Injection Mold Maker

Five-Star yearly capability is up to 500sets mold per year, the biggest reach 20 tons, and the largest size is 2.5m x 2.5m.

Five-Star Tooling has a full set advanced mould manufacturing equipment, 6 sets CNC machines, 13 sets EDM machine, 3 sets middle-speed wire cut machine, 2 sets slow speed wire cut machine, 13 sets milling machine, 3 sets lathe machine, 2 sets mold die fitting machine, 8 sets injection machine from 60 tons to 470 tons.

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Chapter 1: The Introduction of the Injection Mold

1.1 Introduction

There is a close relationship with all kinds of mold, which are referred to our daily production, and life in the use of the various tools and products, the large base of the machine tool, the body shell, the first embryo to a small screws, buttons, as well as various home appliances shell.

Mold’s shape determines the shape of these products, mold’s precision and machining quality determine the quality of these products, too.

1.2 Injection Mold general definition

In the industrial production, with the various press and the special instruments which installed in the press, it produces the required shape parts or products through pressure on the metal or non-metallic materials, this special instruments collectively call as the injection mold.

1.3 Mold general classification

Mold can be divided into plastic and non-plastic injection mould

1) Non-plastic mold
a. Die casting
b. Forging dies
c. Die computer panel
d. Die casting

2) For production technology and production, plastic injection molds are divided into different products:
a. Injection molding
b. Inflatable mould
c. Compression molding
d. Transfer molding
e. Hot forming die
f. Rotomoulding mode

Injection moulding is the most popular method in plastics producing process. The method can be applied to all parts of thermoplastic and some of thermosetting plastics, the quantity of plastic production is much more than any other forming method.

Injection mold as one of the main tools of injection molding processing, whose production efficiency is low or high in the quality of precision, manufacturing cycle and the process of injection molding and so on, directly affect the quality of products, production, cost and product updates, at the same time it also determines the competitiveness of enterprises in the market’s response capacity and speed.

Injection mold consists of a number of plates which mass with the various component parts. It divided into:
a. Molding device (die, punch)
b. Positioning system
c. Fixtures
d. Cooling system
e. Thermostat system
f. Road system
g. Ejection system

1.4 type of injection molds

it can be divided into three categories according to the gating system with the different type of mold:

1) intake mold: runner and gate at the parting line, it will strip together with products when in the open mode, it is the most simple of design, easy processing, and lower costing.

So more people operations by using large intake system

2) small inlet mold: it general stay in the products directly, but runner and gate are not at the parting line. Therefore, it should be to design a multi-outlet parting line.

And then it is more complex in the designing, more difficult in processing, generally choosing the small inlet die is depending on the product’s requirements.

3) Hot runner mold: it consists of heat gate, heat runner plate, temperature control box. Hot runner molds are two plate molds with a heated runner system inside one half of the mold.

A hot runner system is divided into two parts: The manifold and the drops. The manifold has channels that convey the plastic on a single plane, parallel to the parting line, to a point above the cavity.

The drops, situated perpendicular to the manifold, convey the plastic from the manifold to the part.

The advantages of hot runner system:
a. No outlet expected, no need processing, the whole process fully automated, save time and enhance the efficiency of the work.
b. Small pressure loss

Chapter 2. Injection Mold

There are many rules for designing molds. These rules and standard practices are based on logic, past experience, convenience, and economy.

For designing, mold making, and molding, it is usually of advantage to follow the rules. But occasionally, it may work out better if a rule is ignored and an alternative way is selected.

In some texts, the most common rules are noted, but the designer will learn only from experience which way to go. The designer must ever be open to new ideas and methods, to new molding and mold material that may affect these rules.

The process consists of feeding a plastic compound in powdered or granular form from a hopper through metering and melting stages and then injecting it into a mold.

Injection molding process: mold is a production of plastic tool. It consists of several parts and this group contains forming cavities.

When it injects molding, mold clamping in the injection molding machine, melting plastic is injected forming cavities and colling stereotypes in it, then it separate upper and lower die, it will push the production form the cavity in order to leave the mold through ejection. The entire process of injection is carried out of the cycle.

An injection mold consists of at least two halves that are fastened to the two platens of the injection molding machine so that can be opened and closed.

In the closed position, the product-forming surfaces of the two mold halves define the mold cavity into which the plastic melt is injected via the runner system and the gate.

Cooling provisions in the mold provide for cooling and solidification of the molded product so that it can be subsequently ejected.

For product ejection to occur, the mold must open. The shape of the molded product determines whether it can be ejected simply by opening the two mold halves or whether undercuts must be present.

The design of mold is dictated primarily by the shape of the product to be molded and the provisions necessary for product ejection. Injection-molded products can be classified as:

1) Products without undercuts
2) Products with external undercuts of lateral openings
3) Products with internal undercuts
4) Products with external and internal undercuts

Chapter 3: The Composition of Injection Mold

3.1 Mold Cavity Space

The mold cavity space is a shape inside the mold, when the molding material is forced into this space it will take on the shape of the cavity space. Injection molding the plastic is injected into the cavity space with high pressure, so the mold must be strong enough to resist the injection pressure without deforming.

3.2 Number of Cavities

Many molds, particularly molds for larger products, ate built for only 1 cavity space, but many molds, especially large production molds, are built with 2 or more cavities.

The reason for this is purely economical. It takes only little more time to inject several cavities than to inject one. Today, most multi-cavity molds are built with a preferred number of cavities: 2, 4, 6, 8, 12, 24, 32, 48, 64, 96, 128.

These numbers are selected because the cavities can be easily arranged in a rectangular pattern, which is easier for designing and dimensioning, for manufacturing, and for symmetry around the center of the machine, which is highly desirable to ensure equal clamping force for each cavity.

3.3 Cavities and Core

By convention, the hollow portion of the cavity space is called the cavity. The matching, often raised the portion of the cavity space is called the core.

Most plastic products are cup-shaped. This does not mean that they look like a cup, but they do have an inside and an outside. The outside of the product is formed by the cavity, the inside by the core.

Usually, the cavities are placed in the mold half that is mounted on the injection site, while the cores are placed in the moving half of the mold.

The reason for this is that all injection molding machines provide an ejection mechanism on the moving platen and the products tend to shrink onto and cling to the core, from where they are then ejected.

Most injection molding machines do not provide ejection mechanisms on the injection site.

For moulds containing intricate impressions, and for multi-impression plates from single blocks of steel as with integer moulds.

The cavity and core plates from single blocks of steel as with integer moulds. The cavity and core give the molding its external and internal shapes respectively, the impression imparting the whole of the form to the molding.

3.4 The Parting Line

To be able to produce a mold, we must have at least two separate mold halves, with the cavity in one side and the core in the other.

The separation between these plates is called the parting line and designated P.L. Actually, this is a parting area or plane, but, by convention, in this intext, it is referred to as a line.

The parting surfaces of the mold are those portion of both mold plates, adjacent to the impressions, which but together to form a seal and prevent the loss of plastic material from the impression.

The parting line can have any shape, many moldings are required which have a parting line which lies on a non-planar or curved surface, but for ease of mold manufacturing, it is preferable to have it in one place.

The parting line is always at the widest circumference of the product, to make ejection of the product from the mold possible, with some shapes it may be necessary to offset the P/L, or to have it at an angle, but in any event it is best to have is so that it can be easily machined, and often ground, to ensure that it shuts off tightly when the mold is clamped during injection.

If the parting line is poorly finished the plastic will escape, which shows up on the product as an unsightly sharp projection, which must then be removed; otherwise, the product could be unusable. There is even a danger that the plastic could squirt out of the mold and do personal danger.

3.5 Runners and Gates

Now, we must add provisions for bringing the plastic into these cavity spaces.

This must be done with enough pressure so that the cavity spaces are filled completely before the plastic “freezes”(that is, cools so much that the plastic cannot flow anymore).

The flow passages are the sprue, from where the machine nozzle contacts the mold, the runners, which distribute the plastic to the individual cavities, the wall of the runner channel must be smooth to prevent any restriction to flow.

Also, as the runner has to be removed with the molding, there must be no machine marks left which would tend to retain the runner in the mold plate.

And the gates which are small openings leading from the runner into the cavity space. The gate is a channel or orifice connecting the runner with the impression.

It has a small cross-sectional area when compared with the rest of the feed system. The gate freezes soon after the impression is filled so that the injection plunger can be withdrawn without the probability of void being created in the molding by suck-back.

Chapter 4: What Products Can Be Made from Injection Mold?

When creating a product that requires molded plastic parts, depending on the type of application and type of part you want to produce, you have several processes to choose from.

One of the most popular processes to achieve high quality and cost-effective plastic parts is injection mold.

Injection mold is a manufacturing process for producing parts in large volume – from thousands to millions. The melted resin is injected into a hollow mold until it is completely filled.

The injection mold process uses high temperature and extreme pressure to sufficiently fill the interior with molten plastic resin or liquid polymers. The molds are then cooled to release completed plastic parts.

The process is highly versatile and can produce a myriad of parts for a wide variety of applications.

Typical Products Made with Plastic Injection Mold
Electronic housings
Remote controls
Computers
Televisions
Medical equipment
Home Appliance
Other consumer electronic components

Molded closures:
Containers
Components
Drinkware

Machinery and Automotive Components: 
Bumpers
Dashboards
Radio controls
Cup holders
Many other interior and exterior elements

Healthcare Industry
Plastic bottles
Medicine cups
Medical tubes
Medicine packaging
Injectors

Commercial Products:
Electrical Boxes
Mop Heads
High-end Trash and Recycling Receptacles
Vending Machine Components
Equipment Housings

Medical Components: 
Sharps Disposal Bins and Wall Mounts
Medication Trays

Commercial Construction:
Conduits for Concrete Beams
Insulators
Raised Flooring Panels

Residential Construction:
Roofing Vents
Railing Gaskets
Deck Fasteners

Consumer Goods:
Skateboard Storage Racks
Barbecue Accessory
Bird Feeder
Tackle Boxes
Toilet Seats

Toys and Hobbies:
High-end Collectible Models
Decorated Children’s Furniture

Food Service:
High-Temperature Serving Pans
Bread Trays
NSF Food Service Products

Sporting Goods:
Training Device
Exercise Tools

Short-Run 3D Printed Components:
Electrical Knobs
Specialty Buttons
Fixtures

Chapter 5: How Does Injection Mold Work?

Injection molds must have a high precision match between the two mold halves in order to perfectly control the material flow. Creating the mold is crucial to building a seamless, precision product.

Injection molds are typically constructed using steel or aluminum, and precision-machined to form the features of the desired product.

The injection mold process is fairly repetitive once a functional, errorless mold has been produced.

It also has a low scrap rate relative to other manufacturing processes such as CNC machining which cut away considerable portions of the original material blank in a subtractive process.

The Injection mold process is highly repeatable and reliable for high volume production. Once the first part is produced, the second is going to be practically identical, due to the ability to make multi-cavity injection mold parts, where multiple parts are made with one cycle.

Other advantages are the wide range of material selection, low labor costs, minimal scrap losses, and minimal requirements for post-mold finishing operations.

The major disadvantages of injection mold are the initial costs of the mold design, which tends to be high due to design, testing, and tooling requirements and the longer required lead times.

Some custom complex parts may encounter problems during the injection mold process such as warpage or surface defects. Therefore, injection molded parts must be designed with careful consideration of any change in geometry as they cool and the material selection to assure stability.

The process of injection mold may seem like a complex one, but it’s the most common manufacturing method because of its capability and efficiency to produce a plethora of everyday items.

Injection mold is one of the most cost-effective ways help you to build both functional prototypes and end-use products. Contact Five-Star to get a free quote for your injection mold or precision components project