Blog 42: Introduction to Vacuum forming
One of the most traditional and widely used processes for processing plastic materials is vacuum forming, also known as thermoforming. It is a process used in manufacturing to form plastic materials. We use vacuum-produced things every day and they are all around us. A heated sheet of plastic is wrapped around a single mold using suction during the vacuum forming procedure.
Vacuum forming is utilized in a broad variety of manufacturing processes, from the production of small custom parts on desktop devices to the production of massive parts on automated industrial machines.
This procedure uses a vacuum to force thermoplastic sheet material onto a core or tool after it has been heated until it is malleable. This production has a huge volume and requires a lot of capital, yet has very low production costs.
Now From forming areas as little as 150 mm by 150 mm to forming areas as large as 2 m by 2 m for extremely large industrial-scale goods, vacuum forming is available in a variety of forms and sizes. A number of materials, including wood, plastic, epoxy resin, foam, and even aluminum, can be used to create the forming cores or tools. Typically, you don’t need to make steel tools because plastic doesn’t need to be really hot or under a lot of pressure for them to last for thousands, if not hundreds of thousands, of cycles. In general, they can be either male (convex) or female (concave), but forming tools do need enough airflow so that the result can quickly pop off (or out of) the mold.
Although more draft always improves, a minimum of 3° of the draft is advised. It’s difficult to make undercuts, just like with thermoforming. Although it is possible, there are generally less expensive alternatives to make your goods.
Step-by-step process of Vacuum forming
Although vacuum forming dates back to the 1930s, it is still becoming more and more important today.
For prototypes and limited runs of specific forms, no other technique can offer the low cost, simplicity of tooling, efficiency, and speed of reproduction. Here is how the sequential vacuum forming method operates:
- Clamp: A sheet of plastic is placed in an open frame and clamped into place.
- Heat: The plastic sheet is heated to a softening temperature when it becomes malleable and suitable for molding.
- Vacuum: The heated, malleable plastic sheet is placed inside a framework that is lowered over a mold and vacuum-assisted pulled into position on the opposite side of the mold. Tiny holes must be bored into female (or convex) molds’ crevices for the vacuum to successfully draw the thermoplastic sheet into the desired form..
- Cool: The plastic must cool after being shaped around or into the mold. For larger items, fans and/or cool mist may be employed to expedite this stage of the manufacturing process.
- Release: The plastic can be taken out of the mold and loosened from the structure once it has cooled.
- Trim: The finished component must be separated from the surplus material, and any sharp edges may need to be trimmed, sanded, or smoothed off.
The Pros Vacuum Forming
Because vacuum forming offers a combination of design flexibility at a relatively low cost as compared to other production processes, many manufacturers, designers, and other professionals like it. Vacuum forming has advantages that include:
Vacuum forming is often less expensive than other manufacturing processes, such as plastic injection molding, especially for short production runs (250–300 units per year). The cheaper cost of tooling and prototyping is a major factor in vacuum forming’s affordability. Tooling for injection molding can be two to three times more expensive than tooling for plastic thermoforming or vacuum forming, depending on the surface area of the parts being created and the dimensions of the clamp frame.
Because tooling can be produced more quickly, vacuum forming has a quicker turnaround time than other conventional manufacturing techniques. The time needed to make vacuum-forming tools is typically half that needed to produce injection molding tools. Turnaround times can be significantly shorter when molds are made with 3D printers. Vacuum forming makes it possible for companies to distribute innovative designs to customers more quickly by improving production process effectiveness.
With vacuum forming, designers and producers have the freedom to test out new ideas and create prototypes without incurring significant costs or delays. In contrast to conventional manufacturing processes, molds can be simply replaced and/or modified because they can be built of wood, metal, structural foam, or plastics that have been 3D printed.
In the late 1970s and early 1980s, Dick Teal employed vacuum forming to test out prototypes of John Deere snowmobile parts, primarily because it made tooling affordable. Additionally, vacuum forming enables designers to provide customers with more color choices and customization options. This provides numerous firms the ability to create personalized products with unique designs for customers at a reasonable price, like dental retainers.
Manufacturing Sterile and Food-Grade Materials
Vacuum forming is frequently used by producers to create food-grade containers and components for the medical sector because it works well with polymers that can be sanitized or maintained free of impurities. For instance, vacuum-formed food storage containers are often made of high-density polyethylene (HDPE).
Due to its resistance to acidic substances, HDPE is a suitable material for vaccum forming containers for cleaning supplies. To produce parts that can endure sterilization procedures and adhere to strict medical and/or pharmaceutical criteria, vacuum forming uses medical-grade polymers.
The Limitations of Vacuum Forming
Vacuum forming has significant drawbacks in addition to its many advantages. Only items with relatively thin walls and straightforward shapes are suitable for vacuum forming. Vacuum forming makes it challenging to create concave pieces with a deep draw and the resulting parts might not have a constant wall thickness.
Additionally, other plastic manufacturing techniques may be more economical for very large production runs, even if vacuum forming is frequently the most cost-effective option for small to medium production numbers.
Vacuum Forming Applications
Vacuum forming is not appropriate for every design or shape, but it is still the most economical and effective way to handle the widest range of plastic processing applications. High-profile clients using Formech vacuum forming machines include Apple, Google, Disney, Bolshoi Ballet, Ford, Tesla, Ferrero Rocher, Nestle, Makita, Royal Air Force, Philips, Yale University, Dupont, and many more. These clients are involved in a variety of industries, including electronics, film & theater, automotive, aerospace, confectionery, packaging, education, and many more. These prestigious businesses and organizations’ continued use of vacuum forming shows that the technique is still the best option for a vast variety of applications..
Typical Products Produced using vacuum forming
- Baths & Shower Trays
- Yoghurt Pots
- Boat Hulls
- Machinery Guards
- Vehicle Door Liners
- Refrigerator Liners
- Sandwich Boxes
- Parts of vehicle cabs
- Exterior Shop Sign
Automotive and Transportation
Many components for vehicles, buses, boats, and airplanes are made by manufacturers using vacuum forming. Vacuum shaping is used to create everything from truck beds to floor mats to bumpers for cars.
Vacuum forming gives designers the ability to test out new prototypes during the development process and enables automakers to offer consumers a variety of color and detail options.
Many industrial crates and machine-specific containers are made by manufacturers using vacuum forming.
Because industrial producers can utilize a choice of flame-retardant and UV-resistant materials, vacuum forming is a perfect manufacturing process for items predominantly used outdoors or ones that may come into contact with a heat source. For instance, UV-blocking acrylic (PMMA) and fire-resistant UL 94 V-0 polyvinyl chloride (PVC) can both be vacuum produced.
Packaging and Displays
There’s a good possibility the packaging for a product you purchase that comes in plastic that matches its design was created using vacuum forming. Products including razors, toothbrushes, electronics, cosmetics, and cleaning supplies frequently come in vacuum-formed packaging.
Additionally, vacuum forming is frequently used in the production of marketing displays, point-of-purchase (POP) displays, and grocery aisle end cap fixtures.
Because vacuum forming is compatible with food-grade plastic and can generate pieces that are simple to sanitize, it is frequently utilized for food packaging.
Vacuum formed products include fruit jars, plastic egg cartons, and cracker trays.
A wide variety of consumer goods are produced utilizing vacuum forming. Manufacturers can use vacuum forming to produce a variety of goods, including children’s toys, travel gear, and home furnishings.
Vacuum forming is frequently used in the manufacturing of medical parts and components that need to be antimicrobial or resistant to contamination.
This includes hospital bed parts, medical packing, pharmaceutical trays used to store tablets, and exterior MRI and CT equipment bits.
Custom Parts and Special Effects
Many businesses employ vacuum forming to produce unique and customized items, such as special effects props.
Materials for Vacuum Forming
The manufacturing process of vacuum forming is suitable with a variety of thermoplastics. The most widely utilized polymers are:
- Acrylic (PMMA)
- Acrylonitrile butadiene styrene (ABS)
- Polycarbonate (PC)
- Polyethylene (PE)
- Polyethylene terephthalate glycol (PETG)
- Polypropylene (PP)
- Polystyrene (PS)
- Polyvinyl chloride (PVC)