Research and Forecast of Injection Molding Machine Industry in China, 2014-2018

The injection molding machine belongs to the plastic machinery type that has the largest output and application volume in China, as well as being the main force of China's plastic machinery export. In 2013, the export volume of injection molding machines was 22,946 sets with the export amount of USD 932 million; in 2012, the export volume was 24,830 sets, so the export volume in 2013 declined, but the export value in 2013 increased 3.78%, which fully shows that the average price of export products of China's injection molding machines is gradually growing. With the increasing demand for plastics, plastic machinery industry has huge market potential. From the global perspective, the top three plastic machinery types are injection molding machine, extruder/extruder production line and blowing molding machine, which account for more than 80% in the plastic machinery total output value. Among them, injection molding machine accounts more than 50% of the total output value of these three main types of plastic machines. 

In 2013, the output of China's injection molding machines was about 82,000 sets, rising by 4.21% compared with 2012. On the whole, the growth of China's injection molding machine industry gradually slowed during the year of 2007 to 2013, but the output was still rising. During 2007 to 2013, the average growth rate of output of China's injection molding machines was 4.77%. 

As this report estimates, the market supply volume of China's injection molding machines will reach 86,175 sets by 2014, 89,612 sets by 2015 and about 101,095 sets by 2018

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Minimize Sink Marks in Injection Molding

How to Minimize Sink Marks in Injection Molding

Sink marks are caused when a plastic part is not thoroughly packed out. This results from less plastic entering the mold than the volume of the mold was designed to hold. As the plastic cools, it shrinks. When insufficient plastic is injected into the mold, the thicker cross sections will sink as there is not enough plastic there to completely hold the desired structure. The three main reasons for this are poor gating location, poor processing conditions and insufficient gate or runner diameter.

Instructions

1.                            Poor Gating Location

1

Thin sections of plastic will freeze off before thick sections. Determine if the part has uniform wall thickness.

2

If the wall sections are uniform and the gate is relatively central to the part, move on to the next possibility.

3

If the wall sections are not uniform, make sure that the part is gated into the thickest section. This allows the thicker sections to fill with material before the thin sections freeze off and starve them.

2.                            Poor Processing Conditions

4

Running a mold too cold or molding a part with too short of a cycle time can cause a part to be insufficiently packed. First, weigh five parts produced at the current molding conditions and determine the average part weight.

5

Increase the cycle time by 10% and produce five additional parts.

6

Weigh the parts, and determine if there is a noticeable increase in the average part weight.

7

If there is an increase in weight, return to step two and repeat the experiment. Continue repeating until there is no significant change in part weight.

8

If after step two there is no change in part weight on the first attempt, repeat the series of experiments with a different process variable, such as mold temperature. Increase mold temperature by 10 degrees Fahrenheit and repeat the test.

3.                            Insufficient Gate or Runner Size

9

Insufficient gate and runner diameters may allow the runner to freeze before sufficient plastic is injected into the mold. To check for this, first determine the designed volume of the part.

10

Determine the specific gravity of the plastic resin that is being used. The material supplier can give that information if it is not readily known.

11

Calculate the designed part weight. The part weight in pounds is found by multiplying the part volume in cubic inches x specific gravity x .0361. Weigh a set of five parts and determine the actual average weight of the part.

12

If the part weight is below the calculated part weight, increase the gate or runner diameter by one standard size. Mold new parts and weigh.

13

Repeat the process as needed. Once the actual part weight reaches the calculated weight, optimal gate and runner size have likely been

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Advantages of Injection Molding

Injection molding is a method of creating plastic products. Most plastic products are made using injection molding. This process is attractive to manufacturers because of multiple advantages it provides over other plastic molding methods. Overall, injection molding is simpler, more reliable, more versatile and more efficient than most other types of injection molding.

High Pressure

Plastic injection molding operates at a very high pressure, meaning that the melted plastic is pressed harder against the mold than in other molding processes. This provides the advantage of a greater amount of detail in the design of the piece being molded, included complex geometry or detailed features.

Speed

The injection molding process is also very fast compared to other molding processes. A full injection molding process takes very little time, which allows for far more products to be generated from the same mold. Therefore, you get a lot more mileage out of a single mold. Injection molding is highly efficient.

Automation

Injection molding is a highly automated process. Most injection molding is done by machines that a single operator can run. Therefore, very little overhead will have to go into paying the labor force in a plastic injection molding process.

Monomer-Free

Injection molding is a monomer-free process. Monomers are a type of plastic that create a lot of fumes, which many people have a negative physical reaction to. Therefore, any molding process that employs monomers require a good deal of ventilation. If you use injection molding, you will not have to worry about these problems.

Multiple Plastic Types

When you use injection molding, you have the option of molding two different types of plastic at once. This process is called co-injection molding. Therefore, you do not have to worry about access to a particular type of plastic.

Thermoplastics

Injection molding makes use of thermoplastics. Thermoplastics can be injected into the mold, then the excess can be remelted and used again. Therefore, injection molding can save you on materials. Thermoplastics can also come in a wide variety of densities or strengths.

Fillers

Injection molding provides you with the option of using fillers in your molds. Fillers are used to reduce the density of the plastic as it is molded as well as provide greater strength to the product once it is molded. This is another method of reducing the total cost of the process.

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What’s hot runner mold?

  It use an assembly of heated components in plastic injection molds that inject plastic into the cavities of the mold. There are two general types of runnerless molds  - the insulated system and the hot runner system. Hot runners mold retain the advantages of the insulated 
  runner system over conventional cold runner system and eliminate a number of the disadvantages. Hot runner system is one of the more important enhancements you can incorporate into a mold to improve molded part quality, reduce production times and remain price competitive

  Injection Mold with Hot runner Solution will use reliable hot runner system and mold design tools. Our engineering department work harder and quicker than any other supplier to offer you new design ideas and mold concepts using any kind of hot runner system.with long history of experience and reliability for plastic injection molding and hot runner mold manufacturing,  we can deliver the best solutions. 
  Although there are many hot runner manufactures , a few major components is same:
  1. Hot runner plate (MANIFOLD)
  2. Nozzle

3. Temperature Controller
  4. Auxiliary parts

  Advantage of hot-runner mold in injection molding industry  

 Why some many customer select hot runner to make injection mold .This is mainly due to such injection mold has following salient feature:

  Less plastic raw materials: in the age of expensive oil and raw materials . hot runner technology is the effective way to reduce the materials cost.

  Quickly cycle time for injection molding, Due to no cooling time constrains runner system.

  Plastic can be more uniform state injection into each cavity, the result is consistent quality
  parts. Such injection molding components of good quality and low residual stress after ejection part distortion. reduce product costs, improve product quality

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Types of Plastic Injection Molds

Plastic injection molds create objects when melted plastic is forced into mold cavities. They often are used in mass-manufacturing operations to create products such as toys, kitchen utensils, bottle caps and cell phone stands. You can spot items constructed using an injection mold by the "flash lines" of extra plastic around the seams. Here are four major types of injection molds commonly used.

Cold Runner Molds

Cold runner molds are the most common type of plastic injection molds. These molds use a sprue and runner to inject plastic into each cavity. However, the sprue and runner harden along with the part once it solidifies. Workers then cut these pieces off and recycle them. This can create a problem with waste, which may make them less economical to use.

Two-Plate Cold Runner Molds

Two-plate cold runner molds are so named because they feature two plates that fit together. There is only one parting plane, and that is where the runner must be located. This is the simplest type of cold runner mold.

Three-Plate Cold Runner Molds

Three-plate cold runner molds have three pieces, which means there are a pair of parting planes. The three pieces are the runner plate, the moveable plate and the floating plate. The runner plate contains the sprue and half the runner. The moveable plate contains the part's ejector system and half the part's geometry. The floating plate contains the other halves of the runner and geometry. The system can be located at either parting plane, and the piece can be gated anywhere on the surface to provide flexibility.

Hot Runner Molds

Hot runner molds deliver plastic in a different way. While cold runner plastic injectors cool along with the part, the runners in hot runner molds are situated inside the mold and kept at a temperature higher than the plastic's melting point. This means the sprue and runner never have the chance to harden. This also reduces the amount of wasted plastic. However, hot runner plastic injection molds require more skill and maintenance and have a higher baseline cost. However, they often pay for themselves based upon the material savings.

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What Is Injection Molding Used for?

Injection molding is used for manufacturing plastic, rubber and metal. Materials are fed through a heated barrel in the machine and forced into a mold where it will cool and take its shape. An injection molding machine can stamp out metal car shell parts, rubber valve steam seals, and even plastic toys for kids.

 

Plastic

Injection molds uses plastic to make toys for children, milk containers and movie cases. It also makes other plastic products such as combs, kitchen utensils and dust pans.

Rubber

Injection molds make many rubber automobile parts. It makes valve steam seals and oil seals for the engine. It also makes earplugs, rubber hoses and telecommunications items.

Metal

Injection molds can stamp out small to large items. It can stamp out automobile parts from spark plugs and floor pans to ball bearings. It also can stamp out items like TV hangers and knitting needles.

 

 

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injection molding （2）

injection molding

 

Injection molding is a plastic manufacturing process whereby granules of plastic are heated until they melt and are then forced into a specially designed mold. Once in the mold the plastic is allowed to cool and hardens into the form of the mold. Injection molding is widely used in industry to produce plastic artifacts like computer casings, toys and cookware.

Barrel

·                                 The key part of an injection molding tool is the barrel. This is a metal cylinder that houses the reciprocating screw. The plastic granules are emptied into the barrel via the hopper and while in the barrel a combination of heat from the heaters and friction from the reciprocating screw liquidizes the plastic pellets. At the end of the barrel is an injection nozzle, through which the molten plastic is injected into the mold.

Reciprocating Screw

·                                 The reciprocating screw sits inside the barrel of the injection molding device. This tool rotates and forces the plastic pellets through the barrel and into the mold. In appearance, the reciprocating screw is roughly cylindrical, tapering slightly to a point at one end. Its outer surface is shaped into a screw thread.

Hopper

·                                 The hopper is a tool used to store the plastic granules before they enter the barrel. It consists of a large funnel into which the plastic granules are deposited before they enter the barrel.

Heater

·                                 The heaters sit around the barrel and raise the temperature of the plastic granules to the point at which they melt. This enables the molten plastic to be injected into the mold. The heaters sit wrapped around the cylinder and are powered by electricity.

Mold

·                                 The mold and the corresponding mold cavity determine the final shape of the injection molded artifact. There are certain limitations on the design of the mold and the design of the molded artifacts caused by the necessity of being able to remove the artifact once it has solidified.

Mobile Platen

·                                 The platen is a mobile flat plate that is used to push the mold and the mold cavity together. This ensures that the molten plastic migrates to every part of the mold and mold cavity. The platen is held in place against the mold by a clamp.

Clamp

·                                 The purpose of the clamp is to hold the mold and the platen as close together as possible while the molten plastic is setting into the final shape of the injection molded artifact. The clamp is often adjustable so the pressure on the platen can be increased to ensure that the molten plastic has reached every part of the mold cavity.

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key point of injection mold design (1/2)

Injection molded parts design point.

1, the product produced using the injection molding process , the plastic in the mold cavity uneven cooling and uneven shrinkage and the design is unreasonable , prone to various defects in the product: Sink mark , weld lines , bubble, deformation, ejector mark, flash.

 

2 , in order to obtain high-quality plastic products, we must fully consider its structure in the design process of products, combined with the following.Analysis method to avoid defects according to the main structural features of injection molding products.

 2.1 direction and mold parting line

     At the beginning of each products designed, must first to determine its direction and mold parting lines , in order to ensure as much as possible to reduce Pulling and eliminate the impact on the appearance of the parting line .

2.1.1 determine the direction of the mold , ribs, clips and other structured products should be designed as the mold the direction, in order to avoid reducing core pulling, extend tool life .

2.1.2 Example: bumper mold direction is generally the direction of the vehicle body coordinate χ , if designed to mold the direction of the axis χ  Inconsistent, you must specify the angle at which the product graph..

2.1.3 determine the direction  , you can select the appropriate parting lines to improve the appearance and performance.

2.2  draft angle.

2.2.1 appropriate draft angle to avoid product scratch . draft angle should be greater than 0.5 degrees for smooth surface, fine  Surface greater than 1 degree, coarse surface greater than 1.5 degrees.

2.2.2 appropriate draft angle can avoid parts’ injury .

2.2.3 for the deep cavity design, requires the outer surface slope angle less than the inner surface , to ensure that no deviation when injection , to obtain a uniform thickness of the product , and to ensure the opening portion of the product density of the material strength.

 

2.3Wall thickness of products

2.3.1 certain kinds of plastic wall thickness range , generally 0.5 ~ 4mm, when the wall thickness is more than 4mm, the cooling time is too long , resulting in sink mark and other issues, should consider improve and changing the product structure.

2.3.2 The wall thickness would cause surface and sink mark.

2.3.3 products with uneven thickness would cause bubble and sink marks.

 

2.4 reinforcing rib

2.4.1 strengthen the rational application of ribs , increase product rigidity and reduce distortion.

2.4.2 stiffener product wall thickness must be less than 1 / 3 , otherwise the surface would have sink mark

2.4.3 ribs should be greater than the slope of one side of 1.5 °, to prevent ejector mark .

 

 2.5 Chamfer

2.5.1 rounded product may cause stress concentration is too small , causing cracking products .

2.5.2 rounded mold cavity is too small,may cause stress concentration , leading to the cavity cracking.

2.5.3 Set reasonable chamfer , but also can improve mold processing technology, can be directly used as cavity milling cutter R , While avoiding inefficient power processing.

2.5.4 Different chamfer may cause moving parting line should be combined with the actual situation of choosing different fillets or clearance angle .

 

  2.6 Hole

2.6.1 shape of the hole should be as simple as possible , and generally rounded.

2.6.2 consistent axial and mold the direction of the hole , core pulling avoided .

2.6.3 When the hole when the aspect ratio is greater than 2 , should be set stripping slope . The diameter of the hole should be at this time trails size ( the largest real Body size ) is calculated .

2.6.4 blind hole aspect ratio is generally not more than four .

2.6.5 the distance from the hole to the edge of product is generally greater than the aperture size.

 

2.7 injection mold core-pullingmechanism and avoid

2.7.1 When the plastic parts can not be successfully mold press release direction , pulling mechanism should be designed . Pulling mechanism of complex products can be molded Structure, but can lead to product patchwork line , sink mark and other defects, and increase the cost of shortening the life of the die mold .

2.7.2 The design of injection molding products, such as no special requirements to avoid pumping core structure . If the direction of the axial hole and tendons change, then trying other methods.

 

 

 

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