Disadvantages of Blow Molding

Blow molding is the process in which hollow, plastic containers are made. Air is blown into molds to form items such as thermoplastic bottles, tubing and milk jugs. While blow molding allows companies to manufacture high volumes of plastic containers, which are significantly cheaper than glass, there are a few disadvantages to the process. Some disadvantages include environmental hazards and a significant dependence on petroleum.

Environmental Disadvantages

Plastic products made by the process of blow molding aren't biodegradable, which presents an obvious environmental hazard, especially when empty containers find their way to landfills. When disposed of in landfills, plastic products are buried and remain in the earth forever. Their oil-based material then becomes part of the soil and runs the risk of threatening plant life, animals and groundwater.

Dependence on Petroleum

Aside from the gasoline industry, plastic manufacturers depend on millions of gallons of petroleum in their quest to produce blow-molded products. Because oil is the most important agent in thermoplastics and blow molding is becoming more streamlined and automated, the process plays an ongoing threat on a diminishing world oil supply.

Process and Material Limitations

Although blow molding has been automated and can produce mass quantities of products, the process is largely limited to hollow forms. These forms are delicate and contain various thicknesses which must be precise, which often results in wasted material in the process of arriving at containers with proper dimensions and specifications. In some cases, thermoplastic is stretched to save on material, which can lead to substandard containers.

      skype: lee.ivy66

      ivylee886@gmail.com

Free Technology Co., Ltd
http://www.freetech-mould.com

The Plastic Manufacturing Process

1.                            Plastic Injection Molding Process

Injection molding is one of the main methods by which parts are manufactured from plastic. The first step in the injection molding process is to feed plastic pellets into the hopper, which then feeds the pellets into the barrel. The barrel is heated and contains a reciprocating screw or a ram injector. A reciprocating screw is typically found in machines that produce smaller parts. The reciprocating screw crushes the pellets, making it easier for the plastic to be liquefied. Toward the front of the barrel, the reciprocating screw propels the liquefied plastic forward, thereby injecting the plastic through a nozzle and into the empty mold. Unlike the barrel, the mold is kept cool to harden the plastic into the correct shape. The mold plates are held closed by a large plate (referred to as a movable platen). The movable platen is attached to a hydraulic piston, which puts pressure on the mold. Clamping the mold shut prevents plastic from leaking out, which would create deformities in the finished pieces.

2.                            Plastic Extrusion Molding Process

Extrusion molding is another method of manufacturing plastic components. Extrusion molding is very similar to injection molding and is used to make pipes, tubes, straws, hoses and other hollow pieces. Plastic resin is fed into a barrel where it is liquefied. A rotating screw propels the liquefied plastic into a mold, which contains a tube-shaped orifice. The size and shape of the tube determines the size and shape of the plastic piece. The liquefied plastic then cools and is fed through an extruder, which flattens the plastic and forms the piece into its final shape.

Issues That Arise in the Plastic Manufacturing Process

A number of complications can arise during the plastic manufacturing process, including burned parts, deformities, surface imperfections and brittle parts. Parts become burned when the molds are not kept cool or if the melting temperature in the barrel is too high. Additionally, if the reciprocating screw becomes jammed or is not rotating fast enough, liquefied resin will remain in the barrel too long and become scorched. Surface imperfections and deformities occur when the surface temperature of the mold is uneven, if the molds are not clamped tightly enough or if the melting temperature is too high. Brittle pieces are formed when not enough liquefied resin is injected into the mold or if the plastic hardens before the mold can be filled. Regular testing and calibration of injection and extrusion molding machines is critical to ensure that the process runs smoothly.

http://www.freetech-mould.com/Successful%20Case.html

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

http://www.freetech-mould.com

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

China injection molding shop www.freetech-mould.com

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

www.freetech-mould.com

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.

c

China injection molding www.freetech-mould.com

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.

c

 china professional tool maker

www.freetech-mould.com

 

 

 

 

Profession Tool Shop in China

Free Technology Co.,Ltd(www.freetech-mould.com)

was established in 1993, being specialized in mould design and manufacture. At present, Free tech is located in Shajing,Bao‘an, Shenzhen, has a factory of 8,000 square feet and more than 300 employees, including 20 engineers,we use UG,Pro-E,AutoCAD,Matercam and Catia as our CAD software,and mould managment system, passed ISO9001:2000 quanlity assurance system in 2005.

The company owns a wide range of advanced equipments, for example: Fanuk high speed CNC from Japan,3200mm CNC milling center, 3500mm (CNC) EDM machine, precision wire-cutter,1200mm hole-drilling machine,1600-ton plastic injection molding machine, Japanese automatic 3D scanner,Mitutoyo coordinate measure mahine,Mitutoyo projector,etc.....

For over 20 years,Free tech has made varieties of moulds for famous companies. They included automobiles for HONDA、TOYOTA、Nissan, Ford, air conditioner for DAIKIN, electrical tools for Panasonic,washing machine for HITACHI, TV for 3 Bird,monitor for DELL,Acer,etc,80% of moulds are exported to USA, UK,France,Germany,Sweden,Spain and Japan etc.....

Our company have insisted on management theory of “Customer Centered, Based on practice, Develops on quality & reputation”. We supply our customer high quality mould with reasonable price. We are looking forward to your visiting our company and cooperating with you sincerely.

Free technology is a professional mold manufacturer specializing in mold research and development.Over the past 20 years, our business has spreaded into the following fields: --Part Research & Design --Plastic Mold Manufacture & Injection Process --double color mould machining --Precision Component Machining --Die Casting Mold Manufacture--Rubber & Silicone Part--blow mold and metal part Our products has been distributed into USA, UK, Ukraine, UAE,Canada, Russia, Italy, New Zealand, Japan,Australia and so on.....

Free-tech mold has gained good feedback from our customers,and has established a customer base. However, one of our business strategy is to develop new customers and to give our best servivce to more companies. If you have any inquiry on molds or parts, please feel free to contact us , we will make your design into the perfect actual products. You are welcome to visit our plant to get more information about us.