Precision injection molding in China

Precision injection molding and the common plastic molding difference

The characteristics of precision injection molding is: the size of the injection molded parts with high precision, small tolerance.

precision injection molding

precision injection molding

To achieve the requirements of precision injection conditions must be met:

(1) the mold material is better, rigid, cavity dimension precision and template between positioning accuracy is higher, lower surface roughness.

(2) to adopt precision plastic molding machine.

(3) to adopt precision molding process.

4) to choose suitable for precision injection molding process of the material. Commonly used precision molding materials have several: POM, POM = CF (carbon fiber), PNM = GF (glass fiber), PA \ FRPA66 (enhanced PA), PC, etc.

Precision injection process can ensure the size precision injection molding is the important way to control the shrinkage of injection molded parts, including: thermal contraction, disguised contraction of molded parts, orientation and compressed contraction and elastic recovery.

Common injection molding features are: precision is not high, the size of injection molded parts are typically can be assembled into standard, requirements for the appearance of the injection molded parts is relatively high, if necessary, may use the second processing (oil, for example) to improve the appearance of defects. Ordinary injection molding don’t need to use special precision injection molding machine, also do not need to specially designated materials, general common thermoplastics can be used to production. So ordinary injection molding technology is widely used in modern plastic industry.

Introduction to 3D printing technology

3D printing, i.e. a rapid prototyping technique, which is a digital document based on the model, the use of powdered metal or plastic materials may be bonded by way of the printed layer by layer technology to construct the object.
3D printing materials are usually printers using digital technology to achieve. Often in the mold manufacturing, industrial design and other fields are used to make the model, and then gradually for direct manufacturing of some products, there have been made using this technique to print parts. The technology in the jewelry, footwear, industrial design, architecture, engineering and construction (AEC), automotive, aerospace, dental and medical industries, education, GIS, civil engineering, guns, and other fields have applied.

Everyday life of ordinary printer can print flat items used computer design, and the so-called ordinary printers and 3D printer works basically the same, but somewhat different printing materials, printing materials are ordinary printer ink and paper, while the 3D printer built with metal , ceramic, plastic, sand and other different “printed materials”, are real materials, the printer connected to the computer through computer control can be “printed material” layer laminated together, eventually became the blueprint on your computer kind. In layman’s terms, 3D printer can “print” of a 3D object in real devices, such as printing a robot toy car printing, printing of various models, and even food, etc.. The reason colloquially called “printer” is a reference to the technical principles of ordinary printer, because the process of layering and ink-jet printing process is very similar. The three-dimensional printing technology called 3D printing technology. [2]
There are many different 3D printing techniques. They differ in the way that the material is available, and to create build parts with different layers. [6] 3D printing materials are commonly used in fiberglass nylon, durable nylon material, gypsum materials, aluminum, titanium, stainless steel, silver, gold, rubber-like material.

type Technologic Raw material
press 熔融沉积式 (FDM) Plastics molding
string 电子束自由成形制造(EBF) Any alloy
coins 直接金属激光烧结(DMLS) Any alloy
电子束熔化成型(EBM) Titanium alloy
选择性激光熔化成型(SLM) Titanium alloy,Cobalt chromium alloy, stainless steel, aluminum
选择性热烧结(SHS) Plastics molding
选择性激光烧结(SLS Plastics molding
powder spray 3D printing 石膏3D打印 (PP) Gypsum
Layer press 分层实体制造(LOM) Paper, plastic film, metal film
Photopolymerization 立体平板印刷(SLA Photocurable resin
数字光处理 (DLP) Photocurable resin

3D printing technology is not used in mass production, so some experts advocate 3D printing is the third industrial revolution, this argument is just agimmick.Foxconn OEM for Apple iPhonehas been for many years.Gou made​​ with 3D printing phones to illustrate 3D printing products can not only see, because we can not add electronic components, electronic productscan not be produced as the amount of these products.3D printing even without the production of electronic products,but by material constraints,other products can be produced very little, “even if the products produced, can not mass production, but also on the brokenYishuai.
“3D printingis indeed more suitable for some small-scale manufacturing,especially high-end customized products, such asauto parts manufacturing, although the main material is plastic, but the future of metallic materia ls will certainly be applied to 3D printing in the past,” said Crump, 3D printing technology has entered thedental, jewelry, medical industry,the scope of future applications will be more widely available.

3d printing gun
3d printing + injection molding in china

China quality molds and products supplier selection

Aston Martin complain china plastic injection molding company

Aston Martin complain china plastic injection molding company

 Luxury sports car maker Aston Martin has announced a global recall

Aston Martin ignore its internal processes for a range of procurement, vendor and product monitoring problems,since November 2007 produced a total of 17,590 sports car, called the discovery of parts of China for the production of sub-suppliers in Shenzhen KEXIANG mold companies(Shenzhen KeXiang Mould Tool Co Limited) use fake plastic material. In this regard, caught in storm in Shenzhen KEXIANG mold company responsible Ang Zhang announced that denies its production Aston Martin • Over parts. China has a lot of plastic injection molds and products manufacturer, they serve different target customers, some companies large scale, but the basic outsourcing, in fact, customers need to find is a real experience, and provide long-term senior custom mold for overseas customers and plastic products suppliers, CN-MOULDING no doubt that customers really need to find manufacturers.Since its establishment in 1997, the years from different companies for their commitment to providing quality automotive parts, medical equipment, industrial supplies, electronic components, small appliances mold design and manufacture of lastic products processing factories. The company currently employs 80 people,The significance of the quality of the enterprise:

Quality control for plastic injection molding in china

Parts made in a plastic injection molding process can have their own unique set of possible defects. That is why all of our employees are trained to spot these problems. The following is a listing of the most common defects associated with the plastic injection molding and transfer/compression molding processes:

Sink Marks: Sinking is caused by the outer skin of plastic solidifying while the material inside is still molten and viscous. As it cools and solidifies, the material compacts . The best way to avoid these dimples is to design the part with a consistent wall thickness. However, many times the effect of the sink mark can be minimized by adjusting molding parameters such as injection pressure and time.

Gas marks (burning): When molten plastic is injected into a mold cavity, the air that is in that cavity needs a place to escape. If the hot compressed air cannot escape, it may leave burn mark on the part. The best way to avoid gas marks is to strategically locate air vents of the proper depth within the mold. Adjustments to process parameters such as injection speed and screw speed can be altered to reduce or eliminate burning.

Custom plastic injection molding in china—-RIM technology

Custom plastic injection molding in china

Custom plastic injection molding in china

Custom Plastic Injection Molding in china for RIM

RIM (reaction injection molding), Chinese commonly known as reaction injection molding , is the late 1970s, first developed in Europe and America . Is different from the traditional injection molding and other molding process is a special process .
The principle is:
The two reaction materials ( polyurethane component and resin mixture ) with a stirrer were placed in a temperature-controlled feed tank , through accurate measurement , at high pressure into the mixing head at the start of injection , the mixing head of the valve to open , the reactants into the mixing chamber under pressure , speed fierce collision , near the atmospheric pressure and then flows into the mold , the exothermic chemical reaction in the mold to form a polyurethane polymer . This process can be simplified to : Store → Measurement → mixing → ​​filling → ​​curing → top out → post-processing.
RIM molding process is particularly suitable for large-scale ( large ) housing member .

PU resin first by Bayer (Bayer) (PU industry founder ) , Professor invented in 1937 , has been 70 years old .
Polyurethane with high strength, abrasion resistance , tear resistance, flex resistance, low temperature resistance and oil resistance, excellent chemical resistance and good blood compatibility , etc. , etc. . Polyurethane foam products made ​​of resin , elastomers, coatings, adhesives , fibers, synthetic leather and other varieties of auxiliary surface material , which is widely used in transportation, electronics, shipbuilding , civil engineering , light industry and textile and other sectors , products and varieties yearly basis, in the material industry occupies important proportion of the current usage of the PU after PP, ABS, PVC. since the late 1930s since the advent of its applications continue to expand , production increased year by year , is developing very rapidly .
RIM process has the advantage ( own summary , we hope to supplement ) :
1 , shorten product development cycles , reduce product development costs
RIM technology to make product design becomes more free, more casual , and its expression on the product to better reflect the designer’s whim , and because of the low viscosity of the reaction material , good fluidity , can be very small in the case of pressure under molding complex parts ; due process of low pressure injection of RIM , low requirements of the mold , the mold is usually done using epoxy or aluminum material , so the cost is only a fraction of the equivalent injection mold , the processing cycle more is the injection mold can not match, the process is particularly suitable for short production and prototype production, can greatly shorten the product development cycle and saving development costs and speed to market share opportunities ;
2, can be molded article of a large area of good quality and the appearance and structure of the

Custom plastic injection molding in cina process of RIM

RIM molding process of product size and stability , aesthetically pleasing ( up to Class A surfaces ) , impact resistance and good corrosion resistance ( up to PC / ABS performance ) , for forming a larger area of ​​housing has unparalleled advantages, RIM product thickness range is very large, the same cross-section of molded parts can vary between from 6mm to 28mm , which is the other process can not be compared , it can be integrally molded article thickness variations in order to improve the quality of products reliability , good performance surface coating , which can meet different process requirements , formulated by adjusting the ratio of raw materials can be made into a hard surface such as density polyurethane foam structures of different products to meet the diverse needs of customers ;
3 , the product package inserts simple process
A variety of inserts can be placed in the injection mold before the RIM material , so that the RIM material in the molding process to complete the package insert , steel or aluminum structural frame , electronic sensors , circuit boards, batteries, antennas, magnets, glass, metal parts so you can use RIM technology package, thereby reducing or even eliminating secondary processing sectors , so you can : Protect your important and sensitive components from dust, oil , corrosive chemicals pollution ; make your product You can work in wet or even water ; increased intensity of your product and protect critical components from impact damage from impact or slow ; way so your products can be in more extreme environments.
4 , easy to mold paint spraying
In the RIM process, prior to injection can be coated with polyurethane paint and gelcoat in the mold . Gelcoat or polyurethane paint in the molding process and polyurethane materials combined into one, resulting in mold decoration finished parts , greatly reducing the cost and increasing the secondary painting after processing efficiency.
RIM technology because of its superior product performance are widely used in automotive parts and modification parts, engineering machinery covering parts , medical equipment , instrumentation , electronics, machinery and equipment covering parts , industrial parts , chemical components , sports and other fields, as alternative materials such as metal , has incomparable advantages and prospects .

want to know more for custom injection molding in china or custom plastic injection molding in china, visit our website or http://www.youtube.com/watch?v=XkftBb5lYgc

with video

Reference page at : http://www.plastic-injectionmoulding.com/tag/china%20custom%20injection%20mold.html

China injection molding and plastic mold making industry hard

injection molding

Injection Molding in China

From China’s income situation difficult to see Chinese private enterprises, including ours plastic injection molding industry,The U.S. has 70% of the injection molding industry to move back, and if China plastic mold injection molding industry to continue to survive, to break the monopoly of state-owned enterprises is inevitable.

Chinese household financial investigation and Research Center data show that “the financial industry, utilities, real estate is the highest level of annual wage income of three industries, other industries typically 1.9 to 2.6 times.” Investigation of the center come from different ownership enterprises wages of view, state-owned enterprises, the average wage level of 54,000, only 29,000 private enterprises, state-owned enterprises is the private sector average wage level is about 1.9 times. The average wage income of foreign companies is as high as 86,000.

“State-owned monopoly industries due to hold the telecommunications, electricity, energy, high-value resources, it was easier profitable addition to pay state taxes, as well as considerable profit retention by allowing for the issuance of employee benefits or develop shopping malls, resorts, hotels and other sideline; The relative crowding together in the competitive private manufacturing, consumer goods, foreign trade and other fields. junior staff the income gap between the two conservative estimate of about 2 times. “Zou Wenjiang said.

Analysis of state-owned enterprises pay system is not difficult to find, in addition to employees of state enterprises fundamental wage income, but also includes wages of hidden income, such as a variety of bonuses, subsidies, insurance, prepaid cards, in-kind and other benefits. Industry insiders estimate that this part of the income of employees of state enterprises accounts for about half of total revenue.

Chinese household financial investigation and research center director, dean of Southwest University of Finance and Economics plow willing to accept new financial reporter in an interview that, according to various sources of income contribution to income inequality perspective, wage income gap is caused by China’s current income uneven distribution of one of the main income gap on the overall contribution rate of 40 percent. Followed by the industrial and commercial income disparities, income up 20% of households with an average income of 22,000 yuan business, the average household income of the lowest 20% Business operating income of only 200 yuan. Typically, the main source of income of low-income households or agricultural production, 20% of the lowest-income households, accounting for nearly 50% of agricultural income, wage income and business income accounted for only 13% and 5%. This reflects the current low rate of return of agricultural production reality.

Our website, you will see what is the real Chinese competitors, the responsible plastic injection molding maker  -Fair competition in a non-potent weed

china injection molding and mold making industry with the recession

china injection mold

china injection molding

As has been the China Europe customer service injection molding and mold manufacturing plant, we feel the order is very intuitive and sensitive, China’s official manufacturing data released in July rose slightly, with the outside world last month, the Chinese economy had negative growth not as expected.

But by the HSBC (HSBC) at the same time released independent survey said that “Chinese manufacturers face significant deterioration in the business environment.” For this argument, China injection molding and mold makers are very much support, both from China Order injection mold or injection products, this year’s decline in new orders in large quantity, we are still doing the old customer’s order last year, but next year how kind of hard to say.
China officially released on Thursday July the government purchasing managers’ index (PMI) increased from 50.1 in June to 50.3, which means that manufacturing conditions improved slightly. However, the release of China HSBC PMI index fell to 48.2 in the previous month, but July’s 47.7 for the 11 months to the lowest level.

For the manufacturing sector, PMI reading above 50 indicates expansion in manufacturing, production is less than 50 indicates contraction. Most analysts had expected in July will be the official index fell below 50, they pointed out that China’s overall economy is continuing to slow. Injection molding industry with respect to China, the Chinese mold making opportunity is good, but now Chinese social values ​​make fewer and fewer good injection mold maker, this is affecting the Chinese mold and injection molding industry.

HSBC and the differences between the official data will be re-triggered a kind of market speculation: Chinese government is trying to show a more optimistic picture of the Chinese economy, to support the people’s confidence in the Chinese economy, despite slowing economic growth.
ANZ Bank (ANZ), chief China economist Liu Ligang (Liu Ligang) said that official data “will not change our overall assessment that Chinese economy continues to deteriorate.”

In recent weeks, Chinese officials seem to have begun to take the initiative to stabilize investor confidence of economists and commentators, so they believe that despite three years of China’s economic growth to slow down gradually, but the Chinese economy in good condition.
Two findings appear gaps, one possible reason is that HSBC survey focused on relatively small-scale private manufacturers, while the official PMI index mainly reflects the large-scale state-owned enterprise situation.
Not only is China the actual molds and injection molding industry slowdown in other sectors is not good, but a lot of excess capacity in the current circumstances it is not necessarily a bad thing, China mold manufacturing and injection molding industry need to rely on technology development, rather than by selling mold like selling iron did survive. Labor advantage is gone, China mold manufacturing and injection molding industry to rely on technology and management to survive.

Plastic Injection Moulding material —-PEI

Plastic Injection Moulding

Characteristics of PEI and in application of plastic products:
PEI: poly-ether imide with excellent mechanical properties, electric insulation properties, high radiation resistant, good resistance to low temperature and wear resistance, which is accessible via microwave.

As PEI both excellent high-temperature mechanical properties and wear resistance, steering valves can be used in the manufacture of water pipe valves and fittings. Due to its high flexibility and strength, heat resistance, is an excellent coating and film-forming material, and they can apply in the electronics industry coatings and thin films.

Main characteristics of continuous operating temperature range (long-term exercise -200–170) glass transition temperatures and thermal denaturation temperature close, up to 330 degrees at low/high temperature melting point has maintained high mechanical strength, high hardness, high outstanding resistance to creep resistance, good toughness of precipitation.

So PEI widely used, mainly used in the electronics industry: Shell connectors, General and micro-relays, circuit boards, coils, soft circuits, secret mirror, high precision optical components, high-temperature insulating Board. Automotive industry: connectors, high power lights and indicator lights, control of vehicle cabin external temperature sensors, control of air and fuel mixture temperature sensor, medical equipment and so on.

This our company’s production of PEI products :

Our company specialized in plastic injection moulding mold design, production and plastic injection molding production.
Materials include not only the commonly used ABS,PP,PC,PA and so on, but also covers special plastics such as PPEK,POM,PPT,PEI and so on.

China Plastic Injection Moulding

If you are looking for a company offering quality and precision manufacturing in the field of plastic injection moulding, Cnmoulding Plastic Mouldings is at your disposal. Being at the forefront of the China market for plastic mouldings, we have developed our experience in the design, creation, innovation, manufacturing and delivery of plastic injection mouldings for a variety of purposes.

Our precision manufactured plastic parts and components are used throughout a host of industry sectors.

Our efforts as a team in the field of initial concept design and in the manufacturing stage are the guarantee of quality injection moulding, and we can offer you quality in the preparation of CAD drawings, research and design, tooling, etc – all your needs for plastic injection moulding. With more than twenty years experience we are able to deal with all volumes, sizes and shapes

panels for cars, mechanical parts, as well as small plastic mouldings such as bottle caps, spools, combs, etc.
In special plastic injection moulding materials if you face any technical problems in product development, please visit www.cnmoulding.com www.injectionmoldchina.com or www.chinamoldmaker.org for solution

New technology for plastic injection molding china

new injection molding technology in china

china plastic injection molding technology

plastic injection molding in china, china injection molding

Gas-assisted injection molding china technology is the development of a new type of technology in order to overcome the limitations of conventional injection molding china by injection molding engineering sector general concern, since the 1990s, the use of gas-assisted technology, improve product accuracy, surface quality, to solve large size and wall thickness varied deformation of the product, improve product strength, reduce stress, save plastic materials greatly simplify mold design, widely used in automobiles, household appliances, office supplies as well as household products and many other fields. It is called the second revolution of the plastic injection molding china process. CAE software for simulation of gas-assisted injection molding china process, help us to understand the melt filling in the molding process, the gas-assisted filling, gas protection pressure molding process, to avoid the injection melt insufficient, the gas pressure is too large, cavitation, blowing wear surface depression occur to determine the the melt gate, gas inlet position, the runner dimensions airway size optimization and airway reasonable arrangement, material selection, process conditions set, and according to the analysis of repeated calculation results to determine a set of best process to ensure the success of a test mode. In recent years we have succeeded in using the software for CAE analysis of gas-assisted injection-molded parts for home appliances and automobiles, and achieved good results.

gas-assisted  china injection molding process

Gas assisted injection molding molten resin injection, gas injection, gas holding pressure, gas recovery, part ejection, and several major steps. First by the gate to the mold cavity after the molten resin is injected, and then inject a constant pressure of an inert gas (usually nitrogen), the role of promoting the resin is enriched to various parts of the mold cavity by means of gas pressure, so that the plastic member to finally form a hollow section while maintaining the full shape. And from the interior of the resin packing, the gas pressure becomes the holding pressure. Gas emissions occur at the end of the cooling mold. Compared with the conventional injection molding process, a gas-assisted filling stage, and the packing stage holding pressure by air pressure. Holding pressure, can reduce stress and prevent Warpage products. Due to the pressure exerted by the gas can effectively pass, can ensure that the parts on the inner surface of the pressure distribution uniform to compensate for volume shrinkage during the cooling of the melt, and also to avoid the deformation of the part ejection. Using gas assisted injection molding, is controlled by the amount of plastic to control the injection cavity articles the hollow ratio and the shape of the airway. Gas-assisted injection molding pressure control method and volume control method are two ways.

2 gas-assisted china injection molding and china mold maker technology features

2.1 is capable of forming wall thickness difference larger products and complex three-dimensional hollow products

Gas-assisted technology into the airway wall thickness at the hollowed design, thus ensuring the thickness difference the larger molding quality of the products, the use of gas-assisted technology, but also to simplify the structure of the products. Parts due to the large wall thickness difference had to be divided into several parts, molding and then together, forming one gas-assisted technology.

The 2.2 injection pressure is low

Gas from the gate to the end of the current to form a continuous flow passage, no pressure loss can be realized in low-pressure injection molding, therefore, the residual stress is smaller parts, warpage deformation is small, dimensionally stable.

2.3 to eliminate sink marks, improve the quality of the product surface

In the the gas packing process, the contraction of the plastic secondary penetration by the gas to be compensated, so that the parts will not sag In addition, the use of gas-assisted injection molding, the thicker part of the products can be hollowed out to reduce or even eliminate sink marks.

In addition, to enhance the strength and stiffness, but also save materials, shorten the molding cycle.

China injection molding injection molding china  china mold maker

what is custom injection molding process in china

custom injection molding
 

custom injection molding china  is a process of shaping plastic by melting it and injecting it into a predesigned mold. The process was first designed in the 1930s and was originally based on metal die casting designs. It offers many advantages to alternative manufacturing methods, including minimal losses from scrap (since scrap pieces can be melted and recycled), and minimal finishing requirements. This process differs from metal die casting in that molten metals can simply be poured; plastic resins must be injected with force.

The china custom injection molding process uses large injection molding machines, which advance the resins through six major processes to produce everything from computer parts to plastic Halloween spiders. Although this machine is a complex piece of equipment, custom injection molding in china will consists of two basic elements: the injection unit and the clamping unit. The process starts with a mold, which is clamped under pressure to accommodate the injection and cooling process. Then, pelletized resins are fed into the machine, followed by the appropriate colorants. The resins then fall into an injection barrel, where they are heated to a melting point, and then injected into the mold through either a screw or ramming device.Then comes the dwelling phase, in which the molten plastics are contained within the mold, and hydraulic or mechanical pressure is applied to make sure all of the cavities within the mold are filled. The plastics are then allowed to cool within the mold, which is then opened by separating the two halves of the mold. In the final step, the plastic part is ejected from the mold with ejecting pins. The completed part may contain extraneous bits called runners, which are trimmed off and recycled. The entire process is cyclical, with cycle times ranging from between ten and 100 seconds, depending on the required cooling time.

China custom injection molding process requires some complex calculations. Every different type of resin has a shrinkage value that must be factored in, and the mold must compensate for it. If this value is not precisely determined, the final product will be incorrectly sized or may contain flaws. Typically, this is compensated for by first filling the mold with resin, holding it under pressure, and then adding more resin to compensate for contraction. Other complications may include burned parts resulting from the melt temperature being set too high, warpage resulting from an uneven surface temperature, or incomplete filling due to a too slow of an injection stroke.

Injection molds china themselves can be surprisingly expensive, sometimes upward of $100,000 US Dollars (USD). If the desired part quantity is great enough, however, the mold cost becomes relatively insignificant, and the resulting plastic parts are very reasonably priced. Some molds are made with more than one cavity; these multicavity molds cost more than their single cavity counterparts, but due to increased production efficiency, the cost per part is minimized.

China custom injection molding method can be used with a variety of plastic resins. The most popular resins for this type of molding include polypropylene (PP), polyethylene (PE), and ABS. Each has its own set of advantages and disadvantages, and they are chosen based on the desired characteristics of the final part.

 

China plastic injection molder designer experience for slider

Overview of Plastic injection molder slider design—china mold maker experience

china mold maker technology with slider

china mold maker technology with slider

When the side wall of the plastic molding products with a hole recess boss, plastic injection molding products not directly emerge from the injection mold forming holes, grooves and bosses molded parts must be made of the activities, known as core activities. Completion of the activity type out and reset mechanism called pumping yi institutions.

(A) Classification of core-pulling mechanism

1 motor core pulling mold, rely on the action of the inspection injection mold, core-pulling machine with the active core, the core extraction. Core pulling motor with large ejection force, labor intensity, high productivity and easy to operate, widely used in production. Their transmission mechanism can be divided into the following categories: bevel pillar core oblique block core pulling, rack and pinion core pulling.

Manual pumping core mold, relying on human to extract core activities either directly or through pass parts. The disadvantage is that production, labor-intensive, and restricted, it is difficult to get a large core pulling force, the advantage of the mold structure is simple, easy to manufacture, manufacturing mold cycle is short, suitable for the trial and small batch production of plastic products. Characteristics of plastic products limitations, can not use the motor core pulling, you must manually pumping the core. Manual core pulling their transmission mechanism can be divided into the following categories: a screw mechanism core pulling, rack and pinion core pulling activities insert core, core-pulling.

3. Hydraulic pumping the core of the core activities, relying on the hydraulic cylinder, and its advantages can be replaced according to the size of the ejection force and the length of the core-pulling distance the core hydraulics, to get a larger ejection force and longer pulling distance , due to the use of high-pressure liquid as the driving force transfer smooth. The disadvantage is that the operation process, but also the whole set of hydraulic core pulling device, therefore, its use is limited in scope, it seldom used.

(B) core-pulling distance and the calculation of the ejection force

Core from the plastic molding monk pumped without prejudice to the plastic products prolapse of the monk, that core pulls in the direction of the distance, called core-pulling distance. Pulling distance should be equal to the molding hole depth plus 2-3mm.

A. Pulling distance calculation as shown in Figure 3-102.

Calculated as follows:

To S = Htgθ (3-26)

Where

S —— pulling distance (MM)

The H —— oblique guide posts required to complete the core pulling stroke (MM)

theta —– oblique angle of inclination of the guide post, and generally 15 · 20 ·

(2) the calculation of the ejection force plastic products in the cooling package tight core, resulting in the force of the package tight, To the core extracted must overcome the resistance of the friction caused by the package tight force, this force is called the ejection force at the beginning of core pulling the moment required release force.

Affect the ejection force of many factors, broadly summarized as follows;

(1) core forming part of the surface area and cross-sectional geometry: a core molding part of the area is large, wrap-tightening force, the mold clamping force; product shape of the cross-sectional area of ​​the core, including the tightening force is small, and also its releasing; core cross-sectional shape is rectangular or curved, package shipping force, the release force is also large.

(2) The plastic shrinkage, coefficient of friction and rigidity: The plastic shrinkage, large clamping force on the core package, the release force is also large; good surface lubricity performance plastics, the release force is small; soft plastic, hard plastic required ejection force small.

(3) The wall thickness of the plastic products: inclusive area of ​​the same size plastic products, thin-walled plastic products shrinkage, the ejection force is also small shrinkage; captured wall plastic products, mold release force.

(4) plastic products the same side at the same time the number of core-pulling: When plastic products have more than two hole slot on the same side of the pumping mechanism pulls into plastic products have more than two of the same side of the hole slot, the use of sampling World institutions at the same time pulls, due to the contraction of plastic products Pitch, the ejection force.

(5) The active core molding surface roughness: the active core molding surface of the contact surface of the plastic article Pulling relative friction against the release force, have a great impact, therefore, the injection molder surface should be smaller roughness (usually Rα0.4um), processing of grain to the requirements and pulls in the same direction.

(6) plastic injection molder process; injection pressure, dwell time, cooling time for the ejection force. When the injection size, dwell time is short, the ejection force. Long cooling time, condensing contraction of plastic products is substantially complete, the package tight force, ejection force.

Under the influence of various factors, the ejection force computing power formula is as follows:

F = Lhp (u * cosα-sinα)

Wherein F —- ejection force (N)

The L — core activities are cross-sectional shape of the plastic products package tight perimeter (MM)

H — forming part of the depth (MM)

P — unit area packet clamping force, and generally … 12Pa;

u — friction slope (°)