How is Thermoforming Process Used in Product Manufacturing?
Thermoforming is a process used to heat a thermoplastic sheet until it gets soft. The sheet is stretched across a single-sided mold and then it is manipulated. Then it is cooled down into the desired shape. Some of the most common methods are used to get the sheet to conform to its final shapes such as vacuum-forming, mechanical forming and pressure-forming.
The process of thermoforming has innumerable uses and can be used using different industries. Let us understand the process through a brief overview, its benefits, and major applications.
Main Terminology
The process of thermoforming uses some key terminology with which you must be familiar. Understanding the difference between the terms is important to deliver a successful project or else it might lack luster.
Thermoforming: It is a general term that involves transforming a plastic sheet into a 3-dimensional shape by using vacuum, heat and pressure.
Thermoplastics: It refers to a type of plastic made from polymer resins. These become homogenized when heated.
Vacuum Forming: It is a specific process that involves heating and stretching the plastic across a mold using a vacuum. Generally, the mold is open and the force involved with forming the sheet is limited to about 15 PSI.
Pressure Forming: In this process, a pressure box is added to the tooling package. It uses both the vacuum and positive air pressure. This process generates about three to four times the forming pressure just the way vacuum forming does. Therefore, fine details such as surface textures can be formed on the mold without costing extra.
Twin Sheet Forming: As the name suggests, there are two molds for this process: one on the top, other on the bottom. Therefore, two sheets of plastic are heated and formed at the same time. A fused joint is placed around the perimeter of the mold when the air pressure is injected in the sheets.
This process is perfect to form hollow parts that require a distinct upper and lower shape.
Stages of Thermoforming
Like any other process, there are several stages of thermoforming. Thermoforming process goes through the following stages:
Designing
Prototyping
Final tooling
Production
Shipping
Equipment Used for Thermoforming
The thermoforming process is carried out by using a few pieces of equipment. The process would require two pieces of equipment such as a pressure former or a vacuum former.
The process may also require a three or a four-station rotary transformer. The secondary operation of the process also needs CNC robotic routers. Normally the bed used for this piece of equipment does not exceed 60”X 120”. The tooling process needs machine aluminum molds, composite or temporary molds, cast aluminum molds, or even male/female molds.
Features of Thermoforming
Before discussing the benefits, we will look into the features of thermoforming which makes the process favorable over other types of molding processes.
Some of the main features are as follows:
The same material can be used to create several finished parts.
It allows the detection of possible design and fit issues before it gets really late.
Saves a lot of time and money.
Ideal when using large parts.
Now, let us look into the benefits.
Benefits of Thermoforming
There are a lot of benefits of thermoforming process to both end user and manufacturer such as:
Efficient
Cost-effective
Short lead time
Easy to add details
Freedom of design
To know more about the benefits, read this blog.
Thermoforming Applications
The thermoforming process can be used in a wide variety of applications. Some of the common ones are as follows:
Retail clamshell packaging
Packaging blisters
Pick and place trays
Material and handling tray and covers
Shipping trays
Medical packaging
Pop displays
Packaging inserts
General Practices
Here are some of the general practices that you must follow to complete the thermoforming process.
Draw the dimensions to and from a controlled surface.
The controlled surface must be against mold.
The thickness of the stock material may vary by +/-10%.
Material stretch should be based on mold configuration and depth of the draw.
Thermoplastics
These are the final products that result from the thermoforming process. One of the major benefits of thermoplastics is their tolerance to repeated activation. So, it can be reshaped and reheated as many times as required. Such characteristics also make thermoplastics recyclable
Further, due to chemistry, thermoplastic materials show the same characteristics as rubber and have strength similar to aluminium.
The temperature tolerance of thermoplastic materials differs. Some materials are able to retain their properties up to 100 degrees F, while others are able to withstand temperatures up to 600 degrees F.
Most thermoplastics do not have a known solvent at room temperature and also function well both as electrical and thermal insulation. These can also be electrically conductive if the metal or carbon is added.
Nature of Thermoplastics
Thermoplastics has a long history that dates back to the mid-1800s. These were specifically used as a substitute for ivory and now these have grown to be a part of everyday life.
Some common places where you can see thermoplastics are:
• Sports equipment
• Toys
• Auto parts
• Compact disks
• Food storage containers
• Eyeglass lenses
• Grocery bags
• Bulletproof vests
Vacuum Forming
Thermoforming and vacuum forming are related concepts. In fact, vacuum forming is a type of thermoforming process. However, at the same time, there are some differences too. So, let us distinguish between the two processes.
Vacuum forming involves some additional processes too that cause the plastic to conform to the mold. Compared to thermoforming, vacuum forming has more restrictive uses. It is normally reserved for applications that use shallow plastic parts which are required to be converted into cavities.
Other important information about vacuum forming includes the following:
Suitable Materials
There are just a few materials that are suitable for vacuum forming applications. The best ones are:
• Thermoplastics
• HIPS
Uses
Vacuum forming is great for some specific applications because the vacuum-formed components can replace complex fabricated sheet metals, plastic injection molding and fiberglass.
Some places where you can see vacuum forming evidence are as follows:
• Kiosks
• ATMs
• Medical imaging enclosures
• Diagnostic equipment
Issues With Vacuum Forming
Despite all of the positive attributes, vacuum forming does have drawbacks. Some of the common issues include are:
• Molds can easily absorb moisture forming bubbles.
Thermoset Plastics
Thermosets are synthetic materials which get strengthened when they are heated. Although they are closely related to thermoplastics, there are a few differences between both. Unlike thermoplastics, thermosets cannot be remolded or reheated.
Characteristics of thermoset plastics are as follows:
Thermo stability and performance.
Dimensional stability
Resistance to heat, creep, corrosion
Superior hardness
Comprehensive strength
Excellent moldability
Creation of Thermoset Plastics
Thermoset plastics can be created in different ways such as compression, injection molded and compression-injection. Regardless of the method of creation, heat is needed to mold the material.
Common Uses of Thermosets
Thermosets are known for their strength, permanent bonds that are irreversible. Some examples are:
• Electrical housing components
• Insulators
• Heat shields
• Circuit breakers
• Switchgear
• Motor components
• Thrust washers
• Ash cups
• Valve covers
• Disc brake pistons
• Knobs and handles
Other components that are easily exposed to heat or electricity
Materials Used for Thermosets
Common materials used for thermosets are as follows:
• Melamine formaldehyde
• Polyester resins
• Phenolic resins
• DAP (Diallyl Phthalate)
• Epoxy
• Urea-formaldehyde
About Us
Vacumatic is a commercial vacuum packaging machine manufacturer in Australia. We deal in the manufacturing and export of custom-built machines such as vacuum chamber machines, tray-sealing machines, thermoforming machines, die blocks, die lifting devices etc. To know more about our services, contact us.
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