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What are the 2 types of Extrusion Blow Moulding Machines?

August 15, 2021

Blow moulding is a manufacturing process used for the production of plastic bottles, containers, and custom shapes. At Central Machinery and Plastic Products, we use extrusion blow moulding (EBM). EBM bottles are easily identifiable by their pinch line across the base of the bottle. This line is created as the mould cavity closes on the parison and the tail is trimmed off.

The extrusion blow moulding process can be broken down into two subcategories: Continuous extrusion blow moulding and Accumulator (Intermittent) extrusion blow moulding.

In continuous blow moulding, the plastic is extruded constantly while the machine runs. With accumulator extrusion blow moulding, the extruder runs for a designated amount of time and fills a reservoir with plastic; after the reservoir has been filled, a ram is activated and pushes the material from the reservoir through the extrusion head.

An EBM machine can be used to manufacture a wide variety of bottles, containers, and shapes commonly used to make products we use in daily life such as oil bottles, peroxide bottles, shampoo, and personal care items among many others. Accumulator EBM machines are often used to make large parts or products that require thick walls, such as Gallon, Water coolers and gasoline containers/drums.

1. What are the Features and applicability of continuous extrusion blow moulding?

  • The parison is continuously extruded throughout the cycle.
  • It can only be used with materials that have good melt strength.
  • It also can only be used for short cycle times.

The moulding equipment for continuous extrusion blow moulding is simple, requires little investment, and is easy to operate. It is a moulding method commonly used by domestic small and medium-sized enterprises.

Continuous extrusion blow moulding can be achieved with a variety of equipment and operation methods. It includes the extrusion of one or more parisons; the use of more than two moulds; the use of more than one mould clamping device; the use of reciprocating, flat turntable, vertical turntable type clamping devices, etc.

Continuous extrusion blow moulding is suitable for medium-capacity containers or hollow products, large-volume small containers, PVC, and other heat-sensitive plastic bottles and hollow products.

Medium-capacity containers or hollow products require larger extrusion embryos. The extrusion time of its embryo is also longer, beneficial to the extrusion of the embryo and the inflation of the embryo. Cooling and product de-moulding are carried out simultaneously, and completed at the same time, to achieve continuous extrusion blow moulding. CMP’s moulding method can continuously blow moulds of 50ml to 10L containers.

Large batches of small containers, such as bottle containers, because of the small amount of parison, the time required to extrude the parison is small. Usually, the extrusion of the parison and the inflation moulding of the parison cannot be completed at the same time. However, when mass production of small containers, the use of two or more moulds and mould clamping devices can relatively delay the moulding cycle of blow-moulded containers to achieve continuous extrusion blow moulding.

For hollow products such as PVC and other heat-sensitive plastics, due to the continuous extrusion of the embryo, the residence time of the material in the extrusion process is short and it is not easy to degrade, so the blow moulding of PVC and other plastics can be carried out in a long-term and stable manner. This moulding method is also suitable for blow moulding of LDPE, HDPE, PP, and other plastics.

2. What are the Characteristics and applicability of Accumulator extrusion blow moulding?

  • The plastic material that is extruded is stored in an accumulator.
  • When the mould opens, the accumulator pushes the material out of the die to form a parison.
  • It is used for parts with long cycles and materials with a low melt strength

With the accumulator method, an accumulator gathers melted plastic and when the previous mould has cooled and enough plastic has accumulated, a rod pushes the melted plastic and forms the parison. In this case, the screw may turn continuously or intermittently. With continuous extrusion, the weight of the parison drags the parison and makes calibrating the wall thickness difficult. The accumulator head or reciprocating screw methods use hydraulic systems to push the parison out quickly by reducing the effect of the weight and allowing precise control over the wall thickness by adjusting the die gap with a parison programming device.

Accumulator extrusion blow moulding can be divided into three ways. That is:

  1. Accumulator extrusion of intermittent operation of the extruder, separation of storage device and head.
  2. Accumulator extrusion blow moulding with blow moulding, storage device, and machine head integrated.
  3. The accumulator operation of the extruder and the intermittent forming of the parisons have low production efficiency.

The accumulator extrusion blow moulding method in which the storage device is integrated with the machine head is widely used. It includes an accumulator extrusion blow moulding of a right angle head with a storage cylinder and a right angle head of a storage cylinder with a program control device.

In this way, the storage cavity is set in the machine head, that is, the storage cavity is integrated with the flow path of the machine head, and the parison can be quickly formed by moving the annular piston downward to press out the melt. The storage cavity volume of this machine head can reach more than 250L, and it can blow moulding large products. Multiple extruders can be used to feed the machine head intermittently.

To know more about our Accumulator series, please visit our product page.

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Mold Support & Venting

On the outside, blow molds are provided with support surfaces to prevent damage to the cutting edges, especially in set-up mode, i.e. when closing the mold without plastic. The mold support also serves to transfer excess clamping force.

DESIGN GUIDELINES FOR BLOW MOULDING MOULD

Guide pins and guide bushings from common standard parts suppliers are usually used as blow mold guides. The guide length should not exceed 1 * D. This is particularly important for mold movement machines to avoid damaging the parallel guidance of the clamping unit and the blow mold guide. The bore for the bushing must be drilled towards the rear of the mold or be cleared laterally to be able to easily remove pressed in material and ensure a clean closing of the blow mold.

HOW TO SELECT TOOLING IN BLOW MOULDING MACHINE :

With a basic understanding of the differences in the types of head tooling
available, we can now look at calculations that will help make our tooling
choices. It is important to keep these points in mind:
Parison diameter is dependent on head tool size, resin characteristics,
regrind content, temperature, and punch-out speed.
Head tooling diameter is determined by part shape and size.

ROLE OF AIR IN BLOW MOULDING

In a blow molding machine, air has multiple purposes: pre-blow and inflation air expands the parison until it contacts the mold wall to reproduce the shape of the blow mold. The inflation air presses the material against the mold wall to reproduce surface details such as lettering, surface textures, etc. Furthermore, the inflation pressure promotes good and permanent contact between the mold wall and the polymer, since the polymer starts to shrink during the cooling period. In addition to these functions required directly with the actual blow molding process, air is required for pneumatically activated functions in the machine, such as the insertion of a blow needle to move molded parts (core pulls) or doors in the machine’s safety guard.

PLC in EBM 

Until the late 1970s to early 1980s blow molding machines were primarily delivered with contractor control. This type of control offered the advantage that the electrical components could be checked by appropriately trained maintenance personnel and easily replaced in the event of a fault. Changes in the machine control system could be made with the help of simple auxiliary devices. However, the disadvantages were the susceptibility to faults and short service life due to wear of mechanically moving parts, the large number of components (up to 150 contactors, 12 temperature controllers, etc.), the size of the components, and how these elements were connected. This type of control was called “hard-wired programmed logic controller”.

CLAMPING UNITS IN EXTRUSION BLOW MOULDING

In all extrusion blow molding processes, a blow mold consisting of two halves closes around the parison once it has reached its full length. These two halves of the mold are mounted on the so-called mold mounting platens, which from part of the clamping unit (or closing unit).

RADIAL WALL THICKNESS DISTRIBUTION IN BLOW MOULDING

In blow moulding, the wall thickness distribution of the finished article is essentially determined by the wall thickness distribution of the parison, its position in relation to the blow mould cavities, and the local stretching paths.

SWELLING BEHAVIOUR OF THE PARISON

The visco – elastic behavior of the thermoplastics (here the memory effects) in conjunction with the flow channel geometry in the head causes the diameter of the parison to change after leaving the die. The wall thickness also changes and thus the length of the parison. This phenomenon is called ‘; die swell’’.

MANDREL HEADS IN EBM

In mandrel heads (also referred to as ‘’heart – shaped – curve heads’’, or cardio did heads) the solid core part is massively integrated into the basic structure of the head. These heads are also called side-fed heads.

SPIDER HEADS IN EBM

The main task of parison heads (blow heads or even just heads) is to divert the compact melt flow as supplied by the extruder into a vertical downwards flow movement and to form melt tube with a uniform circumferential wall thickness distribution.

EXTRUDER WITH GROOVED FEED ZONE

Blow moulding machines with grooved barrel extruders are universal machines for all types of polyolefin; the grooved barrel system is,however, indispensable for high molecular weight, high viscosity raw materials. In these extruders, the cylinder wall in the feed section features tapered longitudinal grooves.

SMOOTH BORE EXTRUDER

Blow molding machines with smooth – bore extruders are more or less limited to the processing of low to medium molecular weight polyolefin types. Smooth bore extruders are less expensive than those with a grooved feed zone and show less screw wear.

Is a Blow Molding Machine Used to Make Anything Other than Plastic Bottles?

For manufacturing plastic bottles, experts rely on a state-of-the-art blow molding machine. With this particular process, a manufacturer produces a broad range of finished products in varying sizes and shapes. Because of that, multiple industries depend on a professional company to make a specific type of plastic bottle needed.

What Are the Future Trends of Plastic Molding Machines?

Although the plastic molding industry took a hit this year due to the instability within the automotive industry, it’s still on target for breaking records. After all, the plastic molding machine is something that a broad range of industries rely on for both internal operations and the making of consumer goods. As demand increases, you can expect to see some exciting changes for plastic molding machines.

Can Extrusion Blow Molding Produce Complicated Shapes

When it comes to extrusion blow molding capability, most people think of standard plastic bottles, tight-head containers, jars, and larger water containers. However, the extrusion blow molding process can do much more. In fact, when using a technologically advanced extrusion blow molding machine, it can produce finished products with complicated shapes, and in varying sizes.

Rotational Molding: Advantages and Disadvantages

Rotational moulding offers a number of benefits, but it’s not the best production process for every part. So how do you decide if it’s a fit for you? Understanding the advantages and disadvantages of the process is the first step toward making a decision with confidence.

HOW TO START A TOY-MAKING BUSINESS WITH EBM IN INDIA?

Before starting the toys making business, it is important to do market research. It is important to collect as much information as possible about this business so that you get the knowledge of exactly what kind of toys are in demand in the market.

WHY INDIAN GOVT. ENCOURAGES TOY MAKING BUSINESSES MAKING BUSINESS

Indian government motivates and urges the Indian startups in the toy sector to maximize manufacturing and increase the reach of Indian made toys to the world. After holding a meeting with senior officials and ministers, the Prime Minister make a statement and urge the start-ups and young blood to innovate in the toy sector. Also, PM has given the suggestion to the educational institutions to arrange competitions in toy technology and design.

Biodegradable vs. Recyclable Plastics

Biodegradable plastics undergo digestion by microbes to form natural bi-products and what is known as humus (a sludge that makes an excellent plant fertiliser). It also produces gas which is officially known as biogas. Biozone’s landfill-biodegradable plastics have proprietary additives that help them biodegrade naturally in landfills. Once the biodegradable packing ends up in a landfill, it attracts the necessary microbes that break down the plastic into its natural components.

The Future of the Extrusion Blow Molding Machine

Everywhere you look, competition among different industries has exploded. Thanks to a thriving market, companies that once struggled now see incredible success. Just as businesses need ways to stay ahead of the competition, so do extrusion blow moulding machine manufacturers. Because of that, they continually push to come up with more innovative solutions.

Why CMP Machines are the BEST?

Innovation is at the heart of any successful company. Innovation keeps an organization at the top of their game, allowing them to flex their competitive muscles and take pride in the work they do.

What is Multilayer Extrusion Blow Moulding Machine?

Nowadays literally all humankind use plastic products 24/7 all over the world. It is super easy to get access to all kinds of plastic products. You might have come across bottles that have a shiny layer on the outer side, or different colours on the outer and a different one in the inner. So, what it is? It is a multilayer extrusion product. Well, let me explain to you how what it is exactly.

Exterior Surface (Mold Cavity) Design

The inner and outer walls of the part are formed simultaneously and integrally, but interior and exterior designs are essentially independent so we review them separately. As the design develops, the designer should begin thinking about the interaction of the plastic and the mould that will produce the part. The visual exterior of many products is formed in one half of the mould called a cavity. Following are some of the features of mould cavities the designer will want to consider.

Interior Surface (Mold Core) Design

The inner and outer walls of the part are formed simultaneously and integrally, but interior and exterior designs are essentially independent so we review them separately. As the design develops, the designer should begin thinking about the interaction of the plastic and the mould that will produce the part. The interior surface of double-wall blow moulded parts is normally formed by a mould core. Since the mould core must fit inside the cavity, there should be no question it meets the same core blow ratio = W>2D overall size requirement as the cavity.

About Parison and Parison Control

Parison blow moulding of intricate plastic bottles and other plastic parts requires air pressure control that is precise, repeatable and rapid responding. Proportion-Air offers electronic closed-loop pressure and flow control used to improve processes in the plastics blow moulding industry.

Why CMP Blow Moulding Machine?

Multiple industries and outside manufacturing companies depend on advanced extrusion blow moulding machinery. Without the right machine, there would be no way to produce superior quality products and we, at CMP, provide quality over quantity. Let us go through the advantages you will get for using CMP’s machine.

Information about the series of Extrusion Blow Moulding Machines in CMP

Have you ever seen a person at the fair or the mall during the holidays, blowing glass to create beautiful, artistic designs? It’s mesmerizing how a random piece of coloured glass can be manipulated by precisely placed hot air and become such a masterpiece. This art form inspired the current method of manipulating plastics to form many of the items we use every day, from water bottles to toys and so many things in between. This artful method is called Extrusion Blow Molding and it’s a common and inventive way of mass-producing hollow, lightweight products that are also durable and waterproof

How to select a Blow Moulding Machine?

The reputation of the blow moulding machine manufacturer you do business with has a lot to do with the quality of the equipment it sells. The right company takes great pride in offering its customers top-of-the-line products at a competitive price. Buying a blow moulding machine can be a nerve-racking experience for fresh entrepreneurs.

Types of products manufactured in Extrusion Blow Moulding Machine

Blow moulding is a manufacturing process for forming and joining together hollow plastic parts. In general, there are three main types of blow moulding: extrusion blow moulding, injection blow moulding (one stage), and injection stretch blow moulding (two stages). In the extrusion blow moulding process (EBM), plastic is melted and extruded into a hollow tube (a plastic parison). This plastic parison is then captured by closing it into a cooled metal mould. Air is then blown into the parison, inflating it into the shape of the hollow bottle, container, or part. After the plastic has cooled sufficiently, the mould is opened and the part is ejected. It is designed to manufacture high volume hollow plastic products.

Types of material used in Extrusion Blow Moulding Machine

When choosing a material for blow moulding; cost, density, flexibility, strength, and other factors should be considered into what resin is best for your part. If the elastomeric properties of the material are exceeded, a hole will tear through the material resulting in a defective part. Other relevant properties are largely based on your application and might include mechanical, physical, chemical resistance, heat, electrical, flammability or UV resistance.

Extrusion Blow Moulding Machine VS Injection Blow Moulding Machine

If you operate a business that requires specially formed plastic bottles or containers, such as juice and water bottles or liquid soaps and shampoos, it’s to your benefit to understand the various manufacturing processes for making those bottles and containers.

The process of Extrusion Blow Moulding Machine

Extrusion Blow Molding is the simplest type of blow moulding. A hot tube of plastic material, called a parison, is dropped from an extruder and captured in a water-cooled mould. Once the moulds are closed, the air blown through the top of the neck of the container. When the hot plastic material is blown up and touches the walls of the mould, the material freezes, the container now maintains its rigid shape.

What is Extrusion Blow Moulding Machine?

Blow moulding is an umbrella term for forming hollow plastic parts by inflating a molten plastic tube or parison until it fills a mould and forms the desired shape. Think of it as inflating a balloon inside of a water bottle. The blow moulding process begins with melting down the plastic and forming it into a parison. The parison is a tube-like piece of plastic with a hole in one end through which compressed air can pass. Water channels are carved into the mould to assist in cooling.

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