PLASTIC INJECTION MOLDING.

PLASTIC INJECTION MOLDING.

Definition of Molding Injection.Injection molding is a manufacturing process for producing parts or items from other materials such as plastic resin materials, rubber, food, fiber and other be finished or semi-finished goods for daily use.

Process of Plastic Injection :  Selected material will put in the hopper into containers with a certain heat temperature, as appropriate. After that the material is forced through on the screw barrel after set the barrel temperature follow material dilution conditions or parameter adjustment. Once the molten, material will last through a predetermined mold process. When the material has been entered into the mold complete and sufficiently, the mold will be open for processed materials out of the mold for cooling. And then the material part will ejected from mold and this substance is called the part.

Material Flow :                                                                Machine Picture :

                  

Type of Machine.

There have 4 type of Injection machine:-

A) Hydraulic Machine, B) Electric Machine, C) Mechanical Machine and D) Hybrid Machine.

The Popularity of Plastic Injection Products.

In the current economic situation and the growing world population increase resulting growing demand for plastics products dramatically. This resulted in savings for related items in plastics products is not enough. With that, will make the manufacture of plastics are increasingly in demand.

Examples of plastics products in demand are: -

1) Dish - If you work in the country other course you use plastic plates for home use because of easy to carry if you frequently switch housing.

2) Cup - not easy to break if dropped and if you have many children.

3) Hang Shirt - Every person has at least 10 hangers and if in every home has a lot of households, then multiply hanger purchased.

4) Basin - A bathroom definitely have one bucket for water storage. If every house has 3 bathrooms, there will certainly 3baldi every home. That does not include every day how many houses to be built.

5) Chair - Are you able to buy the product from the type of wood or iron. Of course, every house is too expensive and there is only 1set wood or iron.

6) Etc.

Among the most popular of manufacturing plastics injection is: -

1) Easy to attract customers.

2) Easy to obtain raw materials.

3) Easy to handle injection machine.

4) Production of products of daily use.

5) Large scale production.

6) Easy to grant a license.

7) Easy to get working.

8) A stable product.

9) Easy to open company loan approval.

10) Less competition.

Flow of  Plastic Material Injection. ( 8 Step )

1) Plastic Material / Resin.

Introduction of Plastic Material.

Plastic material is any of a wide range of synthetic or semi-synthetic organic solids that are moldable. Plastics are typically organic polymers of high molecular mass, but they often contain other substances. They are usually synthetic, most commonly derived from petrochemicals, but many type are partially natural.

Original Material.  

Material Types.

1) PET, 2) HDPE, 3) PVC, 4) LDPE, 5) PP, 6) PS, 7) ABS (Acrylonitrile Butadiene Styrene), 8) POM, 9) Others.

Plastic ABS Material (Original Material).

It is a terpolymer made by polymerizing styrene and acrylonitrile in the presence of polybutadiene. The proportions can vary from 15 to 35% acrylonitrile, 5 to 30% butadiene and 40 to 60% styrene. The result is a long chain of polybutadiene criss-crossed with shorter chains of poly(styrene-co-acrylonitrile). The nitrile  groups from neighboring chains, being polar, attract each other and bind the chains together, making ABS stronger than pure polystyrene. The styrene gives the plastic a shiny, impervious surface. The butadiene, a rubbery substance, provides resilience even at low temperatures. For the majority of applications, ABS can be used between −20 and 80 °C (-4 and 176 °F) as its mechanical properties vary with temperature. The properties are created by rubber toughening, where fine particles of elastomer are distributed through out the rigid matrix.

Mix Material.

Depend on the request by Customer to using 100% original material or mixing 20% + 80% (20% regrind material with 80% original material) and or 50% + 50% (50% regrind material with 50% original material).

Original (80%)                                             Regrind (20%)
 

Mixer Machine











Regrind Material.

Regrind material is unused material from gating and runner for part after injection process will recycle as a regrind material.

Crush Material.

Crushed material is unused material from part after injection process that cannot reused for recycle due to content of material was changed itself such as V0 material. This is also including part after spray process, printing process and or rejected part after dropped for scrapped. 

2) HOPPER DRYER. 

Pre - Heat Material.

Hopper dryer is a machine for drying material or material temperature heat stabilization to achieve heat balance. This is to facilitate the material to melt when processed into liquid. There are also materials that do not require hopper dryer and will continue through the tank to the screw barrel. For materials that require hopper dryer must adhere to the set temperature to prevent the material from problems such as silver streak or moisture.

Hopper Dryer.

Temperature.

Each hopper dryer include fixed guide for each heat of material as shown below and some material require follow as per plastic material supplier.                               

1) PE, PP, PS  = 60°c                                                                                              

2) Nylon Serles = 75°c

3) Acrylic, ABS, AS =- 80°c ~ 85°c

4) Cellelose Series = 75°c

5) Polycarbonate = 120°c

6) PVC = 50°c 
Temperature Guide Set.

Extra Hopper Loader.

In addition, there are extra tanks hopper dryer to use a lot of items or additional heat is jumper receiver dryer. Attached vacuum hopper functioning to stuck or filter dust before the material is sucked into the second hopper dryers.

Hopper Loader.

3) SCREW BARREL

Screw Barrel to Charge Material.

Screw barrel functioning is a spring steel rod (Screw rod) to push the molten material into the mold through the nozzle barrel. Surrounding the barrel screws are heated to melt the material so easy to enter the mold. Heaters around the screw barrel there are between 3 to 9 items to control the dilution material into the mold. Some machine used 1 ~ 4pcs screw barrel depending of mold size.

Screw Barrel. 

Purge Material.

This is how the material flowed into the mold after dilution for the production of processed parts. This process is also to remove the excess heat material from mold and how to clean the barrel nozzle.

Nozzle Head.

Nozzle head is a medium to convey the material to the mold and this is also will call charge material to mold

Maintenance for Chrooming.

Each screw chrome barrel must be arrange for maintenance once every 6 months depending on the level and timing of use to prevent material that has been inject there that would appear black spots from crust material. 

4) MOLD / TOOLING

Mold / Tooling.

Mold or mould is a design to appear material to be part after process dilution material. If small item to produced, it is smaller mold design and use of the machine. If large items to be produced, then the greater the shape of the mold and the machine used. They have 2side of Mold Core and Cavity Side.

Mold Core and Cavity Side. 

Mold Open                                                   Mold Closed

 

Parameter Adjust.

Mold after set up and before mass-production must do some adjustment and recorded into the parameter. 

Part Ejected.

When the material has been entered into the mold complete and sufficiently, the mold will be open for processed parts out of the mold for cooling. And then the parts will eject from mold.

5) COOLING PARTS (Take out parts from Mold).

Take parts from Mold.

There are many ways for cooling processed parts. The normal way that is done is the normal air temperature transfer parts for cooling. Items will be taken from the mold either manually or auto (drop or robot).

a) Manual       - Too dangerous and easy to crash the body.

b) Auto Robot - 1) Robot Arm. (High cost but safety)

                            2) Arm Swinger.

c) Auto Drop   - Safe cost but Part easy to scratch / damage.

Manual.                                     Robot Arm.
                                       

Auto Drop.                                 Robot Arm Swinger.

    

Mass – Production (Product the Part).

Mass-production.

Mass production is a large scale to produce a part after the completion of the material processed through dilution base on customer order or market order.