tooling for a typical tubular riveting operation. systems may be direct-acting or work through lever systems (FIG. FIG. sets are commercially available in a wide variety of shapes to mate with The number can be extended to as many as may be convenient to load. Inductors must have sufficient cooling to avoid overheating. Sheet holder for aligning holes during riveting. and cooling techniques. The actual value depends on the ratio The use of component FIG. 12 where two welds are made with each or tin-coated for clamping onto battery terminals. In FIG. timer; (6) power interrupter; (7) foot switch; (8) secondary loop; (9) They are made with chamfered or dog-point ends. For emitted light to the eye and skin, great care must be taken when performing [34.5 MPa]). but they generally require special thread forms. cap screws are available for applications having head clearance problems. The hole may have been drilled in both pieces prior to mating. The maximum 30. solder at a predetermined rate (FIG. be two to three times the radius for through-heating, and 10 times the radius Thus an elementary workholder irregularly shaped sections where efficiency is not too important, gaps of The same fixture could be mounted on a powered rotating base Typical assemblies for several types of threaded fasteners The fixture can be mounted on a table while an operator applies heat with and heavy components, is their usefulness as pilots to facilitate mating The tool used to apply deformation pressure may be a common hammer, pneumatic 36). heat conduction and cooling. together. Square-head bolts have square-shaped, external wrenching heads. If the shape of the workpiece will not support itself in an upright or convenient FIG. due to the design. There are many types of lasers, but the two mainly For high-quantity production good fixture welds. Often, a fixture will maintain the proper part relationship during welding The fixture design principles for nut runners are: screw blank prior to roll threading and becomes a permanent part of the assembly FIG. Bent bolts are cylindrical rods having one end threaded and the other bent FIG. induction brazing may require significant tooling/fixture design and development. its terminals. characteristics. Solid inductors usually are self-supporting, as are single-turn inductors. Clamping pressure can be used to counteract D = depth of heat penetration, in. of the workpiece material. process, the worker may hold a torch closer to the workpiece for a longer To correctly machine a part, it must be held in a fixturing setup that guarantees The flow of alternating If a fix ture acts as a chill for one part of the joint, this may result and cross-wire welding. The electrical characteristics of a high-frequency power source determine stroke of the welder without any markings, indentations, or discoloration A wide latitude of shape is permitted. as preheating and post-weld heat treating. in a predrilled hole, holding a pneumatic hammer against the head of the the screw threads closely, with no clearances necessary. distortion occurring during welding and FIG. Washers commonly used include Since the exact amount of metal heated in a brazing operation depends on Electrode nose shapes are illustrated in FIG. Dearborn, material will decrease the welding current and lower welding efficiency. guns) are commercially available in a wide range of types and sizes. These machines are available to perform: These machines vary in sizes from small bench to large floor models. gas welding. 33a). They are available with be made of copper, stainless steel (used for tungsten inert gas), titanium, thick nesses. unsupported rivets or eyelets that will not withstand the single impact required FIG. The theoretical depth of current penetration mentioned previously increases This method has several limitations, tapping screws, and captive screws. or with a series of hammer blows. welds are required. the transformer. In some situations, coaxial leads may be necessary (450 kHz and power presses with hopper-feed mechanisms. a suitable mandrel. the worker applies a fastener. with temperature and must never exceed the radius of the stock being heated. precisely locate the workpiece relative to the driver. The For a brazing operation, an inductor can be made by forming copper tube on Tip area is a function of the workpiece material called "offset."). Tapping screws are The laser should be mounted in a firm structure to prevent vibration. clinches. factor in some of the welding processes. FIG. attain a high production rate. confines of the coil), two to three times as much energy (kilowatt seconds They are made from .007-in. 8 shows backing bars designed for use with gas, which may be used to Stapling is a joining operation using pre formed, U-shaped wire staples. welding process. on one side of the assembly. square inches (kW/in.^2 ). output transformer. usually have square or hex heads, gimlet or cone points, and thin, sharp, (0.05-0.38 mm) at the brazing temperature. backing bar in certain situations. surfaces for the weld joint design. all cases. Protect the root of the weld from the atmosphere. Since many composites are compromised when subjected to drilling or localized The locating elements may be movable so parts can be positioned outside of per piece based on 1 kW/in.^2 of surface area. flashing and upsetting, followed by discontinuation of the welding current. Insulate all gage pins, clamps, locators, index pins, etc. plates are used to keep workpieces flat and control distortion. Laser welding Hex and square nuts, sometimes referred to as full nuts, are the most common. It must This process will produce a better weld for They are made with slotted, recessed, or wrenching heads in various head 1 reflects the degree of heat input associated with a given Machine screws. 47. 38 shows a hydraulic riveting yoke.). used as it would necessitate heating entirely too much metal. Stamped nuts are made with integral mass. Water for cooling should be circulated as close to the tips as possible. Tapping screws will cut or form mating threads when driven should be approximately equal to the material thickness plus the clinch allowance. Gun and hammer tackers Silver ceramic, or a combination of several metals (sandwich construction). FIG. caused by welding brings the parts into the correct relationship to each 25. In many cases, 27. 50 illustrates locking a ring to a shaft with center-punch staking. 7 shows In assembly of structural steel components. A fixture loop or throat is the gap surrounded by the upper and lower riveting (both produce similar outcomes) as it does not require drilling and. is used for coils with appropriate water cooling. in incomplete bonding and a defective joint. to minimize heat loss while providing sufficient support and locating points. Sems are avail able in various Figure A. 1. must control the piece part configuration for periods of days without losing The type of adhesive used is the main element to consider in the design and infrared-oven curing. has been cut to the correct coil length. of components, which expedites automatic assembly. In manual welding, it is sufficient If it is convenient for a worker to hold the of the clinch for full-tubular and bifurcated rivets should be figured at The ends of bent It should be noted that, in some cases, the filler metal may wet and flow exerts pressure on work. NEXTArticle Indextop of page, Applications Determine the depth of heat penetration on plain carbon steel using Equation bonding material to flow. 4. Most cap screws are made from steel, stainless steel, brass, bronze, or aluminum innumerable light blows while the hammer spins. FIG. The peening and spinning Backup bars may parts to be joined. Fixture Design explores If the parts threaded on one or both ends or throughout their lengths (FIG. When high production requirements preclude the use of a longer heating FIG. Holes Too much restraint can through the clamping dies after the welding current is applied. 48 illustrates flat and loop clinches. In this manner, Featured are: requirements for workholding; nut, then a simple workholder may be advantageous. They are generally supplied with plain (as or assembly components after they have been disengaged from their mating 20, clamps must be supported underneath moving out of alignment during the welding process. The tooling must hold the work pieces in correct relationship during joining, will in crease the cure rate so fixtures must with stand the required heat The tooling material must be stable at the intended process temperatures. but also in many cases, either accelerate or retard the flow of heat. Cap screws. Again, 4. The fixture material should not be affected in the weld zone and should Minimal heat loss from the welding area is Screws are available in a wide variety of types and sizes to suit specific 49 illustrates the parts and clinching dies of the retaining-ring assembly. (FIG. 25 illustrates a nest-type fixture to hold mating workpieces within In some cases, materials have actually hole in the components, into which a screw is to be inserted. Induction heating is resistance heating with current flow meeting resistance. be fixtured in the correct location. fixtures are often used. standardization efforts have made most threaded fasteners interchangeable. when designing the workpiece. 31. on, and two joints are brought together by means of cam control to establish most joint designs on small parts, a single turn is sufficient. solid dies. formation pressure is exerted by the bucking bar. utilized optical scanners that followed a paper template or digital tape are used. Turns used. and the machine if high production is required. Sequence of punching and riveting operations. Support the molten weld; govern the weld contour. to a stationary-type rivet unit or machine. welds in a defined place, whether the weldment is in the correct position I^2 R must have a time factor, t, to become: Additional depth results from the current following the path of least resistance are located with Reference to each other (mated), and placed between the more metal than necessary and be less efficient. Such an inductor is insufficient 39 shows the sequence of a punching and riveting operation used in 46 provides examples of staple nomenclature. Other bent bolts, such as U-bolts, have both ends threaded. 6. of heat required. a batch furnace. Holes could be drilled prior to or during the riveting sequence. the area into the preceding value of kilowatt seconds to determine the approximate Ir regularly shaped gears, and other components on shafts. used in the T-slots of machine tools. and unloading. have more prongs to engage the threads on the mating fastener. In the physical joining process, parts are made to join along their contacting automatic wire-stitching machines are ideal for fastening components together. 13 illustrates the principle of indirect welding, which is ordinarily It is also possible to select the adhesive that best meets individual job The time The leads to the inductor should be kept as short as possible and close the water eliminates ultra violet emissions. The flux also covers and protects the area by shielding Bolts are externally threaded fasteners generally assembled with nuts (FIG. This fixture consists of locating elements for two or more parts, and rivet have nesting capabilities, which allow more than one part per material sheet. 54). The rivets are fed from a hopper to a feed track. FIG. as for inside diameter (ID) inductors, except that the leads must be brought The water copper) brazed to the inductor. 37. The design also permits making welds in a horizontal position. 1. components. than bolts with square heads. into staplers. on the lower anvil. de sign can be readily adapted for designing welding fixtures. styles and with spaced (course) inch or metric threads. or both. compensate for poor procedure development or selection of the wrong brazing The strips are wound together and The weight of the equipment is minimized by using special high-strength, Initiating pres sure is exerted by the hammer while 24). forming their own threads. although electron beam curing is primarily applied to laminating and coating To accomplish this, large fixture masses should not be placed close to the flat (plain), conical, spring, and toothed lock. The fixture design principles are the same as described previously. Estimate the volume of metal expected to be brought to brazing temperature. the surface finds itself should be as uniform as possible. (0.38-127.00 mm). in quantity to the belt of a tunnel furnace or to a rack for processing in If a corner of a workpiece overheats, Less expensive cycle, the ID coil efficiency can be improved by using an inside core that recommended, as cooling water will cause rust problems with steel or any to the machine table exactly under the driver. (Type D was formerly high-current transformer; (3) primary coils; (4) tap switch; (5) welding to the coil axially instead of radially (FIG. If the leads are not a continuation or part of the inductor and a brazed Air operated This can be accomplished of a large number, a continuous coil can be used, through which parts are Hot coils can be made of copper tubing which, except for extremely low power for assemblies subjected to harsh environmental conditions, such as high Thus, two workpieces may be bolted together to ensure alignment during subsequent Extensive The process must account for the differences in the coefficients of thermal 26 shows the same fixture altered of components a worker can conveniently handle. The worst contamination and assist and control the joining process by affording adequate support. Eighth Edition. in assembled parts, mating with preformed internal threads, or cutting or The sticks are loaded manually In some cases, it is desirable to use a combined with prongs formed to engage mating threads. The portable riveting yoke and can be improved by use of laminations as shown. heat from the inside. by low-cost stapling machines. The principal advantage of adhesive bonding is improved FIG. The power available is determined by the equipment to be used. The riveting process is extremely varied-it may be rivet set placed in the nozzle of an air hammer, or a complete forming die are illustrated in FIG. to accommodate various types of positioning devices. 39 illustrated the sequence of operations. Power density and heating time are closely related to the design of the In a precise high-production process, the instrumentation any accurate locating devices from flash. FIG. in which the work to be heated is correctly positioned so the required heating to various configurations. If a single-turn inductor is tooling and/or fixtures. the workpiece so the holes are conveniently positioned, and it should support Regardless of the material used in the induction-brazing process, the inductor temperatures and corrosion. This is particularly true for fixturing that maintains critical tolerances. square heads and coarse-pitch, 60 stub threads. compression, adhesives provide a reliable solution. control method. Name three methods of adhesive curing. nuts usually are limited to light duty and special assemblies. fixture may be part of the machine. to create the strongest possible bond. the field of an induction work coil. increases the magnetic flux outside of the coil. For automatic One of the two workpieces being assembled may be tapped to receive the threaded of Computer-Aided Manufacturing. Keep all magnetic materials, particularly ferrous materials, out of the light) or infrared radiation (wavelengths longer than visible light) to create the number of turns in an inductor. 12. and there is a relationship between the frequency of the alternating current, Many of the machines After 10 screws have been driven to secure one side shield, the cabinet is but distort after removal from the fixture. Doyle, D. Criteria for Proper Adhesive Selection: From Application to Viscosity. on a traveling bridge. or accelerating the cure. Laser cutting is primarily used on different types of numerically controlled for arc-welding fixtures include: The fixture must exert enough force to pre vent or minimize parts from (60.00 50.00 in. FIG. of processes, such as cutting, drilling, metal forming, heat-treating, cladding, (ultraviolet, microwave, electron beam, and infrared) curing. and the forces incurred in the joining process must be relatively small. There are eight possible types of loading on a bond line: Adhesives generally are weak in peel and cleavage and stronger when subjected clinch easily when struck by the contoured riveting tool. The purpose of a welding fixture is to hold the parts to be welded in the This can be obtained by using more power, or time, Some brazing and soldering be welded. Round-head bolts have thin circular heads with rounded or flat top surfaces The amount of energy (kilowatt seconds) is determined by the volume of metal The fixtures also hold the workpieces of a continuous operation, clear passage; proper support or rigidity to maintain its designed shape; insulation to avoid electrical breakdown (spacing or an air gap between a thread-en gaging impression (arched prongs) in a flat piece of metal (FIG. be no wider than the bore diameter; for greater coverage, multi turn inductors Focusing the beam produces intense heat, which causes localized melting The inductor is a primary winding for a transformer with the However, this may actually be the result of an inadequate heating (mm) t = time, sec. FIG. kW (21,600 kJ) for the Nd:YAG and up to 50 kW (180,000 kJ) for the CO2 for or assembly to a required depth to provide a brazed joint. Excessive distortion may result with this Larger rivets used in structural work are de formed with hydraulic or air-operated of the small focused laser beam diameter. a wide range of standard and special types, sizes, materials, and strengths, that used in the physical joining process. and efficiently heating any selected area of an electrically conductive part Low thermal-conductive materials, such as ceramics, often are used to minimize mechanical joining without tooling. Welding electrodes should be easily and quickly replaceable. From the Fundamentals of Tool Design video series, which comprises nine nozzle of the rivet gun receives and retains the rivet set or die. FIG. fixtures, grinding fixtures, and broaching fixtures. When there are large changes in diameter in the section to be heated, the Workpieces being assembled The same locating methods used in workholder This gap or loop is an intense magnetic field, within which Lasers deliver energy in the form of light. studs provide fixed external threads, and nuts are the only components that principle of wire-stitching machines. the manufacture of automobiles and appliances and in other mass production Brazing and soldering are fundamentally the same processes. They are used for the preliminary The mass of any tooling or fixtures that will be heated during the process, 29. This a flat bearing surface. for heating such an area is shown in FIG. head the rivet. 28. The clinching contour of riveting tools must be free of nicks and circular Plasma-arc cutting can be used to cut irregular shapes. For 1,200 F brazing material, convert to kilowatt seconds by multiplying FIG. used to assemble the parts of a timepiece or the structural members of a They FIG. Many workpieces can be held for to it. When welding copper and aluminum, FIG. design should al low sufficient room between the worktable and focusing optic Beyond the primary requirements that the fixture precisely locate and hold As shown in FIG. mated with a preformed brazing ring or foil between them. (a) location-the fixture must align the workpiece precisely with the nut Such hybrid processes Often, several parts may be joined mechanically and wide inductor can be made of .25 x 1.00 in. The minimum clinching radius for tubular rivets enable tailoring the weld by adding filler material to match the desired assembly work. metal of a ring against the knurled portion of a shaft. Pressure may be applied continuously workpieces for heat localization. The key to designing fixtures for cutting operations is allowing Holes are drilled and rivets hardening. any magnetic material will be affected. 42. Conventional methods of adhesive curing include convection steel wire. Because laser energy is delivered to the workpiece without mechanical force, FIG. If heat loss is too rapid, the weld may develop cracks. Consider a piece of plain carbon steel being heated for brazing or surface masking tape, surgical tape, and labels applied through the use of pressure 43. A round locating pin is attached parts. clearance, fixture damage may result. or coil while workpieces are loaded and unloaded. on large parts where heat must penetrate. action of these machines is either mechanical or pneumatic. may be machined to match the part. such as ceramic, stainless steels, and titanium, which are not as easily machines may be used for delicate assembly operations. A thin weldment requires larger backup to promote heat transfer In most cases, all standard jig positioned between electrodes that exert heavy pressure, conduct the current, may result in: bulging of the edge of the piece being riveted; buckling or other distortion, particularly if thin material is used; and/or. usually is obtained by introducing a flux that cleans, dissolves, and floats up). 7. 33. bolt and nut are the most common. standard jig and fixture components where applicable. Polishing the punch tips in the direction of metal flow, The proper rivet or eyelet length it to proper length, forms it into a U-shape, and drives it against a grooved It also is used The determination of how many parts are to be is accomplished (FIG. (resistance is high). proper heat dissipation to prevent distortion. This material, which can be purchased in round bars, is then made a core types of points. Provide sufficient water cooling to prevent overheating. Simple welding fixture using gravity to help locate parts. The most important consideration for arc welding is whether the parts will by capillary action. often can be used to advantage in even the most simple joining operation. Holders and adapters are mounted in may be brought through a hole in the center of the core. are used to drive wire staples. or more parts located and pinned or clamped in position. operations: oxy flame, plasma-arc, and laser. required. Flat clinches are used when the stitched joint must carry heavy loads, such design always must be accompanied by proper procedure development to prevent Proper design and/ or using materials, If there is insufficient (mm) F = frequency in cycles/sec. surfaces through the application of heat or pressure, or both. For higher production rates, these fixtures must be even in part, should be minimized as best as possible to limit the amount is no need for other operations such as punching or drilling prior to fastening. The success of brazing and soldering depends on part cleanliness, temperature usually is due to oxidation during the process. the pressure increases to 5,000 lbf/in.^2 (34.5 MPa) for the rivet upsetting heat loss to and/or through a fixture component. or not. Machine screws have slotted, recessed, or wrenching heads in a variety of adhesive. metals. In The degree and type of distortion in their holes. 35. Threaded fasteners are used for a wide variety of applications, and the 2. (0.18 mm) thick strips of transformer steel, .25-in. From FIG. proper relationship be fore, during, and after welding. Automation typically locates the anticipated bands from electrodes to secondary; (10) electrodes; (11) cylinder that 53. water. or solid copper that has been drilled out or machined to provide water passages. FIG. consideration in selecting a proper setscrew. blast (a), flood (b), or concentrate in the weld area (c). (4.8 mm) in diameter. Temperatures can range from a few hundred degrees set blocks can be interchangeable to accommodate varying workpieces, and rivet, holding a bucking bar against the end of the rivet, then cycling Rivet FIG. Tooling may be required to hold parts in correct relationship to one another These machines are small by 700. This is quite similar to locating parts for gas welding. 35). 16. There are, however, design principles that apply to These may be leveraged or air operated. FIG. point contacts with the material and, therefore, less strength than flat position, a simple nesting fixture may be required. Delayed-tack adhesives (Class IV) are heat activated to produce a tackiness The design of tooling for adhesive joining does not differ greatly from A 1.00-in. Clamps used in welding fixtures must hold parts in the proper position and to drive the fasteners. Soldering and brazing differ from welding in several respects. Other means of locating include capillary attraction, the thickness of the alloy film, and consequently the magnets. A material with greater heat-conducting ability requires less At times, mechanical joining may be considered as the tooling method materials to be welded, the fixturing, or other weld-related processing such Underhead serrations FIG. The power density is approximately due to the hardening ability of the workpiece at the line of cutting, and used, laminations are cut in a C-shape and stacked tightly around the turn, dependent upon the particular filler metal alloy, base metal being joined, The inductor design is integral to the success of any induction-heating of the filler metal. tip can be calculated by: d = diameter of the electrode tip, in.