| .. Resources .. Signs Alphabet .. Vacuum Forming Signs .. Stephen Way, Introduction to Vacuum Forming and the Sign Industry |
Introduction to Vacuum Forming and the Sign Industry |
Stephen Way |
 |
What is vacuum forming?
Simply put, vacuum forming is the process of taking a flat sheet of plastic and changing it into a contoured shape. This is achieved by clamping a sheet of plastic in a frame and heating it until it becomes soft and flexible.
The heated sheet is then stretched over a mould and the air is removed from underneath the mould cavity allowing atmospheric pressure to force the plastic over the mould. The plastic sheet then takes the shape of the mould. The plastic is then cooled to retain it's shape and finally removed from the mould and trimmed as required to create a finished part.
Thermoforming is any process of forming thermoplastic sheet to change it's contour. Vacuum forming is one of these processes however this term is also often used to refer to all sheet forming techniques.
Although vacuum forming has been utilised in the sign and display industries for many years, it is now becoming a major player with the recent introduction of a range of new materials and techniques which is revolutionising the thermoforming industry.
Decorative films are rapidly gaining recognition in the marketplace. A selection of colours, wood grains, marbles, stainless steel and even chrome and gold laminates are allowing vacuum formers to produce products that have the benefits of plastics and the appearance of the replaced material.
Once thought to be unusable in forming applications, UV inks have transformed the production of vacuum formed products particularly in the signage and promotional display area. These inks and decorating production techniques would be familiar to graphic screen printers.
There is also a myriad of coloured 3M vinyls available which have been specifically developed for thermoforming processes. They are UV stable for outdoor signage and have up to a 9 year warranty in outdoor conditions after being vacuum formed.
OCE
Oce have just marketed a 3D signage digital inkjet printer which allows signmakers to print directly onto rigid plastic substrates, and then use vacuum forming technology to create a 3D sign. Utilising the latest in distortion software the signmaker can turn a quality graphic into a 3D display. www.oce.com/au
Cyberform Industries, an Australian company with a background in the sign industry, recently launched the SUCK-A-TRON 2000 which is a precision vacuum forming machine designed to give the entire sign and display industry access to vacuum forming technology.
This technology has traditionally been the domain of a few larger companies mainly due to the high machinery costs and high running costs. The SUCK-A-TRON 2000 overcomes both these impediments and also provides a host of innovative features. www.cyberform.com.au
LED Applications
The continual improvements in LED lights is also opening up new areas for vacuum formers. The combination of LED's and vacuum forming are giving some sign makers a competitive edge in the marketplace where illuminated signs and displays are required. This combination has several advantages over the more traditional neon or fluorescent in many cases.
Apart from the savings in running cost and maintenance, LED's radiate a very small amount of heat and can be easily and safely attached to plastic formed parts. This gives the manufacturer more creative scope in designing as he doesn't need to consider deep channels for lighting and can greatly reduce fabrication time. They are also more flexible for bending around smaller areas.
Vacuum formed under bench lighting is becoming a popular application. Because LED's run off 12 or 24 volts and don't get hot this also overcomes a safety issue.
Plastics manufacturers are continually experimenting with forming materials. Most of the commonly formed plastics are familiar to the sign industry and include ABS, Acrylic, Polystyrene/HIPS, Polycarbonate, Polypropylene, PVC and PETG.
However new materials for specialised uses are constantly being developed, eg. Polycarbonate/ABS which combines the strength characteristics of polycarbonate with the good forming capabilities of ABS. HIPS (high impact polystyrene) is popular in the sign and display industry for it's low cost, good forming qualities, is easily machined and can be painted or screenprinted.
Vacuum Forming Advantages
Vacuum forming offers several processing advantages over other forming processes such as rotational, blow and injection moulding. Because of the low forming pressures used, low cost tooling can be utilised also making it economical to fabricate large parts. Moulds can be made of relatively inexpensive material, can be made in house and in a very short time. This can result in short lead times and makes it economical to run prototypes, small runs and one off custom jobs.
There is a wide range of mould making materials to suit different production requirements. Selection will depend on what tolerances and cosmetics are needed, how many parts to be produced and how much you can afford to spend on a particular project. These include plaster, modelling clay, wood/MDF, polyester or fibreglass, epoxy resins, aluminium and sprayed metal.
A popular mould material with the signage industry is MDF because it is readily available, inexpensive, easy to fabricate into a shape, and it breathes - eliminating the need for vent holes in the mould. Also many sign makers have CNC routing equipment which will allow them to quickly manufacture more complicated moulds. There are also many pattern makers around who specialise in these types of moulds.
Many vacuum forming machines in Australia have been imported, custom built or home made to suit the production of a particular product and cannot be easily adapted to take on other forming projects. However new vacuum forming machines are getting more and more sophisticated particularly with excellent zoning and efficient heating elements.
To get the best forming results using any material, it is essential that the plastic sheet is uniformly heated over the entire surface and thickness. So heating is one of the most important ingredients in the vacuum forming process. There are numerous types of heating elements used, the most common of which are calrod, ceramic elements and quartz heaters, each having certain advantages and disadvantages over the other.
Starting your vacuum forming business
It is now economically possible for a business to enter the vacuum forming market at an advanced level and purchase a precision machine that can easily be upgraded when required, and therefore will never be outdated and, dare I say it, last a lifetime.
A growing number of screen printing and sign shops are adding vacuum forming technology to complement their image making capabilities, which allows them to maintain complete control over the entire printing and forming process, adds tremendous margins, gives them a huge competitive edge and the flexibility to quickly produce a quality 3D product.
This process also gives the sign maker the chance to be creative when it comes to general signage, as a limited amount of knowledge can produce a simple sign that looks a million dollars. Vacuum forming is only limited by the imagination. It is a very cost effective alternative to large cut out or fabricated letters, as one mould can produce many coloured 3D letters in a fraction of the time taken, and material cost in fabricating.
Vacuum forming machines are simple to operate and require a very minimal amount of training or skill. Obviously with more practical use the operator will become more familiar with the different types of plastics and their forming capabilities.
Limitations
Like most things however, vacuum forming does have its limitations. For example if you needed to produce 100,000+ of the same product you would choose injection moulding.
Although tooling and set up costs are much more expensive, scale of economics would make this option more cost effective. However, as far as the sign and display industry is concerned what would seem like a limitation, (undercuts, part detail or creating larger parts than the frame size for example), can usually be overcome with good mould design.
New vacuum forming materials and techniques will continually become available, and this spells an exciting time for the sign and display industry. If you're looking for that competitive edge it might be worth looking into - you may find that one of these machines could pay dividends!
|
|
Login
None