BTEC First Engineering Learning aim A Know about engineering processes used to produce modern engineered products

Aerospace Automotive Communications Electrical/Electronic Mechanical Biomedical Chemical

Learning objectives: - Bigger picture: - Know about engineering processes used to produce modern engineered products Learning objectives: - Be able to explain what is meant by the term fabrication Describe a range of different fabrication processes used within engineering Be able to explain the manufacture of PCB and surface mount technology Success criteria: - Provide a description of different fabrication techniques Correctly identify different fabrication techniques Correctly describe the manufacturing process of PCB Literacy key words: PCB etching, surface mount technology

Engineering processes BTEC First Engineering Processes can be divided into groups, which are linked by the features of the processes. Machining Forming Fabrication Electrical/ electronic Teacher notes (PS 3): Items such as car lock nuts could be turned, while milling is used to get a smooth finish to a casting. Casting is used for things such as making car engine blocks; forging is used for products such as spanners and crankshafts. Welding is used to join sheet steel, such as in a structure, or for making products such as skips. PCB manufacturing and surface mounting can be associated with almost all electronic products. Casting Forging PCB manufacture Surface mount Turning Milling Drilling Welding Shearing © Pearson Education Ltd 2012. Copying permitted for purchasing institution only.

Divide the various joining techniques into permanent and non permanent Rivets Adhesive Solder Bolt Screws Threads Welding Nails Pressed joints Permanent Non permanent

Divide the various joining techniques into permanent and non permanent Rivets Threads Bolt Solder Adhesive Nails Screws Welding Pressed joints

Fabrication processes: Engineered products/parts need to be joined up in some way. Sometimes the solution is as simple as a nut, bolt and washer, but on other occasions a more permanent method is required. Assembling is done by welding, binding with adhesives, riveting and threaded fasteners

Welding . . . One of the most efficient methods of permanently joining two pieces of metal together. It can be done in many different ways but most methods use intense heat to fuse the metal together. A number of energy sources – a gas or electric, laser or ultra sound – can be used.

Homework – due 4th February 2014 Welding process Description Advantages   MIG welding  common industrial welding process. It uses electricity to generate the heat required to weld materials. MIG stands for metal inert gas.  Suitable for large scale production  Varying thickness of materials can be joined  Reduced cost due to no further cleaning required Oxy-acetylene  A gas welding process where a flame is produced using a mixture of oxygen and acetylene. No pressure on the product is required – the heat is there to control the welding of parts.  Ease of controlling the low and high temperatures needed for welding, brazing and soldering  Relatively inexpensive in comparison with other welding processes and commonly found in school workshops   Spot welding http://www.youtube.com/watch?v=WKZlxpMTV6o  A type of electrical resistance welding generally used to join sheet material together. The basic principle uses a transformer with a primary winding and a secondary winding connected to copper electrodes.. When the two electrodes trap the sheet material they generate enough heat to fuse the two together.  The process is free from fumes or spatter  Requires little or no maintenance  Cost effective

Surface mount Surface-mount technology (SMT) is a method for producing electronic circuits in which the components are mounted or placed directly onto the surface of printed circuit boards (PCBs). An electronic device so made is called a surface-mount device (SMD). In the industry it has largely replaced the through-hole technology construction method of fitting components with wire leads into holes in the circuit board. Both technologies can be used on the same board for components not suited to surface mounting such as large transformers and heat-sinked power semiconductors.

Printed circuit board Electronic circuits in schools and industry are normally manufactured through the use of PCBs (Printed Circuit Boards). The boards are made from glass reinforced plastic with copper tracks in the place of wires Components are fixed in position by drilling holes through the board, locating the components and then soldering them in place. The copper tracks link the components together forming a circuit.

Process of manufacturing a PCB and SMT Printed circuit board (PCB) manufacture The Surface Mount Technology (SMT) process 1. 1. 2. 2. 3. 3. 4. 4. 5. 5. 6.

Process of manufacturing a PCB and SMT Printed circuit board (PCB) manufacture The Surface Mount Technology (SMT) process Components are soldered to the surface of the board Producing the artwork The finished board is then inspected for imperfections Designing the layout Conveyor belts are used to transport the boards to the reflow soldering oven PCB etching Populating the board and soldering The board is heated to a temperature that melts the solder plate Drilling the board Place components using pick and place robot Apply solder paste to copper pads