Industrial and Commercial processes AIM To be able to DESCRIBE the processes of blow moulding, injection moulding, vacuum forming and line bending thermoplastics To be able to EXPLAIN the advantages and disadvantages of using these methods for batch and mass production of graphic products. To be able to describe the process of printing directly onto thermoformed products

Structural packaging nets A net, also known as a development, is a flat 2D shape than can be cut, scored and folded to produce a 3D shape. Nets are widespread in the production of packaging using cartonboards. The packaging of a product is extremely important as it serves four main functions. To contain the product safely while in transit using suitable materials and containers. To protect the product while in transit to avoid breakages and unnecessary wastage by using suitable materials. To dispense the product in a safe and convenient manner by using suitable closures. To advertise the product for retail purposes in order to initially attract the customer’s attention and then provide essential information. Many companies produce standard packaging nets for designers to adopt and simply add individual graphic identity. This ultimately will save valuable time and costs in developing a product to market. There is also an internationally recognised system using diagrams of net constructions and symbols that avoids the need for lengthy and complicated verbal descriptions, especially useful in the global marketplace.

Designing and creating packaging nets The accuracy of the drawing is extremely important when constructing nets. When drawing nets, technical drawing equipment or CAD programs should offer accuracy and consistency. To produce an accurate net the final 3D shape will need to be developed and drawn either by hand or on computer. This will enable the shape, size and layout of the net to be drawn more easily. The net will need to show the following constructional information: cut lines — a continuous line where the material is to be cut fold lines — a broken line where the material is to be scored, folded, bent or heated tabs — essential constructional information especially for paper, card and board showing where glue is to be applied or where dust flaps or tucks are required the closure system annotation — will assist in labeling edges, sides and features in relation to one another

Making the die form Packaging nets or cartons need to be cut to shape after printing, and before assembly or gluing. The cutters used are called dies and the stamping process is called die cutting. Making a die form is still a skilled hand-crafted process, which involves cutting and shaping hardened steel rulers and matrix strips that will either cut or crease the cartonboard on the die cutting machine. Ejector rubbers are added to cutting rulers in order to push the cartonboard away from the rulers after a cut has been made. The die form is then mounted on the die-cutting machine. This process will be the major cost in the setting up of the carton-making job. To the left shows an example of how the cutting blades for a die are set. Above provides a side on example of how the cutters stamp out the material

Folding and gluing The carton blanks are then folded and glued on a highly automated gluing line. The first operation is to pre-fold one of the creases, and then the carton will travel to an automatic gluing station. The gluing module is ‘timed’ by a simple control system. When the front edge of the card blank breaks a light beam it triggers a device that squirts tiny drops of glue in quick succession. These form a row of adhesive that will soon be used to fasten the assembled carton. The final fold is made and the edges are held together under moving belt until they reach the final stage. The cartons are stacked up and compressed, using carefully controlled pressure, under another pair of slow-moving rubber belts. Here the adhesive has time to cure, before the cartons are removed and packed for transit. The cartons are then shipped to the customer’s site for assembly and filling

There are three main processes for use with thermoforming plastics Injection moulding Blow moulding Vacuum forming Line bending Many items are mass produced using thermo forming processes to mould and shape plastics. Thermo plastics are commonly used because they can be: moulded very easily Waste produced can be recycled

Injection moulding This can produce large quantities of identical products very quickly This is the most widely used industrial method to produce moulded plastic items Injection moulding is fully automated and involves little labour The product produced is self finishing and requires very little hand work 1.Plastic granules are fed from hopper in to a heated barrel by an Archimedean screw 2.The plastic is forced under pressure into a mould 3.Once the product is formed, the mould opens and the product ejected

Injection moulding process

BLOW MOULDING Can produce large quantities of identical products very quickly Is widely used to produce hollow objects such as bottles Blow moulding can produce very intricate mouldings e.g. screw threads for bottles 1.A small hollow tube called a Parison is extruded downwards between two halves of the mould. 2.The mould then closes around the neck and the base. 3.Hot compressed air is blown in to the parison 4.The parsion expands out to the walls of the mould and forms the bottle shape. 5.Once cool, the newly formed bottle is ejected from the mould.

Vacuum forming Probably the easiest method of thermoforming plastic in schools To vacuum form you first need to make a mould, usually out of MDF, as it is easy to shape and has a good surface finish. The mould is placed on the platen. It is then lowered to sit above a vacuum cavity. HIP sheet is securely clamped down above the mould and heated by the heater. Once soft, the platen is raised and the vacuum is turned on, forming the HIP sheet over the mould.

The same method is used in industry but on a much larger scale. Commercial vacuum forming uses a plug to help form an accurate shape

Dome blowing Dome blowing is the process of forming domes, spheres and oval shapes, usually out of acrylic. The sheet of acrylic is softened in an oven and transferred to a dome- blowing machine, where it is clamped under a circular ring. Air pressure is applied, which blows the material upwards and forms it into a perfect dome shape. Commercial dome blowing can produce perfect domes of a maximum diameter of two metres without distortion. This process is used to produce signage and point-of-sale displays.

Line bending Line bending involves heating a thermoplastic sheet material such as acrylic over a strip heater, along a narrowly defined line, until it becomes soft and pliable. It is then usually bent over a former. Thermoplastics may be bent to any angle by using a jig or a former or, if the angle is not critical, simply by bending the thermoplastic sheet by hand and then holding it until it cools. This process allows items such as display stands, leaflet dispensers, detail pockets and acrylic signs to be made from flat-sheet material.

ProcessAdvantagesDisadvantagesPlastics used Applications Injection moulding Ideal for mass Low cost in volume Precision moulding Self finishing High initial set up cost Mould expensive to develop and produce Nylon, ABS, PS, HDPE, PP Casings for electronic products. Containers for storage and packaging Blow moulding Intricate shapes can be formed Can be hollow Ideal for mass or continual flow production High initial set up costs Large amounts of waste material produced HDPE LDPE PET PP PS PVC Plastic bottles Containers Fizzy drinks bottles Shampoo bottles Vacuum forming Ideal for batch production Inexpensive Easy to make moulds Can be easily modified Mould needs to be accurate to prevent webbing Acrylic Hip PVC RPS Chocolate box trays Yoghurt pots Blister packs Line Bending Ideal for one off and batch production Straight bends are produced efficiently Low set up costs Precise temperature control gives precise bend Computer controlled bending can produce many duplicate parts Bends must be accurately marked before folding Acrylic can bubble if over heated Formed bend must be allowed to cool, otherwise will bounce back Acrylic, PS,HIPS,PVC Displays and leaflet holders