Plastic Vacuum Forming FAQ

Plastic vacuum forming is a process where a plastic sheet is stretched on a female mold with a cavity, it is then heated to a specific softening point, and then vacuum pressure force is applied on the plastic sheet, forming it into the mold to have the right 3D shape.

WeProFab is one of the best vacuum forming companies who can manufacture kinds of vacuum forming products. They could be used in a wide range of applications, such as vacuum formed packaging, stackable containers, plastic pallets, plastic blister, polycarbonate police shields, acrylic domes, signage, and many other custom vacuum forming products.

WeProFab is a vacuum forming plastic manufacturer who can do vacuum forming for thin and small products. We can also do large and thick sheet vacuum forming.

Vacuum forming for thin and small products is normally applied to vacuum formed packaging, such as plastic blisters, plastic component trays, makeup trays, and more. In many cases, they are made from PVC vacuum forming, PETG vacuum forming, and PET vacuum forming. WeProFab is vacuum formed trays manufacturer. Plastic trays can be used in a wide range of applications.

Large and thick sheet vacuum forming is also called heavy gauge thermoforming. It uses thick plastic sheets to do vacuum forming, in order to make large and heavy plastic products such as acrylic bathtub, HDPE pallets, plastic enclosures, polycarbonate police shields, and more.

WeProFab is also one of the vacuum forming plastic manufacturers who can handle different kinds of vacuum forming materials. We can do vacuum forming acrylic for acrylic bathtub and acrylic skylight. We can handle vacuum forming polycarbonate for polycarbonate police shields and polycarbonate skylight. We can do ABS vacuum forming for ABS enclosures and ABS housing. We can do HDPE vacuum forming for plastic pallets. We can handle vacuum forming polypropylene for PP containers. We can do PETG vacuum forming for PETG blister. We can do polystyrene vacuum forming for PS containers.

WeProFab is the vacuum forming plastic manufacturer who can make your required vacuum forming plastic products according to your drawing and specifications.

Plastic Vacuum Forming: The Ultimate Guide

What is Plastic Vacuum Forming?

It refers to plastic fabrication method which involves heating of a flat plastic sheet until it becomes pliable and then applying a vacuum to make it possible for it to shape accordingly.

What are the Benefits of Plastic Vacuum Forming?

• It allow for design flexibility which is essential given that it makes it possible for products to attain the company’s or designer’s aesthetics.
• Products made of vacuum forming tend to be relatively precise as far as design specification are concerned.
• This is specifically vital for components which require to fit into other objects.
• It provides an economical option for production given that it is generally simple and time efficient.
• The net effect of this is that it helps in ensuring that the products get into the market faster and at the same time liberating time to focus on detail of the product.
• Plastic vacuum forming is also comparatively cost-effective since it utilizes low pressure hence needs small quantity of less complex tools.
• It is also possible to produce large components all from a single sheet which is essential as far as reducing on production cost is concerned.

Can you Vacuum Form PVC?

Yes you can. And for better results, it would be ideal to vacuum form PVC on automatic forming machines.

What are the Disadvantages of Plastic Vacuum Forming?

• It is somehow difficult to produce as many pieces as faster as you would do with other processes. Of course vacuum forming is somewhat cheaper but you need to always regulate it apart from also being slow.
• You only need to use plastic pieces that are shallow since deeper pieces present the chances of twisting or warping in the process. And in any case you need to use deeper pieces, you’ll have to take extra precautions which eventually leads to additional cost.
• In some instances, it leads to distortion given that the plastic material might start to form bubbles due to air pockets which get into the sheet as it is stretched and molded.
• Vacuum forming of plastic is also vulnerable to several problems such as absorbed moisture among others, which tend to weaken it hence affecting the quality of the final product.

What are the Stages in Plastic Vacuum Forming?

Professional plastic vacuum forming involves the following stages;

 Steps in vacuum forming – Photo credits: Mampshire signs

· Creating the Mold

It is the first step that you have to undertake.

Construction of the mold needs to take particular shape which plastic shall form around.

If possible, it is always important to ensure that the mold has angled edges. The essence of this is that it will enable the part to pop out plastic the moment vacuum forming is complete.

· Put the Mold in Vacuum Former

Vacuum former is an oven where you place the mold then clamp the plastic sheet above it and not necessarily on the mold.

· Place the Heater on Top of the Plastic

The heater on the vacuum former is put above the plastic as a way of making it to heat up and eventually warm up the plastic sheet to ensure that ideally flexible and moldable.

· Moving the Shelf in the Direction of the Plastic

The plastic material should be at the appropriate temperature within a few minutes to enable molding.

· Switching on the Vacuum

In this case, you only need to turn on the vacuum former which will, in turn, eliminate the air from the machine.

It is what makes it possible for the plastic material to form the actual shape of the mold.

· Take out the Plastic from the Vacuum Former

Remove the plastic material from the vacuum former once it has cooled.

Then you need to remove mold from the machine then try to trim any unnecessary or excess plastic from the sheet.

Is there a difference between Vacuum Forming and Thermoforming?

Yes.

Vacuum forming is a technique of plastic thermoforming.

Of course, the two refer to the process of shaping plastic material to a suitable part and component.

How Does Plastic Vacuum Forming Compare to Other Thermoforming Techniques?

In mechanical forming, the pressure is exerted mechanically to force thermoplastic material into or around the mold by direct contact.

What happens here is that the core plug pushes the thermoplastic sheet in the mold cavity the forces it into a desirable profile.

Drape forming involves heating and stretching down of a plastic sheet over a male mold.

It then uses gravity to pull the plastic sheet depending on the mold’s profile.

Alternatively, vacuum application can be ideal to draw the sheet to the mold to provide additional details to the inner side of the component.

Pressure forming, on the other hand, involves utilization of a vacuum underneath the sheet in addition to the application of air pressure on the rear side of the sheet to assist in forcing it into the mold.

It is the additional force that makes it possible for the formation of relatively thick sheets.

Moreover, it allows for the creation of sharp corners, undercuts, finer details, and texture, among others.

In matched die forming, the formation of the two halves of the part takes place with no air pressure or vacuum.

Heating of the plastic sheet takes place until it becomes soft then followed by clamping of the two molds to form the part.

It is an ideal process for parts which essentially don’t have huge draws.

In-line thermoforming involves the movement of the material film from a trundle onto the in-line tool and through the heating zone.

So what happens is that the heated plastic sheet moves into the creating unit where the vacuum or pressure forces the material on to the mold.

Afterward, it moves to a different section where cutting of the formed components takes place.

In twin sheet forming, pressure or vacuum simultaneously forms two sheets of thermoplastic with one mold at the bottom and the other one on top platens.

In this method, immediately, molding of plastic material occurs; it stays in the molds.

And while it still maintains the forming heat, both molds are conveyed together under intense pressures as they are welded where the molds determine a weld.

Free forming on the hand involves clamping of acrylic sheet in a frame, and compressed air or vacuum draws the sheet to the desirable sheet.

It utilizes an electric eye to determine whether or not the ideal depth is attained and cuts off the pressure.

In free forming, there is no mark-off given that it’s only air that gets to touch the sheet of material.

In the stretch forming technique, plastic sheet is heated and then hard-pressed over a mold and successively cooled.

This technique provides a high degree of repeatability, offers efficiency, and it is quite faster.

Can ABS be Vacuum Formed?

Yes. In fact, it is among the most popular types of thermoplastic materials commonly used in vacuum forming as a result of its suitable properties.

When was Vacuum Forming Invented?

1964 is the year it was a vacuum forming the machine was invented, perfected and patented following a series of improvements in the 1950s.

Can you Vacuum Form Polycarbonate?

Yes, and it is among the most popular plastic materials for the vacuum forming process.

What Products are made Using Plastic Vacuum Forming?

• Automotive headlight covers
• Economical plastic pallets
• Plastic trailers
• Recreational goalie
• Plastic totes
• Engine blocks pallets
• Plastic mower hoods
• Vehicle door liners
• Exterior shop designs
• Boat hulls
• Shower trays
• Machinery guards

Is there a Minimum Thickness Requirement for Plastic Vacuum Forming?

Not necessarily because the thickness requirement for this process is dependent on several factors, including height, general size, pocket depth, and many other complexities.

However, a rule of thumb for minimum material thickness in vacuum forming is that it has to be thinner during part formation.

Vacuum forming plastic

Can Polycarbonate be Vacuum Formed?

Most definitely.

It actually displays some of the exceptional mechanical properties, thus making it an ideal type of plastic for vacuum forming.

How do you Design Plastic Vacuum Forming Mold?

Plastic vacuum forming

It is a process that is quite involving.

The first step in this process is always to obtain your mold.

This is what shall guide you on how the replicas of your final parts will be like.

At this stage, it is also vital to ensure that you consider drafting angles since it allows you to remove your molded part from the mold easily.

The second step is the preparation and printing of the model.

While at this, it is necessary to look into the different print settings.

A good idea here is to increase shells as well as infill settings to form a stronger mold that can withstand vacuum forming pressures.

Step three involves the preparation of the mounting fixture.

It is significant to secure the mold to an extra fixture to hold it in position against various possible forces likely to occur during machine operation.

The fourth step is loading and heating the plastic material to the required temperature.

At this stage, it is recommended that you select thinner sheets, particularly if your machine doesn’t form larger amounts of suction or heat consistently.

The ideal temperature for heating the plastic should be about 400°F.

The next stage involves pressing of the heated plastic material over the form.

It is here that you’ll realize that vacuum suction pulls out all the air, and the material starts to cool immediately.

The sixth step is allowing the material to cool immediately the air is eliminated from under the plastic and formed over your mold.

Remove the formed part and place it aside to cool. If you need more, you can repeat the process.

But once you achieve the required number of parts, you can as well go ahead and cut away any spare plastic.

What is the difference between Plastic Injection Molding and Vacuum Forming?

Plastic injection molding involves creating of plastic components by melting plastic sheets and injecting it into an injection mold tool.

Vacuum forming, on the other hand, involves making of plastic components by melting plastic sheets over a vacuum forming tool.

Another difference is that in injection molding, you can attain exceptionally small tolerances and achieving identical products repeatedly.

On the other hand, in vacuum forming, you can only attain reasonable tolerances, but only when the material is stretched into or over a tool.

You can use plastic injection molding to make extremely detailed parts since the material is injected inside the mold.

In vacuum forming, however, versatility is limited given that plastic material is stretched into or over the mold.

Can you Vacuum Form Polypropylene?

Yes, but you ought to find the right grade of polypropylene if you need to get ultimate desirable results from vacuum forming.

Does Plastic Vacuum Forming has Size Limitation?

Yes, it does, but it all depends on various factors surrounding the process, such as type of machine, type of plastic, size, and desirable configurations, among others.

PC Forming process

What are the Common Problems in Plastic Vacuum Forming?

1. Moisture Absorption

• It causes the formation of bubbles within the inner layers of the plastic material.

The solution to this problem is the drying of the plastic material for a longer duration at a relatively high but sub-melting temperature.

2. Webbing

• It leads to formation of the web around mold as a result of material’s overheating.

To solve this challenge, always ensure that carefully monitor the heating temperature and regulate it accordingly.

Also, you may check the mold to ensure that its size is appropriate and that the mold parts are not closer together.

• You can as well consider using female tool rather than male tool in the even that webbing occurs in between parts of the tool.

3. Uneven Heating of the Sheet

• The ideal resolution for this is always to screen out the hot spots and to check the forming oven for features which are overheating.

4. Sticking Parts

• It causes the objects formed to always stick to the mold.

Solving this problem requires ensuring that there is always an angle of at least 3 degrees.

5. Excessive Material for the Task

• Always ensure that you use a reasonably small plastic sheet to make it possible for the mold to stretch the material more.

Can you Vacuum Form HDPE?

Yes. In fact, it is one of the popular plastic materials commonly used in vacuum forming as a result of excellent strength, durability, and ability to withstand temperature range.

What Factors Affect Quality of Plastic Vacuum Forming?

• Material size
• Shape
• Heating temperature
• Draft angle
• Texture(Surface quality)
• Undercuts
• Radii
• Tolerance
• Part integrity and functions

After Plastic Vacuum Forming, What Other Finishing Operations are there?

1. Guillotining

• It refers to a method of removing vacuum formed parts from the sheet in a clean way.

It is ideal for parts of low volumes where straight lines are not an issue.

2. CNC Machining

• It is the most suitable way of creating holes and features on vacuum formed parts.

3. Roller Cutting

• It is used for cutting vacuum formed products from the original material of the vacuum forming sheet.

4. Drilling

• It is used for creating simple holes in the vacuum formed parts, especially for small quantities.

5. Vertical Press Cutting

• It refers to the precise technique for cutting vacuum formed items using press and precision made cutting tools.

How do you Choose Plastic Vacuum Forming Machine?

Plastic vacuum forming machine

You need to look into the following factors when selecting an ideal vacuum forming machine;

• Height of the machine
• Sheet width
• Air pressure
• Thickness range of the material
• Draw depth
• Dimensions of the machine
• Forming area
• Power consumption
• Clamping force
• Air consumption
• Knife length

Is Plastic Vacuum Forming Tooling Expensive?

Not necessarily.

It is considered to be comparatively affordable to most of the other methods of plastic fabrication.

In addition, you can as well make tooling from wood for first off and prototype parts.

What do you need to Start Plastic Vacuum Forming?

The essential thing to have is the concept.

Once you have the concept you’ll work with professional design engineers throughout the design process.

It is to ensure that they come up with the right fundamental elements.

Ultimately, you’ll attain the desirable vacuum formed part that meets your requirements.

How does Male Mold and Female Mold in Plastic Vacuum Forming Compare?

A male mold is also referred to as positive mold.

It is the element that allows the plastic material to be stretched over it, after which the vacuum application enables it to draw the plastic down onto raised mold surface.

On the other hand, a female mold, also known as negative mold refers to the element where the application of vacuum draws the plastic down into a cavity.

An ideal way of determining the most appropriate type for you involves considering different aspects such as tolerances, surface finish, and shape of finished part, among others.

Figure 6 Male mold vs female mold

Which Material is Suitable for Plastic Vacuum Forming Mold?

Characteristically, the ideal material for plastic vacuum forming mold are thermoplastics with a set of features that emanate from their properties, atomic makeup and additives variance.

Some of these materials include;

• PP
• HDPE
• PMMA
• PETG
• LEXAN
• HIPS