Injection molding is a manufacturing process used to create objects from thermoplastic and thermoset polymers.
The manufacturing turning process begins with the injection of a molten polymer into a mould tool cavity.
The polymer then cools and solidifies to produce the desired object. Injection moulding has many advantages, including the ability to produce large quantities of high-quality products quickly and inexpensively.
In this article, we will analyze in detail the advantages and disadvantages of this article on injection molding so that you have a good reference when you decide to manufacture injection moulding parts.
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Injection molding is an injection-cum-molding molding method. It requires the use of injection molding machines, plastic raw materials, injection molds, and other equipment to achieve.
At a certain temperature, the molten multiple plastic materials are stirred by a screw, injected into the mold cavity with high pressure, and then cooled and cured to obtain a molded product.
This method is suitable for the mass production of complex-shaped parts and is one of the important processing methods.
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The injection molding produces process can be roughly divided into the following 6 stages:
(1) Mold closing
(2) Injection
(3) Pressure-holding
(4) Cooling
(5) Mold opening
(6) Product removal
The above process is repeated to produce products in the batch cycle.
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The injection molding method is fast and efficient, the operation can be automated, there are many color varieties to choose from, the shape can be simple to complex, the size can be large to small, and the product size is accurate, the product is easy to update, and can become a complex shape of the parts.
(1) Since the melt plasticization and flow modeling of molding multiple plastic materials are carried out in the barrel and mold cavity respectively, the mold can always be in the state of making the melt condensed or cross-linked and cured quickly, which is conducive to shortening the molding cycle.
(2) When molding, the melt is injected into the mold after it is locked, and the melt with good flowability has little wear on the mold cavity, so a set of molds can produce large quantities of injection molded products.
(3) One operator can often manage two or more injection molding machines, especially when the molded parts can be unloaded automatically, and more machines can be managed, so the labor required is relatively low.
(4) All the molding processes, such as mold closing, plastic material addition, plasticization, injection, mold opening, and demolding, are completed by the action of injection molding, which makes the injection process easy to fully automate and realize program control.
Source:https://www.pinterest.com/pin/144115256818879038/(5) Because of the high pressure during the injection molding process, it is possible to mold plastic parts with complex shapes, clear surface patterns and markings, and high dimensional accuracy.
(6) More than one kind of material can be molded by co-injection; it can effectively mold materials with hard skin and foaming heart, thermosetting plastics, and fiber-reinforced plastics.
Since the molding can be done with precise mold and precise hydraulic system, and with the use of microcomputer control, it is possible to get products with high precision.
(7) High production efficiency, two sets of molds can contain dozens or even hundreds of cavities, so dozens or even hundreds of plastic parts manufacturing can be molded in one molding.
(8) The molded parts only need a small amount of trimming to be used, and the scrap produced during the injection molding process can be reused, so there is very little waste of raw materials during injection molding.
(9) Injection molding has the advantage of using multiple plastic materials simultaneously to manufacture one part. For example, the molding of TPU or metal inserts with plastic parts is also possible.
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(1) Easy quality control: very high surface accuracy and very small shape error for the same batch.
Injection molding is a highly repeatable process. This means that the second part of the production will be the same as the first part. This provides excellent control over product consistency and part reliability in high-volume production.
(2) Low process cost: High initial tooling cost but low cost per part. The main advantage of injection molding is the ability to concentrate on scaling up production.
Once the machine and mold are ready, the price per unit of the product during production is very low. As more parts are produced, the price drops dramatically.
(3) Suitable for mass production: Generally, it is only suitable for mass production; the injection moulding process is suitable for mass production with complex shape products and other molding processing fields.
(4) High production efficiency: general production cycle of injection molding: 30s-60s/mode; little or no labor, once the parameters of the injection molding machine are adjusted, it can maintain continuous production without the need for manual and frequent adjustment.
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(1) High initial investment cost: Fast production injection moulding requires an injection moulding machine, injection molding equipment, injection molds, other auxiliary equipment, etc.
Because the cost of injection molding machines and injection molds are relatively high, so the start-up investment is large, it is not suitable for small batch
Therefore, it is not suitable for the production of small quantities of plastic parts.
(2) High design requirements: If you want to mass-produce parts, you need to make sure the design is correct the first time, because if you need to change the mold later due to design problems, the cost of changing the mold is also relatively high.
(3) High skill requirements: The quality of molded products is limited by a variety of factors, so the technical requirements are higher and more difficult to master.
High requirements for the operating skills of injection moulding machine operators, which generally require 5-10 years of experience.
Higher technical experience requirement for mold design and production personnel, generally also need 5-10 years of experience.
Source: https://www.pinterest.com/pin/362469470020450808/(4) Longer pre-production lead time consuming: The key apparatus of injection molding is the mold, but the cycle of mold design, different tool manufacturing techniques, and mold trial is very long and slower to put into production.
Depending on the size and structure of the product idea, it usually takes 25-40 days to make the injection mold.
After the mold is ready, it takes several times to debug the injection moulding machines parameters during the sample-making stage to reach the most available parameters for fast production injection moulding, which also takes some time.
(5) Due to the limitation of cooling conditions, it is more difficult to mold thick-walled plastic parts with large variations.
(6) disadvantages of injection moulding High initial costs – the main disadvantage of plastic injection moulding is the plastic injection moulding tool, plastic injection moulding machine and its auxiliary equipment which are very high. Lead time – from product conception to the final part, it can take months of design, reviews, testing and tool manufacturing.
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Before you attempt to produce parts through injection molding, consider the following tips:
(1) Financial Considerations
Up-front costs: Preparing for the production of injection-molded products requires a significant initial investment. It is best to know this key point in advance.
(2) Production Quantity
Determine the number of parts to be produced, injection moulding manufacturing is the most cost-effective manufacturing technique.
Determine the number of parts that you want to gain from your investment (consider the costs of design, testing, production, assembly, marketing, and distribution, and the expected price point of sales).
(3) Design Considerations
Part design: Simplifying product geometry and minimizing part count early on will provide benefits.
Tooling design: Consider in advance the defects that may occur during production when designing the mold. Consider gate locations and run simulations using mold flow software such as Solidworks Plastics.
(4) Production Considerations
Cycle time: Reduce cycle time as much as possible. Use technically sophisticated tools. Small changes can make a big difference, and cutting a few seconds from your cycle time can result in significant cost savings as you produce millions of parts.
(5) Assembly
Design your parts to minimize assembly. The main reason is that the cost of assembling simple parts in the injection molding process is still relatively high. If you can optimize the assembly process in manufacturing processes, you will save a lot of labor costs.
Factors affecting the quality of injection molding
(1) Injection Pressure: the reason for the need for injection pressure is because the resistance of the melt flow process should be offset, or the resistance of the flow process should be eliminated by the pressure of the injection machine, which is the opposite, to ensure a smooth filling environment.
(2) Injection Time: a reasonable injection time is conducive to the ideal filling of the melt, while the ear is very important for improving the surface quality of the product and reducing dimensional tolerances.
(3) Injection Temperature: injection temperature must be controlled within the appropriate range, the temperature is too low, the molten material is not plasticized well, affecting the quality of molded parts and increasing processing difficulties; too high temperature, the raw material is easy to decompose.
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If you have a high-volume plastic injection production project to produce, consider injection molding as a process. We have some important suggestions for you to consider.
(1) You need an experienced product designer and injection mold design engineer to optimize the product appearance design and product structure design before plastic mold manufacturing, to prevent the cost of changing the mold later due to the unreasonable design and structure.
(2)Before formally Injection Mold Manufacturing, it is recommended to barrel through CNC Prototyping or 3D Printing Prototype for assembly and functional testing.
(3) Find a company with product design engineers, injection mold design engineers, mold production engineers, injection moulding machine debugging engineers, quality inspection engineers, and have several English fluent salesman to ensure that the project is in terms of technology, quality, and communication can be carried out smoothly.
If you don’t know much about the industry, you can call Zetarmold to provide the whole project service.
With Zetar, you can have your project come true in a matter of days. With more than 20 English speakers and 7 experienced product designers and mold design engineers on hand to support the manufacturing process from idea to reality – let us help turn your dream into a reality!