Blow molded parts-Blow Molding vs. Injection Molding: What's the Difference? | The Rodon Group®

The machine has a 20 lb. We boast a deep understanding of the blow molding process and possess a unique ability to blow mold a wide range of materials and part sizes. We manufacture our proprietary line of bulk food gravity dispensers under the Best Bins name. Other industries served include agriculture, automotive accessories, furniture manufacturing, medical, RV, and safety equipment. Pet All Manufacturing Inc.

Blow molded parts

The high-density polyethylene cargo organizer provides truck owners with a versatile and easy-to-use organizer for pickup truck beds. This Blow molded parts involves flawless support culminating in successful global product delivery. Overall the shrinkage of the interior will match the shrinkage of the exterior. SPI currently produces, assembles, warehouses and distributes their bulk food container product line. Waniuk February

Runner fuck. Custom molding the future

As in the cavity, the plastic begins to stretch to fit the mold contour. The process is divided into three steps: injection, blowing and ejection. Many engineering-grade resins can be blow molded. The molds are then cooled to release complete plastic parts. Blow molding creates very uniformly, Blow molded parts containers. The diameter of Blow molded parts cylindrical parison that forms a double wall part must allow enough material to enter the mold to adequately form each half of the part. The thinning caused by stretching results in weakness. No increase in barrier strength as the material is not biaxially stretched. A deep core with little draft and a sharp corner will produce a thin, weak-walled part. As the core is pushing the parison into the cavity it is possible for the opposite sides of the parison to touch before the air is injected to form the part. The result is either a part with a very thin, weak section all around the welded web or, if the nearby material tears when the parison is inflated, it blows out and no part forms. Creating Structure H. The most common approach is angling the sidewall and putting a radius or an chamfer-angle at the corner. The design Blow molded parts certain complex parts will require Only cuties vibrators in the parting-line location in order to stay within this relationship. Venting When the mold closes the parison is captured at the pinch-off.

The Custom-Pak blow molding design guide provides you with basic design tools for making engineered blow molded parts.

  • Blow molding BrE moulding is a specific manufacturing process by which hollow plastic parts are formed and can be joined together.
  • The Custom-Pak blow molding design guide provides you with basic design tools for making engineered blow molded parts.
  • When creating a product that requires molding plastic parts , you have several processes to choose from, depending on the type of application and type of part you want to produce.
  • This experience involves dedicated support culminating in successful product delivery globally.
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The Custom-Pak blow molding design guide provides you with basic design tools for making engineered blow molded parts. This guide focuses on the extrusion blow molding process.

No two designs are alike, so the mold and process must be adjusted to optimize each design. Software products can help predict molding characteristics and our engineers are here to help make your product great. Our design assistance is confidential and free. Blow-Molding Process B. Materials C. Capturing the Parison D. Exterior Cavity-Mold Design E. Interior Core-Mold Design F. Air Space G. Creating Structure H. Some of the least expensive materials are also the easiest to process.

Polyethylene PE and polypropylene PP are the most popular blow molding resins. PE is currently less expensive but PP tends to be stiffer which sometimes offsets the cost difference. These materials are resistant to most chemicals. These materials usually form parts matching the principles discussed in this design guide. Many engineering-grade resins can be blow molded. These resins require special consideration prior to molding.

Most require drying before processing, specially designed extruder screws and specific processing conditions. The design criteria in this guide may not apply to parts molded from some engineering resins. Please obtain the correct design information for your specific project directly from our engineering personnel. The plastic material stretches like the gum and if it gets too thin it ruptures.

Since the parison is extruded as a tube, it is easy to make a tube or bottle shaped part, not much stretching occurs. The two mold halves open, the parison is inserted,the mold halves close and the part is blown.

The split between mold halves is known as the parting line. There is often a knife like edge on the parting line around the part shape known as pinch-off. If the part shape to be molded is changed from a tube into a flat panel type part, the parison tube must be flattened to make the panel.

When this happens the circumference of the parison becomes the surface that needs to cover the width of the panel. If the parison does not extend to all areas of the pinch-off, it must stretch the rest of the way.

The soft plastic can stretch only a short distance before it begins thinning. Like the bubble gum, the first thin spot is weakest and it gets thinner fastest until it pops. As the complexity of the part progresses to double-wall shapes with side walls and inner contours, the parison must not only be captured at all points along the parting line, but it must also meet the material thickness needs for the variety of molding conditions specific to each area of the part.

Many of the design criteria used to make a tray with molded inner shapes will be the same for designing a complex industrial part. 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 mold that will produce the part. The visual exterior of many products is formed in one half of the mold called a cavity. Following are some of the features of mold cavities the designer will want to consider. A bottle is a typical example of a blow molded part formed using 2 cavity mold halves.

The result is excellent material distribution in a round bottle. But, not all parts will be round. As designers start to push the limits of draw down into cavities, how far should they go? The answer depends on the elongation elasticity of the material and how thin a wall you are willing to accept. So, try not to design your cavity-cavity part to be deeper than the width. Many industrial parts are formed using a combination of cavity and core mold elements where the core forms interior shapes.

The core changes the blow ratio parameters. The diameter of the cylindrical parison that forms a double wall part must allow enough material to enter the mold to adequately form each half of the part. Half of the cylindrical parison is used to form the exterior half cavity of the part and the other half of the cylindrical parison forms the interior half core of the part.

Since there is no flow of material along the mold walls only stretching , it follows that the depth of the cavity D should be no more than one-half the length or width of the cavity W. A part design utilizing cavity depths that exceed this relationship will be subject to severe thinning or blow-out. The design of certain complex parts will require changes in the parting-line location in order to stay within this relationship.

These steps in the parting line must include clearance for repeated opening and closing of the mold halves and be positioned so they do not shear the parison during mold-close.

The plastic parison sticks and begins to solidify as soon as it hits the mold. The material then stretches to fill the cavity as blowing progresses. There is no flow of material along the mold walls. There are three aspects of thinning to consider. The thinning along sidewalls and in corners is the reason that parts should have outside draft angles. Exterior draft is not critical to part removal from cavities since the plastic shrinks away from the outer mold walls as it cools.

Draft is recommended when exterior walls are to be textured. Because of this, cavity design must avoid features that contribute to thinning. There are a variety of corner configurations that improve or alleviate this problem. The most common approach is angling the sidewall and putting a radius or an chamfer-angle at the corner. Part removal may be a problem with back-draft sections.

Back-drafted areas can lock the part in the mold. If possible, a part with back draft on one side should have an equal positive draft on the opposite side. Otherwise, molds may need moving sections to remove the back drafted feature. Shrinkage varies by material, the rate of temperature change and the thickness of the material. For PP and PE materials, the material thickness is the best predictor.

Designs that allow wall thinning variation to occur in the part may result in warped parts. The thin areas will shrink less before cooling than the thick areas. The variation in shrinkage rates and distances can cause the part to warp.

The skin of the material against the mold metal will cool and take a set before the material not actually touching the mold metal. The result is a tendency for outer walls to warp inward and is offset by the tendency of the inner wall to warp outward. The use of structural ribs, welds between walls, arcs or steps can create a structure that helps reduce warpage.

To control dimensions, surface appearance and warpage, it is important to have as much control over the cooling of the part as possible. Flow rate is a major factor in heat removal and cycle time. By creating turbulent flow, heat extraction and cycle times can be improved.

To control warpage in many designs, it is essential that the mold cooling be targeted to provide extra heat extraction in the heavier wall portions of the part.

The overall flow pattern also affects the part quality. Water warms as it flows through the mold. A cold mold surface can also cause problems in reproducing surface details such as texture. Tooling engineers can target water lines near each critical section of the mold to provide the dimensional control and appearance you need. When the mold closes the parison is captured at the pinch-off.

When air is blown to expand the parison, the trapped air becomes compressed by the expanding parison until an interior — exterior pressure equilibrium is reached. When this occurs, the parison will not completely touch the mold wall. Venting can be easily located at the edge of any insert in the cavity.

Slotted vent inserts or porous metals can be purchased and fit into nearly any location. Some venting methods will produce visible markings on the finished part.

Texture, inserts and other techniques can be employed to mask the markings made at the vent location. The interior surface of double-wall blow molded parts is normally formed by a mold core. The half of the parison that is draping over the mold core is already beginning to set as the air is injected into the parison. As in the cavity, the plastic begins to stretch to fit the mold contour. Almost no flow occurs.

Unlike the cavity, some different rules apply. As the mold halves close on the parison, the core presses against the parison and forces it into the cavity until the pinch-off is sealed around the perimeter of the part. The highest point on the core forms the deepest depression inside the part. If the double-wall part design has a dividing wall between two compartments, this wall is formed by stretching the plastic into a groove in the mold core.

As the plastic begins stretching into a groove, it begins to thin. If the groove is too deep, the plastic quickly reaches the point where it thins until the internal air blows-out through the wall to the outside of the part.

It is also an excellent way to provide stacking strength when dealing with heavy loads G. Floor space required is high, although compact systems have become available. The thin areas will shrink less before cooling than the thick areas. When the part is blown, the fixed plastic walls stretch no flow to meet the sidewall of the core. For example, moldings produced from amorphous materials are much more difficult to trim than crystalline materials.

Blow molded parts

Blow molded parts

Blow molded parts

Blow molded parts. What is Injection Molding?

This is the least-used of the three blow molding processes, and is typically used to make small medical and single serve bottles.

The process is divided into three steps: injection, blowing and ejection. The injection blow molding machine is based on an extruder barrel and screw assembly which melts the polymer. The molten polymer is fed into a hot runner manifold where it is injected through nozzles into a heated cavity and core pin. The cavity mold forms the external shape and is clamped around a core rod which forms the internal shape of the preform.

The preform mold opens and the core rod is rotated and clamped into the hollow, chilled blow mold. The end of the core rod opens and allows compressed air into the preform, which inflates it to the finished article shape. After a cooling period the blow mold opens and the core rod is rotated to the ejection position.

The finished article is stripped off the core rod and as an option can be leak-tested prior to packing. The preform and blow mold can have many cavities, typically three to sixteen depending on the article size and the required output. There are three sets of core rods, which allow concurrent preform injection, blow molding and ejection. Disadvantages: only suits small capacity bottles as it is difficult to control the base centre during blowing.

No increase in barrier strength as the material is not biaxially stretched. Handles can't be incorporated. This has two main different methods, namely Single-stage and two-stage process.

Single-stage process is again broken down into 3-station and 4-station machines. In the two-stage injection stretch blow molding process, the plastic is first molded into a "preform" using the injection molding process. These preforms are produced with the necks of the bottles, including threads the "finish" on one end.

These preforms are packaged, and fed later after cooling into a reheat stretch blow molding machine. In the ISB process, the preforms are heated typically using infrared heaters above their glass transition temperature, then blown using high-pressure air into bottles using metal blow molds. The preform is always stretched with a core rod as part of the process.

Advantages: Very high volumes are produced. Little restriction on bottle design. Preforms can be sold as a completed item for a third party to blow.

Is suitable for cylindrical, rectangular or oval bottles. Disadvantages: High capital cost. Floor space required is high, although compact systems have become available. In the single-stage process both preform manufacture and bottle blowing are performed in the same machine.

The process explained: Imagine the molecules are small round balls, when together they have large air gaps and small surface contact, by first stretching the molecules vertically then blowing to stretch horizontally the biaxial stretching makes the molecules a cross shape. These "crosses" fit together leaving little space as more surface area is contacted thus making the material less porous and increasing barrier strength against permeation. This process also increases the strength to be ideal for filling with carbonated drinks.

Highly suitable for low volumes and short runs. As the preform is not released during the entire process the preform wall thickness can be shaped to allow even wall thickness when blowing rectangular and non-round shapes. Restrictions on bottle design.

Only a champagne base can be made for carbonated bottles. From Wikipedia, the free encyclopedia. Barnes; Quoc Pham; Theodore A. Waniuk February Materials Today. Small Scale Recycling of Plastics. Intermediate Technology Publication. Authority control NDL : Categories : Packaging Molding processes Industrial processes.

Namespaces Article Talk. Views Read Edit View history. Our core software, mechanical and human technologies insure future profitability and growth.

Our commitment to our customers, community and employees is embodied in our value statement and quality policy. That same innovative spirit exists today.

You will find our injection and blow molding presence on a wide range of parts. SPI Industries is an industry leading custom molder known for our customer oriented ability to deliver production solutions and product quality; driven by a relentless pursuit of continuous improvement. Our rich history as a custom molder has provided extensive experience handling the basic Nylons, ABS, PP, PE and specialized engineered resins including various grades of Thermoplastic Rubber.

While our technical molding capability and press sizes are continually changing to keep pace with the needs of our customers, we have expanded into Proactive Solutions for our customers such as part Design Feasibilities, Prototyping services, various Short Term and Long Term Take-over Tooling methods along with complete Third Party Logistics handling of your specialty products shipped to distribution chains globally. SPI Industries values are based on integrity and reflected in the Long Term relationships with our customers.

SPI is simply the collective personality of every employee that works here.

Blow Molding Design Guide – Custom-Pak, Inc.

Blow molding blow moulding , or plastic blow molding, is a fabricating process that manufacturers use to create hollow plastic parts and products. It is named blow molding because it involves blowing compressed air into molten plastic so that it expands like a balloon and takes a particular shape. Read More….

Request A Quote. Western Industries provides custom plastic blow molding product design, engineering, mold design and extensive capabilities and manufacturing expertise for mid- to large-part products, in both single- and dual-head processing.

At Blow Molded Products, we have experience doing custom blow molding for a multitude of industries, including furniture, sporting goods, health and safety, electronics, and more.

With blow molding presses from 1 to 80 lbs. We make it our goal to personalize our projectsto ensure client success. LHB Plastics offers a full range of services, from molded parts to complete assembly. Additional services include engineering support, finished part testing, in-house 3D rapid prototype part printing, and more. Since , Hi-Rel has provided top-quality blow molded plastic components and unmatched customer service. We handle every aspect of the blow molding process here in our facility, from prototyping to sampling and production.

At Hi-Rel, no project is too difficult for us to handle. Exi-Plast is a custom blow molder with 25 years of experience providing customers with quality deliver of unique projects ranging in size from drain tile connectors to bulk parts up to 40 lbs.

Exi-Plast is a full service provider advising customers from concept to commercialization. North American Plastics is ISO certified, providing custom plastic injection molding and blow molding products across America. If you need a worry free solution for your project, allow us to serve you as well.

Manufacturers use the blow molding process in order to form a smooth, airtight, uniform product that does not need to be assembled. Also, blow molded products are capable of holding a variety of substances such as herbicides, pesticides, cosmetics, and automotive oil. Some of the many industries that use blow molded plastics include: automotive manufacturing, food and beverage, lawn and garden, waste collection and recycling, storage and transportation, organization, office, healthcare and more.

Manufacturers use blow molding to make numerous products. Examples include: automotive ducting, water bottles, food storage containers, plastic totes, recycling cans, garbage cans, gallon drums, hoses, planters and watering cans. Also, manufacturers blow mold cases and any other hollow consumer item that has a three-dimensional shape.

After they sold the rights to their invention in to the Hartford Empire Company, a select number of manufacturers across the country began using the blow molding process for their purposes. One of the first items American manufacturers mass produced was the plastic bottle. While the method had incredible potential, prior to World War II, manufacturers did not have access to many types of plastic. In WWII, the need for synthetic plastics increased, and engineers responded by designing many new varieties.

This trend continued after WWII, when manufacturers began producing plastic containers for the home. One of the first items American manufacturers mass produced was the plastic bottle in By , 60 years later, the US was producing upwards of ten billion plastic soft drink containers.

While plastic and plastic injection is as popular and present as ever, there is now a movement to use materials that create less potential waste and litter. One way that plastics manufacturers are seeking to keep up with the green movement is by creating new products from recycled products. The plastic utilized for these processes are all thermoplastic resins. They include acetal, polysulfone, polyamide, polystyrene, butadiene styrene, polyvinyl chloride PVC , polycarbonate and high-density polyethylene HDPE.

Acetal, or more technically Polyoxymethylene POM features: high dimensional stability, low friction, high rigidity, high strength and hardness. Most often, manufacturers employ it for engineering applications like fasteners, gear wheels, ball bearings and lock system fabrication. Polysulfone thermoplastics are durable, strong, rigid and thermally stable polymers.

These high-performance plastics are highly resistant to a variety of chemicals with pH levels between 2 and 13, including: bleaches, electrolytes, alkalis and mineral acids. They are reasonably resistant to hydrocarbon oils and surfactants. They have above average compaction resistance, so they work well in high pressure applications.

Polyamides are characterized by their durability and strength. They can occur naturally or be made synthetically. Polystyrene is an inexpensive polymer used for a variety of purposes that do not require sealing from water or air. It is available as a solid material or a foamed material think Styrofoam. Manufacturers use it to blow mold plastic containers and bottles of all sorts.

However, polystyrene takes a very long time to biodegrade, and has been found in alarming quantities in the Pacific Ocean and along shorelines. Butadiene styrene, not to be confused with styrene-butadiene rubber SBR , is a thermoplastic elastomer made from styrene and butadiene. It is more commonly known as acrylonitrile butadiene styrene, or ABS. ABS is strong, shiny, heat resistant and impact resistant. PVC, also known as vinyl, is one of the most widely used polymers in the world.

It is available as a flexible or rigid material. Some of its many blow molding applications include: bottles, plumbing components and non-food packaging. Polycarbonates are thermoplastic polymers that feature carbonate groups in their makeup. They are strong, durable and impact resistant. However, they have poor scratch resistance and poor chemical resistance.

HDPE is a thermoplastic known for its high tensile strength and high strength-to-weight ratio. It is also water resistant and solvent resistant. This recyclable thermoplastic material works well as: potable water storage, bottles, piping, food storage, plumbing boxes, electrical boxes, bags and more. There are three methods in which blow molded plastic products can be produced: extrusion blow molding, injection blow molding, and stretch blow molding.

All of these processes consist of just a few main steps, which vary the most in the early stages. All blow molding processes share the steps of 1 melting and forming the plastic, and 2 introducing air pressure.

The first step in the blow molding process involves melting the plastic, and then using injection molding to form it into a preform, or parison. A parison is a piece of plastic shaped like a tube with a hole on one end which allows compressed air to pass through. The preform, which is soft and moldable, is pushed by a metal ram and expanded to the designated height of the product. The parison or preform is then clamped into a mold cavity.

The ultimate shape of the blow molded plastic depends on the shape of the mold cavity. Air pressure is introduced to the inside of the parison via a blow pin. The air pressure causes the parison to expand like a balloon and fully take the shape of the mold cavity. The final product can be cooled either by running cold water through the mold, by conduction, or by evaporating inconsistent fluids within the container.

The blow molding process takes a few seconds; blow molding machines are capable of producing up to 20, containers in an hour. Once the plastic part has been cooled and hardened, the mold opens up and allows the part to be ejected. When preparing a custom blow molding procedure, manufacturers must decide on a few different things, mainly: the material they will use, the blow molding process they will use and the shape of the mold cavity.

The decisions they make depend entirely on the client application specifications and requirements. For example, if the product requires strong compaction resistance, they will likely consider a material like polysulfone. While blow molded products come in an assortment of standard shapes and sizes, there are some products that are used for special applications and must be made via custom blow molding. Blow molding service providers routinely craft custom molds so that you can receive the most well-tailored product possible.

To make sure you are on the same page, they will first create a prototype to share with you. Custom blow molding takes longer but yields great results. However, if you are short on time or your budget is small, your manufacturer can also blow mold your products with a standard mold.

They typically have a wide variety of standard molds with which they make commonly shaped and sized containers, jars and the like. Extrusion blow molding is the simplest of the three blow molding methods.

Extrusion blow molding involves melting plastic extruding it into a parison, then expanding the parison with compressed air. Extrusion blow molding allows for a wide range of sizes, shapes, handle ware, and openings for containers.

Notably, extrusion blow molding only makes hollow products. When creating the containers, the extrusion blow molding process utilizes two mirror molds, which result in a seam running down the middle of the product. Injection blow molding hybridizes the processes of blow molding and injection molding. During the injection molding process, the plastic preform is injection molded before being blown into a mold inside the injection blow molding machine.

The injection blow molding process is not suitable for manufacturing any kind of handle ware but is permissible for small containers. These processes are often used to manufacture bottles for beverages such as water and juice. ISBM injection stretch blow molding involves injection molding a preform, and then moving it to the next station to be blow-molded. ISBM is a costly process, and is used to manufacture liquor bottles, water bottles, and peanut butter jars.

RHB reheat and blow molding involves purchasing a preform from another vendor who has already injection-molded the material. The preform is reheated to prepare it for the blow-molding process. RHB is much more cost-effective than ISBM, because it eliminates the need for injection molding equipment and provides access to various pre-made preforms.

The blow molding process has many advantages, especially when compared to other methods of plastic manufacturing. First, blow molding is cheaper than injection molding. In part, this is because it requires so few tools. Second, unlike many others, blow molding is suitable for fabricating plastic parts that are hollow. Third, blow molding has a faster cycle time than other processes, such as rotational molding.

Blow molded parts

Blow molded parts

Blow molded parts