ProtoTYPING: Life in a Vacuum

Everyone of us has had this experience. You have just bought a new product that you have been lusting for or received as a gift. You are giddy with excitement and want to get your hands on it. The only thing that separates you from that moment of joy is a thin piece of plastic blister packaging. Then disaster strikes. You pull and rip and it doesn’t yield. Then you (likely) swear a little, get a pair of scissors, and cut straight through the beautiful insert card and probably the instruction manual. A small setback, but you are almost there. Then you pull and rip again. Nothing. Another few cuts with the scissors, more ripping, then you grab both sides of the plastic and pull as hard as you can. The plastic suddenly gives way, and in an instant, the package opens, your new product flies through the air and bounces twice on the floor before coming to a rest 10 feet from where you started.

Being one with an innovative mind, once you have dusted off your new product and finished fuming about the battle that just transpired, you may have wondered how the blister pack was made. The process used to make most of the blister packaging of some consumer products is called vacuum forming. While there are no tried and true methods to share with you to help open packaging without frustration, I can reveal how vacuum forming works, the products that are made with it, and how the Edison Nation engineering team uses the technology in their product development activity.

Vacuum forming is a type of deformation molding. This means that a piece of stock material is stretched over a mold shape to make a part. In contrast, most consumer goods are made by injection molding where liquid material is forced into a mold cavity and left to freeze into shape. In a vacuum former, a piece of stock plastic is locked down above the mold form and a vacuum chamber. A heater is brought in close proximity above the piece of plastic and allowed to warm the plastic to a prescribed temperature. When the material is at temperature, the mold form is lifted up and brought in contact with the hot plastic. At the same time, a vacuum pump is activated in the mold chamber and causes the hot plastic to stretch and wrap around the mold form to make the desired shape. The cycle time for the process varies with the thickness and type of plastic being molded, but typically takes between 20 and 60 seconds. Once the plastic cools, the part is removed from mold and it stays frozen in place.

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Schematic of a vacuum former

While blister packaging is one of the most common uses of vacuum forming, there are plenty of finished products that are made with this process. Some examples of vacuum-formed parts are bath tubs, interior car panels, back lit signs, and R/C car bodies. Even the pump cover on the OMAX waterjet cutter featured last month was made from a piece of vacuum formed ABS. A big advantage of vacuum forming is that it only requires a one-sided mold, so the tooling costs are typically lower than an injection mold that requires at least a two-piece mold. It’s also a very scalable process, and can be used to make parts that are just a couple of inches to bigger than 6 feet. In addition, it can be used with many types of plastics, so it is a very robust manufacturing process.

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?Vacuum formed ABS cover on the OMAX waterjet in the EN shop

The Edison Nation engineering team uses a Formech 508FS vacuum forming machine to help make prototype parts and packaging for a variety of projects. It has a 19? x 17? forming area and a 11.5? maximum part height, which is a perfect size for many of the Edison Nation projects. The process starts with making a mold. This can be done by machining a mold with our Tormach CNC machine,?cutting a shape on the laser cutter, or by 3D printing the shape. Then, we reinforce it with wood, bondo, or urethane so that it will stand up to the load from the vacuum pressure, and polish the contact surface so that the molded parts will be smooth. Then, we cut a sheet of material, set the heating power and heating time on the machine, and pull the heater over the plastic. Once the time is up, the heater is pushed away, the lever is lifted to get the mold in contact with the plastic. Then the vacuum is turned on and the material flows around the mold into the desired shape. We have used the vacuum former to make packaging for products like Hot Huez, and the Grapple toddler toy tether. We have also used it to make parts for the Everyday Edisons products like the carpet cleaner and the microwave steam cleaner that both aired in Season 4. We have also used it to make some covers and liquid holding vessels from ABS plastic for various projects.

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The Formech FS508 vacuum former

 

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Prototype packaging molds in the EN vacuum former

Vacuum forming machines are available in a variety of sizes and qualities, and there are plenty that are accessible to the at home maker and certainly for a small shop. Desktop vacuum formers can be found for a little over $1000 and they increase in price and size from there. There are also plenty of tutorials online that will help you to build one from scratch. So it is a very accessible process for a broad range of prototypers and makers.

Vacuum forming technology has had an enormous impact on both the packaging as well as finished consumer goods industries. It is a simple process that only requires one mold half and is scaleable from handheld items to swimming pools. It can also be used with a wide variety of materials making it a very robust way to manufacture products. The Edison Nation team uses the technology frequently to prototype products and packaging, and it may be a technology that you can use on your next project.


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