Welcome to our ultimate buyer&#;s guide for choosing the best plastic injection molding machine! In this comprehensive guide, we&#;ll walk you through the important factors to consider when purchasing a plastic injection molding machine. Whether you&#;re an industry professional or a hobbyist, we&#;ve got you covered with valuable insights and tips.

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Understanding Plastic Injection Molding Machines

Plastic injection molding machines have revolutionized the manufacturing industry, allowing for the efficient production of complex plastic parts. Whether you are new to the world of injection molding or a seasoned professional, having a comprehensive understanding of these machines is crucial. In this blog post, we&#;ll delve into the ins and outs of plastic injection molding machines, exploring their components, operation, and benefits.

How Does The Plastic Injection Molding Machine Work

Plastic injection molding is a manufacturing process that has revolutionized the production of a wide range of plastic products. From toys and automotive parts to medical devices and kitchen appliances, this technology has become an integral part of various industries. But have you ever wondered how a plastic injection molding machine actually works? In this blog post, we&#;ll take a deep dive into the inner workings of these machines and shed light on the intricate process that brings your favorite plastic products to life.

1. The Basics:

A plastic injection molding machine is a complex piece of machinery that enables manufacturers to produce large quantities of plastic parts with high precision and efficiency. It essentially consists of three main components: the injection unit, the clamping unit, and the control system. Let&#;s explore each of these components in detail.

2. The Injection Unit:

At the heart of the plastic injection molding machine is the injection unit. This unit is responsible for melting the plastic pellets and injecting the molten material into a mold cavity. The process starts with the plastic pellets being fed into a hopper, where they are gradually heated and melted. Once the plastic reaches its liquid state, it is injected into the mold through a nozzle, guided by a screw or a plunger mechanism.

3. The Clamping Unit:

While the injection unit takes care of melting and injecting the plastic, the clamping unit holds the mold in place and ensures that it remains closed during the injection process. This unit consists of two platens, the stationary platen and the moving platen, which are operated by hydraulic or mechanical systems. The mold is mounted between these platens, and once the plastic is injected, the clamping unit applies pressure to keep the mold closed until the plastic solidifies.

4. The Control System:

To ensure smooth operation and precise control over the molding process, a plastic injection molding machine is equipped with a sophisticated control system. This system manages various parameters such as temperature, pressure, and injection speed, allowing manufacturers to achieve the desired quality and consistency in the final product. Advanced machines may even feature computer numerical control (CNC) capabilities, enabling automated and programmable operation.

5. The Cooling and Ejection Process:

After the plastic is injected into the mold and solidifies, it undergoes a cooling process to harden and take the shape of the mold cavity. Cooling can be achieved through a variety of methods, such as circulating water or air through the mold. Once the plastic has cooled down, the mold is opened, and the newly formed plastic part is ejected from the machine using ejector pins or other mechanisms.

6. Post-Processing:

While the plastic part may be ready for use after the ejection process, some additional post-processing steps may be required. This can include trimming excess material, adding surface finishes, or even assembling multiple components together. These post-processing steps ensure that the final product meets the desired specifications and is ready for distribution or further assembly.

Different types of plastic injection molding machines

Plastic injection molding has revolutionized the manufacturing industry by allowing for the mass production of plastic products with precision and efficiency. Central to this process are the plastic injection molding machines, which come in various types and configurations. In this blog post, we will explore the different types of plastic injection molding machines and their unique features. There are several types of plastic injection molding machines available in the market, each designed for specific applications. The most common types include:

1. Hydraulic Injection Molding Machines:

Hydraulic injection molding machines are the most common and widely used type of machines in the industry. They utilize hydraulic systems to power the injection process, where plastic material is melted and injected into the mold. These machines are known for their high production output and robustness. They can handle a wide range of materials, including thermoplastics and thermosetting plastics.

2. Electric Injection Molding Machines:

Electric injection molding machines have gained popularity in recent years due to their energy efficiency and precision. Instead of hydraulic systems, they rely on electric motors to drive the plasticizing screw and the hydraulic system. These machines are quieter, cleaner, and more environmentally friendly compared to their hydraulic counterparts. They also offer faster cycle times and better repeatability, making them suitable for high-precision applications.

3. Hybrid Injection Molding Machines:

As the name suggests, hybrid injection molding machines combine the best of both hydraulic and electric machines. They utilize a combination of hydraulic and electric drive systems, offering improved energy efficiency while maintaining the high production output of hydraulic machines. Hybrid machines are known for their versatility and are often used in industries where energy consumption and cost savings are crucial factors.

4. Two-Shot Injection Molding Machines:

Two-shot injection molding machines, also known as dual-shot or multi-shot machines, are designed to produce plastic parts with multiple colors or materials in a single cycle. These machines have two injection units that can inject different materials sequentially or simultaneously. Two-shot molding allows for the creation of complex and aesthetically pleasing products, reducing the need for secondary operations or assembly.

5. Multi-component Injection Molding Machines:

Similar to two-shot machines, multi-component injection molding machines are designed to produce parts with multiple materials or components. These machines have multiple injection units, each capable of injecting a different material. Multi-component molding offers endless possibilities for product design, enabling the creation of parts with varying hardness, texture, color, or material properties.

6. Vertical Injection Molding Machines:

Unlike the horizontal machines mentioned above, vertical injection molding machines have a vertical clamping unit and an injection unit positioned vertically above it. These machines are particularly suitable for over-molding or insert molding applications, where a pre-molded part or insert needs to be encapsulated with plastic. Vertical machines are also preferred for molding parts with complex geometries or when floor space is limited.

Factors to Consider Before Purchasing Plastic Injection Machine

Are you in the market for a plastic injection machine? As the demand for plastic products continues to rise, investing in a reliable and efficient injection machine can be a smart business move. However, with so many options available, it&#;s crucial to consider several factors before making a purchase. In this blog post, we will explore the key factors that you should take into account when buying a plastic injection machine.

1. Machine Type:

There are various types of plastic injection machines available, each designed for different purposes. These include hydraulic, electric, and hybrid machines. Hydraulic machines are known for their high production output and are suitable for large-scale manufacturing. Electric machines, on the other hand, offer energy efficiency and precision, making them ideal for intricate and precise applications. Hybrid machines combine the benefits of both hydraulic and electric machines. Consider your production needs and the type of products you intend to manufacture before selecting the machine type.

2. Machine Size:

The size of the plastic injection machine is another crucial factor to consider. The machine&#;s size will depend on the size and complexity of the products you plan to produce. Small machines are more suitable for producing smaller plastic components, while larger machines are capable of producing larger parts. Assess your production requirements and space availability to determine the appropriate machine size for your business.

3. Production Capacity:

The production capacity of the machine is measured in terms of shot weight and production rate. Shot weight refers to the maximum amount of plastic that the machine can inject into the mold, while the production rate indicates the number of parts the machine can produce in a given time frame. Consider your anticipated production volume and the desired cycle time to select a machine with the right production capacity for your needs.

4. Quality and Reliability:

When investing in a plastic injection machine, it&#;s crucial to prioritize quality and reliability. Look for machines manufactured by reputable brands known for their durability and performance. A reliable machine will ensure consistent production and minimize downtime, ultimately leading to improved productivity and profitability. Consider reading customer reviews and seeking recommendations from industry experts to gauge the quality and reliability of different machine models.

5. Maintenance and Support:

Like any other machinery, plastic injection machines require regular maintenance to ensure optimal performance and longevity. Before purchasing a machine, inquire about the availability of spare parts, technical support, and after-sales service. Choose a supplier or manufacturer that offers comprehensive maintenance and support to avoid unnecessary delays and disruptions in your production process.

6. Cost and Return on Investment (ROI):

Last but not least, consider the cost of the plastic injection machine and the potential return on investment. While it&#;s important to find a machine that fits your budget, it&#;s equally crucial to assess the long-term benefits and ROI it can provide. A reliable and efficient machine may have a higher upfront cost but can lead to significant cost savings in terms of reduced material waste, energy consumption, and increased production efficiency.

 

Researching Injection Molding Machine Manufacturers and Suppliers

Investing in an injection molding machine is a significant decision for any business. The quality and performance of the machine can directly impact the efficiency and productivity of your operations. Therefore, it is essential to conduct comprehensive research to ensure that you choose a machine that meets your specific requirements and industry standards.

Researching injection molding machine manufacturers and suppliers will enable you to gather valuable information about the different options available in the market. You can compare features, specifications, pricing, and customer reviews to make an informed decision. Additionally, thorough research can help you identify manufacturers and suppliers that have a strong reputation for delivering reliable machines and excellent customer service.

A. Reputation and reliability of manufacturers:

When investing in a plastic injection molding machine, it&#;s essential to choose a reputable and reliable manufacturer. Research the manufacturer&#;s reputation in terms of quality, customer support, and after-sales service. Look for injection molding machine manufacturers with a proven track record and positive customer feedback.

B. Quality certifications and standards compliance:

Check if the injection molding machine manufacturer holds relevant quality certifications, such as ISO , which ensures that their manufacturing processes meet international standards. Compliance with industry-specific standards, such as automotive or medical, may also be important depending on your application.

C. Customer reviews and testimonials:

Reading customer reviews and testimonials can provide valuable insights into the performance and reliability of the machine you are considering. Look for reviews from customers who have similar production requirements or industry applications.

D. Comparing prices and warranties:

Compare the prices and warranties offered by different injection molding machine manufacturers. It&#;s important to strike a balance between cost and quality. Consider the long-term value of the machine and the level of support provided by the manufacturer.

E. Request Quotes:

Contact the shortlisted injection molding machine manufacturer and suppliers to request quotes for the injection molding machines that meet your requirements. Compare the pricing, warranties, and after-sales support offered by each company. Be sure to inquire about any additional costs, such as installation, training, and maintenance.

F. Check References:

Ask the manufacturers and suppliers for references of previous customers who have purchased their injection molding machines. Contact these references to gather feedback on the machine&#;s performance, durability, and overall satisfaction with the manufacturer or supplier.

G. Attend Trade Shows and Exhibitions:

Trade shows and exhibitions related to the plastics industry are excellent opportunities to meet face-to-face with injection molding machine manufacturers and suppliers. You can see the machines in action, discuss your requirements in detail, and ask questions directly to the company representatives. Take note of the manufacturers and suppliers that impress you with their machines and knowledge.

H. Consider After-Sales Support:

Injection molding machines require regular maintenance and occasional repairs. Therefore, it is essential to choose a manufacturer or supplier that offers reliable after-sales support. Inquire about their technical support, availability of spare parts, and warranty terms. A reputable injection molding machine manufacturers will provide comprehensive support to ensure that your machine operates optimally throughout its lifespan.

Evaluating Plastic Injection Machine Specifications and Features

In the world of plastic manufacturing, having the right equipment is crucial for achieving high-quality results and efficient production processes. One of the key machines used in this industry is the plastic injection machine. These machines play a vital role in creating a wide range of plastic products, from simple everyday items to complex components.

When it comes to selecting a plastic injection machine, there are several important factors to consider. Among them, specifications and features take center stage. In this blog post, we will dive deep into the evaluation of plastic injection machine specifications and features to help you make an informed decision.

1. Clamping Force:

One of the most critical specifications to consider is the clamping force of the machine. This refers to the amount of pressure the machine can exert to keep the mold closed during the injection process. The clamping force should be chosen based on the size and complexity of the product you intend to manufacture. Too little force can result in mold opening and misalignment, while too much force may lead to deformation or damage to the mold.

2. Injection Capacity:

The injection capacity of a plastic injection machine determines the maximum volume of molten plastic it can inject into the mold. It is crucial to choose a machine with an injection capacity that matches your production needs. A machine with a higher injection capacity may be necessary for larger and more complex products, while a lower capacity machine may be sufficient for smaller components.

3. Injection Speed:

It plays a significant role in determining the quality of the final product, as different materials require different injection speeds for optimal results. A machine with adjustable injection speed can offer greater flexibility in accommodating various types of plastics.

4. Screw Diameter and L/D Ratio:

The screw diameter and L/D (length-to-diameter) ratio of the injection machine&#;s screw are crucial specifications that impact the plasticizing process. The screw diameter determines the amount of material that can be processed, while the L/D ratio affects the plasticizing efficiency and homogeneity. Choosing the right combination of screw diameter and L/D ratio is essential for achieving consistent and high-quality plasticization.

5. Control System and User Interface:

A modern plastic injection machine should have a user-friendly control system and interface. This allows operators to monitor and adjust various parameters easily, ensuring precise control over the injection process. A well-designed control system can enhance productivity, reduce setup time, and minimize the risk of errors.

6. Safety Features:

Safety should always be a top priority in any manufacturing environment. Look for machines with safety features such as emergency stop buttons, guards, and interlocks. These features help prevent accidents and protect operators from potential hazards.

7. Energy Efficiency:

As sustainability becomes a growing concern, opting for an energy-efficient plastic injection machine can lead to significant cost savings in the long run. Look for machines with energy-saving features such as servo motors and variable frequency drives, which can reduce power consumption without compromising performance.

8. After-Sales Support:

Lastly, consider the reputation and after-sales support of the machine manufacturer. A reliable manufacturer will provide technical assistance, spare parts availability, and regular maintenance services to ensure the smooth operation of your plastic injection machine.

Evaluating the specifications and features of a plastic injection machine is crucial for selecting the right equipment for your manufacturing needs. Consider factors such as clamping force, injection capacity, speed, screw diameter, control system, safety features, energy efficiency, and after-sales support. By carefully assessing these aspects, you can make an informed decision and invest in a machine that will deliver high-quality results, enhance productivity, and contribute to the success of your plastic manufacturing business.

Conclusion:

With our friendly guide, you&#;re now equipped with the knowledge needed to choose the best plastic injection molding machine for your needs. Remember to carefully assess your production requirements, research manufacturers, evaluate specifications/features, and consider support and budgeting factors. Investing in the right machine will help you achieve high-quality results and enhance your overall productivity in plastic injection molding.

How to Choose the Right Injection Mold Machine 

introduction

Injection molding is a widely-used manufacturing process in the plastics industry. To ensure optimal production efficiency, product quality, and cost efficiency when selecting a plastic injection molding machine, we will cover key factors to consider when making this choice. Furthermore, we&#;ll answer common questions such as &#;How do I know what size injection molding machine I need?&#; or &#;What are the three basic types of injection molding machines?&#; with keywords like &#;injection molding machine,&#; &#;plastic injection molding,&#; and more to get you on your way.

What to Consider When Selecting an Injection Mold Machine

A. Dimension of the Machine

The size of plastic injection molding machine plays a significant role in determining production efficiency and product quality. Here are some factors to take into account when deciding on the ideal machine size:

Product Requirements: The size, weight, and complexity of a product dictate its optimal machine size. Generally speaking, larger items require larger machines.

Mold Size: The size of a mold used for injection molding determines the machine required. Larger molds necessitate larger machines.

Shot Size: The amount of plastic material required for each shot of injection molding determines the machine size. Larger shots necessitate larger machines.

Clamping Force: The clamping force required to hold a mold closed during injection molding determines its size. A stronger clamping unit requires larger machines.

To calculate the required machine tonnage and injection volume, consider the following:

Tonnage: Calculate the tonnage required by multiplying the projected area of the part being molded by the pressure required to inject the plastic material into the mold. This calculation determines the force needed to hold the mold closed during the injection.

Injection volume: Calculate the injection volume by multiplying the part volume by a factor of 1.5 to account for material shrinkage during the molding process.

Overall, choosing the right machine size is critical to ensure efficient and effective injection molding production

B. Type of Injection Molding Machine

1. An overview of various injection molding machine available on the market today

Injection molding machines come in three basic varieties: hydraulic, electric, and hybrid. Each has its advantages and drawbacks; ultimately, which type best meets your production requirements depends on what works best for you.

Hydraulic injection molding machine are the oldest and most widely used type of machine. Their high clamping force makes them perfect for producing large parts, though they use more energy and have slower injection speeds compared to electric machines.

Electric injection molding machines have become more and more popular due to their energy efficiency and faster injection speeds. Furthermore, these machines provide precise control of the injection process which ultimately results in higher product quality. On the downside, electric machines have lower clamping forces compared to hydraulic ones, making them better suited for smaller parts.

Hybrid injection molding machine bring together the benefits of both hydraulic and electric machines, offering faster injection speeds with greater energy efficiency compared to hydraulic machines while having greater clamping force compared to electric ones. Unfortunately, they tend to be pricier than either type of machine.

When selecting the type of machine to use, take into account factors like production efficiency, energy consumption, and product quality. Electric machines may be cost-effective in the long run due to their lower energy usage but may not be suitable for large parts requiring high clamping force. Ultimately, selecting the correct type of machine depends on your specific production needs.

C. Injection Molding Process Parameters

When selecting an injection mold machine, parameters like injection pressure, speed, and screw diameter When selecting an injection mold machine, parameters like injection pressure, speed, and clamp tonnage must be taken into account. Here are a few things to keep in mind when making your selection: clamp tonnage must be taken into account. Here are a few things to keep in mind when making your selection:

Injection Pressure: This refers to the force required to inject melted plastic into a mold cavity. It depends on both the viscosity of the plastic material and the size and shape of the cavity. Higher injection pressure may lead to better product quality but also increases defects.

Injection Speed: This refers to the rate at which plastic material is injected into a mold cavity. It depends on the size of the injection unit and desired filling time. A higher injection speed can result in improved production efficiency, but may also increase defects.

Clamp Tonnage: Clamp tonnage refers to the force necessary to hold a mold closed during injection molding. It depends on the size and shape of the mold as well as the material being used. Adequate clamp tonnage is essential for maintaining consistent product quality by avoiding defects.  

When setting parameter values for your product, take into account both technical specifications and raw materials used. For instance, certain plastic materials may need higher injection pressure to achieve the desired quality.

Maintaining accurate parameter values throughout the production process is essential for achieving optimal product quality and production efficiency. Regular upkeep and monitoring can help prevent deviations in parameter values, thus minimizing the risk of defects.

D. Other Factors to Consider

Physical fit and technical requirements of the machine

The injection machine should be physically suitable for the workspace and production needs

Technical requirements should be considered, such as compatibility with the plastic material being used

Power consumption and energy efficiency

Electric injection molding machine generally have lower power consumption than hydraulic machines

Hybrid machines offer a balance between energy consumption and performance

Availability of parts and technical support

Choose the right injection molding machine manufacturer that offers reliable technical support

Availability of parts and maintenance services should also be considered.

Production cost and return on investment

Consider the production cost and potential return on investment when choosing an injection molding machine

The right machine can lead to increased production efficiency and cost savings in the long run.

Conclusion

Selecting the ideal injection mold machine is critical for the success of plastic injection molding. By taking into account factors like machine size, type, process parameters, and other important details, manufacturers can guarantee optimal production efficiency and high-quality finished products. When selecting a machine it must meet both product-specific needs as well as plastics industry requirements while considering factors like power consumption, parts availability, and production cost. Doing this allows manufacturers to achieve the balance between performance and cost efficiency which then leads to more profitable operations overall.

Plastic Injection Molding Machine Selection. Get It Right!

Plastic Injection Molding Machine Selection &#; Why It Is Important

Selecting the right plastic injection molding machine is one of the most important criteria in making quality parts consistently and profitably. The right machine will help keep costs low and make you more competitive. This will allow you to sell more parts, earn more money and at the same time establish a reputation as a quality manufacturer.

Even better, you will have the security of long term customers.

How To Keep Your Costs Low:

Minimize reject rate (set a target <1%) Click here to read about how to eliminate warpage quality issues.

Reduce energy consumption of all injection molding machines

Have faster cycle times

Eliminate unscheduled machine downtime &#;(no breakdowns)

A properly selected plastic injection molding machine will give you all of the above.

Common Machine Selection Mistakes And Their Consequences

The best way to appreciate the importance of correct plastic injection molding machine selection is to list the most common mistakes made when selecting machines and the effect on part quality and productivity.

Mistake #1
Buying Used Injection Molding Machines That Don't Work

The key to buying a reliable used machine is to find one that has been fully inspected and tested before delivery so that you won&#;t suffer loss of production due to multiple breakdowns.

Click here to see a case study of how incorrect machine selection can effect part quality Example #2).(opens in a new window)

Mistake #2
Selecting Large Screw Diameters.

Large screw diameters can cause quality problems due to material degradation. When small shot sizes are used with large screw diameters, the plastic material spends more time being heated by the barrel heaters compared to large shot sizes. Material degradation is more likely to occur if the shot size is small compared to the injections units maximum shot capacity especially for heat sensitive materials.

Another problem with large screw diameters are the large shearing forces generated during screw rotation, this can also degrade the material and is likely to lead to reject parts.

Mistake #3
General Purpose Screws

The advantage of a general purpose screw is that they can be used with most plastic materials such as PP, PE, Nylon, PET and PC so they are very flexible and good for moulding companies that mould a variety of different materials.

The disadvantage is that, for some materials, part quality and productivity rates will be lower compared to more advanced injection molding screw designs such as the barrier screw. Click here to learn more about screw selection.

Mistake #4
Injection Pressure Limited.

To consistently make quality parts the molding process must not be limited by the injection pressure. It is advisable to have at least 10% injection pressure in reserve so that the injection molding machine can automatically adjust to normal variation in the plastic material viscosity.

Insufficient injection pressure will produce short moldings.

The injection units screw diameter governs the available maximum injection pressure so it is critical to choose the correct diameter when buying a plastic injection molding machine.

Mistake #5
Inadequate Clamp Tonnage

If clamp tonnage is too low then it will be difficult to produce quality parts. Low clamp tonnage means inconsistent weights, flash, short shots, wall section variation, poor surface finish and size variation.

Machine and mold wear will be excessive.

Mistake #6
High Energy Consumption

Have you ever noticed how there is almost no difference in your cars fuel consumption with 2 people in it compared to just 1 person? A moulding machine is the same. A small mold will require almost as much energy to open and close the platen compared with a medium size mold. A properly selected plastic injection molding machine will use power very efficiently.Click here to learn about how to reduce your energy bill on your existing machinery by changing parameters in the plastic injection molding process.

The type of machine design also plays a significant role in power consumption. There are 3 types of machine designs: fully hydraulic, fully electric and hybrid machines. Hybrid machines are partly electric and partly hydraulically operated. Selection largely depends upon the type and quantity of parts to be molded.

Plastic Injection Molding Machine Selection Process

1. Know the plastic parts you intend to mold
2. Select machine type: Hydraulic, hybrid or electric
3. Calculate clamp tonnage requirements
4. Calculate the injection unit size.

1.Know The Plastic Parts You Intend To Mold

The process of selecting the right machine starts with knowing the particular plastic parts that will be moulded by the machine. Molding parts that are not suited to the machine will result in frustration with on-going quality problems, slow cycle times and machine and mold damage.

If you are planning to buy Cap or Closure Molds then click here to get a quick mold quote from a reputable mold maker. (Opens in a new window)

You should know the part:

Plastic material

Weight

Length x width x height

Average wall section

Gate location

Maximum flow length from the gate

Estimated cycle time. Click here to estimate cycle time.

Quality requirements

Annual quantity requirements. Click here to get to the production calculators used for scheduling.

In addition you should also know the mould size and weight.The correct part information will then allow you to find the injection unit size, clamp tonnage requirements and machine type.

2.Select Machine Type

Types of plastic injection molding machine designs available:

Fully Hydraulic

Fully Electric

Hybrid - combination of hydraulic and electric drive

Fully Hydraulic Machines

The types of hydraulic machines available are defined by the type of clamp design, type of hydraulic pump design and the presence or absence of an accumulator.

Clamp design is either a toggle clamp or by hydraulic ram.

Hydraulic pump design can be a constant displacement pump (also called fixed displacement pump), a variable displacement pump (also called a piston pump) or a servo pump (also called frequency control or RPM control) .

If an accumulator is present then some machine manufacturers use it to drive the entire machine, while others use it for the injection stage only. Accumulators are required for molding of parts which have wall thicknesses in the range of 0.3mm to 0.8mm &#; this is known as thin wall molding.

Accumulators might also be required for moulding thicker parts but this must be checked on a case by case basis.

Which one is suitable for you?

It depends on your priorities.

Here are some criteria to consider before selecting a hydraulic moulding machine:

Buy a new or used machine

Purchase price

Energy efficiency

Plastic material to be processed

Part design

Mould design

Clean room requirement

Cycle time requirement

Hold time requirement

Local service agent capability

If low power consumption is a priority then choose a hydraulic machine with a servo pump as this is the most energy efficient of the fully hydraulic machines. A servo pump will only operate when the machine requires movement, the rest of the time it is using minimal power. However, the purchase price is 10%-15% higher than a hydraulic machine with a constant displacement pump or even a variable displacement pump.

Keep in mind a servo pump control will only save you power if you have long cooling times or machine inactive times such as long take out time for robot.

Fully Electric Plastic Injection Molding Machines

Every movement of the machine is done with direct drive electric servo motors only drawing power when movement is required so they are very energy efficient. Electric machines have excellent repeatability which virtually guarantees consistent part quality.  This makes them suitable for molding medical devices. Click here to learn more about medical injection molding.

Electric machines are suited to clean room operations because there is no hydraulic oil that can leak on to the floor. Click here to learn more about electric molding machines.

Hybrid Plastic Injection Molding Machines

A hybrid plastic injection molding machine uses a combination of hydraulic drive and electric direct drive. The hydraulic drive is used to generate fast injection speeds when moulding thin wall parts. The rest of the machine uses electric drive servo motors and each axis of the machine has its own dedicated motor. For example, the mould opening/closing stroke has its own motor.

These injection molding machines are very energy efficient

3.Calculate Clamp Tonnage Requirements

Clamp tonnage requirements for your plastic injection molding machine can be calculated by:

In order to find the tonnage using the simple calculation the following part information is required:

Plastic material

Length x width x height

Projected area (length X width)

Average wall section

Gate position

Maximum flow length from the gate

Number of cavities in the mold

The average cavity pressure is also required and this information is available in some plastic injection molding machine manufacturers hand book for certain materials.

Most injection molded parts average cavity pressures lie in the range of 300-800 bar. Parts with long flow paths and thin walls will have pressures in the upper range while parts with short flow lengths and thicker wall sections will have much lower pressures.

Plastic material selection also influences the cavity pressure.

In addition, you need to know the mold weight and size so that you can check that the mold will physically fit into the machine and that the machine can carry the mould weight. Click here to learn about our mold design services.

4.Calculate The Injection Unit Size

To select the right unit for your plastic injection molding machine you must know part:

Plastic material

Cycle time

Cooling time

Shot weight (part weight, cold runner weight and number of cavities)

Peak injection pressure requirement

Plasticizing rate

Injection rate

Hold time and pressure

For a specific tonnage machine, manufacturers usually offer 2 injection units to choose from. Both units usually have 3 different screw and barrel assemblies on offer. In order to select the correct assembly, the shot size must be calculated as a percentage of the injection capacity and must lie between 25% and 65% so that good quality parts can be made.

Most screw and barrel assemblies are rated in grams of general purpose polystyrene (GPPS). To calculate the shot capacity for materials other than for GPPS the melt density needs to be known.

Lets assume we have a screw and barrel assembly with a screw diameter of 56mm and the capacity is 510 grams of GPPS. What is the injection capacity for polypropylene (PP)?

 

 Assume melt density of GPPS = 0.945 grams per cubic centremeter

 and melt density of Polypropylene  = 0.74 grams per cubic centremeter

 

(Be sure to use melt density & not room temperature density for this calculation)

 

Calculation to find injection capacity for PP:

(Density of PP/Density of GPPS)xBarrel capacity of GPPS grams

 =(0.74/0.945)x510 grams=399 grams PP

So maximum injection capacity of PP for this 56mm screw diameter is 399 grams.

Next we need to make sure the shot size is within the maximum and minimum limits of between 25% and 65%.

If the shot size for the injection mould is 110 grams (includes cold runner) then the shot size as a proportion of the total injection capacity is:

 =(110/399)x100= 28%

which is within limits.

Click here to get to the Injection Capacity Calculator (opens in a new page).

Contact us to discuss your requirements of china plug injection molding machine. Our experienced sales team can help you identify the options that best suit your needs.

Additional reading:
An In-Depth Guide to Purchasing Rubber Particles for Industrial Use

 

Next, the following 3 criteria must be confirmed to be within limits of the injection unit with the 56mm diameter screw. 

Injection pressure

Plasticizing rate

Injection rate

These can be found in one of 2 ways:

The first is by experience - perhaps you have a similar part in production in which case you can read the pressure directly off the screen. Be sure to check the screw diameter is the same.

The second is by computer simulation but keep in mind the results are only as good as the information that is entered. It is advisable to check these results against some real life examples.

Just remember, the screw diameter selected is crucial to long term part quality and productivity.

 

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How to select a Plastic Injection Molding Machine

 

 

Buying an injection molding machine is not a small investment. Buying a machine that is too large is a waste of money, while a machine that is too small is not suitable. Therefore, choosing the right machine for the product is the most important thing for the buyer. The supplier recommends the right machine and suggests how to choose the machine is the first lesson the supplier provides to the buyer.

In order to understand the various steps of selecting an injection molding machine more systematically, the following content and detailed instructions are for this purpose.

 

Nowadays, there are too many injection molding machines on the market. It is only considered that the injection machine is too simple and the clamping force is not comprehensive. It is necessary to combine the two to make a choice.

Injection weight is an important parameter of an injection molding machine, and it is the most useful and critical parameter for selecting an injection molding machine. Expressed in gram or ounze, although this parameter is simple and easy to understand, it can also be easily misunderstood. the reason is simple. When the plastic material is determined, the weight of the plastic part can be determined. Therefore, it is easy for them to use the injection weight to select an injection molding machine. In fact, the definition of injection weight refers to the maximum plastic injection weight that the injection device can reach when the screw performs the maximum injection stroke under the screw. Air shot state (not injected into the mold); this parameter reflects the processing capacity of the injection molding machine to a certain extent; it can be measured or calculated theoretically (theoretical value and measured value may be different). The material used in the test is usually ordinary PS with a density of 1.05.

 

 

Steps to determine the injection weight

 

 

Calculate the product weight first: W = product weight + gate system weight, where: W is the weight required for injection. In actual situations, there are two situations to consider.

 

 

When the injection molded product is polystyrene (PS), the injection volume of the injection molding machine should be Wps; Wps = (1.3 ~ 1.1) × W (product weight + total gate system weight), when the product requirements are high, The coefficient in the above formula should take a large value, otherwise, it can take a small value.

 

 

When the product is the imitation method of other plastics (named X plastic), first calculate the theoretical injection volume of the plastic should have Wx; Wx = (1.3 ~ 1.1) × (product weight + total weight of the gate system); then according to the plastic The density (X) is converted into the actual weight of the PS material Wps, the conversion formula is: Wps=Wx×1.05/Vx

 

 

According to the calculation results of the Wps and LOG manuals, select the appropriate injection molding machine.

 

Remarks: The relationship between injection weight and injection volume

 

The injection weight is more than just the injection volume multiplied by the density of PS. Measure the injection weight, and the injection volume is a theoretical value. Because the plastic material will flow into the gap between the barrel and the screw during injection, and the non-return ring needs to move backwards to reach the closed position, the injection volume is doubled because the density of PS is greater than the injection weight.

 

 

Products with low requirements, such as toy dolls: the total weight should be 85% of the injection weight; in high-demand injection molding; such as crystal products, 75%.

 

 

Do not use an injection molding machine with an excessive injection weight

 

The total weight of plastic and runner plastic should be between 35% and 85% of the injected weight. The lower limit is due to the following three considerations: the bending of the plate; the residence time of the plastic in the barrel and the power consumption per kilogram of injection molded parts. The use of small molds for small injection molded parts will cause excessive bending of the pressure plate, resulting in warping (affecting product quality), and even cracking of the pressure plate. Use an oversized injection molding machine to inject small plastic parts. If the residence time of the molten material is too long, it may cause the melted plastic in the barrel to decompose.

 

Injection speed

 

For ultra-thin-walled products, high fluidity materials are used to make the molten plastic flow at an ultra-high speed to ensure that the thickness l of the surface layer formed by cooling and solidification after the molten material contacts the mold wall is as thin as possible, which is to delay the generation time of the solidified skin as much as possible. So it involves the issue of injection speed. In terms of experience, the injection speed can be 1 to 1.5 times the flow length ratio.

 

There are two important factors to calculate the clamping force: 1. Projection area; 2. Cavity pressure.

 

Projected area (S) is the largest area seen from the line of sight of mold opening and closing.

 

 

Cavity pressure determination (P)

 

 

The cavity pressure is affected by the following factors

 

 

Number and location of doors

 

 

Door size

 

 

Product thickness

 

 

Viscosity characteristics of materials used

 

 

Injection speed

 

 

 

2.1 Grouping of thermoplastic flow characteristics

 

 

Group 1 PS PE PP

 

 

Group 2 PA6 PBT PET

 

 

Group 3 PU soft PVC

 

 

Group 4 ABS as POM

 

 

Group 5 PMMA PC/ABS PC/PBT

 

 

Group 6 PC PEEK rigid UPVC

 

 

 

2.2 Viscosity grade

 

Each group of plastics mentioned above has a viscosity (flowability) grade. The relative viscosity grades of each group of plastics are as follows

Group Multiplication Constant (K)

The first group ×1.0

The second group ×1.3&#;1.35

The third group ×1.35&#;1.45

The fourth group ×1.45&#;1.55

The fifth group ×1.55&#;1.70

The sixth group ×1.70&#;1.90

 

 

2.3 The cavity pressure is determined by the wall thickness, and the ratio of the flow rate to the wall thickness

 

P=P0&#;K (multiplication constant)

 

 

2.4 Determination of clamping force (F)

 

F=P&#;S=P0&#;K&#;S

 

There are many different types of injection molding machines, and choosing the right type can bring greater benefits to your business.

 

 

Hydraulic injection molding machine

 

Hydraulic presses have historically been the only option available to molders until Nissei Plastic Industrial Co., LTD introduced the first all-electric injection molding machine in .

Hydraulic machines, although not nearly as precise, are the predominant type in most of the world, with the exception of Japan.

 

 

Electric injection molding machine

 

The electric press, also known as Electric Machine Technology (EMT), reduces operation costs by cutting energy consumption and also addresses some of the environmental concerns surrounding the hydraulic press. Electric presses have been shown to be quieter, faster, and have a higher accuracy, however the machines are more expensive.

Read this article to learn more: Electric VS Hydraulic Injection Molding Machine

 

 

Hybrid injection molding machines

 

Hybrid injection (sometimes referred to as &#;Servo-Hydraulic&#;) molding machines claim to take advantage of the best features of both hydraulic and electric systems, but in actuality use almost the same amount of electricity to operate as an electric injection molding machine depending on the manufacturer.

 

You can cooperate with a large number of injection molding machine manufacturers in the market.

But, have you ever tried to choose a Chinese injection molding machine supplier? You may be influenced by what others say, but injection molding machines from China are actually the best, most reliable, and most trustworthy.

 

 

 

Give you two reasons to choose a Chinese manufacturer

 

 

China has the most complete industrial chain in the world. The industry has developed rapidly for decades and has already reached a world-class level.

 

 

China has a huge cost advantage, which is not only reflected in labor costs. At the same time, China has a large number of talents, a complete supply chain and excellent production technology, which brings huge cost advantages to Chinese manufacturing.

 

Besides you can get it with them at the best and most competitive price, you can also establish relationships with other suppliers in the future.

 

 

 

How to find a Chinese injection molding machine manufacturer

 

It is very important to find a suitable and excellent injection molding machine manufacturer. It affects your business development, including your cost, production efficiency and product quality.

To find a injection molding machines manufacturer in China, you can use the following methods:

 

B2B platform

 

 

Alibaba

 

China's largest foreign trade export website, where you can choose injection molding machines suppliers and manufacturers in different regions.

 

Made in China

 

Made-in-China.com specializes in the promotion of Chinese products and only accepts Chinese suppliers to release relevant product information. It is currently the only large-scale B2B platform whose sole mission is to promote Chinese products.

 

Global Sources

 

Focus on foreign trade of domestic small and medium-sized enterprises, and provide professional services for foreign buyers.

 

Google

 

Generally, the brand manufacturer websites that you can search through Google are quite professional. And they respond more quickly and professionally than B2B platforms.

 

 

 

How to choose the right Chinese injection molding machine manufacturer

 

In order to be able to choose a suitable injection molding machine manufacturer, you can refer to the following points:

 

Check reviews and customer feedback

 

One way to determine whether a supplier of injection molding machines is reliable is to check what their previous customers have said about them. Most (if not all) injection molding machine suppliers will post customer feedback on their website.

 

Check the "About Us" section

 

It is very important to check their website and navigate to the "About Us" section they have. If you think they are good at doing what they do best, don't hesitate to call them. On the other hand, if you can&#;t find what you need, try to contact them and start a conversation.( About Us)

 

Contact the manufacturer of the injection molding machine

 

Unless you contact them, you actually don't know anything about the supplier.

By sending them an or call, you can determine how they will conduct their business. You can check and evaluate their urgency by paying attention to their response speed to messages and inquiries; you can feel the feeling of working with them.

By performing these three things, you can reduce the time for inspection and everything, and reduce many detours.

 

 

 

 

Write at the end

 

 

Purchasing an injection molding machine is a big investment, and choosing the right injection molding machine is very important. Through the above steps, you can get the specifications of the injection molding machine you need and the injection molding machine manufacturer suitable for you. Each manufacturer will provide a different solution. Please carefully ask the injection molding machine supplier for all details to ensure that you get the product you want. Please select the most suitable manufacturer after horizontal comparison. Hope this guide is helpful to you.

Finally, we recommend Log-Machine, China's top injection molding machine manufacturer. We provide high-quality injection molding machines and low prices. The log machine will be your ideal partner. Click here to learn more.

Contact us for more information.

 

 

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