White metals are a type of metal that is also known as light-colored alloys. White metals are widely used as a basis for plated silverware, embellishments, and different lead-based or tin-based alloys. In the majority of cases, white metal welding can be found on jewelry, door handles, fusible plugs, and miniature figures.
But how can one weld white metal?
White metal welding is a less popular and less often used technique. Knowledgeable welders fit into this particular market, make more money, and are more difficult to replace. There are two main reasons to learn as much as possible about welding these alloys.
Let’s get started.
White Metals: What Are They and How Do They Work?
White metal, sometimes known as pot metal, is a zinc-based alloy with minimal amounts of copper, tin, or magnesium added to achieve the desired properties. Aluminum alloys, as opposed to zinc-based alloys, can withstand higher temperatures and have better mechanical properties.
Pot metal is classified into three types based on their chemical composition: zinc, aluminum, and magnesium. The most common type is zinc alloy, which has a melting point of up to 725°F (385°C)
What is the common white metal application?
White metals can be used in a variety of ways. It’s mostly found in ornaments, ornamental items, and novelty items. It’s not uncommon to see it in jewelry, both high-end and low-cost. Figures, medals, metallic hangings, wall decorations, and plaques can also be made or repaired using pot metal. It’s also utilized as a roofing material in metal sheets and as a casting form for die-castings.
What Makes White Metals So Unique?
White metal typically contains antimony, tin, cadmium, zinc, lead, bismuth, aluminum, or magnesium.
Unfortunately, several of these metals are toxic by nature, preventing their usage as pot metal.
Despite the fact that magnesium, aluminum, and zinc alloy are the most commonly used metals, they still need to be mixed with other metals to provide the needed properties.
Zinc alloys are the most widely utilized due to their low melting points and low temperatures. Cast zinc and rolled zinc are the two most common types of zinc used in welding. Additional metals, such as zinc, silicon, magnesium, and manganese, are frequently added to cast aluminum alloys in small proportions. This is done to improve the materials’ engineering properties.
Characteristics of White Metals
Pot metal has a high friction coefficient, ductility, and softness while still being exceedingly durable. It has an intermetallic composition that is hard, brittle, and wear-resistant. As a result, they are unsuitable for bearing applications.
The mechanical characteristics of pot metal are as follows:
- It’s fragile at room temperature and needs to be heated to improve mechanical performance.
- Light.
- Before doing any spot welding, the metal surface may need to be mechanically abraded.
- Wear-resistant.
- It has a lower melting point than steel but a higher electrical and thermal conductivity.
- Shock-resistant.
- The coefficient of friction is low.
- A stiff but ductile substance
Benefits Of White Metals
The white metal is helpful in the production process for a variety of reasons. To begin with, it is inexpensive, lowering the cost of raw materials and making products more widely available. Second, they’re easy to mold and work with, allowing anyone to make one-of-a-kind items or swiftly repair them.
Welding on White Metal (How To Weld Zinc)
Pot metal is a low-cost material to work with, although it is difficult to weld. Due to their weak structure and low melting point, operators may find it challenging to weld these metals.
Because various sorts of metals are made up of a range of metals, it depends on which metal is the dominant form.
Because most white metals contain zinc or aluminum, they must be treated as these elements when welding. Even yet, determining its melting point may be challenging. A welder can quickly wreck everything if he or she isn’t careful. Cast aluminum is substantially easier to weld than zinc alloys, especially when it comes to TIG welding. One of the most challenging tasks is selecting the appropriate welding rods.
There are various welding electrodes created expressly for pot metal, the most popular of which is the JB weld, but even with that, you can’t guarantee satisfactory outcomes. Some people believe that repairing a crack with a pot metal restoration kit rather than welding is a better alternative. An appropriate approach is to clean the weld area, bevel it, and apply epoxy to the crack.
Here are some useful ideas to bear in mind if you still want to weld it.
The Flame is changing
Ensure that your welding torch is set to carburizing mode. Take care not to get any soot on the welded links, though. Because the oxyacetylene flame or plasma can be fairly hot when working with pot metal, a smaller tip is preferable. Low-temperature soldering or the usage of a superalloy are two options.
Use extreme caution while using a torch because the spelter can heat up and melt the solder. It’s a good idea to practice on a broken statue or another useless item.
Choosing the Right Rod (Zinc Welding Rods)
A pot metal stick welder’s welding rods are usually made of pure zinc. You might also use a die-casting alloy made of the same metal as the one you’re welding. A small amount of metal flux, 50 percent zinc chloride, and 50 percent ammonium chloride can also be added to pot metal rods. The ones made by JB Weld are believed to be the best.
White Metal Welding Techniques
When it comes to welding pot metal components, many people simply cross their fingers and hope it sticks. Because pot metal is a lower-grade metal, most people utilize a pot metal repair kit instead of welding it. Because it is a low-cost metal, it is also commonly used to create castings.
If you do decide to do it, it’s best to heat the casting component until the base metal liquefies. The flame should be turned in a parallel direction and face the surface. As a result, the base metal and the rod both attain the same temperature, keeping the metal soft.
Resistance Welding of Zinc Alloys
Resistance welding pot metal, as opposed to gas and arc welding, is used with rolled alloys since it requires the least amount of heat. Soundproofing walls are also included.
Spot welding is most commonly used on lap joints and flanges. The thickness of the metal sheet determines the size of the overlap. Make sure to degrease and clean the work area before starting to weld.
Application of Zinc in Resistance Welding
Solid zinc is resistance welded with low electrode forces and steel utilizing currents matching to low electrode forces. Cavities and internal defects are obvious, but they can be reduced by applying a forging force.
The same properties apply to cast zinc cast alloys as they do to rolling alloys. It’s a good idea to remove the additional coatings that most casings come with.
Conclusion
In today’s business, white metals, sometimes known as pot metals, are frequently used. Repairing or welding can be challenging, but if you follow the appropriate steps, you should have no problems.
With 8 years of experience a senior welding instructor and safety equipment researcher and writes articles, reviews and guidelines on helmets and other welding and safety gears at Welder Choice, and other written works have been published in various publications.