Plastic Pressure Forming FAQ

Pressure forming involves stretching plastic sheet, heating to a pliable temperature, then applying vacuum force from female tooling, and pressure force from male tooling to form the plastic sheet into a finely detailed 3D shape.

WeProFab is one of the best pressure forming companies who can manufacture different kinds of pressure forming products. They can be used in a wide range of applications, such as different medical equipment shells, vented equipment shells, office equipment shells, scientific instrument shells, control pads, golf cart shells, heavy-duty plastic crates, heavy-duty plastic pallets and many more.

Compared to injection molding, pressure forming has many advantages for low and medium volume projects. The tooling cost of pressure forming will be cheaper. It is more cost-effective for low and moderate volume projects. Pressure forming is able to make very large plastic products.

Large and thick sheet pressure forming is also called heavy-gauge pressure forming. It will use thick plastic sheets to do pressure forming, in order to make large and heavy plastic products with detailed 3D shapes such as heavy-duty plastic pallets, HDPE pallets, medical equipment shells, golf cart shells and many more.

WeProFab is also one of the pressures forming plastic manufacturers who can handle different kinds of pressure forming materials. We can pressure form HDPE for HDPE pallets. We can handle pressure forming polycarbonate for polycarbonate machine guards. We can do ABS pressure forming and plastic painting processes for ABS medical equipment shells. We can do PVC pressure forming for PVC pallets.

WeProFab is a pressure forming plastic manufacturer who can customize your required pressure forming plastic products according to your drawing and specification.

Pressure Forming: The Ultimate FAQ Guide

What is Pressure Forming?

It refers to an advanced plastic manufacturing process that involves transforming plastic material to a comparatively complex and detailed profile.

Pressure forming is a popular thermoforming technique.

You can as well describe it as more or less improvement of the vacuum forming process.

Pressure forming process

Why use Pressure Forming?

• It makes it possible for you to spend less cost of tooling by a greater margin compared to other process such as injection molding.
• It helps in creating highly consistent molded parts that have comparatively tight tolerances ideal for applications which require such tolerances, especially for precise fit-ups.
• It enables you to form comparatively large parts, which is critical in a wide range of applications.
• You can use this process to create complex geometries, such as undercuts, among others.
• This process makes it easy for you to attain faster prototyping as well as quicker time to market the parts accordingly.
• It provides you with the best alternative for replacing wood, sheet metal as well as fiberglass components.
• It allows you to create parts which have functional details or fine cosmetics like louvers or vents.

What are the Disadvantages of Pressure Forming?

• It is a one-sided process hence resulting in changes in wall thickness, which becomes somewhat difficult to control during the process as it would be in the two-sided process.
• It also makes it difficult to mold slits, holes, and apertures using pressure forming, which implies that you’ll have to produce them in subsequent steps.

How does Pressure Forming compare to Vacuum Forming?

Vacuum forming vs pressure forming – Photo courtesy: Visual Pak

Both of these are methods of thermoforming processes.

However, they tend to vary and also conform in a wide range of ways as follows;

• In pressure forming, heating of plastic sheet to pliability occurs, which is then pressed against a 3D mold using vacuuming the air between mold and the material.

While at it, air pressure is also applied above the plastic sheet.

Vacuum forming, on the other hand, involves heating of plastic material to pliability then pressing it against 3D mold by vacuuming out the air between the mold and the plastic material without applying air pressure.

• Both of these thermoforming techniques are cost-effective, provide relatively faster tooling, and also able to form very large parts.
• Pressure forming is ideal for complex shapes, parts with louvers and vents, as well as projects that require somewhat tighter tolerances.

Vacuum forming, on the other hand, is suitable for sharper details, projects that need undercuts and tighter tolerance, as well as those that require molded in-texture.

• Most of the products formed from pressure forming are used in varied applications, including office equipment, medical apparatus, control panels, scientific instruments, and multi-part assemblies, among others.

On the other hand, products formed from vacuum forming are used as a point of purchase displays, fitness equipment, pool and spa, recreational automobiles, and automotive aftermarket, among others.

How does Positive Mold compare to Negative Mold?

• When using a positive mold, also known as male mold, plastic material is stretched over the mold, and then a vacuum is applied as a way of drawing plastic into the mold’s surface.

On the other hand, when using negative mold, also known as female mold, the drawing of the plastic material into the cavity by vacuum occurs.

• Positive mold is seen in a convex shape designed to trap the whole molding resin whenever the mold closes, whereas negative mold are present in bowl-shaped craters.

What Plastic Materials are used in Pressure Forming?

• HDPE
• PET
• PETG
• ABS
• PVC
• HIPS
• PS

When does Pressure Forming Fit?

It is fit when in need of producing relatively large-sized parts with moderate production volumes.

It is also fit when there is a need for creating complex geometries and attaining more precise levels.

How Thick are Materials you can Pressure Form?

It depends on various factors, including the particular type of plastic material that you are pressure forming.

In general, however, you can pressure form a plastic sheet with up to 500 inches thickness.

What Tooling is needed for Pressure Forming?

Billet aluminum is the core tooling necessary for pressure forming.

Moreover, the billet aluminum is temperature regulated as a way of attaining ideal repeatability as well as high cosmetics.

What are the Design Considerations for Pressure Forming Mold?

Tolerance

• In most instances, there will be variance in tolerances from part to part, of course, depending on different elements such as shape, materials, size, number of cutouts, and other configurations possibilities.

Material Thickness

• Ordinarily, material starting thickness becomes thinner after part formation.

Nonetheless, the level of thinning is also dependent on the depth of draw, shape, size radii, and fillets, among others.

Draft Angles

• Generally, the draft angles for negative mold should be 2°-4° as a way of preventing lockup of a part in mold.

However, texturing on the tool side, complex configurations may need a more daft angle.

Radii and Fillets

• It is always vital to know that large fillets and radii create stronger parts and form thicker corners.

How does Pressure Forming Work?

Pressure forming – Photo courtesy: Ray Plastic

A pressure box is added to the non-mold side of the plastic sheet.

After that, the molten plastic material forms a seal between the mold and pressure box.

What follows is the addition of air pressure of up to 60 PSI to the non-mold side of the plastic material.

This is in addition to pulling off the vacuum on the side of the mold.

This is what enhances the forming pressure to about three to four times more than what is present in vacuum forming.

It is the added pressure that helps in the formation of thermoformed parts that have relative sharp details.

Which is Better, Pressure Forming, or Twin-sheet Thermoforming?

Each process is unique in its way and offers different advantages as well as disadvantages accordingly.

Therefore, the better option here all depends on what you specifically want to attain and the particular application.

What is Undercut in Pressure Forming?

It refers to an inward-facing flange which tends to add fundamental value to the ultimate product in the pressure forming process.

Undercut in this process can also include other features which are not essentially parallel to the mold’s pull out direction.

Can you Achieve Fine Texture with Pressure Forming?

Not in all cases.

It depends on the type of plastic material that you’re using to form the part and other factors surrounding the process too.

What is the Requirement for Ribs and Louvers in Pressure Forming?

The distance between each rib and louver must be greater than or equal to its depth.

What are the Common Problems in Pressure Forming?

– Thinning

• This arises especially during the process when the plastic material is stretched too thin hence leading to the possibility of cracking. A suitable way of preventing this from happening is by using plug assists.

–  Cold Flow

• It happens when plastic material in the cavity loses excessive heat and begins to solidify before the cavity is filled.

The ideal way of preventing this is by regulating the temperature settings appropriately and always using suitable types of plastic materials.

Why is Controlling Temperature of Tooling System Critical in Pressure Forming?

It is critical because without regulating it, the tool would certainly heat up during the process, given that it continuously comes into contact with more heated plastic sheets.

So it prevents waiting for the tool to cool between each part of molding, which would rather slow down the process significantly.

What Components and Parts can you make though Pressure Forming?

• Control panels
• Monitor bezels
• Computer fronts
• Scientific instruments
• Medical equipment
• Multi-part assemblies
• Vented equipment enclosures
• Detailed components