Servo Energy-saving Injection Molding Machine

What is injection molding machine?

Injection molding machine, or (Injection moulding machine), also known as an injection press, it is a machine for making plastic products by the injection molding process. It usually consists of two main parts, an injection unit and a clamping unit. 

Machines are classified primarily by the type of driving systems they use: hydraulic, mechanical, electrical, or hybrid. What we sell is Horizontal Clamping Mechanical injection molding machine.

Injection molding machines work by adding plastic granules by means of a container into a warmed barrel. These granules are then liquified utilizing radiator groups and the frictional activity of an accompanying screw barrel. The plastic is then infused through a spout into a mold cast where it cools and solidifies to the shape setup of the mold pit. The mold is mounted on an adjustable plate. When the part has hardened, the plate opens, and the part is shot out utilizing ejector pins.

Injection molding machine sizes can run anywhere from 5 tons of clamping force to over 6000. The higher the tonnage, the larger the machine. In fact, injection molding machines are classified based on tonnage, or more precisely the clamping force or pressure.

pressure ensures that the mold remains closed during the injection process. Too little or too much pressure can cause part quality issues as well as flashing, where excess material surfaces on the edge of the part. The viscosity of the plastic being used is also impacted by pressure. MFI or Melt Flow Index is a measure of the melt of a thermoplastic polymers ease of flow.

How Injection Molding Machine work?

Injection molding machines work by adding plastic granules by means of acontainer into a warmed barrel. 

The plastic is melted in the injection molding machine and then injected into the mold, where it cools and solidifies into the final part.

Why choose Injection Molding machine? (Advantage of injection molding)

Injection Molding Machine Related Industry:

Automotive Industry	Electronic Industry	Home Appliance Industry	Packaging Industry
Daily Commodity	Stationery/Toy Industry	Medical Industry	Construction Industry

Injection Molding is a manufacturing process for producing parts in large volume. It is most typically used in mass-production processes where the same part is being created thousands or even millions of times in succession.

Injection molding machine is used to produce a variety of products including household appliances, consumer electronics, power tools, and automotive dashboards. Injection molding is also used to produce several everyday items such as toothbrushes or small plastic toys. Many medical devices, including valves and syringes, are manufactured using injection molding as well.

The Advantage of Injection Molding Machine is as bellowing:

• Injection molding enables complex shapes to be manufactured, some of which might be near impossible to produce economically by any other means.
• Good dimensional accuracy: That is, the second part you produce is going to be practically identical to the first one etc. This is a wonderful characteristic when trying to produce brand consistency and part reliability in high volume production.
• Injection molding machine produces low scrap rates relative to traditional manufacturing processes like CNC machining
• Injection molding is wonderful for this kind of high volume production because the high initial costs pay the manufacturer back over time with low per unit costs. Once the initial costs have been paid the price per unit during injection molded manufacturing is extremely low. The price also tends to drop drastically as more parts are produced. 

How to choose an injection Molding Machine?

Choosing a correct plastic injection molding machine is one of the most important points in making high quality parts and getting more profit. The correct model machine will help you keep costs low and make you more competitive.That will help you to sell more products, earn more profit and meanwhile establish a high reputation as a perfect manufacturing supplier. Even can always get the long-term cooperated clients.

In general, customers who have been in the plastic injection molding industry for many years have the ability to judge and choose the correct injection molding machine to produce. However, under certain conditions, the customer may need the assistance of the manufacturer to decide which model and which kind injection molding machine to use, even if the customer may only have sample or even just idea of the product, and then ask whether the manufacturer’s machine can produce, or which model comparison suitable for.

In addition, some special products may need to be equipped with special devices such as accumulators, closed circuits, injection compression, etc.,

The most important factors that often affect the selection of an correct injection molding machine include molds, products, plastics, molding requirements, etc. Therefore, the following information must be collected or available before making the selection:

1. Mold size (width, height, and thickness), weight, special design, etc.
2. Plastic type of final product.
3. The appearance size (length, width, height, thickness), weight, etc. of the injection molded product.
4. Molding requirements, including a few, product quality, production speed and so on.

Steps of Plastic Injection Molding Machine Selection: 

1> Clearify what you would like to produce

2> Calculate the relevant injection amount weight

3> Calculate clamping force requirements

4> Clearify the mold size and opening stroke, confirm the mold can be fit on.

1.Clearify what you would like to produce

The process of selecting correct machine model  starts with knowing the particular plastic product that will be msnufacturing by the machine. If the final product is not suited to the machine will result in troubles with on-going quality problems, slow cycle times, even machine and mold damage and etc.

We need inforation as bellowing:

• Plastic material 
• Weight
• Length x width x height 
• If have 2D/3D drawings will be best.
• Average wall section (Thickness)
• Output rate requirements. (how many pcs per hour you plan to manufacture? )

At least with these information we can know the mould size. The correct information will help you to find the suitable injection unit size, clamping force requirements and other requirements.

multi cavity injection molding

2. To calculate the relevant injection amount according to the weight of  the injection molding machine

(1)  when the product is made of polystyrene, the injection amount is Wps. Wps = (Product weight + Total weight of the casting head system)

When the requirement of product quality is high, the larger value of the coefficient should be applied.

(2)   if the product is made of other kind of plastics (call X plastics), according to the above method, first calculate the theoretical injection amount of the plastics Wx:

Wx = (1.3~1.1)×(Product weight + Total weight of the casting head system)

But Wx can not be simply used to decide the injection amount of the machine, it must be transformed into Wps value, here is the transforming equation:

Wps = W×1.05/vx

vx  —— the specific gravity of the plastics

Eg: if a article is made of polystyrene (PE), and the calculated weight is 175g, the casting channel system is about 20g, the with the above equation:

Wx = 1.2×(175)+20)=234g

You can look up the specific gravity of PE – Vx =0.92 So, Wps = 234×1.05/0.92=267g

So the best choice is 10.5 ounce (200g) injection molding machine made by our company.

3. Calculating Mold-locking/ Clamping force P according to the vertical projection area of the injecting product on the molding board (head board or second board):

Mold-locking/clamping force = mold-locking force constant  × projection area of the product

That is, P = KPS In the equation:

P  —— Mold-locking force (t)

S  —— Vertical projection area of the product on the molding board (cm²)

Kp —— Mold-locking force constant (t/cm²) Kp values given at the following table (Table 5)

Table 5 Mold-locking force constant Kp (for the injection of nice product)

4. the inner space between tie bar is decided according to the outline size of the mold 

the opening stroke of the injecting machine should be decided according to product height. The later should be larger than the former.

Opening stroke calculation

Other subsidiary factors that may need to be considered

(1)   The capacity of the injection molding machine should be consistent  with the height of your mold;

(2)   Ejector stroke, ejecting force;

(3)   Process factors;

(4)   The particles of plastics (including recycled materials) should be even and not be too big and long, otherwise it is very difficult to put them into the machine and the normal production may be influenced.