Why Plastic Injection Moulding is So Popular

Plastic Injection moulding is one of the most popular and versatile methods for mass producing plastic parts, as it has multiple advantages over other methods of plastic moulding.

Injection moulding is used in a huge variety of products, but why is it so popular as a technique?There are 5 Reasons as follows:
Low labour costs
Injection moulding equipment usually runs with a self-gating, automatic tool to keep operations streamlined and production ongoing, requiring minimal supervision.
Details and complex shapes
Due to the huge pressure (more than any other plastic moulding method) that injection moulding causes, the material is pressed excessively hard against the mould, meaning that very specific details and complex geometry can be flawlessly integrated into the design.
Speed
The high output rate of the injection moulding process makes it very popular. Every machine is different, however generally only about 15 to 30 seconds pass between cycle times!
Strength
Fillers within the injection moulds mean that the density of the plastic can be reduced while it is being moulded, helping add greater strength to the finished product. In fields where strength is a vital property to the plastic part (e.g aerospace or automotive), injection moulding offers the best option.
Multiple types of plastic
Through co-injection it is possible to integrate more than one type of plastic into the product simultaneously with its production. This takes away the worry about using a specific type of plastic.

Plastic injection moulding manufacture creates a huge range of products for all industries in a thorough, precise and cost-effective manner. To learn more about our manufacturing capabilities and discover what makes us different, please visit our website: :jweimolding.com . If you’re ready to jump into your next project with us, request a quote . No matter your need,contact us today so we can help your business .

Basics Of Injection Molding

Injection molding is a manufacturing process commonly used for fabricating items from plastic case and toys to automotive body parts, cell phone cases, water bottles, and containers. Essentially many of the plastic parts that we use in every-day life are injection molded. It is a quick process to create a mass amount of identical plastic parts. The flexibility in shape and size achievable by the use of injection molding has consistently widened the boundaries of design in plastics and allowed substantial alternatives of traditional materials due to design freedom and light weighting.

How does it work?
An injection machine is made up of three primary components – the feed hopper, the screw and the heated barrel. Plastic granules for the part are fed into the heated barrel by a hopper. Plastic that is placed in the hopper is usually in powder or granular form although some resins, for instance silicone rubber, may be a liquid and might not entail heating. The material is then melted utilizing the frictional action of a reciprocating screw accompanied with heater bands. The molten plastic is then injected through the nozzle and into a mold cavity – it may seem easy, but injection molding is actually a very complex process. While in the mold cavity, the material cools and solidifies to the configuration of the cavity. When the part has hardened, the moveable platen that the mold is mounted opens and the part is ejected using 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.
For example, a machine that is capable of delivering 80 tons of clamping pressure is rated for 80 tons. This 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.
Another factor in sizing the correct machine is shot size and mold dimensions.
The clamping unit’s main function is to close and open the mold as well as ejecting the parts. Two of the most common types of clamps are the toggle clamps and the hydraulic clamps. Toggle clamps are traversed by hydraulic cylinders. These clamps use mechanical connections to generate greater forces than a hydraulic cylinder of the same size that uses a direct connection.
While the fundamentals of injection molding remain somewhat constant, the more technology we introduce into the existing clamp and injection processes the more complex the considerations become when developing a mold or building a machine for injection molding.

Jingwei molding has more than 15 years experience in plastic injection molding and mold making. Your High Volume, Custom Plastic Parts Injection Molding Specialist. To learn more about our manufacturing capabilities and discover what makes us different, please visit our website: :jweimolding.com . If you're ready to jump into your next project with us, request a quote . No matter your need, contact us today so we can help your business face all of the changes and challenges of today's competitive marketplace.

The necessity of drying plastics resin

Moisture affects the quality of the molded part in different ways, and the extent is determined by either the specific resin being processed or the purpose of the part. Improper or incomplete drying can create problems, either when the part is being processed or when the product is in use, or sometimes, both.
Drying plastics resin is done to reduce or eliminate problems caused by too much or too little moisture in plastic material as it is being processed. Most processors accept the need to pre-dry plastic resins, particularly hygroscopic resins, but many don’t understand the basics of resin drying.
There are 4 fundamental drying parameters for all polymers:
Heat
The first fundamental drying parameter is heat. The pellet will not release its moisture if you don’t heat it. Hygroscopic polymers are strongly attracted to water. The water molecules are bound to the polymer chains. Heat weakens the forces bonding the water molecules to the polymer chains, causing the molecules to move powerfully. If the temperature is high enough, the force binding the molecules to the chains are reduced, which allows for free movement of the water molecules to move the drying process along.
Dew point
The second fundamental drying parameter is dew point. Dew point is the temperature at which the air condenses. When the pellet is surrounded by the low vapor pressure of the dry air, it causes freed moisture molecules to move to the surface of the pellet.
Drying time
The third fundamental drying parameter is drying time. Plastic pellets do not dry immediately. First, they must be heated to let water molecules move freely, then enough time must pass for the molecules to de-fuse to the hygroscopic pellet surface.
Airflow
The fourth fundamental drying parameter is airflow, which carries heat or dry heated air to the material in the drying hopper. There must be a low dew point heated air forced over the material in order for the molecules of moisture to be detached from the chains and moved to the pellet surface where the airflow will carry the moisture away. Dry air volume must be sufficient enough to develop and maintain the desired temperature profile in the hopper.
To prevent defects, drying must be done properly in the molding or extrusion process. You can increase and optimize the molding times and extrusion rates by uniform drying to a low, consistent moisture level, maintaining a constant temperature, keeping the drying system in working condition, and using dryers that offer the latest drying technology to avoid temperature or point spikes, or any other issues that could arise.

ingwei molding has more than 15 years experience in plastic injection molding and mold making. Your High Volume, Custom Plastic Parts Injection Molding Specialist. To learn more about our manufacturing capabilities and discover what makes us different, please visit our website: :jweimolding.com . If you're ready to jump into your next project with us, request a quote . No matter your need, contact us today so we can help your business face all of the changes and challenges of today's competitive marketplace.

Introduction to Injection Molding

Injection molding is going be a big part of your journey to market. Regardless of your technical background you at least need to understand injection molding at a basic level.3D printing is the technology used for prototyping plastic parts, injection molding is the technology used for manufacturing.

Basics of Injection Molding

Injection molding is an ancient technology that has been used since the late 1800’s. Injection molding machines incorporate a huge screw to force molten plastic into the mold at high pressure. This screw drive method was invented in 1946 and is still the method used today.
An injection mold consists of two halves that are forced together to form a cavity in the shape of the part to be produced. Hot, liquid plastic is then injected at high pressure into this cavity.
The high pressure is needed to ensure that the plastic resin fills in every crook and cranny of the mold cavity.
Once the plastic has had time to cool, the two halves of the mold are pulled apart, and the part is ejected.
Although designing for injection molding can be quite complicated, and the cost of the molds themselves are incredibly expensive, there is one huge reason why injection molding is still used today.
No technology can beat injection molding when it comes to producing millions of identical copies of a part at an incredibly low price.

Cost of Molds

Injection molds are expensive, and you’ll most likely need a few of them, so their total cost can be quite significant. The more parts you need to produce with the mold the more expensive the mold.This is because the mold must be designed to withstand incredibly harsh conditions. Over and over again a mold is subjected to high temperature and high pressure.These two destructive forces act to quickly degrade the molds to the point of not producing parts of sufficient quality.
In order to tolerate this harsh environment injection molds are made from hard metals. The hardness of the metal required is typically determined by how many parts you plan to produce with the mold.
For example, a mold designed to produce 10,000 parts can be made of a much softer metal than a mold designed to produce 1 million parts.
Aluminum is a popular choice if you are producing less than 10,000 parts and works well for low volume production. Once you reach higher production volumes you will need to switch to a harder metal such as steel.
The harder the metal, the more difficult it is to make the mold, so the higher the cost. It also takes much longer to produce a mold from a hard steel. This is because molds are created by milling so a hard mold requires even harder milling tools.

Design for Manufacturing

The high cost of the molds is only one of the issues with injection molding. The other downside to injection molding is that it greatly complicates, and restricts the actual design of your plastic pieces.
Once you have a perfectly working prototype from a 3D printer, you then have to spend significantly more time and cost making it work for injection molding.
Keep in mind that you should design your plastic parts for injection molding from the beginning. Some requirements of injection molding, such as draft, can be delayed at least until your second prototype.
But other requirements, such as uniform wall thickness and undercuts, need to be implemented from the very start.
Draft
A main issue with injection molding is that your plastic parts have to be removed from the mold. Once the plastic has cooled, the two halves of the mold are opened and the newly formed plastic piece is removed.
For example, any 3D design for injection molding must incorporate draft. Draft simply means adding a slight angle to any surfaces that are parallel to the direction the part is pulled from the mold. In most cases 1 to 2 degrees is sufficient.
Some experts will tell you that you should include draft in your 3D model from the very start.
While I agree that incorporating draft is important to do early in the development process, I’ve found that it creates unnecessary complications with your first few prototypes.
I generally recommend adding draft once you have a high degree of confidence in your prototype. For most products this means adding draft after the first or second prototype version.
Ejector pins
Ejector pins are used to remove the plastic parts from the mold. As the name implies, these are small cylindrical pins which push outwards to eject the part from the mold.
The location of the ejector pins is not trivial so you need to give some thought to their placement. Ideally, you want them to be located where your part is structurally strong to prevent the part from warping on ejection.
Secondly, the ejector pins tend to leave small marks on the product where they make contact. If you look closely at most plastic parts you will be able to see these tiny, circular indentations from the ejection process.
You want to design your product with this in mind. Strive to have these pins make contact with the part in places that are not critical for the appearance of your product. You may even try to hide the ejector pin marks under a label or logo.
Side actions
If you are unable to easily remove your plastic part from a simple two-piece mold you can use something called side actions.
Side actions are parts of the mold that are inserted during molding, then pulled out before the main mold sections are pulled apart. Their direction of movement is perpendicular to the pull director of the two main mold halves.
Try your hardest to avoid needing side actions, since they add considerable cost and complexity to the molds.
One of the main ways to eliminate side actions is by avoiding the design of undercuts. An undercut is a feature that prevents the part from being removed from the mold with a single pull.
Many times placing a slot underneath the feature will allow the use of a single pull mold instead of requiring side actions.
Uniform wall thickness
One aspect of injection molding that has a huge impact on your product design is the requirement for uniform wall thickness.
After injecting plastic into the mold it is essential that the plastic cools at a uniform rate. If cooling isn’t uniform the part may warp.
Therefore, when designing products for injection molding it’s key to use ribs instead of thicker sections. Designing a part that keeps a uniform wall thickness definitely takes some experience to do correctly.
Two of the most common errors made by 3D designers who don’t understand injection molding are using non-uniform wall thicknesses and requiring the use of side actions.
So make sure whoever does your 3D design knows not to make these rookie mistakes.
Radius/chamfer corners
Perfect corners and edges are not practical to achieve with injection molding. The hot resin simply can’t be forced with enough pressure into the mold to perfectly fill sharp edges. At least, not reliably over large production volumes.
Therefore, all edges and corners should be either rounded or chamfered to allow the resin to fill them more uniformly and consistently.
Cold runners versus Hot runners
Runners is the term used for the channels incorporated into a mold for the hot resin to travel through to reach each cavity.
Larger runners allow the resin to flow more easily and at lower pressures. However, large channels require more time to cool and create more scrap, both of which impact the part cost.
Smaller runners, on the other hand, minimize cooling time, scrap, and ultimately part cost. The downside to small runners is the higher pressure required to force the hot resin to flow through them.
A solution that facilitates the use of small runners while also minimizing the required pressure is to use what are known as hot runners.
Small heating elements are incorporated into the mold near the runners so as to keep the resin more molten allowing it to flow more easily at lower pressure.
Nothing is ever free though, and the downside of hot runners is the additional mold complexity which always translates into additional costs.
In most cases, at least initially, you are best off using only runners without heating elements which are referred to as cold runners. Remember, always start with the simplest, lowest cost solution.
Small heating elements are incorporated into the mold near the runners so as to keep the resin more molten allowing it to flow more easily at lower pressure.
Nothing is ever free though, and the downside of hot runners is the additional mold complexity which always translates into additional costs.
In most cases, at least initially, you are best off using only runners without heating elements which are referred to as cold runners. Remember, always start with the simplest, lowest cost solution.

Single-cavity / Multi-cavity

You can eventually decrease your molding time by using multiple cavity molds. This serves to increase your production speed and reduce your manufacturing part cost.
Multiple cavity molds allow you to produce multiple copies of your part with a single injection of plastic. But don’t jump into multiple cavity molds until you have worked through any tweaks or changes to your initial molds. It is wise to run at least several thousand units before upgrading to multiple cavity molds.
Entrepreneurs with a limited budget will want to maximize the use of single cavity molds unless you have a manufacturer financing your mold costs.

Family molds

In most situations, you will need a separate mold for each custom plastic piece required for your product. At a minimum you’ll need at least two pieces: a topside and a bottom side.
But many, if not most, products require more than just two pieces of plastic. Molds are very expensive so the cost to purchase multiple molds is a huge financial obstacle.
You should always strive to design your product to minimize the number of unique custom plastic pieces required.
Another option to reduce the number of molds needed is through the use of a special type of multi-cavity mold called a family mold. A family mold allows you to consolidate multiple molds all into a single mold.
Whereas a typical multi-cavity mold creates multiple copies of the same part, a family mold creates different parts at one time.
Sounds great doesn’t it? Unfortunately, nothing is ever easy and every solution has tradeoffs. The main issue with family molds is they require each part to be pretty much the exact same size.
Otherwise, one part will fill up with resin before the other cavities. A family mold must be designed so all of the cavities fill up with resin at nearly the same rate.
That obviously limits their usefulness since it’s unlikely that all of the pieces needed for your product will be the same size.

Material selection

There is an incredible variety of plastic resins at your disposal each with its own characteristics. Two of the most commonly used resins for hardware products are Polycarbonate (PC) and acrylonitrile butadiene styrene(ABS).
Polycarbonate has a much higher impact strength and has a much higher-quality appearance compared to ABS. However, PC is of course more expensive than ABS.
Polycarbonate is the most popular plastic used in higher end hardware products because of its higher impact strength and its better aesthetics.
If appearance is critical for your product then PC is most likely the way to go. If your product is low-cost then ABS may be the best choice.
Bring Your Custom plastic injection mold/molding Project to The JW industry ,we have access to resources that help reduce production costs even further. We proudly offer a total concept solution from design and tooling to material selection, production, and fulfillment .Contact us today to request a free quote and find out how our industry experience and expertise will benefit you with your next project.

Many Processes Of Plastic Parts Production

When it comes to plastic part production, injection molding is among the least expensive processes available. Due to the initial investment of the mold, return on investment should be an important consideration when making the decision on what type of part manufacturing process to use.
Part Manufacturing Considerations:
Part manufacturing volume is a major consideration. If you anticipate needing lower volumes in the tens or perhaps even hundreds of parts per year, plastic injection molding may not be for you. You should also consider other part manufacturing processes such as fabrication, polymer casting, 3D printing, or vacuum/thermo-forming, depending on the geometry of the part.
However, if you do anticipate larger part manufacturing quantities that would justify the initial investment of an injection mold, you must also consider the shape of the part when determining what process to use. Below is a rundown of various plastic part manufacturing processes and the geometry that best suits them
Part Manufacturing Processes:
Injection Molding: A part with relatively consistent wall thickness, and no internal voids.
Blow Molding: Think of a balloon being dangled inside of a cavity, injected with air, and formed in the shape of the cavity. Bottles, Jugs, Balls. Anything small with an internal void.
Vacuum (Thermo) Forming: Somewhat interchangeable with injection molding, this process starts with a sheet of heated plastic, and is vacuumed onto a form and cooled to create the desired shape. Packaging clamshells, lids, trays, blisters, as well as vehicle door and dash panels, refrigerator liners, utility vehicle beds, and plastic pallets.
Rotational Molding: Larger parts with internal voids. A slow but relatively efficient way to manufacture smaller quantities of large parts such as gas cans, oil tanks, bins and refuse containers, boat hulls.
Fabrication: Used for smaller quantities of parts due to high labor costs, this process usually involves cutting and gluing sheet stock to match your specifications.
Plastic Part Manufacturing Experts
If you think injection molding might be the right process for your project, feel free to contact us for a free quote or visit our website:jweimolding.com

Injection Molding vs CNC Machining

When moving from design to creating your parts, you must decide how to make the parts. Two common methods are CNC machining and injection molding. Both of these have advantages and disadvantages when choosing between them. Which is the Right Choice?

Let’s look at each process:

CNC Machining:
CNC Machining is a process used in the manufacturing sector that involves the use of computers to control machine tools. Tools that can be controlled in this manner include lathes, mills, routers and grinders. The CNC in CNC Machining stands for Computer Numerical Control.
Injection molding:
Injection moLding process produces large numbers of parts of high quality with great accuracy, very quickly. Plastic material in the form of granules is melted until soft enough to be injected under pressure to fill a mould. The result is that the shape is exactly copied.

Which process is right for you?
In general, this can be looked at as a trade off between multiple of different characteristics; speed, volume, material,
tolerances/surface finish, and design. Each on of these can be a gating facture in using one process vs. the other and might even require changes to the part in order to manufacture.

Volume:
The main focus here is price per part. Which is cheaper changes depending on volume. CNC is cheaper when you need a few parts up to a few hundred. While you do get some benefit of volume in the price, it is typically seen between a few parts and a hundred. At larger volumes, you do not get any additional benefit of volume. This is from distributing the setup cost over the number of parts made.

The actual cost per part of injection molded parts is significantly cheaper that machined parts. Unfortunately, for injection molding, the creating of the mold can be a large upfront cost. This is spread out across the number of parts made to determine the cost per part. At a certain volume, even with the large upfront cost of the molds, injected parts become cheaper than machined. As more parts are created, the gap in cost becomes greater. This crossover can occur from as little as 100 parts up to about 5000.
Speed:
This is the simplest. For low volume of parts, CNC machining is the fastest. If you need 10 parts in 2 weeks, CNC machining is probably your only solution. If you need 50,000 parts in 4 months, injection molding is the way to go. Injection molding requires time to make the mold and ensure the parts are in tolerance. This can take anywhere from a few weeks to a few months. Once this is done, creating parts using the mold is a very fast process. The up front time investment of injection molding will pay off at high volumes.

Material:
CNC machining offers a greater selection of materials that can be used to create the parts. This can be very important deciding factor if a high performance plastic or a specific plastic is required.

For injection molding, the material selection can be more limited.

Tolerance / Surface Finish:
The advantage of CNC machining. With most materials, a tighter tolerance can be held and a better surface finish can be obtained. One advantage of injection molding is the repeatability from lot to lot. Molds can last for millions of parts with minimal wear. This allows for the parts from one batch to the next to be almost identical. With CNC machining, each part is put on the machine to be created and more variability will be seen.

Design:
Machining allows for great flexibility in the design. Many features can be easily made with machining that would be very difficult or cost prohibited in molding. Some of these include, overhangs, large walls with no drafts and variable wall thicknesses.

On the other hand, injection molding allows for deep features, square holes and living hinges to be produced easily that could be difficult and expensive with machining.

As you can see, the decision between machining vs. injection molding is not straightforward. You need consider the advantages of both from tolerances, price and design features to perform the final desicion.

Jingwei industry has served the injection molding and CNC machining industry for over 15 years and has a team dedicated to providing you with the most cost effective solutions for design and manufacturing your new products.To know more,Please visit us at :jweimolding.com or via info@jweimolding.com.

Injection molding is a complex process

Injection molding is a widely used process for high volume production of thermoplastic resin parts. It can produce complex parts with different combination of plastics and fillers and has a high efficiency ratio between applied material and the end product.

Despite major advantages of injection molding, there are significant difficulties in controlling quality of the molded part. These difficulties arise not only from the complex dynamics of the process and unpredictable behavior of the material under temperature-pressure fluctuations, but also from the lack of consistent relationships between the material properties, machine parameters, mold geometry and molded part quality. There are several sources of variation in the injection molding process which include material properties, process machinery, mold design, environmental fluctuations, and human interaction. If these factors had precisely defined and deterministic effects on the process, the quality of the molded part could be easily controlled. However, there are many interactions between stochastic factors, resulting in frequent irregularities in process parameters so the ideal state of constant quality does not exist. Examples of such irregularities include mold and melt temperatures that can drift from their set values, changes in polymer properties from batch to batch, and the machine and tool performance, which alter as they wear. Besides these major factors there exists small natural fluctuations making the process even more unpredictable.

There are several different approaches to quality control and process optimization that are used in industry today,such as expert systems, continuous process control, regression modeling, and design of experiments. Unfortunately, none of these approaches deliver 100% quality assurance. Difficulties in regulation arise mainly from non-linear character of the process and interactions between inputs that make the relationships between machine parameters and part quality not obviously defined. At the same time, the number of variables adds difficulty in evaluation of the significant parameters. Thus, a more capable quality control system requires a process model that not only describes the relationship between the process parameters and the resulting part quality, but is also capable to learn and express the process nonlinearities and complexities. Because of the stochastic correlations between the process parameters and characteristics of part quality, such a model should also be adaptable to the changing process conditions.

To overcome the difficulty require the engineers have wide knowledge and humble attitude. It is a course of researching, and should be complex.

SO,injection molding is a complex process!

Contact an experienced Chinese plastic injection molding company, Jingwei industry via info@jweimolding.com

How many steps of making an injection molding mold?

When we mention a mold for injection molding, generally it is a tool made by steel. How a cubic steel was changed into a mold which could manufacturing thousands of plastic part? There are several processes involved.Let’s make a simple intro of mold making

Milling

After confirming the drawing of the mold and preparation of the raw material, the first step is to mill the raw cubic steel. A injection molding mold is comprised of two sections. One is the mold base, which is purchased from the professional mold base supplier, the second is mold core or cavity, which is divided into fixed plate and moving plate. Both sentions need to be milled. However, for the mold core, there are some complex geometries which could not be shaped by milling machine. Then we have to got to the second step.

EDM

EDM means electrical discharge machining, generally we use copper as an intermediate. The copper will be finely machined to the reversed shape of the mold core. And the copper will be fixed on the EDM machine, the electricity flow through the contact surface between the copper and the steep, which would creat the spark to erode the steel. Most of the mold core are made by this method. However, it is not finished, we have to go to the third step.

Polishing

The EDM process will leave the groove on the surface of the steel. In order to get the better finish and easy ejection, the surface of mold core have to be polished. This job is boring, and often made by women who has enough patience and strict spirit. Polishing a pair of mold could last 12 hours or even longer. Actually the job has becomed a heavy burden for the mold maker in the developed countries, because it can not be replaced by robot.

Assembly

When the mold base is milled and the mold core is completed, we go to the final step of assemblying, it has to be made by experienced worker too. It is a high skill job. Bad assembly could lead to failure of the injection molding.

That’s a simple intro of mold making. Contact an experienced Chinese plastic injection molding companies, Jingwei industry via info@jweimolding.com

An Introduction to Plastic Injection Molding

Plastic Mould is a kind of tool used to product hundreds of or thousands of plastic parts. Most of our daily used plastic parts are made by plastic injection molding.

While plastic injection molding may not be rocket science, it is still a very complex manufacturing process. It involves great attention to detail and there are many factors to take into consideration. First, the part design must be developed and maximized for manufacturability. Then a mold must be built. This involves computerized as well as hand tooling. The mold must then be tested along with resin and color options to determine the best formulation for the project. Press size and configuration are required to begin the manufacturing process. Once all the preliminary phases are complete, fine tuning of the mold and materials may be required before production runs are scheduled.

Plastic injection molding is the most used method of manufacturing plastic parts with wall thickness between 0.5mm to 5mm. There are some other methods of plastic forming like blow molding for the hollow products, compression molding for the super large parts, extrusion molding for the long and unregular tubes or pipes.

Screw Plasticating

When we come to the step of injection molding, the raw material is poured into the hopper on the top of the injection molding machine. There is a barrel under the hopper with a screw inside. The temperature increases, the screw rotates and the molten raw plastic material slowly moving on the barrel. This process is called plasticalting, the solid raw material is change into flowable liquid. At first, we need to set the proper indexed like the temperature, pressure and speed accroding to the plastic material and mould structure.

Injection Molding

When the flowable palstic is homogenised inside the barrel, the material is injected into the mold cavity in a short time, maybe less than one second. When the cavity is overpacked, the volume of injected material is more than the part in order to compensate the shrinkage, the pressure is reduced and the cooling system start to work. After the parts are solidified, the back platen of press moves and ejects the parts. Then the process completes.

The key factor is to adjust the press indexes to accommodate with the specific material and mould. Before we start the mass production, the sample shots should be run for several times until the production process is stable. Generally, the period between finish of mould making to offical production should be less than 2 weeks. The time of mould trials should be less than 3 days. Or the injection molding supplier is lacking of experience or the mould maker is not professional.

Jingwei molding has more than 10 years experience in injection molding. Contact us via info@jweimolding.com.