AGS-TECH Inc. - Global Custom Manufacturer, Integrator, Consolidator, Outsourcing Partner
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Joining & Assembly & Fastening Processes
We join, assemble and fasten your manufactured parts and turn them into finished or semi-finished products using WELDING, BRAZING, SOLDERING, SINTERING, ADHESIVE BONDING, FASTENING, PRESS FITTING. Some of our most popular welding processes are arc, oxyfuel gas, resistance, projection, seam, upset, percussion, solid state, electron beam, laser, thermit, induction welding. Our popular brazing processes are torch, induction, furnace and dip brazing. Our soldering methods are iron, hot plate, oven, induction, dip, wave, reflow and ultrasonic soldering. For adhesive bonding we frequently use thermoplastics and thermo-setting, epoxies, phenolics, polyurethane, adhesive alloys as well as some other chemicals and tapes. Finally our fastening processes consist of nailing, screwing, nuts and bolts, riveting, clinching, pinning, stitching & stapling and press fitting.
• WELDING : Welding involves joining of materials by melting the work pieces and introducing filler materials, that also joins the molten weld pool. When the area cools, we obtain astrong joint. Pressure is applied in some cases. Contrary to welding, the brazing and soldering operations involve only the melting of a material with lower melting point between the workpieces, and workpieces do not melt. We recommend that you click here to DOWNLOAD our Schematic Illustrations of Welding Processes by AGS-TECH Inc.
This will help you better understand the information we are providing you below.
In ARC WELDING, we use a power supply and an electrode to create an electric arc that melts the metals. Welding point is protected by a shielding gas or vapor or other material. This process is popular for welding automotive parts and steel structures. In shelded metal arc welding (SMAW) or also known as stick welding, an electrode stick is brought close to the base material and an electric arc is generated between them. The electrode rod melts and acts as the filler material. The electrode also contains flux that acts as a layer of slag and gives off vapors that act as the shielding gas. These protect the weld area from environmental contamination. No other fillers are being used. The disadvantages of this process are its slowness, need to replace electrodes frequently, the need to chip away the residual slag originating from flux. A number of metals such as iron, steel, nickel, aluminum, copper…etc. Can be welded. Its advantages are its inexpensive tools and ease of use. Gas metal arc welding (GMAW) also known as metal-inert gas (MIG), we have continuous feeding of a consumable electrode wire filler and an inert or partially inert gas that flows around the wire against environmental contamination of the weld region. Steel, aluminum and other non-ferrous metals can be welded. The advantages of MIG are high welding speeds and good quality. The disadvantages are its complicated equipment and challenges faced in windy outdoor environments because we have to maintain the shielding gas around the welding area stable. A variation of GMAW is flux-cored arc welding (FCAW) which consists of a fine metal tube filled with flux materials. Sometimes the flux inside the tube is sufficient for protection from environmental contamination. Submerged Arc Welding (SAW) widely an automated process, involves continuous wire feeding and arc that is struck under a layer of flux cover. The production rates and quality are high, welding slag comes off easily, and we have a smoke free work environment. The disadvantage is that it can only be used to weld parts in certain positions. In gas tungsten arc welding (GTAW) or tungsten-inert gas welding (TIG) we use a Tungsten electrode along with a separate filler and inert or near inert gases. As we know Tungsten has a high melting point and it is a very suitable metal for very high temperatures. The Tungsten in TIG is not consumed contrary to the other methods explained above. A slow but a high quality welding technique advantageous over other techniques in welding of thin materials. Suitable for many metals. Plasma arc welding is similar but uses plasma gas to create the arc. The arc in plasma arc welding is relatively more concentrated in comparison to GTAW and can be used for a wider range of metal thicknesses at much higher speeds. GTAW and plasma arc welding can be applied to more or less same materials.
OXY-FUEL / OXYFUEL WELDING also called oxyacetylene welding, oxy welding, gas welding is carried out using gas fuels and oxygen for welding. Since no electric power is used it is portable and can be used where there is no electricity. Using a welding torch we heat the pieces and the filler material to produce a shared molten metal pool. Various fuels can be used such as acetylene, gasoline, hydrogen, propane, butane…etc. In oxy-fuel welding we use two containers, one for the fuel and the other for oxygen. The oxygen oxidizes the fuel (burns it).
RESISTANCE WELDING: This type of welding takes advantage of joule heating and heat is generated at the location where electric current is applied for a certain time. High currents are passed through the metal. Pools of molten metal are formed at this location. Resistance welding methods are popular due to their efficiency, little pollution potential. However disadvantages are equipment costs being relatively significant and the inherent limitation to relatively thin work pieces. SPOT WELDING is one major type of resistance welding. Here we join two or more overlapping sheets or work pieces by using two copper electrodes to clamp the sheets together and pass a high current through them. The material between the copper electrodes heats up and a molten pool is generated at that location. The current is then stopped and the copper electrode tips cool the weld location because the electrodes are water cooled. Applying the right amount of heat to the right material and thickness is key for this technique, because if applied wrongly the joint will be weak. Spot welding has the advantages of causing no significant deformation to workpieces, energy efficiency, ease of automation and outstanding production rates, and not requiring any fillers. The disadvantage is that since welding takes place at spots rather than forming a continuous seam, the overall strength can be relatively lower as compared to other welding methods. SEAM WELDING on the other hand produces welds at the faying surfaces of similar materials. The seam can be butt or overlap joint. Seam welding starts at one end and moves progressively to the other. This method also uses two electrodes from copper to apply pressure and current to the weld region. The disc shaped electrodes rotate with constant contact along the seam line and make a continuous weld. Here too, electrodes are cooled by water. The welds are very strong and reliable. Other methods are projection, flash and upset welding techniques.
SOLID-STATE WELDING is a bit different than the previous methods explained above. Coalescence takes place at temperatures below the melting temperature of the metals joined and with no use of metal filler. Pressure may be used in some processes. Various methods are COEXTRUSION WELDING where dissimilar metals are extruded through the same die, COLD PRESSURE WELDING where we join soft alloys below their melting points, DIFFUSION WELDING a technique without visible weld lines, EXPLOSION WELDING for joining dissimilar materials, e.g. corrosion resistant alloys to structural steels, ELECTROMAGNETIC PULSE WELDING where we accelerate tubes and sheets by electromagnetic forces, FORGE WELDING that consists of heating the metals to high temperatures and hammering them together, FRICTION WELDING where with sufficient friction welding is performed, FRICTION STIR WELDING that involves a rotating non-consumable tool traversing the joint line, HOT PRESSURE WELDING where we press metals together at elevated temperatures below the melting temperature in vacuum or inert gases, HOT ISOSTATIC PRESSURE WELDING a process where we apply pressure using inert gases inside a vessel, ROLL WELDING where we join dissimilar materials by forcing them between two rotating wheels, ULTRASONIC WELDING where thin metal or plastic sheets are welded using high frequency vibrational energy.
Our other welding processes are ELECTRON BEAM WELDING with deep penetration and fast processing but being an expensive method we consider it for special cases, ELECTROSLAG WELDING a method suitable for heavy thick plates and work pieces of steel only, INDUCTION WELDING where we use electromagnetic induction and heat our electrically conductive or ferromagnetic workpieces, LASER BEAM WELDING also with deep penetration and fast processing but an expensive method, LASER HYBRID WELDING that combines LBW with GMAW in the same welding head and capable of bridging gaps of 2 mm between plates, PERCUSSION WELDING that involves an electric discharge followed by forging the materials with applied pressure, THERMIT WELDING involving exothermic reaction between aluminum and iron oxide powders., ELECTROGAS WELDING with consumable electrodes and used with only steel in vertical position, and finally STUD ARC WELDING for joining stud to base material with heat and pressure.
We recommend that you click here to DOWNLOAD our Schematic Illustrations of Brazing, Soldering and Adhesive Bonding Processes by AGS-TECH Inc
This will help you better understand the information we are providing you below.
• BRAZING : We join two or more metals by heating filler metals in between them above their melting points and using capillary action to spread. The process is similar to soldering but the temperatures involved to melt the filler are higher in brazing. Like in welding, flux does protect the filler material from atmospheric contamination. After cooling the workpieces are joined together. The process involves the following key steps: Good fit and clearance, proper cleaning of base materials, proper fixturing, proper flux and atmosphere selection, heating the assembly and finally the cleaning of brazed assembly. Some of our brazing processes are TORCH BRAZING, a popular method carried out manually or in an automated manner. It is suitable for low volume production orders and specialized cases. Heat is applied using gas flames near the joint being brazed. FURNACE BRAZING requires less operator skill and is a semi-automatic process suitable for industrial mass production. Both temperature control and control of the atmosphere in the furnace are advantages of this technique, because the former enables us to have controlled heat cycles and eliminate local heating as is the case in torch brazing, and the latter protects the part from oxidation. Using jigging we are capable to reduce manufacturing costs to a minimum. The disadvantages are high power consumption, equipment costs and more challenging design considerations. VACUUM BRAZING takes place in a furnace of vacuum. Temperature uniformity is maintained and we obtain flux free, very clean joints with very little residual stresses. Heat treatments can take place during vacuum brazing, because of the low residual stresses present during slow heating and cooling cycles. The major disadvantage is its high cost because the creation of vacuum environment is an expensive process. Yet another technique DIP BRAZING joins fixtured parts where brazing compound is applied to mating surfaces. Thereafter the fixtured parts are dipped into a bath of a molten salt such as Sodium Chloride (table salt) which acts as a heat transfer medium and flux. Air is excluded and therefore no oxide formation takes place. In INDUCTION BRAZING we join materials by a filler metal that has a lower melting point than the base materials. The alternating current from the induction coil creates an electromagnetic field which induces induction heating on mostly ferrous magnetic materials. The method provides selective heating, good joints with fillers only flowing in desired areas, little oxidation because no flames are present and cooling is fast, fast heating, consistency and suitability for high volume manufacturing. To speed up our processes and to assure consistency we frequently use preforms.
• SOLDERING : In soldering we do not have melting of the work pieces, but a filler metal with a lower melting point than the joining parts that flows into the joint. The filler metal in soldering melts at lower temperature than in brazing. We use lead-free alloys for soldering and have RoHS compliance and for different applications and requirements we have different and suitable alloys such as silver alloy. Soldering offers us joints that are gas and liquid-tight. In SOFT SOLDERING, our filler metal has a melting point below 400 Centigrade, whereas in SILVER SOLDERING and BRAZING we need higher temperatures. Soft soldering uses lower temperatures but does not result in strong joints for demanding applications at elevated temperatures. Silver soldering on the other hand, requires high temperatures provided by torch and gives us strong joints suitable for high temperature applications. Brazing requires the highest temperatures and usually a torch is being used. Since brazing joints are very strong, they are a good candidates for repairing heavy iron objects. In our manufacturing lines we use both manual hand soldering as well as automated solder lines. INDUCTION SOLDERING uses high frequency AC current in a copper coil to facilitate induction heating. Currents are induced in the soldered part and as a result heat is generated at the high resistance joint. This heat melts the filler metal. Flux is also used. Induction soldering is a good method for soldering cyclinders and pipes in a continuous process by wrapping the coils around them. Soldering some materials such as graphite and ceramics is more difficult because it requires the plating of the workpieces with a suitable metal prior to soldering. This facilitates interfacial bonding. We do solder such materials especially for hermetic packaging applications. We manufacture our printed circuit boards (PCB) in high volume mostly using WAVE SOLDERING. Only for small quantity of prototyping purposes we use hand soldering using soldering iron. We use wave soldering for both through-hole as well as surface mount PCB assemblies (PCBA). A temporary glue keeps the components attached to the circuit board and the assembly is placed on a conveyor and moves through an equipment that contains molten solder. First the PCB is fluxed and then enters the preheating zone. The molten solder is in a pan and has a pattern of standing waves on its surface. When the PCB moves over these waves, these waves contact the bottom of the PCB and stick to the soldering pads. The solder stays on pins and pads only and not on the PCB itself. The waves in the molten solder has to be well controlled so there is no splashing and the wave tops do not touch and contaminate undesired areas of the boards. In REFLOW SOLDERING, we use a sticky solder paste to temporarily attach the electronic components to the boards. Then the boards are put through a reflow oven with temperature control. Here the solder melts and connects the components permanently. We use this technique for both surface mount components as well as for through-hole components. Proper temperature control and adjustment of oven temperatures is essential to avoid destruction of electronic components on the board by overheating them above their maximum temperature limits. In the process of reflow soldering we actually have several regions or stages each with a distinct thermal profile, such as preheating step, thermal soaking step, reflow and cooling steps. These different steps are essential for a damage free reflow soldering of printed circuit board assemblies (PCBA). ULTRASONIC SOLDERING is another frequently used technique with unique capabilities- It can be used to solder glass, ceramic and non-metallic materials. For example photovoltaic panels which are non-metallic need electrodes which can be affixed using this technique. In ultrasonic soldering, we deploy a heated soldering tip that also emits ultrasonic vibrations. These vibrations produce cavitation bubbles at the interface of the substrate with the molten solder material. The implosive energy of cavitation modifies the oxide surface and removes the dirt and oxides. During this time an alloy layer is also formed. The solder at the bonding surface incorporates oxygen and enables the formation of a strong shared bond between the glass and solder. DIP SOLDERING can be regarded as a simpler version of wave soldering suitable for only small scale production. First cleaning flux is applied as in other processes. PCBs with mounted components are dipped manually or in a semi-automated fashion into a tank containing molten solder. The molten solder sticks to the exposed metallic areas unprotected by solder mask on the board. The equipment is simple and inexpensive.
• ADHESIVE BONDING : This is another popular technique we frequently use and it involves bonding of surfaces using glues, epoxies, plastic agents or other chemicals. Bonding is accomplished by either evaporating the solvent, by heat curing, by UV light curing, by pressure curing or waiting for a certain time. Various high performance glues are used in our production lines. With properly engineered application and curing processes, adhesive bonding can result in very low stress bonds that are strong and reliable. Adhesive bonds can be good protectors against environmental factors such as moisture, contaminants, corrosives, vibration…etc. Advantages of adhesive bonding are: they can be applied to materials that would otherwise be hard to solder, weld or braze. Also it can be preferable for heat sensitive materials that would be damaged by welding or other high temperature processes. Other advantages of adhesives are they can be applied to irregular shaped surfaces and increase assembly weight by very very small amounts when compared to other methods. Also dimensional changes in parts are very minimal. Some glues have index matching properties and can be used in between optical components without decreasing the light or optical signal strength significantly. Disadvantages on the other hand are longer curing times which may slow down manufacturing lines, fixturing requirements, surface preparation requirements and difficulty to disassemble when rework is needed. Most of our adhesive bonding operations involve the following steps:
-Surface treatment: Special cleaning procedures such as deionized water cleaning, alcohol cleaning, plasma or corona cleaning are common. After cleaning we may apply adhesion promoters onto the surfaces to assure the best possible joints.
-Part Fixturing: For both adhesive application as well as for curing we design and use custom fixtures.
-Adhesive Application: We sometimes use manual, and sometimes depending on the case automated systems such as robotics, servo motors, linear actuators to deliver the adhesives to the right location and we use dispensers to deliver it at right volume and quantity.
-Curing: Depending on the adhesive, we may use simple drying and curing as well as curing under UV lights that act as catalyst or heat curing in an oven or using resistive heating elements mounted on jigs and fixtures.
We recommend that you click here to DOWNLOAD our Schematic Illustrations of Fastening Processes by AGS-TECH Inc.
This will help you better understand the information we are providing you below.
• FASTENING PROCESSES : Our mechanical joining processes fall into two brad categories: FASTENERS and INTEGRAL JOINTS. Examples of fasteners we use are screws, pins, nuts, bolts, rivets. Examples of integral joints we use are snap and shrink fits, seams, crimps. Using a variety of fastening methods we make sure our mechanical joints are strong and reliable for many years of use. SCREWS and BOLTS are some of the most commonly used fasteners for holding objects together and positioning. Our screws and bolts meet ASME standards. Various types of screws and bolts are deployed including hex cap screws and hex bolts, lag screws and bolts, double ended screw, dowel screw, eye screw, mirror screw, sheet metal screw, fine adjustment screw, self-drilling and self-tapping screws, set screw, screws with built-in washers,…and more. We have various screw head types such as countersunk, dome, round, flanged head and various screw drive types such as slot, phillips, square, hex socket. A RIVET on the other hand is a permanent mechanical fastener consisting of a smooth cylindirical shaft and a head on the one hand. After insertion, the other end of the rivet is deformed and its diameter is expanded so that it stays in place. In other words, prior to installation a rivet has one head and after installation it has two. We install various types of rivets depending on application, strength, accessibility and cost such as solid/round head rivets, structural, semi-tubular, blind, oscar, drive, flush, friction-lock, self-piercing rivets. Riveting can be preferred in cases where heat deformation and change in material properties due to welding heat needs to be avoided. Riveting also offers light weight and especially good strength and endurance against shear forces. Against tensile loads however screws, nuts and bolts may be more suitable. In the CLINCHING process we use special punch and dies to form a mechanical interlock between sheet metals being joined. The punch pushes the layers of sheet metal into die cavity and results in the formation of a permanent joint. No heating and no cooling is required in clinching and it is a cold working process. It is an economical process that can replace spot welding in some cases. In PINNING we use pins which are machine elements used to secure positions of machine parts relative to each other. Major types are clevis pins, cotter pin, spring pin, dowel pins, and split pin. In STAPLING we use stapling guns and staples which are two-pronged fasteners used to join or bind materials. Stapling has the following advantages: Economical, simple and fast to use, the crown of the staples can be used to bridge materials butted together, The crown of the staple can facilitate bridging a piece like a cable and fastening it to a surface without puncturing or damaging, relatively easy removal. PRESS FITTING is performed by pushing parts together and the friction between them fastens the parts. Press fit parts consisting of an oversized shaft and an undersized hole are generally assembled by one of two methods: Either by applying force or taking advantage of thermal expansion or contraction of the parts. When a press fitting is established by applying a force, we either use a hydraulic press or a hand operated press. On the other hand when press fitting is established by thermal expansion we heat the enveloping parts and assemble them into their place while hot. When they cool they contract and get back to their normal dimensions. This results in a good press fit. We call this alternatively SHRINK-FITTING. The other way of doing this is by cooling the enveloped parts before assembly and then sliding them into their mating parts. When the assembly warms up they expand and we obtain a tight fit. This latter method may be preferable in cases where heating poses the risk of changing material properties. Cooling is safer in those cases.
Pneumatic & Hydraulic Components and Assemblies
• Valves, hydraulic and pneumatic components such as O-ring, washer, seals, gasket, ring, shim.
Since valves and pneumatic components come in a large variety, we cannot list everything here. Depending on the physical and chemical environments of your application, we do have special products for you. Please specify us the application, type of component, specifications, environmental conditions such as pressure, temperature, liquids or gases that will be in contact with your valves and pneumatic components; and we will choose the most suitable product for you or manufacture it specially for your application.