Soaring Silver – Impacts on the Brazing Industry
Silver pricing has reached a record-high, recently surging to over £2,700/kg. The price remains on an upward trajectory despite a recent plummet, with no current indication of when this trend may stabilise.
Silver brazing is a common industrial joining process used in applications such as refrigeration, air-conditioning and tungsten carbide tooling any many more. As many brazing products contain silver, the significant price increase has greatly impacted the brazing industry, making the purchase of silver-containing products considerably less economically viable for many businesses.
This article explores the main forces driving silver prices, impacts on the brazing industry and the practical steps companies can take to mitigate rising costs.
What are the factors that influence silver prices?
The price of silver is affected by a combination of political and economic uncertainty around the world. Global conflicts and unrest, particularly involving important influencers like the United States, have led investors to seek financial security in precious metals, viewing them as a safe haven. This trend is common where there are periods of political and economic uncertainty.
Another factor is the price of gold. When the price of gold rises, it tends to pull silver prices with it due to increases in investment demand. This demand is caused by investors moving their money into precious metals as a result of determining an increase in market risks.
What are the market trends?
Many markets have been affected by the surge in silver prices. For example, as silver and gold prices climb, demand for jewellery typically declines. Traditionally, higher prices have motivated people to sell their high-value jewellery, resulting in a greater volume of silver being refined and reintroduced into the supply chain – a clear example of supply and demand. This time, however, it seems that geopolitical and investment factors are outweighing any movement on the supply side of the silver market.
Is using a lower silver content brazing alloy ‘the answer’?
Historically, sharp increases in silver prices have prompted manufacturers to consider reducing the level of silver in their silver brazing alloys. However, it is important not to compromise on the quality of brazed joints, even in the face of escalating prices.
Why might reducing the silver level in a brazing alloy not have the desired effect?
1. Changing to a lower silver content ‘cheaper’ silver brazing alloy can introduce other issues and costs, such as increased fuel costs from heating during brazing and more heat stain/oxidation in the heat affected zone, complicating post-braze clean up and finishing processes such as plating.
Lower silver content alloys tend to have longer melting ranges and flow less freely. The more ‘sluggish’ the flow of a brazing alloy, the greater the joint gap needs to be for the alloy to penetrate a given joint depth, and the greater the brazing alloy ‘fillet’ will be built up at the joint opening.
Both factors inevitably mean that more brazing alloy will be used, potentially offsetting any savings on the cost of the brazing alloy from using a lower silver content alloy.
2. For silver-copper-phosphorus brazing rods, it may be tempting to switch to a lower silver or silver-free copper-phosphorus rod. However, this can lead to ductility issues in the joints and potential cracking if the joint is subject to manipulation or vibration in service.
So, what steps can be taken to mitigate the rising cost of silver brazing alloys?
There are some steps practical steps that can be taken to fine-tune the brazing process and potentially save on the amount of brazing alloy used at a time when costs are high.
Choosing Rod Diameter
For hand torch brazing, it is important to optimise the brazing rod diameter as well as the brazing technique, as this can result in significantly lower alloy consumption and shorter heating times, which may offset some of the increased material costs.
Using rods that are too small may cause the alloy to flow too readily through the joint, while using rods with too large a diameter can lead to excessive alloy application and build-up of fillets around the joint opening. Experimenting with different diameter rods will help to find the optimum diameter that will ensure good flow into the joint with reduced fillet build-up.
Do you need a Fillet?
Many companies and brazing operatives who silver braze like to see a brazed fillet at the joint opening. It provides reassuring visual evidence that the joint has been successfully made and that the alloy has sealed the opening. However, in a properly designed capillary joint, the fillet does not necessarily add much in the way of increased strength or leak-tightness. Sectioning a joint will tell you if there is good capillary flow throughout the joint and will therefore not need an excessive fillet. It will also show just how much alloy is ‘spent’ building up a fillet at the joint opening.
Is your joint design optimised?
It is possible that the joint design you have chosen might have been over engineered with a capillary that is longer than necessary, or a joint gap that could be made tighter. There are guidelines for the length of a joint and for optimum joint gaps for each brazing alloy.
Many tubular joints have a degree of ovality because of manufacturing tolerances on the tubes or fittings. This ovality will lead to an inconsistent gap that has to be filled and therefore more brazing alloy being used than necessary. Moving to an alternative joining technique will carry other costs – for example, fuel costs for heating can cancel out any savings achieved by skimping on silver content.
How can VBC Group help?
Refining – A Silver Lining
Refining of scrap silver brazing alloy and surplus or unused stocks of silver enables our customers to recover the locked in value of from scrap. The recovered silver can be sold and the value credited or used against future orders. Essentially, by viewing silver losses as a recoverable resource instead of an unavoidable cost, companies can significantly lower cost-per-joint without impacting alloy performance.
We offer refining options and can advise on alternative products, improved joint design and brazing technique, helping our customers to optimise the use of silver brazing alloys.
Contact us at sales@vbcgroup.com for more information.
