FAQs

The best soldering method is determined by the size of the components you are trying to bond and the size of the solder joint needed. Both parts must be heated simultaneously for the best adhesion and aluminum dissipates heat very quickly.

• Large components: propane torch.
• Small components & thinner aluminum parts: soldering iron

If a propane torch is used on too small of an application, there is a risk of overheating and not creating a good bond between bare metals. For a more detailed explanation please see the Soldering Aluminum with KappAloy instructions for more information.

Modern high-speed bearings use a babbitt alloy of Tin, Copper, and Antimony to form the bearing surface. The rotating shaft rides on top of the harder Tin-Copper and Tin-Antimony molecules, and the softer tin molecules distribute the harder Tin-Copper and Tin-Antimony molecules around the bearing surface. It is critical to bearing life that the force and shock of the shaft is evenly distributed throughout, and this is one of the reasons why composition of the babbitt is extremely important. Other functions include:

• Absorb dirt and debris and carry it away from the rotating shaft
• Provide channels for the lubricant in the gaps between the harder alloys with a scarred tin surface

Over time you should see scarring from the dirt and debris in the Tin Babbitt surface. The bearing surface should be rebuilt before any scarring occurs to the harder and much more expensive rotating steel shaft.  

There are three main things to consider when selecting a soldering iron:

1)     Wattage (Power)

a)     Selecting the soldering iron wattage is more a function of heat reserve (power) than of temperature attained. A higher wattage soldering iron is better able to maintain a constant temperature, as it has more power to apply to the tip during use. How much power reserve is required for your soldering application depends primarily on the composition and mass of the parts being heated and the size of the solder joint.

Example: If you are soldering two large (heavy) Aluminum components over a large joint area, a high-powered soldering iron will probably work best. Aluminum dissipates heat quickly, so it is difficult to get both large parts heated to the soldering temperature at the same time. If your only process is soldering a thin Copper wire to a small Copper tab, you don’t need a lot of reserve power to heat both parts to the soldering temperature. Remember that both parts reaching the soldering temperature is what creates the bond between the solder and parts. If only one is heated to the soldering temperature, the bond to the cooler part may be inconsistent. 

2)     Tip selection (many now come with a variety of interchangeable tips for different joint geometries)

a)     It is also based on the mass of parts and joint area. Choose a tip that will heat the entire joint area on both parts simultaneously.

3)     Simple On/Off Soldering Iron or a Soldering Station that includes temperature readouts and controls, solder iron stand, solder tip cleaning block or wool, etc.

a)     A simple Plug in On / Unplug Off Soldering Iron can be purchased for $10 to $20. Soldering Stations with temperature controls and readouts and all the gear to efficiently complete a wide variety of solder joints on various metals can cost over $250. What you need depends on your current project and your future plans.

Once you select the right iron, use our solder selection tool to find the right solder for your project.

We would recommend:

1. A higher wattage soldering iron. For example, 85 or greater watts
2. A soldering iron that comes with a variety of soldering tips, as you will have several different joint geometries to solder.
3. A soldering iron or soldering station with temperature control, rather than a soldering iron that is either plugged in and hot or unplugged and cold

After your soldering iron is selected, making sure you have the right solder for your project by using our solder selection tool.

Yes, using our steps below you can overcome the difficulties of pre-Tinning a cast iron surface to provide a smoother, more consistent, and longer lasting Babbitt surface. Unlike Steel bearing housings, it is much more difficult to pre-Tin a Cast Iron surface because of oxidation and contaminants in the porosity of the metal that make it difficult to get a solid metal-metal bond.

• Option 1 (most common): Heat and chemical fluxing agents like Kapp Copper-Bond Flux™. By applying a chemical flux appropriate for the temperature range of your Babbitt application, you can remove these contaminants from the bearing housing.

Note: For a very dirty old housing, however, you have to replace the original contaminants – oil, rust, dirt, old Babbitt turnings, etc. – with the oxidation products of the fluxing action. As a result, you need to keep reapplying the flux and heat to get the Cast Iron surface clean enough to accept Babbitt.

• Option 2: Pre-Tinning compound like KappaTinning™Compound. Applying an even coating of Tin to the Cast Iron surface, KappaTinning™ Compound is 50% flux solids and 50% pure Tin. The flux component removes the oxide layer and other contaminants, leaving the Tin ready to bond to the Cast Iron.

Note: While it would be ideal to have a pre-Tinned surface to accept your new Babbitt lining, this may not be possible with many older Cast Iron housings. If you find that the bearing life is significantly degraded by an inability to get sufficient Babbitt lining to stick to the bearing housing, it is probably necessary to try this procedure again or machine a new housing.

Yes! We have general how to solder guidelines that go over in detail the following three general steps:

1. Clean and break the oxide layer on the parts to be joined
2. Apply heat to the parts, not the solder
3. Apply the solder evenly across the joint area and remove the heat

Both Aluminum and Stainless Steel rapidly form a very strong oxide coating over the metal. The smooth and uniform oxide coating is what prevents these metals from corroding away except in the harshest environments. You can solder both, however, by breaking this oxide coating to get the strong metal-to-metal bond between the solder and parts by precleaning, removing the oxide by agitation or flux, and pre-tinning. To learn more, simply follow our how to solder guidelines.

You have two choices for Aluminum-to-Copper electrical component soldering:

• KappAloy9™ solder is the eutectic standard solder for Aluminum-to-Aluminum and/or Copper. It is used extensively in oven soldering and other automated soldering systems. Its eutectic nature makes it ideal for high production automated soldering systems. In addition, it minimizes the heat applied to delicate electronic parts.

• KappAloy15™ may give you more flexibility. With a melting range of 390°F to 550°F (199°C to 288°C), it gives you a slushy range to manipulate your parts before it solidifies completely. Many customers using hand-soldering for structural joints prefer this solder. It is used less often in electrical connections to minimize heating of electrical/electronic parts and potential heat damage. The general rule of thumb is less heat is always better – less distortion, less segregation, less differential cooling of different metals, etc.

For successful soldering of Aluminum parts, the oxide coating must be broken to allow the solder to form a metallic bond with the Aluminum. This oxide coating can be penetrated by scratching the Aluminum surface with a Stainless Steel brush or by using their pairing flux Kapp Golden Flux™. The flux residue can then be removed with warm water and a rag.

You are getting plate deformation because you are heating dissimilar metals. They expand and contract at different temperatures and at different rates. Our recommendation is to minimize the required heating of the parts. In our customers’ experience we see two successful solders for such an application:

• KappAloy9™  - (91% Tin/9% Zinc) solder is the eutectic standard solder for copper and aluminum plates. It is used extensively in oven soldering and other automated soldering systems. Its eutectic nature makes it ideal for high production automated soldering systems.

• KappAloy15™ - (85% Tin/15% Zinc) may give you more flexibility. It has a melting range of 390°F to 550°F and 199°C to 288°C. The solder thus gives you a slushy range to manipulate the parts, before it has solidified completely during cooling. Many customers using hand-soldered for structural parts prefer this solder. It is used less often in electrical connections to minimize heating of electrical/electronic parts and potential heat damage. The general rule of thumb is less heat is always better – less distortion, less segregation, less differential cooling of different metals, etc.

Pairing flux for both:  Kapp Golden Flux™. In our experience, we don’t think you will get a consistent reliable joint in any substantial production of this assembly without flux. With or without the flux, you may get a more reliable repeatable joint by pre-tinning the parts with the solder, and then reheating them with additional solder to join the plates. It will consume more time, but you will get a substantially more consistent joint.

Alumite™ is not the best solder for Aluminum and Aluminum-to-Copper radiator repairs. Instead, the thin extruded and/or sheet Aluminum alloys of radiators are best joined at lower temperatures by either KappRad™ 40 or KappAloy15™. Many who hand solder prefer these solders for their excellent flexibility and wider plastic melting ranges, which allow you to manipulate your parts before it cools. The table below compares these solders to Alumite™.

• KappRad™ has been specifically designed for Aluminum and Aluminum-Copper radiator repair. It has higher strength and vibration resistance than comparable solders and brazing alloys and is applied at a lower temperature to avoid damaging thin and delicate parts.
  • WARNING: Contains Cadmium - a restricted substance under RoHS guidelines. It has specific application waivers in many countries. See the SDS for more information.
• KappAloy15™ is a standard solder for Copper and Brass tubes to an Aluminum sheet. It is used extensively in Aluminum-to-Copper radiator repair, where the higher strength of KappRad is not necessary, or where there are restrictions on the use of Cadmium.
  • Pairing flux for both:  Kapp Golden Flux™ removes the oxide coating in close and inaccessible joints.

GalvRepair™ and Lead-free Galvanite™ are the two solders designed for high quality repairs to galvanized surfaces. Both products use a similar procedure, but their slushy ranges are different:

• GalvRepair™ has been the industry standard of galvanizing repair for over 50 years. 
• Lead-free Galvanite™ was developed specifically to meet this challenge more and more countries, states, and counties are requiring the switch to Lead-free products.

Both GalvRepair™ and Galvanite™ exceed performance standards as specified by ASTM standard A780-92 for repair of galvanized coatings. Both provide a broad slushy range for spreading and smoothing the applied solder over the entire repair area. These broad melting ranges also allow for layered application to build up the protective coating to substantial thicknesses. Please see the instructions below for more application information. The procedure is exactly the same for both repair rod formulas.

In all repairs involving Aluminum, one of the most important steps is breaking the oxide layer on the parts to allow the solder to bond with the part. If you are experiencing good solder flow, but a poor joining, the following soldering process should be completed in rapid succession:

1. The parts to be joined should be brushed with a Stainless Steel brush to loosen their oxide coatings. This “scratching” of the invisible oxide coating is crucial to solder flow and bonding or, if the joint area is inaccessible to scratching/requires solder to flow into a narrow area between parts, Kapp Golden Flux™ should be applied to the joint area to break the oxide layer.

2. The parts should be heated until the flux begins to activate (boil) and turns yellow or brown. Do not overheat the flux. If the flux chars, it becomes a contaminant in your joint. Then you must allow the parts to cool and start over, ensuring all the flux residue is removed
3. Apply the solder rod, dragging the rod through the solder pool to get solder under any oxide remaining on the parts. Do not directly heat the solder rod!

• Difficulty “starting” the solder rod in this step? Is the flux activating but you are overheating the flux and part before you get the solder to flow? 
• This is typically due to the oxide coating on the solder rod itself and you can follow these steps to create a successful bond
• Brush the end of the solder rod with a Stainless Steel brush to break the oxide coating on the solder rod
• If trouble persists, heat the end of the solder rod directly with the heat source to soften the solder and break the oxide barrier to flow, not to melt the solder completely.

There are 3 Questions you need to ask before deciding which solder and flux is best for your copper joint.

1)     Do I have to manipulate the joint before/during it solidifies?

• No: The electronic industry standard for Copper-to-Copper electrical/electronic joints is KappZapp3.5™(96.5% Tin - 3.5 % Silver). This solder both melts and solidifies at 430°F / 221°C so there is little time for placement manipulation after soldering. It is used most often in automated soldering of electrical connections to minimize overheating of electrical components and causing damage. The general rule of thumb is less heat is always better – less distortion, less segregation, etc. Due to the single melting/solidifying temperature that makes repositioning the wires during soldering and cooling difficult. You either overheat the solder/flux, or you are forced to reheat the joint, which weakens the bond.

• Yes: KappZapp4 (96% Tin / 4% Silver) solder has a plastic range of 430°F to 475°F (221°C to 246°C). This allows for some manipulation of the parts without substantially overheating the joint. Your choice depends on how you jig the parts for soldering, and whether you need to adjust the parts during soldering/cooling.

2)     Do you need a flux to break the oxide layer off your connection? And/or does the solder need to flow into a tight, inaccessible space? If yes, use:

• Kapp Comet Flux™ or KappZapp3.5R. Kapp Comet Flux works on non-Aluminum joints in the temperature range of 350°F to 550°F. See Safety Data Sheet (SDS) for more specs. KappZapp3.5R has a Rosin Solder Core for electrical/electronic soldering. This simplifies the soldering process by applying the flux to the joint area using the same solder rod. The flux flows before the solder, removing the oxide layer only in the joint area, and only just as it is needed.

3)     Do you need a higher strength joint to withstand vibration or stress? On something like a speaker wire or air conditioner? If yes, choose from the following for your application: 

• Speaker industry standard: KappZapp7 to join Copper wire to speaker tabs in high vibration setups. This is only recommended where the higher strength is necessary because you are heating the parts to higher temperatures of 430°F to 575°F (221°C to 302°C).
• Pairing flux: Kapp Copper-Bond Flux 

• Electrical/electronic soldering: KappZapp7™ solder is available with a Rosin Solder Core (see KappZapp 7R). This simplifies the soldering process by applying the flux to the joint area using the same solder rod. The flux flows before the solder, removing the oxide layer only in the joint area, and only just as it is needed.

The speaker industry standard for high-end audio/visual and speaker installations is KappZapp7™. This solder is used extensively by audiophiles and the speaker industry to join Copper wire to Copper speaker tabs in high vibration setups. This is only recommended where the higher strength is necessary because you are heating the parts to higher temperatures of 430°F to 575°F (221°C to 302°C).

• Pairing flux: Kapp Copper-Bond Flux™

Alternatively, KappZapp7R™ solder is available with a Rosin Solder Core for electrical/electronic soldering. This simplifies the soldering process by applying the flux to the joint area using the same solder rod. The flux flows before the solder, removing the oxide layer only in the joint area, and only just as it is needed. This Rosin-Cored solder is used most often in hand soldering electrical/electronic parts.

Our Lead-free Galvanite™ is easy to work with and provides a strong bond in body repair and seam buildup. It comes in a rod form - .200” x .250” x 14” long. Galvanite™ has a broad slushy range of 390°F to 570°F (200°C to 300°C). When heated, the slurry can be shaped and spread easily to blend seamlessly with existing Steel surfaces. In many repair projects, the Steel surface is prepared with a Stainless Steel brush. Then, the same brush or a putty knife is used to spread and even out the Galvanite coating as it cools. The Galvanite coating can be built to a substantial thickness, even on vertical surfaces.

Stainless Steel is usually non-magnetic and often has a dull brushed silver finish, while Stainless Steel alloys with high Nickel or Chromium contents can be very shiny and have a mirror finish. These highly polished alloys are much more difficult to solder due to a very strong oxide layer. They typically require the oxide layer to be physically broken by wire brushing or sanding, AND chemical removal of the oxide layer by acid flux. 

Your need for a higher temperature range, as well as higher strength and ductility leads you to KappZapp™ Tin/Silver solders. Which Tin/Silver alloy is best for your Stainless Steel to Copper joints is usually determined by four criteria:

1. Strength/Vibration Resistance
2. Electrical Conductivity
3. Cost, and
4. Rosin Flux-Cored, Acid Flux-Cored or Solid Wire 

As the chart below illustrates, strength, vibration resistance and electrical conductivity all go up with an increase in the Silver (Ag) content of the KappZapp™ solder. The price also increases with the Silver Content. The challenge is to choose the solder that meets your needs without buying more Silver than you need!

Finally, you must choose between solid wire, Acid and Rosin Flux-Cored wire. The flux-cored wires are the easiest to use because the flux for removing the oxide layer from the parts is enclosed in the center of the wire. When the parts are heated to the melting temperature of the solder, the flux flows out and breaks down the oxide layer. This allows a strong metallic bond between the solder and the parts in one step. When using solid solder wire, the oxide layer on the parts must be broken by physical agitation with a Stainless Steel brush or sandpaper, or by a separate liquid or paste flux.