The process is known as screen printing. Silk screen printing is a name first used when the mesh or screen was made of natural silk. Nowadays screen mesh is either made from polyester, stainless steel or nylon. The basic items of equipment required to carry out screen printing are:
This consists of a frame onto which a mesh is attached under tension. The mesh is coated or covered with a photosensitive material. The image to be printed is created photographically on the stencil leaving open areas of mesh through which ink passes. The stencil is also know as "the screen".
A flexible polyurethane blade (sometimes rubber) held in a rigid mount or handle.
Can take the form of a wide range of solids or dyes suspended in a fluid.
This is a general term for the surface that is to be printed. The surfaces can range from bread to biomedical sensors.
The base provides a surface for the substrate to be printed and the upper section secures the screen.
In conventional screen-printing the squeegee carries out two functions. It deflects the stencil and brings it into contact with the substrate. The squeegee is held at an angle of typically 75 degrees to the horizontal. During the printing action the squeegee is moved across the stencil, creating a pressure wave in the ink. The actual point of flow is where the leading edge of the squeegee is in contact with the stencil. This is known as the "Flow Point".
Press types can be split as follows: Flat bed press (further split into hand bench, semi automatic and fully automatic), Cylinder press, Rotary screen press, Container (cylindrical) printer and Carousel textile press.
What makes screen printing so popular is the ability to lay down a film of a wide range of materials on a vast range of substrates. Everywhere you look are examples of the process and many places are hidden. Applications include: Posters and point of sale displays, gaskets, watch dials, key pads, transfers, electronic circuits, car windscreens, road signs, architectural glass, tableware, nameplates, labels, ceramic tiles, vehicle instrumentation, mouse mats, office equipment, membrane switches, estate agents boards, textiles, fuel cells, containers, electronic circuitry, playing cards, scratch cards, heating elements, footballs, baseball bats, cricket bats, tennis rackets, golf clubs, clocks, fine art limited editions, laptops, plasma screen televisions. These are just a selection.
Just like the method explained above for flatbed screen printing, cylindrical items can also be decorated by using a rotary screen printing machine. This is often the method of choice if an item is to be decorated by a design that wraps around more than a quarter of the circumference of. the item. In the promotional market place the most common items to be decorated using this process are pens and mugs. The process works by a cylindrical object sitting on wheels allowing it to spin freely up to 360 degrees. A squeegee is placed directly above the item; this is often referred to as top dead centre. A stencil with the image to be printed containing ink is all that sits between the item and the squeegee. The stencil is then moved in a horizontal motion causing the item to rotate. The stationary squeegee then pushes ink through the stencil onto the cylindrical item.
The image to be printed is created on the printing plate, normally produced by chemical etching. The plate is generally steel or a nylon photopolymer material. Conventional pad printing machines are divided into three families:
Pad printing inks contain solvents. The evaporation of the solvents from the ink is the main mechanism that enables the process to operate. When the ink is contained within the etched image area this evaporation of solvents causes the surface of the ink to become tacky. The shape of the pad is such that when it comes into contact with the tacky surface of the ink the ink sticks to the pad. As the pad lifts the printing surface rolls away from the plate and lifts up ink from the etching.
Whilst the pad moves towards the object to be printed the solvent continues to evaporate from the ink on the pad and the outside of the surface of the ink becomes tacky.
As the pad makes contact with the object and compresses, the print surface of the pad rolls across the object and the tacky surface of the ink attaches itself to the surface of the object. The pad then lefts and the printing surface of the pad rolls away from the surface of the object and releases the ink leaving it laying on the surface. Whilst this is happening the etched portion of the plate is recharge with ink, and the pad returns to pick up another image from the plate.
A whole range of variables will affect pad printing. Etch depth, ink condition, ambient conditions, pad shape, surface finish, hardness and machine speed are the key factors.
A digital transfer is a way of producing full colour designs, which are too complex to be screen printed, for application for garments, caps, or bags via a heat process.
The required image is printed onto white transfer paper. This is then cut out with a plotter, which is a machine that cuts through paper following an outline drawn in Adobe Illustrator.
The transfer paper is then placed onto the object. The correct amount of heat and pressure is then applied. This is a precise process which ensures there is no damage to the surface of the product. The image then adheres permanently to the object.
This method is where lasers are used to engrave, etch or mark an object. The technique is highly technical and complex utilising a computerised system to drive the movements of the laser head. Despite the complexity, very precise and clean engravings can be achieved at a high rate. It is the level of detail that makes it ideal for creating a high quality, cost effective means of personalising a wide variety of materials in particular metal, glass and wood. The laser engraving technique does not involve tool bits coming into contact with the surface of the product being engraved. This means laser engraving is at a distinct advantage over alternative engraving, and less modern technologies, where bit heads have to be replaced regularly.
This is the application of embroidering a logo or design onto clothing, caps or bags, using computerised embroidery machines.
There are two main parts to this process. The first part is 'Digitising' which is when the logo is turned into stitches by physically tracing the design and creating the various types of stitches on a computer programme which will recreate the design and creating the various types of stitches on a computer programme which will recreate the design. The digitiser will decide the best way for the design to be sewn onto the fabric, and will make decisions according to the fabric type and design size. Once the design has been digitised a disk is made which controls the embroidery machines. Now the design is ready for part two. This is the sewing process; firstly the desk is sampled on a loose piece of fabric to ensure that the quality is good and that there are no errors in the digitising. Once the sample has been approved production can commence.
Some designs may need to be modified before they can be embroidered successfully. Small text below 4-5mm may need enlarging slightly and designs with very fine detail may require editing in order to achieve the best overall look.