IBDT AHL TOPIC 11 ADVANCED MANUFACTURING TECHNIQUES 11.1 Joining 11.1.1 Friction welding is a completely mechanical solid-phase process in which heat generated by friction is used to create the ideal conditions for a high-integrity welded joint between similar or dissimilar metals. Friction welding (FW) is a class of solid-state welding processes that generates heat through mechanical friction between a moving workpiece and a stationary component, with the addition of a lateral force called "upset" to plastically displace and fuse the materials. Technically, because no melt occurs, friction welding is not actually a welding process in the traditional sense, but a forging technique. However, due to the similarities between these techniques and traditional welding, the term has become common. Friction welding is used with metals and thermoplastics in a wide variety of aviation and automotive applications. http://en.wikipedia.org/wiki/Friction_welding http://www.spenco.co.uk/ AL-KO heavy duty axles are double end friction welded producing a spindle to tube connection that is stronger than the base material. Friction welding also insures exact axle alignment. The end result is a tougher, more durable axle to withstand the stress of today's increasing mileage and load requirements. http://www.al-kousa.com/prod_hda.htm Please view video at:

IBDT AHL TOPIC 11 ADVANCED MANUFACTURING TECHNIQUES Friction Welding Process Advantages Dissimilar metals can often be easily joined, even some considered incompatible or unweldable. The Friction Welding process is at least twice - and up to 100 times - as fast as other welding techniques. Friction welders are versatile enough to join a wide range of part shapes, materials and sizes. Joint preparation isn't critical... machined, saw cut, and even sheared surfaces are weldable. Resulting joints are of forged quality, with a 100% butt joint weld through the contact area. Since there is no melting, no solidification defects occur, e.g. gas porosity, segregation or slag inclusions. Powder metal components can be welded to other powder metals, forgings, castings or wrought material. No consumables required - no flux, filler, or shielding gases required. The machine - controlled process eliminates human error, and weld quality is independent of operator skill or attitude. It's ecologically clean - no objectionable smoke, fumes, or gases are generated that need to be exhausted. No weld spatter and few sparks produced. Power requirements are as low as 20% of that required of conventional welding processes. No special foundations or power supplies are needed. Process parameters easily monitored. Friction Welding equipment is easily automated for high production rates. http://www.mtiwelding.com/advantages-of-friction-welding.cfm#

IBDT AHL TOPIC 11 ADVANCED MANUFACTURING TECHNIQUES 11.1.2 Explain how two metal parts are welded using friction. Friction Welding is a completely mechanical solid phase process in which heat is generated by friction to produce a high integrity welded joint between similar or dissimilar metals. http://www.fpe.co.uk/friction2.htm http://www.americawestdrillingsupply.com/images/FrictionWelding.jpg http://www.fortunecity.com/village/lind/247/weld_book/fig10-79.gif

IBDT AHL TOPIC 11 ADVANCED MANUFACTURING TECHNIQUES Friction stir welding is a technology invented and patented by TWI (The Welding Institute). In friction stir welding, a tool with a probe attached to its tip is rotated while being pushed against the butt sections of the pieces of metal to be welded. The frictional heat generated by this process softens the metal to produce a plastic flow that effectively stirs the metal from the sections on both sides and melding them together to create a weld. Unlike fusion welding, FSW is a solid phase welding method, so it results in a strongly processed metallographic organization that has excellent mechanical properties. Although it is still a relatively new technology, FSW has already come into practical use for welding aluminum alloys, etc. Moreover, it has outstanding future potential for an extensive range of uses as an applied technology. http://www.m-osaka.com/fsw/en/fsw/about_fsw.html

IBDT AHL TOPIC 11 ADVANCED MANUFACTURING TECHNIQUES 11.1.3 Describe plastic welding. Consider hot air and friction welding techniques. Almost any thermoplastic material can be friction welded, including filled, structural foamed, crystalline, and amorphous materials. There is the possibility of welding dissimilar thermoplastics and alloys, and successful joints can be made with, for instance, PS and ABS, PMMA and PC, and PPO/PA and PA. The main welding parameters associated with friction welding are speed or frequency friction pressure, forge pressure, displacement and duration. These parameters are generally interdependent and for any application a set of weld property optimisation trials would be undertaken prior to mass production of the welded thermoplastic component. http://www.seelyeinc-orl.com/id7.html Hot gas welding This is a plastic welding technique which is analogous to gas welding of metals, though the specific techniques are different. A specially designed heat gun (hot air welder) produces a jet of hot air that softens the parts to be joined, as well as the plastic filler rod. Hot air/gas welding is a common fabrication technique for manufacturing smaller items including and not limited to chemical tanks, water tanks (black, grey, fresh & ballast), heat exchangers, and plumbing fittings. The materials being welded and the welding rod must be of the same or very similar plastic. Welding PVC to acrylic is an exception to this rule. - Seelye, Inc. is one of the leading manufacturers of hot air/gas thermoplastic welders. An example of a typical linear friction welding machine http://www.twi.co.uk/j32k/protected/band_3/jk59.html

IBDT AHL TOPIC 11 ADVANCED MANUFACTURING TECHNIQUES 11.1.4 Explain how two plastic parts are welded together. Only thermoplastics that do not burn or decompose when heated to their softening temperature can be welded. Linear Vibration Welding                                                    The principle behind linear vibration welding is that the parts to be joined are brought into contact, and then moved in a linear reciprocating motion relative to each other, under pressure. The parts are vibrated through a relatively small displacement, commonly referred to as the amplitude, of typically between 1.0 and 1.8 mm, for a frequency of vibration of 200Hz (high frequency), or 2-4 mm at 100Hz (low frequency), in the plane of the joint. Industrial applications tend to be based around joints that are too long to be ultrasonically welded (i.e. greater than around 200 mm) and where higher productivity than hot plate welding is required. http://www.twi.co.uk/j32k/protected/band_3/pjkfwplast.html Spin Welding Spin welding requires a relative rotational motion between the parts to be joined, which always have a circular joint area. The technique can involve relatively simple pieces of equipment such as lathes or drilling machines. A lathe would produce a constant speed during the frictional heating stage (continuous drive friction welding) and a drilling machine would produce a reducing speed characteristic during the frictional heating stage (inertia friction welding). In practice, purpose built machines are generally employed for spin welding to provide greater control and they may be of either the continuous drive or inertia type. Spin welding has been exploited for applications as diverse as the manufacture of polyethylene floats, aerosol bottles, transmission shafts and PVC pipes and fittings. Apart from being a fast technique, another particular advantage is that welds can be formed beneath the surface of a liquid. http://www.twi.co.uk/j32k/protected/band_3/pjkfwplast.html Possible configurations for spin welding thermoplastics 11.1.5 Define permanent joining techniques. A permanent join is a type of fastening that is not supposed to be removed. It is only possible to remove such joins by drilling, cutting or grinding the join away.

IBDT AHL TOPIC 11 ADVANCED MANUFACTURING TECHNIQUES 11.1.6 List a range of permanent joining techniques. Consider pop-rivets, brazing, welding and adhesives. Pop riveting is a technique that is used to join thin pieces of metal and it can also be used to join plastic sheet. The rivet has two parts; the pin and the rivet. The pop rivet pliers are used to pull the pin through the rivet and as this happens the rivet is deformed slightly so that it joins the metal or plastic pieces. This is explained in detail below. This technique is used where the metal or plastic is thin and where the joint does not have to be very strong. It is ideal for joining aluminium or even thin sheet plastic. http://www.diydoctor.org.uk/projects/Poprivets.htm 1. The two pieces of plastic or aluminium are drilled to a size slightly larger than the rivet 2. The pop rivet is passed through both holes in the sheet plastic / aluminium. 3. The rivet pliers are pushed on to the pin of the rivet and the handles are pulled together. As this happens the pin head is pulled into the rivet and the end of the rivet is expanded. Eventually the pin will break off leaving the rivet permanently fixed in position holding the two pieces of plastic / aluminium together.

IBDT AHL TOPIC 11 ADVANCED MANUFACTURING TECHNIQUES Brazing Brazing is the process of joining metal by heating the base metal to a temperature above 800°F and adding a nonferrous filler metal that melts below the base metal. Brazing should not be confused with braze welding, even though these two terms are often interchanged. In brazing, the filler metal is drawn into the joint by capillary action and in braze welding it is distributed by tinning. Brazing is sometimes called hard soldering or silver soldering because the filler metals are either hard solders or silver-based alloys. Both processes require distinct joint designs. Brazing offers important advantages over other metal-joining processes. It does not affect the heat treatment of the original metal as much as welding does, nor does it warp the metal as much. The primary advantage of brazing is that it allows you to join dissimilar metals. http://64.78.42.182/sweethaven/BldgConst/Welding/lessonmain.asp?lesNum=6&modNum=2

IBDT AHL TOPIC 11 ADVANCED MANUFACTURING TECHNIQUES Welding is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material (the weld puddle) that cools to become a strong joint, with pressure sometimes used in conjunction with heat, or by itself, to produce the weld. This is in contrast with soldering and brazing, which involve melting a lower-melting-point material between the workpieces to form a bond between them, without melting the workpieces. Many different energy sources can be used for welding, including a gas flame, an electric arc, a laser, an electron beam, friction, and ultrasound. While often an industrial process, welding can be done in many different environments, including open air, underwater and in space. Regardless of location, however, welding remains dangerous, and precautions must be taken to avoid burns, electric shock, poisonous fumes, and overexposure to ultraviolet light. http://en.wikipedia.org/wiki/Welding Gas welding The most common gas welding process is oxyfuel welding, also known as oxyacetylene welding. It is one of the oldest and most versatile welding processes, but in recent years it has become less popular in industrial applications. It is still widely used for welding pipes and tubes, as well as repair work. The equipment is relatively inexpensive and simple, generally employing the combustion of acetylene in oxygen to produce a welding flame temperature of about 3100 °C. The flame, since it is less concentrated than an electric arc, causes slower weld cooling, which can lead to greater residual stresses and weld distortion, though it eases the welding of high alloy steels. http://en.wikipedia.org/wiki/Welding

IBDT AHL TOPIC 11 ADVANCED MANUFACTURING TECHNIQUES Arc welding uses a welding power supply to create an electric arc between an electrode and the base material to melt the metals at the welding point. They can use either direct (DC) or alternating (AC) current, and consumable or non-consumable electrodes. The welding region is sometimes protected by some type of inert or semi-inert gas, known as a shielding gas, and/or an evaporating filler material. The process of arc welding is widely used because of its low capital and running costs. http://en.wikipedia.org/wiki/Arc_welding Gas metal arc welding (GMAW), sometimes referred to by its subtypes metal inert gas (MIG) welding or metal active gas (MAG) welding, is a semi-automatic or automatic arc welding process in which a continuous and consumable wire electrode and a shielding gas are fed through a welding gun. Originally developed for welding aluminium and other non-ferrous materials in the 1940s, GMAW was soon applied to steels because it allowed for lower welding time compared to other welding processes. The cost of inert gas limited its use in steels until several years later, when the use of semi-inert gases such as carbon dioxide became common. Further developments during the 1950s and 1960s gave the process more versatility and as a result, it became a highly used industrial process. Today, GMAW is the most common industrial welding process, preferred for its versatility, speed and the relative ease of adapting the process to robotic automation. http://en.wikipedia.org/wiki/Gas_metal_arc_welding

IBDT AHL TOPIC 11 ADVANCED MANUFACTURING TECHNIQUES Resistance welding involves the generation of heat by passing current through the resistance caused by the contact between two or more metal surfaces. Small pools of molten metal are formed at the weld area as high current (1000–100,000 A) is passed through the metal. In general, resistance welding methods are efficient and cause little pollution, but their applications are somewhat limited and the equipment cost can be high. Spot welding is a popular resistance welding method used to join overlapping metal sheets of up to 3 mm thick. Two electrodes are simultaneously used to clamp the metal sheets together and to pass current through the sheets. The advantages of the method include efficient energy use, limited workpiece deformation, high production rates, easy automation, and no required filler materials. Weld strength is significantly lower than with other welding methods, making the process suitable for only certain applications. It is used extensively in the automotive industry—ordinary cars can have several thousand spot welds made by industrial robots. A specialized process, called shot welding, can be used to spot weld stainless steel. http://en.wikipedia.org/wiki/Spot_welding

IBDT AHL TOPIC 11 ADVANCED MANUFACTURING TECHNIQUES An adhesive is a compound that adheres or bonds two items together. Adhesives may come from either natural or synthetic sources. Some modern adhesives are extremely strong, and are becoming increasingly important in modern construction and industry. The first adhesives were natural gums and other plant resins or saps. The finding of 6000-year-old ceramics brought astounding evidence to archaeologists about the first practical uses and ingredients of the first adhesives. Most early adhesives were animal glues made by rendering animal products such as the use of buffalo hooves. http://en.wikipedia.org/wiki/Adhesives Natural adhesives Adhesives, from inorganic mineral sources, or biological sources such as vegetable matter, starch (dextrin), natural resins, animal skin, and bioadhesives. A simple paste can be made by mixing flour and water. Natural Adhesive - Pressure sensitive, natural gum based botanical blend, clear-yellow appearance, water-like viscosity, mild alcohol odor. This two gum based formula offers performance superior to most spirit gum and other gum based adhesives. Natural Adhesive dries clear with a matte finish. Categories of adhesives Synthetic adhesives Adhesives based on elastomers, thermoplastic, and thermosetting adhesives.

IBDT AHL TOPIC 11 ADVANCED MANUFACTURING TECHNIQUES Drying adhesives These adhesives are a mixture of ingredients (typically polymers) dissolved in a solvent. Glues such as white glue, and rubber cements are members of the drying adhesive family. As the solvent evaporates, the adhesive hardens. Depending on the chemical composition of the adhesive, they will adhere to different materials to greater or lesser degrees. These adhesives are typically weak and are used for household applications. Some intended for use by small children are now made non-toxic. As an emulsion in water, PVA is sold as an adhesive for porous materials, particularly wood, paper, and cloth. It is the most commonly used wood glue, both as "white glue" and the yellow "carpenter's glue." PVA is widely used in bookbinding and book arts due to its flexibility, and because it is non-acidic, unlike many other polymers. Latex is a name collectively given to a group of similar preparations consisting of stable dispersions of polymer microparticles in a liquid matrix (usually water). Latexes may be natural or synthetic.

IBDT AHL TOPIC 11 ADVANCED MANUFACTURING TECHNIQUES IBDT AHL TOPIC 11 ADVANCED MANUFACTURING TECHNIQUES Cyanoacrylate is the generic name for substances such as methyl-2-cyanoacrylate, which is typically sold under trademarks like Superglue and Krazy Glue, and 2-octyl cyanoacrylate, which is used in medical glues such as Dermabond and Traumaseal. Cyanoacrylate adhesives are sometimes known as "instant adhesives". The acronym "CA" is quite commonly used for industrial grades. Cyanoacrylate was discovered by Harry Coover at Eastman Kodak during World War II when searching for a way to make synthetic gun-sights (a substitute for spider silk). It did not solve this problem, since it stuck to all the apparatus used to handle it. It was first marketed to industry as well as consumers in February 1955 as a product called "Flash Glue" which is still available today. It was patented in 1956 and developed into Eastman 910 adhesive in 1958. Contact adhesives Contact adhesive is one which must be applied to both surfaces and allowed some time to dry before the two surfaces are pushed together. Some contact adhesives require as long as 24 hours to dry before the surfaces are to be held together. Once the surfaces are pushed together the bond forms very quickly, hence it is usually not necessary to apply pressure for a long time. This means that there is no need to use clamps, which is convenient. Natural rubber and polychloroprene (Neoprene) are commonly used contact adhesives. Both of these elastomers undergo strain crystallization. Contact adhesives find use in laminates, such as bonding Formica to a wooden counter, and in footwear, for example attachment of an outsole to an upper.

IBDT AHL TOPIC 11 ADVANCED MANUFACTURING TECHNIQUES Hot melt adhesive (or hot glue) is a form of thermoplastic adhesive that is commonly supplied in solid sticks designed to be melted in a special gun. The glue comes in cylinders of various lengths, and is pushed into an electric hot glue gun. The gun contains a heating element to melt the plastic glue, which operates all the time the gun is plugged in. Squeezing the trigger pushes the stick through the heating element, ejecting molten glue which is initially hot enough to burn and blister skin. The glue is tacky when hot, but hardens and stops being sticky in a few seconds—a minute at most. Reactive adhesives A reactive adhesive works either by chemical bonding with the surface material or by in-situ hardening as two reactant chemicals complete a polymerization reaction. They are usually applied in thin films. Reactive adhesives are less effective when there is a secondary goal of filling gaps between the surfaces. These include two-part epoxy, peroxide, silane, metallic cross-links, or isocyanate. Such adhesives are frequently used to prevent loosening of bolts and screws in rapidly moving assemblies, such as automobile engines. They are largely responsible for the quieter running modern car engines.

IBDT AHL TOPIC 11 ADVANCED MANUFACTURING TECHNIQUES 11.1.7 Discuss how permanent joining techniques lead to planned obsolescence and environmental issues. Permanent joins do not allow for the disassembly and easy maintenance of products. The plastic handles and steel blade of this kitchen knife would prove inconvenient or expensive to separate for recycling. Products, components and subassemblies that are permanently joined are difficult to repair or reuse. They are also difficult and expensive to recycle as the materials may be contaminated by the joint or fastening. 3 11.1.8 Define adhesive. An adhesive is a substance that is applied between two surfaces in order to bond them together. 11.1.9 Identify a range of adhesives suitable for joining metals, woods and plastics. (Table from IGCSE glossary).

IBDT AHL TOPIC 11 ADVANCED MANUFACTURING TECHNIQUES Consider preparation of surfaces, clamping, bonding time, type of material, and health and safety. 11.1.10 Discuss the advantages and disadvantages of using adhesive bonding in products. When stages above are complete the Pieces are cramped together and left For twenty four hours