INSTRUCTION FOR SAFE AND EFFICIENT BRAZING

INSTRUCTION

The information given in this summarises the golden rules of good brazing practice which must be observed if silver brazing alloys are to be usedto their gratest advantage. Careful observation of these rules will assist in attaining a high standard of brazing efficiency and minimise any possible hazards which might accompany misuse of brazing alloys or fluxes.

Rule 1 - USE ONLY CLEAN PART
All parent metals must be clean and and free from all forms of contamination such as scale, dirt,oil and grease,etc.  Failure to observe this precaution will result in unsound joints and could lead to unplesant fuming.   Plated parts should be treated with caution.

Rule 2 - CHOOSE THE RIGHT ALLOY AND ITS MATCHING FLUX
Select the correct combination of brazing alloy and flux (if required) by reference to the appropriate section of this catalogue.  Never use a low melting point alloy with a high melting point or vice versa.

Rule 3 - ALWAYS USE AN ADEQUATE AMOUNT OF FLUX
Not only is it important to select the correct flux but it is also essential that a sufficient quantity is used to protect the joint area throughout the brazing cycle.  As a general rule, too much flux is better than too little.  If the flux becomes exhausted, brazing alloy flow will be restricted, de-wetting may occur and there is the danger that unprotected brazing alloy will be exposed causing fuming.

Rule 4 - APPLY HEAT EVENLY
The object of brazing is heat the parts to be joined to a temperature less than 50°C above the melting point of the brazing alloy, thus allowing it to flow into or along the joint contours.   The lowest melting alloy have melting points below 650°C so that brazing takes place below 700°C -- at a dull red heat.   For this reason avoid direct sunlight or other bright lights which will tend to mask the colour of the joint area.  As the alloy melting point gets higher, the necessary brazing temperature is indicated by an intensifying of the red colour. Bright red, before the colour becomes yellowish, is around 900°C.  When using a torch, heat the joint area generalLy concentrating on the heavier sections to develop an even heat pattern. A!ways concentrate heat on the joint and never attempt to melt the brazing rod by heating directly with a flame. The brazing alloy rod should be applied only when the joint is up to temperature. Avoid fierce, highly concentrated heat sources; for example, if torch brazing use a tip giving a good bushy fiame.  Overheating is a bad practice. Not only may it result in inferior joints but harmful fumes from both flux and brazing alloy may be given off.
 
Rule 5 - ENSURE THAT THERE IS SUFFICIENT VENTILATION
Never under any circumstances should brazing be carried out in confined spaces or under conditions of restricted ventilation. Crouching 'head down’ over the workpiece is a dangerous practice and must be avoided

Rule 6 - SEEK ADVICE IF YOU NOTICE ANYTHNG ABNORMAL
If when brazing an unusual effect occurs, such as the evolution of copious fumes, or any difficulty in application of the brazing materials, stop immediately and seek advice. Just bocause you feel no harmful effects it does not necessarily mean that you aro not at risk.


CAUTION
AIloys containing zinc and cadmium can if used under unsuitable canditions evolve fumes which, if inhaled, aro injurious to health. In the case of zinc, the effect may be unpleasant but temporary. whereas the cadmium fume a poisonous and in severe cases can prove fatal.
 
Fumes may be evolved if these alloys are:

 a) Used without a flux
 b) Used with the wrong grade of flux
 c) Used with insufficient flux
 d) Overhoated above their normal melting ranges
 e) Used on dirty parent metals

Similar considerations apply to fluxes which if heated above their normal operating temperature may break down, giving off irritant gases which must not be inhaled.
General care should be taken in handling fluxes which can sometimes irritate sensitive skins, and the use of gloves, or barrier creams applied before brazing is racommanded. As the Iow melting point fluxes contain fluoride bearing compounds which are classed as poisonous, they should never be swallowed.
It must be emphasized that provided these basic precautions are observed, silver brazing alloys and fluxes can be empioyed with perfect safety.
The silver-copper-zinc-cadmium alloys bave been successfully used in industry for over 35 years on a vast range of applications.