Our clients in the manufacturing industry today deal with a range of issues that come with creating tubes, holes, and hollow passages through metal materials. In these instances, they rely on ballizing to improve their manufacturing work and speed up fabrication processes. As a metal ball bearings manufacturer, we often get a lot of questions regarding ballizing. So we created this convenient FAQ page to answer some of your most common questions so you can get the custom-size balls and bearing assemblies you need.

What is Ballizing?

Ballizing is also known as ball sizing or ball broaching. The process involves using a certain amount of force to push a ball through an opening. The ball has a larger diameter than the interior of the tube or other hollow passage. It's one of several micro-finishing techniques that manufacturers use in their processes.

What is the Purpose of Ballizing?

When manufacturing tubes and hollows in metals, burrs, and other imperfections can be created, these imperfections could lead to the component failing or the materials degrading when placed into use. Ballizing removes these imperfections by smoothing the interior surface of the passage. The metal ball can force the burrs out and remove tool marks within. It can improve the dimensional accuracy of the tube.

How Does Ballizing Work?

Ballizing can be accomplished using a manual method with a lathe, drill press, arbor press, or a mill. It can also be done using automated equipment. The hole or passage becomes lubricated to reduce friction. The ball is placed in the opening as a push rod is used to steady the ball and force it through the hole or passage. Push rods are typically a short length to prevent bending long tubes.

When the ball is pushed through, it compresses the burrs and other imperfections into the metal. The interior diameter of the tube or hole becomes smooth. At the end of the process, the ball is pushed out and collected for the next workpiece. Burrs that were pushed with the ball become pushed out.

Are There Other Purposes For Ballizing?

Ballizing can also be used to improve the diameter of tubes that may have been drilled from both ends. When the tube is drilled, the hole size can become tapered when reaching the middle of the workpiece. This issue leads to larger diameters at each opening and smaller diameters within the passage. Ballizing causes the middle of the tube to have the same diameter throughout while making the interior smoother. You are also able to change the size of the hole depending on the diameter of the precision balls. If you want a smaller opening size, you will switch to a smaller ball and vice versa.

What Factors Should Be Considered When Ballizing?

If performing ballizing on a part that has thin walls, the outside diameter should be reinforced. This reinforcement can prevent unwanted expansion of the interior diameter. Otherwise, the desired hole tolerance can be achieved if the size of the hole is the only concern. The entrance hole as well as the exit hole of the tube may require chamfering. When performing ballizing,

metal burrs forced from the homes may create sharp edges. Chamfering can be done before or after the ballizing process.

What Are Some Specifications for The Ballizing Process?

Ballizing can be used on any type of metal, including stainless steel, tungsten carbide, chrome steel, and other materials. Ball-type materials can include stainless steel, tungsten carbide, chrome steel, and more. You can get a typical repeatable size of ±0.0001 inches and typical hole sizes of 0.010 to 0.500 inches. Ballizing processes can produce a surface finish of 2 μin ra to 8 μin ra. It can also help to reduce the taper of passages by 0.0002 inches.

With the Ballizing process, you get a work-hardened piece that won't leave materials on the interior surface. Ballizing can allow for automated production rates of up to 5,000 parts per hour depending on the manufacturing process and the equipment used. You can use this process for both through holes and blind holes.

What Are The Most Common Materials Used for Ballizing?

Tungsten Carbide is the most commonly used material for ballizing. The high hardness (Rockwell A 90.5-91.5) and resistance to deformation and wear make it an ideal material for this process. Tungsten carbide balls can be customized in small volumes to whatever size the application needs, whereas most other materials are made in a larger batch process. 

Chrome Steel is another common material for ballizing, again due to its high hardness and wear properties. Chrome is also much more economical than tungsten carbide balls. However, chrome balls are not as customizable in size, as they often require a minimum batch of many thousands to be made at a time. In addition, they are not as hard or resistant to damage as tungsten carbide. Other materials like SS440C are less common but still used occasionally for specific applications.

How Much Does It Cost to Perform Ballizing?

Manufacturers find that using the ballizing process is a fast and repeatable procedure. It can be an inexpensive process depending on the types of equipment that the company uses and the ball used. It often costs less than other finishing processes while providing superior results.

Should You Use Ballizing for Your Metalworking Processes?

Each manufacturer has different applications and specifications based on the produced workpiece types. When considering adding ballizing to your processes, consider the number of pieces that will require this process, whether you will use automated or manual tools, the amount of space available for the equipment, and your budget. For more information about the ballizing process and the types of precision metal balls to use, contact Hartford Technologies.