NPTEL; Mechanical Engineering; Advanced Manufacturing Processes (Video) Concepts covered in this lecture: Manufacturing and Manufacturing Systems. ×. Manufacturing covers wide areas of inputs, processes and products. It reaches out to the demands in production for thousands of different varieties and types of . ADVANCED MANUFACTURING PROCESS Metal Forming Semester . This is the material removal Advanced Manufacturing Processes PDF.
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Introduction of Advanced Manufacturing Technology: a literature review. Article ( PDF Available) · March with 7, Reads. DOI: /suslj.v6i These manufacturing processes when further developed bring Advanced manufacturing processes, which includes advanced casting. history of patents and inventions. We create the next- generation materials, components and manufacturing processes that will drive tomorrow's economy.
Accuracy and speed are low when compared to other processes and accuracy of the final model is limited to material nozzle thickness. Constant pressure of material is required in order to increase quality of finish. The Ultrasonic Additive Manufacturing process uses sheets or ribbons of metal, which are bound together using ultrasonic welding. The process does require additional CNC machining and removal of the unbound metal, often during the welding process. Laminated object manufacturing LOM uses a similar layer by layer approach but uses paper as material and adhesive instead of welding.
The LOM process uses a cross hatching method during the printing process to allow for easy removal post build.
Laminated objects are often used for aesthetic and visual models and are not suitable for structural use. UAM uses metals and includes aluminium, copper, stainless steel and titanium. The process is low 3. Sheet Lamination Process The process can bond different materials and requires relatively little energy, as the metal is not melted.
The material is positioned in place on the cutting bed. The material is bonded in place, over the previous layer, using the adhesive. The required shape is then cut from the layer, by laser or knife. The next layer is added. Steps two and three can be reversed and alternatively, the material can be cut before being positioned and bonded.
Sheet is adhered to a substrate with a heated roller. Laser traces desired dimensions of prototype. Laser cross hatches non-part area to facilitate waste removal.
Platform with completed layer moves down out of the way. Fresh sheet of material is rolled into position. Platform downs into new position to receive next layer.
The process is repeated. Benefits include the use of A4 paper, which is readily available and inexpensive, as well as a relatively simple and inexpensive setup, when compared to others. The Ultrasonic Additive Manufacturing UAM process uses sheets of metal, which are bound together using ultrasonic welding. The process does require additional CNC machining of the unbound metal. Unlike LOM, the metal cannot be easily removed by hand and unwanted material must be removed by machining.
Material saving metallic tape of 0. Milling can happen after each layer is added or after the entire process. Metals used include aluminium, copper, stainless steel and titanium. The process is low temperature and allows for internal geometries to be created.
One key advantage is that the process can bond different materials and requires relatively little energy as the metal is not melted, instead using a combination of ultrasonic frequency and pressure.
Overhangins can be built and main advantage of embedding electronics and wiring. Materials are bonded and helped by plastic deformation of the metals. Plastic deformation allows more contact between surface and backs up existing bonds. Post processing requires the extraction of the part from the surrounding sheet material. With LOM, cross hatching is used to make this process easier, but as paper is used, the process does not require any specialist tools and is time efficient.
Whilst the structural quality of parts is limited, adding adhesive, paint and sanding can improve the appearance, as well as further machining.
Paper, plastic and some sheet metals. The most commonly used material is A4 paper. Benefits include speed, low cost, ease of material handling, but the strength and integrity of models is reliant on the adhesive used.
Cutting can be very fast due to the cutting route only being that of the shape outline, not the entire cross sectional area 3. Relatively large parts may be made. Finishes can vary depending on paper or plastic material but may require post processing to achieve desired effect 2.
Limited material use 3. Fusion processes require more research to further advance the process into a more mainstream positioning. Dimensional accuracy is slightly less The term direct write refers to any technique or process capable of depositing, dispensing, or processing different types of materials over various surfaces following a preset pattern or layout.
The ability to accomplish both pattern and material transfer processes simultaneously represents a paradigm shift away from the traditional approach for device manufacturing based on lithographic techniques. However, the fundamental concept of direct writing is not new. Every piece of handwriting, for instance, is the result of a direct-write process whereby ink or lead is transferred from a pen, or pencil onto paper in a pattern directed by our hands. Direct-write technologies are a subset of the larger area of rapid prototyping and deal with coatings or structures considered to be two-dimensional in nature.
With the tremendous breakthroughs in materials and the methods used to apply them, many of which are discussed in this book, direct-write technologies are poised to be far-reaching and influential well into the future. The industry's push toward these technologies and the pull from applications rapidly changing circuits, designs, and commercial markets are documented for the first time here.
Although direct-write technologies are serial in nature, they are capable of generating patterns, of high-quality electronic, sensor, and biological materials among others--at unparalleled speeds, rendering these technologies capable of satisfying growing commercial demands. Laser Direct-Write From the earliest work on laser interactions with materials, direct-write processes have been important and relevant techniques to modify, add, and subtract materials for a wide variety of systems and for applications such as metal cutting and welding.
This is in contrast to lithography, stamping, directed self-assembly, or other patterning approaches that require masks or pre-existing patterns. At first glance, one may think that direct-write processes are slower or less important than these parallelized approaches.
However, direct-write allows for precise control of material properties with high resolution and enables structures that are either impossible or impractical to make with traditional parallel techniques. Furthermore, with continuing developments in laser technology providing a decrease in cost and an increase in repetition rates, there is a plethora of applications for which laser direct- write LDW methods are a fast and competitive way to produce novel structures and devices.
This issue of MRS Bulletin seeks to assess the current status and future opportunities of LDW processes in the context of emerging applications. Direct Write Technologies Patterning is achieved by either rastering the beam above a fixed surface or by moving the substrate or part within a fixed beam.
An important feature of LDW is that the desired patterns can be constructed in both two and three dimensions on arbitrarily shaped surfaces, limited only by the degrees of freedom and resolution of the motion-control apparatus. The key elements of any LDW system can be divided into three subsystems: At the heart of any LDW process is the laser source.
Typical experiments and applications use anywhere from ultrafast femtosecond-pulsed systems to continuous-wave systems employing solid-state, gas, fiber, semiconductor, or other lasing media. In choosing an appropriate source, one must consider the fundamental interactions of lasers with the material of interest. This requires knowledge of the pulse duration, wavelength, divergence, and other spatial and temporal characteristics that determine the energy absorption and the material response.
In beam delivery, there are a variety of ways to generate a laser spot, including fixed focusing objectives and mirrors, galvanometric scanners, optical fibers, or even fluidic methods such as liquid-core wave- guides or water jets.
The choice depends on the application demands, for instance, the required working distances, the focus spot size, or the energy required. The ultimate beam properties will be determined by the combination of laser and beam delivery optics. Finally, the substrate mounting is done in accordance with experimental or industrial requirements and can be manipulated in multiple directions to achieve a desired result.
Robotics and active feed- back control, on either the substrate or beam delivery optics, can add further design flexibility to the technique. There is a vast range of LDW processes. For the purposes of this issue, we categorize them into three main classes: For full PDF Go to www. Schematic illustration of a laser direct-write system.
The basic components of an LDW system are left to right a substrate mounting system, a beam delivery system, and a laser source. In general, this entails processes that result in photochemical, photo thermal, or photo physical ablation on a substrate or target surface, directly leading to the features of interest.
Common processes include laser scribing, cut- ting, drilling, or etching to produce relief structures or holes in materials in ambient or controlled atmospheres. Industrial applications using this technique range from high-throughput steel fabrication, to inkjet and fuel-injection nozzle fabrication, to high-resolution manufacturing and texturing of stents or other implantable biomaterials.
At a smaller scale, inexpensive bench top laser cutting and en- graving systems can be downloadd by the hobbyist or small company for artistic and architectural renderings. More recent developments in LDW- include chemically assisted techniques such as laser-drilling ceramics or biomaterials and laser-induced backside wet etching LIBWE of glass. In fact, one may also consider laser cleaning to be a controlled LDW- process.
For instance, a heat- affected zone HAZ tends to occur in the vicinity of thermally removed material.
This region has structures and properties that can differ from the bulk material and can exhibit additional surface relief. Either of these effects may be beneficial or detrimental, depending on the application. In contrast, a thermal and multiphoton absorption processes caused by ultrafast lasers can reduce the formation of a HAZ and enable features smaller than the diffraction limit.
Typically, these processes rely on thermal modifications that cause a structural or chemical change in the material. A common example of such processes is the rewritable compact disc, in which a diode laser induces a phase transition between crystalline and amorphous material. In industrial applications, one may consider laser cladding, where a surface layer different from the bulk material is produced through melting and resolidification, or solid free-form fabrication SFF approaches such as selective laser sintering SLS , as important modifying processes that would fall under the umbrella of LDWM.
Many LDWM applications require a specific optical response in the material of interest beyond simple thermal effects. Optically induced defects or changes in mechanical properties can lead to many non-ablative material modifications. For instance, photoresists respond to light by breaking or reforming bonds, leading to pattern formation in the material. Alternatively, LDW can cause defects in photo- etchable glass ceramics or other optical materials through single- and multiphoton mechanisms, enabling novel applications in optical storage, photonic devices, and microfluidics.
In this technique, material is added to a substrate using various laser-induced processes. Many techniques are derived from laser- induced forward transfer LIFT , where a sacrificial substrate of solid metal is positioned in close proximity to a second substrate to receive the removed material. The incident laser is absorbed by the material of interest, causing local evaporation.
This vapor is propelled toward the waiting substrate, where it recondenses as an individual three-dimensional pixel, or voxel, of solid material. Such an approach has found important use in circuit and mask repair and other small-scale applications where one needs to deposit material locally to add value to an existing structure.
This general technique has significant ad- vantages over other additive direct- write processes, in that these laser approaches do not require contact between the de- positing material and a nozzle, and can enable a broad range of materials to be transferred. Variations on the general LIFT principle allow liquids, inks, and multi- phase solutions to be patterned with For instance, laser-induced chemical vapor deposition, or multiphoton polymerization schemes of liquid photoresists, can be used to fabricate three-dimensional stereographic patterns.
Examples of this have been demonstrated and show promise for many applications such as fabricating photonic structures or biological scaffolding. The need for direct writing electronic and sensor materials is founded in exciting and often revolutionary applications, numerous examples of which will be given here.
The specific applications presented individually in each chapter are representative of some areas where direct-write technologies could have an impact. As successful applications are commercialized demonstrating the inherent flexibility of direct-write techniques the potential for using direct-write products in other areas grows. Part I is devoted to applications of direct-write material deposition, in particular, applications to defense electronics, chemical and biological sensors, industrial applications, and small-scale power-management applications.
Other exciting applications are on the horizon for use in medicine, tissue engineering, wireless and other communications, optoelectronics, and semiconductors. A typical DED machine consists of a nozzle mounted on a multi axis arm, which deposits melted material onto the specified surface, where it solidifies.
The process is similar in principle to material extrusion, but the nozzle can move in multiple directions and is not fixed to a specific axis. The material, which can be deposited from any angle due to 4 and 5 axis machines, is melted upon deposition with a laser or electron beam.
The process can be used with polymers, ceramics but is typically used with metals, in the form of either powder or wire. Typical applications include repairing and maintaining structural parts. Directed Energy Deposition A4 or 5 axis arm with nozzle moves around a fixed object.
Material is deposited from the nozzle onto existing surfaces of the object. Material is either provided in wire or powder form. Material is melted using a laser, electron beam or plasma arc upon deposition. Further material is added layer by layer and solidifies, creating or repairing new material features on the existing object.
The DED process uses material in wire or powder form. Wire is less accurate due to the nature of a pre- formed shape but is more material efficient when compared to powder Gibson et al. The method of material melting varies between a laser, an electron beam or plasma arc, all within a controlled chamber where the atmosphere has reduced oxygen levels. With 4 or 5 axis machines, the movement of the feed head will not change the flow rate of material, compared to fixed, vertical deposition.
Ability to control the grain structure to a high degree, which lends the process to repair work of high quality, functional parts. A balance is needed between surface quality and speed, although with repair applications, speed can often be sacrificed for a high accuracy and a pre- determined microstructure. Finishes can vary depending on paper or plastic material but may require post processing to achieve desired effect.
Fusion processes require more research to further advance the process into a more mainstream positioning 6. Material Jetting Not in Syllabus Material jetting creates objects in a similar method to a two dimensional ink jet printer. Material is jetted onto the build surface or platform, where it solidifies and the model is built layer by layer.
Material is deposited from a nozzle which moves horizontally across the build platform. Machines vary in complexity and in their methods of controlling the deposition of material.
The material layers are then cured or hardened using ultraviolet UV light. As material must be deposited in drops, the number of materials Polymers and waxes are suitable and commonly used materials, due to their viscous nature and ability to form drops. The print head is positioned above build platform. Droplets of material are deposited from the print head onto surface where required, using either thermal or piezoelectric method.
Droplets of material solidify and make up the first layer. Further layers are built up as before on top of the previous. Layers are allowed to cool and harden or are cured by UV light.
Post processing includes removal of support material. Drop on Demand DOD is used to dispense material onto the required surface. Droplets are formed and positioned into the build surface, in order to build the object being printed, with further droplets added in new layers until the entire object has been made. The nature of using droplets, limits the number of materials available to use. Polymers and waxes are often used and are suitable due to their viscous nature and ability to form drops.
Viscosity is the main determinant Unlike a continuous stream of material, droplets are dispensed only when needed, released by a pressure change in the nozzle from thermal or piezoelectric actuators. Thermal actuators deposit droplets at a very fast rate and use a thin film resistor to form the droplet. The piezoelectric method is often considered better as it allows a wider range of materials to be used.
The designs of a typical DOD print head changes from one machine to another but according to Ottnad, typically include a reservoir, sealing ring, Piezo elements and silicon plate with nozzle, held together with high temperature glue.
The process benefits from a high accuracy of deposition of droplets and therefore low waste. The process allows for multiple material parts and colours under one process. Support material is often required. A high accuracy can be achieved but materials are limited and only polymers and waxes can be used. Binder Jetting Not in syllabus The binder jetting process uses two materials; a powder based material and a binder.
The binder acts as an adhesive between powder layers. The binder is usually in liquid form and the build material in powder form. A print head moves horizontally along the x and y axes of the machine and deposits alternating layers of the build material and the binding material.
After each layer, the object being printed is lowered on its build platform. Due to the method of binding, the material characteristics are not always suitable for structural parts and despite the relative speed of printing, additional post processing see below can add significant time to the overall process. Powder material is spread over the build platform using a roller.
The print head deposits the binder adhesive on top of the powder where required. Another layer of powder is spread over the previous layer.
The object is formed where the powder is bound to the liquid. Unbound powder remains in position surrounding the object. The process is repeated until the entire object has been made. The binder jetting process allows for colour printing and uses metal, polymers and ceramic materials.
The process is generally faster than others and can be further quickened by increasing the number of print head holes that deposit material. The two material approach allows for a large number of different binder-powder combinations and various mechanical properties of the final model to be achieved by changing the ratio and individual properties of the two materials. The process is therefore well suited for when the internal material structure needs to be of a specific quality. Stainless steel 2.
Glass All three types of materials can be used with the binder jetting process. Parts can be made with a range of different colours. Uses a range of materials: The process is generally faster than others. The two material method allows for a large number of different binder-powder combinations and various mechanical properties. Not always suitable for structural parts, due to the use of binder material.
Additional post processing can add significant time to the overall process. It is a means to create highly customized products, as well as produce large amounts of production parts. Products are brought to market in days rather than months and designers save money by using additive manufacturing instead of traditional manufacturing methods. In addition, the risk factor is much lower and those involved can receive near-immediate feedback because prototypes take less time to produce.
For those looking to do rapid prototyping, additive manufacturing is extremely beneficial. The technology lends itself to efficiently create quick prototypes, allowing designers and businesses to get their products more quickly. When done in a large printer, multiple parts can be done at once in less time. A variety of industries use additive manufacturing to fabricate end-use product, consumer and otherwise, including aerospace, architecture, automotive, education, game and medical industries.
The technology is popular among design and architecture firms as well. Industries and businesses that build products and prototypes, as well as short run and on demand manufacturing of components benefit from the use of additive manufacturing. Hybrid machine tools that incorporate CNC and AM could represent the next step for the development of the industry. Materials Used in AM Three types of materials can be used in additive manufacturing: All seven individual AM processes, cover the use of these materials, although polymers are most commonly used and some additive techniques lend themselves towards the use of certain materials over others.
Materials are often produced in powder form or in wire feedstock. It is essentially feasible to print any material in this layer by layer method, but the final quality will be largely determined by the material. The processes above can also change the microstructure of a material due to high temperatures and pressures, therefore material characteristics may not always be completely similar post manufacture, when compared to other manufacturing processes.
The common structural polymers can also be used, as well as a number of waxes and epoxy based resins. Mixing different polymer powders can create a wide range of structural and aesthetic materials.
The following polymers can be used: ABS Acrylonitrile butadiene styrene 2. PC polycarbonate Polyamide Nylon 4. Nylon 12 Tensile strength 45 Mpa 5. During flow forming, the workpiece is cold worked, changing its mechanical properties, so its strength becomes similar to that of forged metal.
Flow forming, also known as tube spinning, is one of the techniques closely allied to shear forming. The two types of flow forming are shown in Fig. The difference is according to the direction of material flow with respect to direction of motion of tool roller. If both are in same direction, then it is forward flow forming and if they are in opposite direction, then it is backward flow forming.
Forward flow forming is suitable for long, high precision thin 6. Flow Forming YEOLA walled components. Backward flow forming is suitable for blanks without base or internal flange. In forward spinning the roller moves away from the fixed end of the work piece, and the work metal flows in the same direction as the roller, usually toward the headstock.
The main advantage in forward spinning as compared to backward spinning is that forward spinning will overcome the problem of distortion like bell-mouthing at the free end of the blank and loss of straightness.
In forward spinning closer control of length is possible because as metal is formed under the rollers it is not required to move again and any variation caused by the variable wall thickness of the per- form is continually pushed a head of rollers, eventually be- coming trim metal beyond the finished length.
The disadvantage of forward flow forming is that the Production is slower in forward spinning because the roller must transverse the finished length of the work piece.
In backward flow forming the mandrel is unsupported. In backward spinning the work piece is held against a fixture on the head stock, the roller advances towards the fixed end of the work piece, work flows in the opposite direction.
The advantage of backward flow forming over forward flow forming: The preform is simpler for backward spinning because it slides over the mandrel and does not require an internal flange for clamping. We can procedure 3 m length tube by using of mandrel. In both the flow forming processes, there is no difference in stress and strain rate.
The major disadvantage of backward tube spin- ning is that backward flow forming is normally prone to non uniform dimension across the length of the product In this Process as shown in Fig. It is usually employed to produce cylindrical components. Most modern flow forming machines employ two or three rollers and their design is more complex compared to that of spinning and shear forming machines. The starting blank can be in the form of a sleeve or cup. Blanks can be produced by deep drawing or forging plus machining to improve the dimensional accuracy.
Advantages such as an increase in hardness due to an ability to cold work and better surface finish couples with simple tool design and tooling cost make flow forming a particularly attractive technique for the production of hydraulic cylinders, and cylindrical hollow YEOLA parts with different stepped sections.
Both spinning and flow forming can also be combined to produce complex components. By rotating mandrel process only cylindrical components can be produced. Wong made observations in his study on flow forming of solid cylindrical billets, with different types of rollers.
A flat faced roller produces a radial flange and a non orthogonal approach of nosed roller produces a bulge ahead of the roller. Traditional multi-piece designs can be formed as a single, seamless piece.
Provide design versatility to produce a unique seamless profile with varying wall thicknesses. Produce cylindrical, conical, or contoured shapes up to 47" diameter. Typical interior finishes of 15Ra without additional manufacturing steps. High material utilization from near-net shape forming process. Low production cost. Very little wastage of material. Excellent surface finishes. Accurate components.
Improved strength properties. Easy cold forming of high tensile strength alloys. Production of high precision, thin walled seamless components. When new technologies were introduced to the field of metal spinning and powered dedicated spinning machines were available, shear forming started its development in Sweden. Shear forming was first used in Sweden and grew out as spinning. In shear forming the area of the final component is approximately equal to that of the blank and little reduction in the wall thickness occurs.
Whereas with shear forming, a reduction in the wall thickness is deliberately induced. The starting workpiece can be thick walled circular or square blank. Shear forming of thick walled sheet may require two diametrically opposite roller instead of one needed for light gauge materials.
The profile shape of the final component can be concave, convex or combination of these two geometries. A shear formed product: In shear spinning the area of the final piece is approximately equal to that of the flat sheet metal blank. The wall thickness is maintained by controlling the gap between the roller and the mandrel. In shear forming a reduction of the wall thickness occurs. The configuration of machine used in shear forming is very similar to the conventional spinning lathe, except that it is made more robust as higher forces are generated during shear forming.
Nowadays on modern machines, it is common to use both shear forming and spinning techniques on the same component. In shear forming, the required wall thickness is achieved by controlling the gap between the roller and the mandrel so that the material is displaced axially, parallel to the axis of rotation. Since the process involves only localised deformation, much greater YEOLA deformation of the material can be achieved with lower forming forces as compared with other processes.
In many cases, only a single-pass is required to produce the final component to net shape. Moreover due to work hardening, significant improvement in mechanical properties can be achieved. Operation The shear forming process is shown in Fig. The inclined angle of the mandrel sometimes referred to as half-cone angle determines the degree of reduction normal to the surface. The greater the angle, the lesser will be the reduction of wall thickness.
Principles of shear forming 1. The mandrel has the interior shape of the desired final component. A roller makes the sheet metal wrap the mandrel so that it takes its shape.
On the other hand, the profile shape of the final component can be concave, convex or a combination of these two. A shear forming machine will look very much like a conventional spinning machine, except for that it has to be much more robust to withstand the higher forces necessary to perform the shearing operation. The design of the roller must be considered carefully, because it affects the shape of the component, the wall thickness, and dimensional accuracy.
The smaller the tool nose radius, the higher the stresses and poorest thickness uniformity achieved. Good mechanical properties 2. This process used widely in the production of lightweight items. Very good surface finish. Applications Typical components produced by mechanically powered spinning machines include rocket nose cones, gas turbine engine etc. Being able to achieve almost net shape, thin sectioned parts. UNIT 2. Key features of welding: Largely used in the following fields of engineering: Friction Stir Welding is a solid-state process, which means that the objects are joined without reaching melting point.
This opens up whole new areas 1. Friction Stir Welding YEOLA in welding technology. Using FSW, rapid and high quality welds of 2xxx and 7xxx series alloys, traditionally considered unweldable, are now possible. Friction stir welding FSW , illustrated in Figure. The process derives its name from this stirring or mixing action.
FSW is distinguished from conventional FRW by the fact that friction heat is generated by a separate wear-resistant tool rather than by the parts themselves.
The rotating tool is stepped, consisting of a cylindrical shoulder and a smaller probe projecting beneath it. During welding, the shoulder rubs against the top surfaces of the two parts, developing much of the friction heat, while the probe generates additional heat by mechanically mixing the metal along the butt surfaces.
The probe has a geometry designed to facilitate the mixing action. The heat produced by the combination of friction and mixing does not melt the metal but softens it to a highly plastic condition.
Friction stir welding FSW: Rotation Speed N W. P Thic kness Retreating side Advancing Side YEOLA As the tool is fed forward along the joint, the leading surface of the rotating probe forces the metal around it and into its wake, developing forces that forge the metal into a weld seam. The shoulder serves to constrain the plasticized metal flowing around the probe.
Friction Stir Welding can be used to join aluminium sheets and plates without filler wire or shielding gas. Material thicknesses ranging from 0. In terms of materials, the focus has traditionally been on non-ferrous alloys, but recent advances have challenged this assumption, enabling FSW to be applied to a broad range of materials. To assure high repeatability and quality when using FSW, the equipment must possess certain features.
With arc welding, calculating heat input is critically important when preparing welding procedure specifications WPS for the production process. With FSW, the traditional components current and voltage are not present as the heat input is purely mechanical and thereby replaced by force, friction, and rotation. Several studies have been conducted to identify the way heat is generated and transferred to the joint area.
A simplified model is described in the following equation: The quality of an FSW joint is always superior to conventional fusion-welded joints. This guarantees high quality even where tolerance errors in the materials to be joined may arise. It also enables robust control during higher welding speeds, as the down force will ensure the generation of frictional heat to soften the material.
When using FSW, the following parameters must be controlled: Only four main parameters need to be mastered, making FSW ideal for mechanised welding. Automotive applications In principle, all aluminium components in a car can be friction stir welded: In larger road transport vehicles, the scope for applications is even wider and easier to adapt — long, straight or curved welds: Typical applications are butt joints on large aluminum parts. Other metals, including steel, copper, and titanium, as well as polymers and composites have also been joined using FSW.
The most common classification of tooling is as follows: Sheet metal press working tools. Molds and tools for plastic molding and die casting. Jigs and fixtures for guiding the tool and holding the work piece. Forging tools for hot and cold forging. Gauges and measuring instruments. Cutting tools such as drills, reamers, milling cutters broaches, taps, etc.
Sheet metal press working tools are custom built to produce a component mainly out of sheet metal. Press tool is of stampings including cutting operations like shearing, blanking, piercing etc.
Sheet metal items such as automobile parts roofs, fenders, caps, etc. The primary function of a mould or the die casting die is to shape the finished product. In other words, it is imparting the desired shape to the plasticized polymer or molten metal and cooling it to get the part. It is basically made up of two sets of components. Different mould construction methods are used in the industry. The mould is loaded on to a machine where the plastic material or molten material can be plasticized or melted, injected and ejected.
To produce products and components in large quantities with a high degree of accuracy and Interchangeability, at a competitive cost, specially designed tooling is to be used. Jigs and fixtures are manufacturing equipments, which make hand or machine work easier. By using such tooling, we can reduce the fatigue of the operator operations such as marking and shall give accuracy and increases the production.
Further the use of specially designed tooling will lead to an improvement of accuracy, quality of the product and to the satisfaction of the consumer and community. A fixture is a work holding 2. Introduction to Tooling YEOLA device used to locate accurately and to hold securely one or more work pieces so that the required machining operations can be performed.
The stamping of parts from sheet metal is shaped or cur through deformation by shearing, punching, drawing, stretching, bending, coining etc.
Production rates are high and secondary machining is not required to produce finished parts with in tolerance. A pressed part may be produce by one or a combination of three fundamental press operations.
They include: Cutting blanking, piercing, lancing etc to a predetermined configuration by exceeding the shear strength of the material. Forming drawing or bending whereby the desired part shape is achieved by overcoming the tensile resistance of the material. Coining compression, squeezing, or forging which accomplishes surface displacement by overcoming the compressive strength of the material. Whether applied to blanking or forming the under laying principle of stamping process may be desired as the use of force and pressure to cut a piece of sheet metal in to the desired shape.
Part shape is produced by the punch and die, which are positioned in the stamping press. In most production operations the sheet metal is placed on the die and the descending punch is forced into the work piece by the press. Inherent characteristics of the stamping process make it versatile and foster wide usage.
Costs tend to be low, since complex parts can be made in few operations at high production rates. Stampings having an irregular contour must be blanked from the strip.
Piercing, embossing, and various other operations may be performed on the strip prior to the blanking station. The operation is often called piercing, although piercing is properly used to identify the operation for the producing by tearing action, which is not typical of cutting operation. In general the term piercing is used to describe die cut holes regardless of size and shape. Piecing is performed in a press with the die.
Preliminary operations before cutting off include piercing, notching, and embossing. Although they are relatively simple, cut-off tools can produce many parts. During parting some scrape is produced.
Therefore parting is the next best method for cutting blanks. It is used when blanks will not rest perfectly. It is similar to cut off operation except the cut is in double line.
This is done for components with two straight surfaces and two profile surfaces. Perforating is also called as piercing operation. It is used to pierce many holes in a component at one shot with specific pattern.
This irregular edge is trimmed in a trimming die. Shown is flanged shell, as well as the trimmed ring removed from around the edge. While a small amount of Material is removed from the side of a component or strip is also called as trimming.
A straight, smooth edge is provided and therefore shaving is frequently performed on instrument parts, watch and clock parts and the like. Shaving is accomplished in shaving tools especially designed for the purpose. These would be broached in a broaching tool. Broaching operations are similar to shaving operations.
Broaching must be used when more material is to be removed than could effectively done in with one tooth. The cutting edges penetrate the material and cuts. The die will be usually a plane material like wood or hard rubber. Lancing cuts are necessary to create lovers, which are formed in sheet metal for venting function.
A simple bend is done in which the line of bend is straight. One or more bends may be involved, and bending tools are a large important class of pres tools. The line of bend is curved instead of straight and the metal is subjected to plastic flow or deformation. Shown in fig is a rather deep shell that has been drawn from a flat sheet. The curl may be applied over aware ring for increased strength.
You may have seen the tops of the sheet metal piece curled in this manner. Flat parts may be curled also. A good example would be a hinge in which both members are curled to provide a hole for the hinge pin. The bulged bottoms of some types of coffee pots are formed in bulging tools.
Figure shows a collapsible tool formed and extruded from a solid slug of metal. In coining, the metal is caused to flow into the shape of the die cavity Coins such as nickels, dimes and quarters are produced in coining tools.
The collar wall can also be used as rivet when two sheets are to be fastened together. Assembly tools assemble the parts with great speed and they are being used more and more. Production equipment and tooling used for various manufacturing processes. YEOLA Stamping Press Die shearing, forming sheet metal Machining Machine tool Cutting tool material removal Fixture hold workpart Jig hold part and guide tool Grinding Grinding machine Grinding wheel material removal Welding Welding machine Electrode fusion of work metal Fixture hold parts during welding Die casting is a permanent-mold casting process in which the molten metal is injected into the mold cavity under high pressure.
The pressure is maintained during solidification, after which the mold is opened and the part is removed. Molds in this casting operation are called dies; hence the name die casting.
Two basic conventional die casting processes exist: These descriptions stem from the design of the metal injection systems utilized. A schematic of a hot-chamber die casting machine is shown in Figure 1. This helps keep cycle times to a minimum, as molten metal needs to travel only a very short distance for each cycle. Hot-chamber machines are rapid in operation with cycle times varying from less than 1 sec for small components weighing less than a few grams to 30 sec for castings of several kilograms.
Hot-chamber die casting is traditionally used for low melting point metals, such as lead or zinc alloys. Higher melting point metals, including aluminum alloys, cause rapid degradation of the metal injection system. Die Casting YEOLA Cold-chamber die casting machines are typically used to con- ventionally die cast components using brass and aluminum alloys. An illustration of a cold-chamber die casting machine is presented in Figure 1. Unlike the hot-chamber machine, the metal injection system is only in contact with the molten metal for a short period of time.
Liquid metal is ladled or metered by some other method into the shot sleeve for each cycle. To provide further protection, the die cavity and plunger tip normally are sprayed with an oil or lubricant.
When used to its maximum potential, a die cast component may replace an assembly composed of a variety of parts produced by various manufacturing processes. Entrapped gas is unavoidable. This phenomenon is also present in vacuum die casting, as the process parameters are virtually iden- tical to that of conventional die casting.
YEOLA Figure 2. In Figure 2. An enhanced die-casting method, vacuum die-casting, has been developed by adding a vacuum device. Because vacuum die casting creates a vacuum inside the mold cavity during casting, gases or air in the melt is removed, decreasing the volume of gas pockets and improving the mechanical properties and smoothness of the resulting surface.
Using an aluminum or magnesium alloy made by vacuum die-casting, aircraft and automotive parts in bulk shapes have been manufactured. The mold is encapsulated in a housing that is sealed and placed above the furnace of molten metal. The sprue or gating, or some form of spout, which is located at the bottom of the mold in the housing, is submerged into the metal. A vacuum is then applied to the housing, which evacuates the atmosphere in the housing to create differential pressure between atmosphere pressure above the melt and inside the mold.
This differential pressure is what forces the molten metal from below the surface into the mold cavity. While gravity pouring has its advantages, within some geometries it can result in a turbulent metal flow that can lead to entrained gas.
The objective of vacuum casting is to control the metal flow as much as possible for a tranquil mold fill. For metal castings that call for a sound, consistent integrity, vacuum casting may deliver. The following advantages of vacuum casting lend the process to precision applications: Vacuum Die Casting YEOLA 1. Avoiding slag and inclusions; 5. Critical metal temperature variations can be more consistently controlled since the mold is taken to the furnace rather than vice versa; 6.
Excellent dimensional tolerances; 8. It is often easier to automate than gravity pouring. Prolongs die life, eliminates debarring operation and increases up time of casting machine. Insem-Aug In these efforts, squeeze casting utilizes two strategies: Squeeze casting is a Combination of casting and forging in which a molten metal is poured into a preheated lower die, and the upper die is closed to create the mold cavity after solidification begins.
This differs from the usual permanent-mold casting process in which the die halves are closed prior to pouring or injection. Owing to the hybrid nature of the process, it is also known as liquid metal forging. Squeeze casting as liquid-metal forging, is a process by which molten metal solidifies under pressure within closed dies positioned between the plates of a hydraulic press.
The applied 7. Squeeze casting YEOLA pressure and instant contact of the molten metal with the die surface produce a rapid heat transfer condition that yields a pore-free fine-grain casting with mechanical properties approaching those of a wrought product.
The squeeze casting process is easily automated to produce near-net to net shape high-quality components. The process was introduced in the United States in and has since gained widespread acceptance within the nonferrous casting industry. Aluminum, magnesium, and copper alloy components are readily manufactured using this process. Several ferrous components with relatively simple geometry for example, nickel hard-crusher wheel inserts-have also been manufactured by the squeeze casting process.
The squeeze casting process, combining the advantages of the casting and forging processes, has been widely used to produce quality castings. Because of the high pressure applied during solidification, porosities caused by both gas and shrinkage can be prevented or eliminated. The cooling rate of the casting can be increased by applying high pressure during solidification, since that contact between the casting and the die is improved by pressurization, which results in the foundation of fine-grained structures.
Macro segregation has been known to be easily founded in most squeeze castings, which leads to non-uniform macrostructures and mechanical properties. It is generally considered that pressurization during solidification prevents the foundation of shrinkage defects. However, it enhances the foundation of macro segregates in squeeze castings of aluminum alloys. Foundation of macro segregates in castings or ingots has been reported to be caused by interdendritic fluid flow, which is driven by solidification contraction, differences in density, etc.
Squeeze casting is simple and economical, efficient in its use of raw material, and has excellent potential for automated operation at high rates of production. The process generates the highest mechanical properties attainable in a cast product. The microstructural refinement and integrity of squeeze cast products are desirable for many critical applications.
The load is applied shortly after the metal begins to freeze and is maintained until the entire casting has solidified. Casting ejection and handling are done in much the same way as in closed die forging.
There are a number of variables that are generally controlled for the soundness and quality of the castings. Time delay is the duration between the actual pouring of the metal and the instant the punch contacts the molten pool and starts the pressurization of thin webs that are incorporated into the die cavity.
Pressure levels of 50 to MPa are normally used. Pressure duration varying from 30 to s has been found to be satisfactory for castings weighing 9 kg. For aluminum, magnesium, and copper alloys, a good grade of colloidal graphite spray lubricant has proved satisfactory when sprayed on the warm dies prior to casting.
Offers a broader range of shapes and components than other manufacturing methods 2. Little or no machining required post casting process 3. Low levels of porosity 4. Good surface texture 5. Fine micro-structures with higher strength components 6. No blow hole. Costs are very high due to complex tooling 2. No flexibility as tooling is dedicated to specific components 3.
Process needs to be accurately controlled which slows the cycle time down and increases process costs. UNIT 3. Shape tube Electrolytic machining, 2.
Electro Jet Machining, 3. Electrolytic In-process Dressing, 4. Electrochemical Grinding, 5. Elctro-chemical Etching 6. Laser based Heat Treatment 1. Because of the presence of this electric field the electrolyte, often a sulfuric acid, causes the anode surface to be removed.
After the metal ions are dissolved in the solution, they are removed by the electrolyte flow. As shown in Fig. In this way a cylindrically shaped hole is obtained.
Rumyantsev and Davydov reported that the process is capable of producing small holes with diameters of 0. It is difficult to machine such small holes using normal ECM as the insoluble precipitates produced obstruct the flow path of the electrolyte. The machining system configuration is similar to that used in ECM. However, it must be acid resistant, be of less rigidity, and have a periodically reverse polarity power supply. The cathodic tool electrode is made of titanium, its outer wall having an insulating coating to permit only frontal machining of the anodic workpiece.
The normal operating voltage is 8 to 14 V dc, while the machining current reaches A. A periodic reversal of polarity, typically at 3 to 9 s pre- vents the accumulation of the undissolved machining products on the cathode drill surface. The reverse voltage can be taken as 0. Reverse 25—77 ms Feed rate 0. The turbulators are normally used for enhancing the heat transfer in turbine engine-cooling holes. Electrolytic In-process Dressing Electrolytic in-process dressing ELID is traditionally used as a method of dressing a metal bonded grind- ing wheel during a precision grinding process.
The Electrolytic In-process Dressing ELID is a new technique that is used for dressing harder metal-bonded superabrasive grinding wheels while performing grinding. Though the application of ELID eliminates the wheel loading problems, it makes grinding as a hybrid process. The ELID grinding process is the combination of an electrolytic process and a mechanical process and hence if there is a change in any one of the processes this may have a strong influence on the other.
The ambiguities experienced during the selection of the electrolytic parameters for dressing, the lack of knowledge of wear mechanism of the ELID-grinding wheels, etc. The process happens in an electrolyte, which gives the ions a possibility to transfer between two electrodes. The electrolyte is the connection between the two electrodes which are also connected to a direct current as illustrated in Figure 2. When electrical current is supplied, the positive ions migrate to the cathode while the negative ions will migrate to the anode.
Positive ions are called cations and are all metals. Because of their valency they lost electrons and are able to pick up electrons. Anions are negative ions. They carry more electrons than normal and have the opportunity to give them up.
If the cations have contact with the cathode, they get the electrons they lost back to become the elemental state. The anions react in an opposite way when they contact with the anode. They give up their superfluous electrons and become the elemental state. Therefore the cations are reduced and the anions are oxidized. To control the reactions in the electrolyze cell various electrolytes the electrolyte contains the ions, which conduct the current can be chosen in order to stimulate special reactions and effects.
The ELID uses similar principle but the cell is varied by using different anode and cathode materials, electrolyte and the power sources suitable for machining conditions. The cell is created using a conductive wheel, an electrode, an electrolyte and a power supply, which is known as the ELID system.
The metal-bonded grinding wheel is made into a positive pole through the application of a brush smoothly contacting the wheel shaft.
The electrode is made into a negative pole. In the small clearance of approximately 0. The ELID grinding wheels are made of conductive materials i. The diamond layer is prepared by mixing the metal and the diamond grits with certain volume percentage, and the wheels were prepared by powder metallurgy. The prepared diamond layer is attached with the steel hub as shown in Figure 2. The grinding wheels are available in different size and shapes. Among them the straight type and the cup shape wheels are commonly used.
The performance of the ELID depends on the properties of the electrolyte. However, the ELID uses an electrolyte in which the oxide is not solvable and therefore the metal oxides are deposited on the grinding wheel surface during in-process dressing. The performance of different electrolytes has been badebhau4 gmail.
The amount of chlorine presents in the water should be considered because it has a positive potential, which has a significant influences on electrolysis. The applications and the advantages of different power sources were compared, and the results were described in the previous studies [Ohmori, , ].
However, the recent developments show that the pulsed power sources can produce more control over the dressing current than other power sources. When the DC-pulsed power source is used as the ELID power supply, it is essential to understand the basics of pulsed electrolysis in order to achieve better performance and control.
ELID is classified into four major groups based on the materials to be ground and the applications of grinding, even though the principle of in-process dressing is similar for all the methods. The different methods are as follows: Normally copper or graphite could be selected as the electrode materials.
The gap between the electrode and the grinding wheel was adjusted up to 0. Proper gap and coolant flow rate should be selected for an efficient in- process dressing. Normally arc shaped electrodes are used in this type of ELID and the wheel used is either straight type. ELID 1 arrangement for spherical superfinishing 2. The problem in micro-hole machining includes the following: The existing ELID grinding process is not suitable for micro-hole machining because of the difficulty of mounting of an electrode.
The smallest grinding wheel for example 0. The small grinding wheels can be pre-dressed using electrolysis in order to gain better grain protrusions.