Manufacturing Processes

MANUFACTURING PROCESSES
ADHESIVE BONDING, BRAZING, SOLDERING, JOINING, AND WELDING OF PLASTICS

Adhesive bonding
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Adhesive bonding is a process in which two similar or nonsimilar materials are solidly and permanently assembled using an adhesive. The term glue is often used to designate natural-based formulas (vegetable or animal) whereas the term adhesive is reserved forformulas which include synthetic resins or elastomers. This distinction is gradually being replaced by the generic use of the term adhesive.

Advantages and disadvantages of adhesive bonding
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Advantages:
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More uniform stress distribution Materials of varying types and thicknesses can now be assembled The material around the joint is little subject toalteration: bonding temperatures are not excessively high, parts are not pierced, and there is no electrochemical corrosion. Elasticity of adhesive joints: vibrations are attenuated Adhesive joints can provide impermeability to air and water as well as insulatation against: electricity, electro-magnetic waves, noise, ... Structures are lighter. Adhesive bonding gives clean-looking results. Productioncost is generally lower than with traditional assembly methods. The assembly operation can be easily automated to achieve high production rates.

Advantages and disadvantages of adhesive bonding
  Limitations:
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to heat is often limited   Mid-term durability in harsh environments (5 to 20 years)   Surface treatment often required   Low resistance to peel stress  Disassembling is difficult   Bonding time can be long in some cases.

Examples of practical applications
Cars are a good example of industrial adhesive bonding applications.   Brake-band linings have been assembled exclusively with adhesives. The fact that these sensitive parts are bonded with adhesives illustrates how reliable adhesive bonding can be when it is properly designed and controlled.  Rear-view mirrors have also been assembled with adhesives. Specially designed repair kits (acrylic-based adhesives) can now be found in many department stores.
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Examples of practical applications
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Side molding is now fixed with double-sided adhesive tape. This type of bonding has a two fold advantage:
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It reduces the number of tools and references parts, It reduces the risk ofwater infiltration and rocker panel corrosion.

Headlights are bonded with adhesives, and on certain models the rear lights are also assembled with adhesives.   The production of "plastic-monoblock" sealed beam lights relies heavily on adhesives
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Examples of practical applications
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All car doors currently use a crimped and glued system: the crimping allows immediatehandling since the adhesive hardens only after it has been submerged in a cataphoretic bath. The adhesive provides i m p e r m e a b i l i ty, t ra n s f e r o f stresses and insulation against noise. Doors and fixed windows on cars, buses, trucks or highspeed trains are assembled with adhesives. Adhesive bonding integrates the window into the structure of the vehicle itself.

Video

Brazing
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Brazing is the joining of metals through the use of heat and a filler metal–one whose melting temperature is above 840°F(450°C) but below the melting point of the metals being joined. It is also known as “Silver brazing," since in most cases the filler metal used is a silver alloy. The term "brazing" refers to a torch brazing process with a silver-bearing filler metal. B ra zi n g i s p r o b a b l y t h e m o s t versatile method of metal joining today.

Brazing
Brazed joints are strong: On non-ferrous metals and steels, the tensile strength of a properly made joint will often exceed that of the metals joined. On stainless steels, it is possible to develop a joint whose tensile strength is 130,000 lb per square inch. (896.3 MPa).   Brazed joints are ductile,...