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Parting Lines Material Choice And Mold Design In Vacuum Forming

There are several important design considerations to keep in mind when creating a product that will be vacuum formed:

Wall thickness: The walls of the vacuum formed product should be thick enough to be strong and durable, but not so thick that they take a long time to cool and become brittle.

Draft angle: It is important to include a draft angle (taper) on the sides of the product to make it easier to remove the part from the mold.

Undercuts: Vacuum forming molds cannot have undercuts, as the part needs to be able to be removed from the mold.

Parting lines: The mold should have a clear parting line to allow for easy separation of the two halves.

Material choice: The material used for vacuum forming should be chosen based on the properties required for the final product, such as strength, flexibility, and resistance to heat and chemicals.

Mold design: The design of the mold is important to ensure that the final product has a high quality finish and accurate dimensions.

Radius of curvature: The radius of curvature can be an important design consideration, as it determines the amount of stretch and deformation that a sheet of plastic will undergo as it is drawn over the mold. The radius of curvature of the mold should be chosen based on the desired final shape of the product, as well as the properties of the plastic material being used. A larger radius of curvature will result in less stretch and deformation, while a smaller radius will result in more stretch and deformation. It is important to choose a radius that is appropriate for the material being used, as excessive stretch or deformation can result in defects or failure of the final product.

In the last article, we talked about the wall thickness, draft angle, and undercuts. Here is the link to the blog:

Now let’s see the parting lines, material choice, mold design, radius of curvature in vacuum forming.

Parting lines

A parting line is the line or surface where the two halves of the mold meet in a vacuum forming process. The parting line is important because it determines where the plastic sheet will be divided as it is drawn over the mold, and it affects the appearance and quality of the final product.

Factors to consider when designing the parting line

There are several factors to consider when designing the parting line for a vacuum formed product:

  • Location: The location of the parting line should be chosen to minimize the visibility of the line on the final product. This may involve placing the line in a less visible location, such as on the underside of the product.
  • Surface finish: The surface finish on either side of the parting line can affect the appearance of the final product. A smooth finish on both sides of the line will result in a smoother, more seamless product, while a rough or textured finish on one side of the line may be more visible.
  • Draft angle: The draft angle on either side of the parting line should be consistent to ensure that the two halves of the mold can be easily separated.
  • Undercuts: The presence of undercuts on either side of the parting line can make it difficult or impossible to separate the two halves of the mold. It is important to design the product to minimize or eliminate undercuts in the area of the parting line.
  • Strength: The location and design of the parting line can affect the strength and stiffness of the final product. It is important to design the parting line to ensure that it does not compromise the overall strength of the product.

Material choice

Material choice is an important factor to consider in vacuum forming, as the properties of the material will affect the final product. Some factors to consider when choosing a material for vacuum forming include:

  • Strength: The material should be strong enough to withstand the forces of the vacuum forming process and maintain its shape under normal use.
  • Elasticity: The material should have a suitable level of elasticity to allow it to stretch and conform to the shape of the mold. Materials with higher elongation are generally more suitable for vacuum forming.
  • Temperature resistance: The material should be able to withstand the high temperatures required for the vacuum forming process without degrading or melting.
  • Chemical resistance: The material should be resistant to the effects of any chemicals or environments it may be exposed to during its lifetime.
  • Cost: The cost of the material should be considered, as it will affect the overall cost of the final product.

Some common materials used in vacuum forming include polystyrene, polyethylene, polypropylene, acrylonitrile butadiene styrene (ABS), and polyvinyl chloride (PVC). It is important to choose a material that is appropriate for the intended use of the product and meets the necessary performance requirements.

What should consider when choosing material for vacuum forming

There are several factors to consider when choosing a material for vacuum forming:

  • Strength: The material should be strong enough to withstand the forces of the vacuum forming process and maintain its shape under normal use. The strength of the material can be evaluated using its tensile strength and flexural strength.
  • Elasticity: The material should have a suitable level of elasticity to allow it to stretch and conform to the shape of the mold. Materials with higher elongation are generally more suitable for vacuum forming. The elasticity of the material can be evaluated using its modulus of elasticity and elongation at break.
  • Temperature resistance: The material should be able to withstand the high temperatures required for the vacuum forming process without degrading or melting. The temperature resistance of the material can be evaluated using its heat deflection temperature and melting temperature.
  • Chemical resistance: The material should be resistant to the effects of any chemicals or environments it may be exposed to during its lifetime. The chemical resistance of the material can be evaluated using its resistance to various chemicals and its overall stability.
  • Cost: The cost of the material should be considered, as it will affect the overall cost of the final product.
  • Availability: The material should be readily available in the required thickness and color to avoid delays in production.
  • Processing characteristics: The material should have good processing characteristics, such as a low melt flow rate and good flow properties, to ensure that it can be easily formed and shaped.
  • Surface finish: The material should have a suitable surface finish for the final product. Some materials, such as polystyrene, have a naturally glossy finish, while others may require a separate finish to be applied.
  • Recyclability: The material should be recyclable to reduce waste and environmental impact.

Some common materials used in vacuum forming include polystyrene, polyethylene, polypropylene, acrylonitrile butadiene styrene (ABS), and polyvinyl chloride (PVC). It is important to choose a material that is appropriate for the intended use of the product and meets the necessary performance requirements.

Mold design

Mold design is an important factor to consider in vacuum forming, as it determines the shape and finish of the final product. Some factors to consider when designing a mold for vacuum forming include:

  • Parting line: The location and design of the parting line should be chosen to minimize the visibility of the line on the final product and ensure that the two halves of the mold can be easily separated.
  • Draft angle: The draft angle should be appropriate for the material being used and the shape and complexity of the product. It should be consistent on both sides of the parting line to ensure that the two halves of the mold can be easily separated.
  • Undercuts: The mold should be designed to minimize or eliminate undercuts, as they can make it difficult or impossible to remove the product from the mold.
  • Surface finish: The surface finish of the mold should be appropriate for the final product. A smooth finish will result in a smoother, more seamless product, while a rough or textured finish may be more visible.
  • Size and complexity: The size and complexity of the mold should be appropriate for the size and complexity of the product. A larger and more complex mold may be more expensive and take longer to produce, but it may be necessary to achieve the desired shape and finish of the product.
  • Material: The material used for the mold should be chosen based on the properties required for the final product, such as strength, durability, and resistance to heat and chemicals. Materials such as aluminum, steel, and silicone are commonly used for vacuum forming molds.
How to make a high-quality mold for vacuum forming

Here are some tips for creating a high quality mold for vacuum forming:

  • Start with a well-designed product: The design of the final product is the most important factor in creating a high quality mold. Make sure the product has a clear parting line and draft angles, and minimize or eliminate undercuts to make it easier to remove from the mold.
  • Choose the right material: Select a material for the mold that is appropriate for the intended use of the product and meets the necessary performance requirements. Materials such as aluminum, steel, and silicone are commonly used for vacuum forming molds.
  • Pay attention to surface finish: The surface finish of the mold is important, as it will affect the appearance and quality of the final product. A smooth finish will result in a smoother, more seamless product, while a rough or textured finish may be more visible.
  • Consider the size and complexity of the mold: The size and complexity of the mold should be appropriate for the size and complexity of the product. A larger and more complex mold may be more expensive and take longer to produce, but it may be necessary to achieve the desired shape and finish of the product.
  • Create a prototype: Create a prototype of the mold to test the design and ensure that it will produce a high quality product. Make any necessary adjustments based on the results of the prototype.
  • Use high precision machining: Use high precision machining techniques to create the mold, as this will ensure that the final product has accurate dimensions and a high quality finish.
  • Properly maintain the mold: Properly maintain the mold to ensure that it is in good condition and produces high quality products consistently. This may involve cleaning and lubricating the mold regularly, and repairing or replacing any damaged or worn parts.

Radius of curvature

The radius of curvature is the radius of the curve formed by the surface of the mold in a vacuum forming process. The radius of curvature is an important factor to consider in vacuum forming because it affects the amount of stretch and deformation of the plastic material as it is drawn over the mold. A larger radius of curvature will result in less stretch and deformation of the plastic, while a smaller radius of curvature will result in more stretch and deformation.

There are several factors to consider when designing the radius of curvature for a vacuum formed product:

  • Material properties: The properties of the plastic material, such as its modulus of elasticity and elongation at break, should be taken into consideration when designing the radius of curvature. Materials with a higher modulus of elasticity and lower elongation will be more resistant to deformation and may require a larger radius of curvature to avoid excessive stretching.
  • Product shape and complexity: The shape and complexity of the product will affect the radius of curvature required. Products with complex shapes or sharp corners may require a larger radius of curvature to avoid excessive stretching or deformation of the plastic.
  • Strength and stiffness: The radius of curvature should be chosen to ensure that the final product has sufficient strength and stiffness for its intended use. A larger radius of curvature will result in a stronger and stiffer product, while a smaller radius of curvature may result in a weaker and more flexible product.
  • Cost: The cost of the mold may increase with a larger radius of curvature, as it may require more material and labor to produce.
  • Appearance: The appearance of the final product may be affected by the radius of curvature. A larger radius of curvature will result in a smoother, more seamless product, while a smaller radius of curvature may result in a more visible seam or deformation.

It is important to choose an appropriate radius of curvature for the final product, taking into consideration the material properties, product shape and complexity, strength and stiffness requirements, cost, and appearance.

Now please allow me to do a brief introduction about our vacuum forming factory:

About Ditaiplastic

Ditaiplastic has been working in the field of vacuum forming since 1997 and today has more than 60 large production machines, more than 40 product patents, 80 employees, and a factory covering 12,000 square meters! It is one of the largest suppliers of vacuum forming in China! Kindly visit us at https://www.ditaiplastic.com contact us at amy@dgdtxs.com.cn or WhatsApp: +86 13825780422

Ditaiplastic wish you a great day!

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