In the field of injection molding, plastic blow molding is an actual practice that focuses on improving the results and returns on investment for complicated plastic parts and products. One aspect of top-quality plastic products is the quality of machinery employed in the process. Any plastic company should first aim to acquire machinery from the highest-quality Extrusion Blow Molding Machine makers. Design of Experiments (DOE) is another aspect of scientific molding involving applying statistics to conduct controlled tests with input and output variables. These tests aim to determine specific values, such as the probability of part failure. By utilizing DOE, manufacturers can optimize their production processes and improve the quality of plastic products.

Blow Molding Process:
Step 1: Plastic materials in their raw form, such as pellets, granules, or powder, are loaded into a hopper container, which is then introduced into a heated cylindrical chamber known as an extruder. The extruder has a rotating screw that moves the material through the room. Some extruders may have one or two revolving screws depending on the design.

Step 2: The raw materials flow from the hopper down through the feed throat onto a large spinning screw operating inside.

Step 3: Since each material has distinct properties, the raw materials are processed at a specific temperature based on their type. Following the heating process, the liquefied plastic is pushed through a tiny orifice called a die to take on the desired shape of the final product.

Step 4: Once the plastic emerges from the die, it is directed onto a conveyor belt to begin the cooling process. Cooling may occur via water or air. The process shares similarities with injection molding, although in this case, the melted plastic is pushed through a die instead of being injected into a mold.

Step 5: The final step of the process involves designing the die for a specific plastic profile to ensure the uniform and smooth flow from the cylindrical profile of the extruder into the desired final shape. Maintaining consistent flow is vital to produce a high-quality end product that meets the required standards.

What is the Design of Experiments (DOE) Approach:
DOE is a systematic, organized approach to solving any engineering problem, whether industrial or scientific The Design of Experiments (DOE) is a field of applied statistics that involves the planning, execution, analysis, and interpretation of controlled tests to determine the factors that influence one or more parameters. As an effective data collection and analysis tool, DOE can be applied to numerous experimental settings.

DOE is applied to four scenarios when solving a scientific or industrial process;
1. Comparative
In this situation, the focus of DOE is to determine whether a change in one factor produces a change or improves any engineering or scientific process.
2. Screening
In this scenario, the goal is to have a ranked list of factors from most important to least important that are affecting an industrial or scientific process
3. Modeling
In this case, the DOE is applied by an engineer to mathematically model any engineering or industrial procedure with great accuracy according to a mathematical function that has a high predictive capability.
4. Optimization
This scenario involves utilizing DOE to determine the most efficient settings of the process factors. In other words, it means to examine each element, the level or magnitude that can make efficient the process response. To improve any industrial process, this type of application is essential.

Benefits of Applying DOE for Optimizing Blow Molding Process:
Three primary objectives accompany every new plastic molding venture;

a) A performance that satisfies the customer.
b) Streamlined production for the manufacturer.
c) Dependability for the end-user.

Achieving all three goals within the stipulated timeline and budget is challenging. Therefore, extrusion molding plastic engineers leverage the Design of Experiments (DOE) to pinpoint defects during the process design stage that could otherwise impede the project's triumph.

The Design of Experiments (DOE) empowers custom injection molders to determine the ideal process window and comprehend the effects of preserving it. DOE's precise mathematical depiction of the correlation between values and desired outcomes is pivotal to scientific molding as a whole, as well as to the three primary aims of any plastic molding project, which are;

High Performance of the Finished Product:
Designing a product or process requires considering various factors. Sometimes, product engineers may need to pay more attention to critical factors such as materials and blow molding settings like blowing speed, melt temperature, the temperature of the blow mold, and inflation ratio. Fortunately, DOE offers a comprehensive evaluation of these factors, identifying sensitivities and potential changes that might affect project specifications and design fulfillment. By raising crucial questions about these aspects' influence, DOE enables corrective adjustments to input values or other standards to guarantee the anticipated performance of the final product.

Production and Operational Efficiency:
Just imagine that you're a manufacturer, and you're gearing up to produce a brand-new product. The last thing you want is to spend time and resources on faulty designs that won't work out. That's where DOE comes in. With Design of Experiments, you can verify the process outcome before manufacture, meaning you can catch any poor designs before they even make it to the production floor. Testing can also reveal any necessary manufacturing changes to correct missteps and prevent faulty plastic parts from slipping through the cracks. Optimizing time and resources at every production step allows you to produce top-quality products.

Reliable and Durable Plastic Products:
The beauty of Design of Experiments (DOE) is its versatility - it can be used to gather valuable data on how your plastic parts will perform in any environmental conditions. This super-detailed knowledge can uncover any annoying design flaws and potential failure risks, giving you plenty of time to make necessary modifications. And guess what? Those modifications lead to better, more reliable products hitting the market. With DOE, you can confidently ensure your products are built to last and withstand whatever the world throws their way.

Some Factors Affecting the Blow Molding Process:
1. Temperature of Parison
The temperature of the parison is a crucial factor in determining the quality of the final product. It directly impacts the stability of the parison shape, the surface finish of the product, the strength of the joint, and the cooling time.

When the performance temperature increases, the product's strength decreases, making it more prone to inflation and deformation. Additionally, ensuring uniform wall thickness becomes a challenge, particularly about the longitudinal consistency of the parison. As a result, the cooling time of the inflation material is prolonged, ultimately leading to a decrease in the production efficiency of the blow molding machine.

Thus, it is imperative to have precise control over the temperature of the parison during the manufacturing process to ensure that the final product meets the desired quality standards.

2. Blowing Speed:
Compressed air serves three critical functions in the blow molding process;

Firstly, it is utilized to apply pressure to the rubber-like tubular preform, causing it to expand and closely adhere to the inner wall of the inflation model cavity.

Secondly, compressed air applies pressure to the inflated parison, which enables the product to acquire its desired shape, surface texture, and images.

Finally, compressed air also aids in promoting product cooling during manufacturing.

The pressure of the compressed air applied during this process is called "blowing pressure." It is important to note that the physical properties of different raw materials (such as their molecular flexibility, melt strength, and melt elasticity) can influence the blowing pressure required to produce high-quality blow-molded products. DOE plays a vital role in determining the blowing pressure.

3. Cooling Period:
Once the parison is inflated and conforms to the mold wall, it is essential to allow for even cooling while maintaining a certain level of air pressure. Prematurely opening the mold can result in uneven cooling and insufficient cooling, which can cause varying degrees of shrinkage in different areas of the product. It can result in undesirable product deformations such as warpage and bottleneck skew.

The duration of the cooling process for blow-molded products can vary depending on factors such as the type of raw material used and the product's shape, size, and wall thickness. The cooling time typically accounts for more than 60% of the entire molding cycle. The length of the cooling time can have a direct impact on the physical and mechanical properties, appearance quality, and production efficiency of the final product. In general, thicker products require longer cooling times.

Improving the cooling efficiency of blow-molded products and shortening the cooling time can significantly reduce the overall molding cycle, thereby increasing production efficiency.

Contact Detail:
Guangdong Leshan Intelligent Equipment Corp., Ltd.
+86-13825501262
[email protected]
www.leshanmachines.com
Foshan City, Guangdong Province, China