Thermoforming of blisters is a manufacturing process where a plastic sheet is heated to a pliable, forming temperature, formed to a specific shape in a mold, and then trimmed. The sheet, or “film” is heated in an oven to a high-enough temperature that is then stretched into or onto a mold, and cooled.
In its simplest form, a small tabletop or lab size machine can be used to heat small cut sections of plastic sheet which are then stretched over a mold using a vacuum process. This method is often used for sample and prototype parts.
In complex and high-volume applications, very large production machines are utilised to heat and form the plastic sheet and trim the formed parts from the sheet in a continuous high-speed process. This method can produce many thousands of finished parts per hour depending on the machine and the mold size.
In the most common method of high-volume, continuous thermoforming of blisters, plastic sheet is fed from a roll into a set of indexing chains that incorporate pins, or spikes, that pierce the sheet and transport it through an oven for heating to forming temperature. The heated sheet then moves into a forming station where a matching mold and pressure-box close on the sheet, with a vacuum then applied to remove trapped air and pull the material into or onto the mold, along with pressurised air to form the plastic to the exact shape of the mold. The sheet containing the formed parts then moves into a trim station on the same machine, where a die cuts the parts from the remaining sheet matrix, or else moves onto a separate trim press where the formed parts are trimmed. The sheet matrix remaining after the formed parts are trimmed is typically wound onto a take-up reel or fed into an inline granulator for recycling.
There are many thermoforming companies out there that produce blisters, but be aware that it’s not easy to find the right one. Do they have the right equipment for your job? Are they capable of making the right tools? And what about reliability, consistency, hygiene? And more importantly, often thermoforming is just one piece of the puzzle. To create a successful packaging solution you need to have all the pieces. Often blisters need to be sealed against another blister or a blister card, or covered by a sealing film. That can be pretty tricky. But don’t worry! At Ecobliss, we always ensure quality and we know how to integrate all the pieces so that there will be no puzzle left for you to solve.
Ron Linssen, Managing Director