Đang tải... (xem toàn văn)
brazing, soldering
Brazing, Soldering, Adhesive- Brazing, Soldering, Adhesive- Bonding, and Mechanical- Bonding, and Mechanical- Fastening Processes Fastening Processes Ir. Tri Prakosa, M. Eng. Proses Manufaktur II, Januari 2010 1 Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Brazed and Soldered Parts Brazed and Soldered Parts Source: Courtesy of Edison Welding Institute. (a) Resistance brazed light bulb filament (b) brazed radiator heat exchangers (c) soldered circuit board (d) brazed ring housing (e) brazed heat exchanger. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Cobe Laboratories Blood Reservoir Cobe Laboratories Blood Reservoir The Cobe Laboratories blood reservoir. The lid is bonded to the bowl with an airtight adhesive joint and tongue-in-groove joint. Source: Courtesy of Cobe Laboratories. Introduction Introduction In almost all the joining processes described in previous lectures, the metals to be joined were heated to elevated temperatures by various means to cause fusion or bonding at the joint. But how to join materials that cannot withstand high temperatures, such as electronic components? What if the parts to be joined are delicate or intricate or are made of two or more materials with very different characteristics, properties, thicknesses, and cross-sections? Institut Teknologi Bandung4 Introduction, con’t Introduction, con’t Today’s lecture first describes two joining processes, brazing and soldering, which permit lower temperatures than those required for welding. In both brazing and soldering, filler metals are placed in or supplied to the joint. They are then melted using an external source of heat and, upon solidification, a strong joint results. Institut Teknologi Bandung5 Introduction, con’t Introduction, con’t Soldering temperatures are lower than those of brazing, and the strength of a soldered joint is not high. Thus brazing and soldering are arbitrarily distinguished by temperature. Institut Teknologi Bandung6 Introduction, con’t Introduction, con’t This lecture also describes adhesive bonding techniques. The ancient method of joining parts with animal glue, as is done in labeling, packaging, and bookbinding, has now developed into an important technology with wide applications in aerospace and various other industries. Institut Teknologi Bandung7 Introduction, con’t Introduction, con’t All the joints described so far are of a permanent nature. In many applications, there are situations where joined parts have to be taken apart for replacement, maintenance, repair, or adjustment. How to take apart (separating), a product without destroying the joint? If we need joints that are truly nonpermanent but are as strong as welded joints-the solution obviously is to use mechanical means, such as bolts, screws, nuts, and a variety of similar fasteners. Institut Teknologi Bandung8 Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. Effect of Joint Clearance on Strength of Effect of Joint Clearance on Strength of Brazed Joints Brazed Joints The effect of joint clearance on tensile and shear strength of brazed joints. Note that unlike tensile strength, shear strength continually decreases as the clearance increases. BRAZING BRAZING Institut Teknologi Bandung10 [...]... chemically or mechanically cleaned to ensure full capillary action; hence the use of a flux is important 15 Institut Teknologi Bandung Filler metals Several filler metals (braze metals) are available and have a range of brazing temperatures, see the Table below: 16 Institut Teknologi Bandung Filler metals Variety of filler shapes: wire, rings, shims, and filings The choice of filler metal and its composition... of brittle intermetallic compounds at the joint, and galvanic corrosion in the joint Filler metals for brazing, unlike other welding operations, generally have significantly different compositions than the metals to be joined 17 Institut Teknologi Bandung Filler metals Because of diffusion between the filler metal and the base metal, mechanical and metallurgical properties of joints can change... unlike liquid-state welding processes in which the workpieces must melt in the weld area for fusion to occur Problems associated with heat affected zones, warping, and residual stresses are therefore reduced in brazing 14 Institut Teknologi Bandung Brazing The strength of the brazed joint depends on: a joint design and b the adhesion at the interfaces of the workpiece and filler metal Consequently,... Teknologi Bandung Fluxes The use of a flux is essential in brazing in order to prevent oxidation and to remove oxide films from workpiece surfaces Brazing fluxes are generally made of borax, boric acid, borates, fluorides and chlorides Wetting agents may also be added to improve both the wetting characteristics of the molten filler metal and capillary action Surfaces to be brazed must be clean and. .. filler metal and capillary action Surfaces to be brazed must be clean and free from rust, oil, and other contaminants 19 Institut Teknologi Bandung Fluxes Clean surfaces are essential to obtain the proper wetting and spreading characteristics of the molten filler metal in the joint and maximum bond strength Sand blasting may also be used to improve surface finish of faying surfaces Because they are... and was first used as far back as 3000-2000 B.C 12 Institut Teknologi Bandung Brazing There are two types of brazing processes: a that was previously described, and b braze welding (Figure b), in which the filler metal is deposited at the joint with a technique similar to oxyfuel gas welding (b) Braze welding 13 Institut Teknologi Bandung Brazing Filler metals used for brazing melt above 450 °C (840... to be joined, and the temperature is raised to melt the filler metal but not the workpieces, (Figure a) (a) Operasi Brazing 11 Institut Teknologi Bandung Brazing The molten metal fills the closely fitting space by capillary action Upon cooling and solidification of the filler metal, a strong joint is obtained Brazing comes from the word brass, an archaic word meaning to harden, and was first... (0.004-0.5 in.) 29 Institut Teknologi Bandung Brazing methods Resistance brazing As in induction brazing, the process is rapid, heating zones can be confined to very small areas, and the process can be automated to produce uniform quality Equipment costs range from $1,000 for simple units to more than $10,000 for larger, more complex units 30 Institut Teknologi Bandung Brazing methods Dip brazing ... Teknologi Bandung Brazing methods Furnace brazing As the name suggests, furnace brazing (FB) is carried out in a furnace The parts are re-cleaned and re-loaded with brazing metal in appropriate configurations before being placed in the furnace Contoh brazing yang dilakukan di dalam tungku(furnace brazing): (a) sebelum, (b) sesudah Perhatikan bahwa logam pengisi berupa kawat 24 Institut Teknologi Bandung... welding operations 25 Institut Teknologi Bandung Brazing methods Furnace brazing Skilled labor is not required, and complex shapes can be brazed since the whole assembly is heated uniformly in the furnace The cost of furnaces varies widely, ranging from about $2,000 for simple batch furnaces to more than $300,000 for continuous vacuum furnaces 26 Institut Teknologi Bandung Brazing methods Induction brazing