Surface finishes
If a printed circuit board (PCB) is being used in a damp environment, such as outside or in a fridge, it is important to protect it. Shiny vanish used to polish a surface. is a thin A polymer is a large molecule formed from many identical smaller molecules (monomers). Polymers can be natural or synthetic. Plastics are long chains of polymers. film that is sprayed or painted onto the PCB and components and this protects it against moisture as well as dust, chemicals and temperature fluctuations.
Many mechanical systems work by moving parts together - this creates friction that, over time, Where an item is damaged by a rubbing motion. the product out. Oiling or reducing friction. A lubricant is anything which reduces the friction between two surfaces. is added to allow parts to slide past each other without causing friction and this slows down wear. For example, oil is used as a lubricant for bicycle chains to improve the performance of the bicycle.
Outer A removable outer layer of a product. of electronic and mechanical products can have surface treatments added:
- Coated with a protective oxide layer by a chemical or electrolytic process. metal gives a coloured protective surface to a metal and is most successfully used on aluminium
- paint can be sprayed on or Heated metal is dipped into powdered or a liquid polymer so that a coating of the polymer is bonded to the metal. to give a protective and How something looks. covering
- flat surfaces can be A printing technique where a mesh is used to transfer the inks onto a material, except in areas where blocking stencil is positioned to stop the ink. with pictures and patterns that decorate and protect products
Fine granular polymer is sprayed on the surface of a metal object - the metal is heated so the polymer melts to form a smooth and normally coloured surface. is a method of attracting paint in a powder form towards an electrically charged object:
- paint that is in powder form is sprayed from a paint gun
- the paint is attracted to the electrically charged object
- a fine and even coat of powdered paint covers the surface of the product and, once heated, the powder melts and produces a 鈥榬un free鈥 paint finish
Heated metal is dipped into powdered or a liquid polymer so that a coating of the polymer is bonded to the metal. is a popular finish for the handles of many tools and coat hooks. It is a straightforward process:
- a piece of metal is heated up to around 250掳C
- once hot, it is then dipped into a polythene in powder form
- this has air blown through it so an even coating of the powder is dusted onto the hot metal, resulting in a smooth and shiny coating on the dipped metal
Polythene is available in many colours and can help improve grip when applied to tool handles.