate type, 2 plate type is more easy becouse just have one opening parting line.