Injection Molding Machines - Types, Costs, How To Choose The Best Machine For Plastic Injection Mold Manufacturing

To produce a plastic product, you need an injection moulding machine. Which is also know as an injection press, the main molding equipment to make thermoplastic or thermosetting materials into various shapes of plastic products by plastic molding mold. There are many different types of molding machines, depending on what you are creating and how the machine affects the product. Divided into vertical injection molding machine, horizontal injection molding machine and all electric. The injection molding machine heats the plastic and applies high pressure to the molten plastic to make it shoot out and fill the mold cavity. Below, we explain everything about injection moulding machine covering:

Types of injection molding machines

The cost of injection molding machines

Injection molding machines selection guide

Working principle of injection molding machine

 

How Many Types Of Injection Molding Machines Are There

When it comes to the injection moulding process, there are many different types of machines to choose from. 

Classified by plasticizing method:

● Plunger type plastic injection molding machine: It has poor mixing and plasticizing properties, so it is necessary to install a diverter shuttle device. Now it is rarely used.

● Reciprocating screw type plastic injection molding machine: The screw is used for plasticizing and injection. It has good mixing and plasticizing properties, and is widely used now.

● Plunger type plastic injection molding machine: plasticizing by screw and injection by plunger are separated.

 

Classified by the type of driving system they use:

● Hydraulic injection molding machine: lower price tag, cheaper parts, stronger parts, have exceptional clamping force.

● Electric injection molding machine: energy efficiency, less down time, faster process, clean operation. 

● Hybrid injection molding machines: open up new degrees of design flexibility, combine the energy savings and accuracy of electric molders with the force-generating capacity of a hydraulic unit. Hybrids have replaced fixed-speed DC pump motors with variable-speed AC drives. These require less maintenance and experience less downtime than an all-hydraulic or all-electric molding machines. What’s more, hybrid injection molding machine is an affordable o ption.

 

How Does A Plastic Injection Molding Machine Work 

The working principle of the injection molding machine is to inject the plasticized molten plastic into the closed mold cavity with the help of the screw force, and obtain the product after curing and shaping.

The molding process of general screw injection molding machine is: firstly, the granular or powdery plastic is added into the barrel, and the plastic becomes molten through the rotation of the screw and the heating of the barrel outer wall. Then, the machine closes the mold and moves the injection seat forward to make the nozzle close to the gate of the mold. Then, the injection cylinder is filled with pressure oil to make the screw move forward, so that the screw can be pushed forward with high pressure and speed. After a certain period of time and pressure to maintain, cooling, solidification and molding, then open the mold to take out the product.

 

How To Choose The Right Machines For Plastic Injection Mold

1. Specifications & model of the molding machine

Since there are many kinds of injection molding machines, it is necessary to correctly judge which injection molding machine should be used for your product at the beginning. This has a great impact on the production cost, quality and production efficiency of injection molding products. Before selecting the specifications and models of the injection molding machine, the performance parameters of the injection molding machine in the product instructions provided by the manufacturer of the injection molding machine should be checked first. These parameter values are the main performance characteristics of the injection molding machine,  according to some technical requirements of the plastic products to be produced.

 

2. Dimensions of the mould

The dimensions of a mould are of the utmost importance when choosing the right injection moulding machine and should be checked at all times. In addition to the mould’s length and width, its height is also a major factor. The machine and the mould must be able to open to more than twice the height of the product in order to remove the product from the mould. This opening is known as the “daylight opening.” Furthermore, there has to be room for the optional use of a robot in the production process.

 

3. Injection speed

Some finished products need high ejection rate and rapid injection to form stably. For example, ultra-thin products, in this case, it may be necessary to confirm whether the injection rate and firing speed of the machine are sufficient, and whether the accumulator and closed circuit control devices are needed. Generally speaking, under the same conditions, the screw which can provide a higher injection pressure usually has a lower shooting speed, on the contrary, a screw that can provide a lower injection pressure usually has a higher shooting speed. Therefore, when selecting screw diameter, the injection quantity, injection pressure and injection rate need to be cross considered.

 

4. Available capacity

A product is assigned to a machine depending on the required capacity. Products in high demand, which require a lot of capacity on an annual basis, are given their own dedicated machine at Rompa.

 

5. Cycle time

The cycle time also factors into the choice of machine. Products with a short cycle time require extremely fast injection moulding machines, the so-called sprinters. These are specialist machines that are more expensive to purchase and maintain.

 

6. Core pullers

A mould can feature multiple hydraulic or pneumatic sliders. Each motion requires a separate core puller. The number of motions an injection moulding machine can control depends on the number of core pullers. The machine must have enough core pullers to control all sliders.

 

How Much Does A Plastic Injection Molding Machine Cost

Depend on the weight of the injection and machine size, brand.

● The weight of the injection is determined. How many tons decide how large product you can do. Usually,large product means cost more. 

● Famous brand like Husky, cincinnati milacron, ferromatik, negri bossi, boy machines are always expensive.

● Machine size from 15 tons to 3000 tons. Even Chinese brand,3000 tons machine also need USD700,000/set. 

● Desktop injection molding machines can range from $ 30,000 to 50,000 typically 5T.

 

Top Plastic Injection Moulding Machines Suppliers

There are also a number of injection molding machine manufacturers to choose from. Here is a list of some of the world’s top companies to give you an overview of the organisations and the machines they produce.

 

ARBURG: Arburg is one of the most established injection moulding machine manufacturers in the market. It’s also one of the largest, with 33 locations across the world.. They can offer customers a number of different machine options, including cube mould and hybrid machines. 

Haitian International: One of the major Asian manufacturers, Haitian International offers both electrical and hydraulic machinery with top quality and best prices. 

Sumitomo Demag: Sumitomo offers a range of injection moulded machinery and some automated and robotic systems. With an approach that it both future-facing and focused on meeting customer needs.

Husky Injection Molding Systems: Husky Injection Molding Systems Ltd. is a leading supplier of injection molding equipment and services to the plastics industry. They design, manufacture and integrate the industry’s most comprehensive range of injection molding equipment, including machines, molds, hot runners, and more.

Milaron: From 6 to 6,000 ton clamp capacities, Milacron offers the widest range of injection machines. A vast selection of machines all focused on performance.