Injection Blow Molding | Exploring Innovative Manufacturing

Table of Contents

injection blow molding final mold
Injection blow molding final mold

1. Introduction

If you’ve ever thought hard about creating a hollow section using injection molding without success, then you may need to try injection blow molding. This method continues to mesmerize manufacturers with its power to revolutionize the crafting of complex hollow parts given the ever-evolving manufacturing techniques.

More importantly, this unique blend of injection and blow molding processes benefits the manufacturer in terms of efficiency, design, and customization all without losing sight of quality.

So, if you feel you know little about this method, then join us on this exciting journey as we unravel the intricacies, applications, advantages, future trends, and innovations of injection blow molding.

2. Understanding Injection Blow Molding

It’s the natural place to start – understanding injection blow molding, given that it forms the foundation on which other knowledge is laid. So, the obvious question is what is injection blow molding (IBM)?

Simply put, IBM takes the injection molding process and blends it with a unique blow molding process to create very challenging or complex hollow parts. This blow molding process is similar to what metal and glass blowers use in creating hollow glass sections but with a unique twist.

Essentially, you take a molten material, after selecting a suitable one, and inject it into the mold typically like any other injection molding process. The twist to this standard practice takes place once the molten material enters the mold. The blow molding part introduces compressed air into the mold with the molten material ensuring that it expands, filling every corner of the mold. What emerges is a hollow section or part based on design specifications.

The precision with which these hollow parts are created is a major benefit of using injection blow molding to create them. No wonder several complex hollow parts like device handles and intricate features are created using this method especially where customization and precision are critical.

3. Advantages of Injection Blow Molding

Injection blow molding is very innovative among other numerous advantages that make this unique manufacturing method so attractive to many manufacturers. The major ones are highlighted below.

  • Design Flexibility: Many manufacturing methods exist for high-quality mold manufacturing that offers many benefits but without the flexibility for designers to flex their imagination. However, injection blow molding is different offering so much flexibility and without boxing designers to a corner. It allows for designing and creating seemingly complex parts with the ability to actualize these designs.
  • Material Efficiency: Getting the design accurately is one thing using the right amount of material without the need for wastage is another. IBM’s unique advantage ensures that products are not just precise but also accurate with material usage.
  • Precise Control: Various parameters are necessary to create intricate features precisely for the product. Fortunately, IBM gives operators the ability to control these parameters with precision which impacts the product quality positively.
  • Cost-Effective Production: Budget is another critical point of the project where IBM shines considering that it allows for optimization of parameters like energy consumption and speed. These parameters directly affect the cost of production and optimizing them is a practical way of saving production costs.  
  • Reduced Post-Processing: Using the right production method often creates an efficiency that reduces the need for post-production processing. This is what IBM offers with intricate hollow parts.
  • Versatility: The ability to create different parts with varying complexities is yet another benefit of injection blow molding seeing that it is versatile and often applied across several industries.
Plastic pellets for injection blow molding
Plastic pellets for injection blow molding pushed through injection screw

4. How Injection Blow Molding Works

Now, that we have a general idea of what makes injection blow molding tick, the time is therefore ripe to get into the finer details of its workings and to fully understand its process. Here we start with the injection phase assuming that the material selection and the design stage are over.

  • Injection Phase: Mostly, thermoplastic materials are the typical suspect often appearing in the form of pellets. These materials are subjected to a melting temperature that makes them fluid and with the application of a specific pressure they are injected into the mold using the injection molding machine.
  • Preform Formation: Once the material is injected into a mold designed for this specific project, the molten material then takes up the shape of the mold and what emerges is a preformed component also known as a ‘parison.’ This will then be taken to the next stage with the blow molding machine.
  • Blow Molding Phase: At this stage, the blow molding machine takes over where compressed air is introduced into the preformed object through its hollow end after it has been transferred into another special mold. The plastic then expands from the introduction of this compressed air taking up the shape of the new mold.
  • Cooling and Ejection: As the new shape of the product is formed, the operator then moves it to the new phase which is the cooling phase where it solidifies and emerges as the final product upon its ejection from the mold.
  • Precision: The point of using a unique process like injection blow molding is to consistently produce quality hollow parts with high-level precision. The repeatability of this manufacturing technique is one of its attractions for many manufacturers.

5. Materials Used in Injection Blow Molding

If a parameter is capable of running an injection blow molding project, material selection will be the parameter, especially in the high-quality mold manufacturing industry. It has a significant impact on how the injection molding project turns out either for good or bad right from the start which is why you need to carefully consider a suitable one for your project. Consequently, we’ve highlighted some common materials often suitably applied in IBM projects.

1. Polyethylene (PE): Probably the most versatile of all the materials used for IBM considering its availability in different forms that include high-density polyethylene and low-density polyethylene HDPE and LDPE respectively. Car bumpers and fenders are some popular HDPE products while bottles and containers are from LDPE.

2. Polypropylene (PP): This thermoplastic is often suitable for various industrial components ranging from medical devices to automotive components due to its suitability for high temperature and impact-resistant properties.

3. Polyethylene Terephthalate (PET): Packaging companies extensively make use of this material for beverages and cosmetic containers given its moisture and gas barrier properties. It is also ideal in situations where transparent packages are required.

4. Polystyrene (PS): When a flawless surface finish becomes a critical requirement in IBM, polystyrene becomes the preferred material. Syringe barrels in the medical field especially benefit from their clear fluid properties.

5. Polycarbonate (PC): Essentially, strength and impact resistance are the core of every product quality, and polycarbonate materials offer these properties in abundance. This is why it is often applicable in IBM applications like lenses, safety goggles, and automotive headlamps to take advantage of its sturdiness and transparency.

Other materials including Thermoplastic Elastomers (TPEs), Acrylonitrile Butadiene Styrene (ABS), Polyoxymethylene (POM), and Poly Methyl Methacrylate (PMMA) all also common materials for IBM. They offer several beneficial properties including flexibility, impact resistance, dimensional stability, and optical clarity.

Injection blow molding design
Injection blow molding design

6. Design Freedom and Innovation

The design stage in any manufacturing is such a critical stage that any mistakes acquired here become a source of time, energy, and cost wastage. It’s no wonder designers are meticulous in their quest to design a quality product. Interestingly, IBM offers several ways to achieve this quality while affording designers the freedom to be innovative. Here are some ways IBM achieves this.

  • Intricate Geometries: Producing complex and intricate shapes has never been easy prior to IBM.  However, since its entrance into the manufacturing world, designers have found it increasingly easy to innovate thinking up complex forms and shapes that lead to novel solutions.
  • Hollow Structures: The adeptness of IBM in the production of hollow sections and parts is one of the major advantages that has continued to endear it to many manufacturers. Its precision and advanced accuracy are second to no other in its class. It often guarantees uniform wall thickness and minimal material waste.
  • Customization and Tailored Solutions: Bespoke component manufacturing that is geared to solving specific challenges is also the forte of injection blow molding. It supports the combination of several parameters including color, material type, and surface finish.
  • Multi-Layered Products: Sometimes there is the need to lay one material over another in the pursuit of an innovative solution which often requires tedious and laborious manufacturing techniques. But not anymore as IBM is a final bus stop for such tailor-made manufacturing.
  • Innovative Materials: Several materials offering different properties and benefits are accommodated under injection blow molding. With these different materials comes the additional benefit of providing sustainable manufacturing with biodegradable and recyclable materials.

7. Lightweighting and Material Efficiency:

Often you hear the term lightweighting in relation to efficiency in manufacturing methods like 3D printing technology. However, the combination of lightweighting and efficiency comes in various forms including the use of innovative materials in producing devices and components in different industries.

But here is the thing, using the right amount of material to achieve a specific product functionality or aesthetic is often a practical way to increase efficiency, especially in the case of injection molding.

Fortunately for manufacturers, IBM is a reputable method for ensuring that materials are not used in excess to overcompensate or over-reinforce a particular product property.  It also ensures that materials are judiciously employed without wastage at any stage further reinforcing the sustainability feature of IBM.

But wait there’s more.

IBM is also the go-to method in the area of rapid prototyping where manufacturers are often racing against time to produce a minimum viable product which informs the feasibility of their project. The reason is that it supports quick iteration of design ideas with rapid prototypes which can be easily tested before embarking on a full-scale production journey. This also gives them leverage in today’s highly competitive and fast-paced market.

Ultimately, IBM becomes the platform for which manufacturers can show their creativity while it empowers them to try out innovative design possibilities.

8. Quality Control in Injection Blow Molding

It is not news anymore that achieving quality in a manufacturing project like IBM is not a result of wishful thinking or hoping for accidental luck. It requires both careful thinking and putting specific measures in place to achieve the required product quality. We’ve itemized some quality controls that can help you achieve high-quality IBM processes.

  • Precision and Consistency: Monitoring all IBM processes including the heating, injection, and cooling phases can help achieve the expected consistency and precision in IBM which are also vital for quality control. Thankfully, cutting-edge equipment with sensors and automation is helping out in this area.
  • Measurement Tools: Ensuring that measurements like dimensions, sizes, and thicknesses are accurate is another vital way of keeping the quality of the injection blow molding project. Also, using tools like CMM, calipers, and gauges is essential to achieve these accurate measurements.
  • Defect Detection: Essentially, defects are the main indication of a lack of quality in any product and the ability to prevent or quickly identify and correct these defects is a major quality control measure. Fortunately, there are tools including advanced optical equipment that can effectively identify the minutest of these defects.
  • Material Testing: While correcting any defects in the final product usually ends all quality measures in production, preventing the occurrence in the first place is often a better choice. This prevention starts with material testing including tensile strength, melt flow, and heat resistance tests to ascertain its suitability for IBM and also for other methods like high-quality CNC Machining.
Injection blow molding facility
Injection blow molding facility

9. Applications Across Industries

It has previously been established that IBM has versatility as one of its major advantages leading to its various applications across different industries and for several custom uses. Here are some of its common industrial applications highlighted below.

1. Pharmaceuticals and Healthcare: Its ability to create plastic containers with precise and consistent wall thickness makes IBM a choice technique for manufacturing pharmaceutical packaging with tamper-proof features.

2. Automotive: With its ease of producing complex shapes and intricate components with durability and precision, IBM is no doubt the best-fit method for automotive elements including fuel tanks, air ducts, and fluid reservoirs.

3. Food and Beverage: The hygiene required for food packaging is one that IBM is very good at providing with its ability to provide aseptic and sterile packaging, especially for beverages and foods that must remain fresh.

4. Electronics: The electronics industry is another one that has benefitted from injection blow molding’s precision given that it requires housings for electronics to be tightly sealed. The precision of IBM guarantees this with high precision and product quality.

5. Construction: One of the little talked about industries that often takes advantage of IBM is the construction industry. It uses high-quality pipes and fittings that are durable and leak-proof all thanks to IBM’s quality and precision advantage.


In conclusion, Injection blow molding has always been associated with precision and quality in manufacturing. However, you can’t fully harness the full benefits of this innovative manufacturing technique without having a comprehensive understanding of its processes.

This modern injection molding method helps manufacturers to stay competitive in a fast-paced highly competitive manufacturing landscape giving them the ability to create high-quality products. Also, the ability to make customized devices increases significantly with IBM as compared to other manufacturing methods as IBM offers so much design flexibility and production versatility.

 In the end, injection blow molding becomes your tool for converting innovative imaginations into reality with products that are quality, durable, and precise once you understand its workings. The ball, as they say, is in your courts. 


Gary Liao

Gary Liao

Gary Liao is the Engineering Manager of TDL Company and has more than 20 years of mold design experience.

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