Ball Screw
What is Ball Screw
A ball screw is a mechanical linear actuator that translates rotational motion to linear motion with little friction. A threaded shaft provides a helical raceway for ball bearings which act as a precision screw.
Advantages of Ball Screw
Ball screws are highly efficient
Ball screws are more efficient than other types of screws, boasting 90% efficiency in comparison to a lead screw’ s 20-80%. This means that ball screws are able to convert more of their rotary motion to linear motion more quickly than other types of screws.
Ball screws are accurate
Ball screws are also known for their accuracy. If a machine requires a screw with a high amount of accuracy, a ball screw is the way to go. Depending on whether you choose a ground or rolled ball screw, the exact level of precision can vary from device to device.
Ball screws lessen friction
The ball bearings of a ball screw serve to reduce friction as the nut moves along the shaft of the screw. This results in less wear to the device in addition to a longer lifespan.
Ball screws are more cost-effective
Ball screws are often used as an alternative to hydraulic or pneumatic systems since they use less external power. This, combined with their long lifespans, makes ball screws a cost-effective option.
Why Choose us
Reputation
A company with a positive reputation is more likely to attract customers. Reputation is built through consistent quality service or products, good customer relations, and reliability.
01
Customer service
The company offers excellent customer service and support, making it easy for customers to resolve any issues they may have with the product.
02
Quality assurance
We prioritize delivering high-quality services, and our output is subjected to quality checks to ensure that our clients receive the best possible services.
03
Competitive pricing
We offer competitive pricing on all our products without compromising on quality.
04
Innovative and unique products
We are always creating innovative and unique products to keep our customers interested and engaged.
05
The 4 components of a ball screw assembly
The main body of the ball screw is its shaft, which consists of a long steel bar with continuous grooves (ball grooves) in it, forming a helical pattern (the thread). The shaft receives the force, allowing the ball screw to rotate.
Inside the nut, there are ball grooves to match the grooves of the shaft. The nut is a part of the recirculatory system that holds a ball bearing. Without the nut, the balls would continually fall out rather than recirculate.
The ball bearings (balls) are what make the ball screw unique from lead screws. Balls are made of steel, and without them, as the nut and shaft move, the friction would be too much. With the help of the ball bearings, a ball screw can efficiently rotate with little to no friction.
On a ball screw, the seal’ s job is to protect the screw from debris and any objects or matter that might otherwise enter the space between the ball screw and the nut. There are two types of seals: standard and high performance.
● Standard Seal — the standard seal comes in two forms: plastic or brush. The plastic form is a non-contact general-purpose seal used to block debris through obstruction. The brush seal brushes debris away and off of the track and is used for rolled ball screws.
● High Performance — high-performance seals are custom made for a specific screw nut and lead combination. They are made with a lip that blocks debris and contaminants while increasing torque only slightly. A high-performance seal is needed for messy jobs such as woodworking or welding.
Types of Ball Screws
Rolled thread ball screws
Rolled thread ball screws are the most common type of ball screws used in the industry. The manufacturing process for these screws involves cold forming the screw and nut threads, resulting in a smoother surface finish and a higher lead accuracy. Rolled thread ball screws suit low to moderate-load applications and offer high efficiency and fast speeds.
Ground ball screws
Ground ball screws are manufactured using precision grinding methods rather than cold forming. The result is a more precise and accurate screw with a higher lead accuracy than rolled thread ball screws. Ground ball screws have higher load capacity and are available with preload for high-rigidity applications. They are more expensive than rolled thread ball screws but are a great option for high-end applications with stringent accuracy requirements.
Precision ball screws
Precision ball screws are designed to deliver the highest accuracy and repeatability in positioning applications. They are manufactured using advanced techniques, including precision grinding of the screw, nut, and balls. Precision ball screws offer high axial rigidity, low friction, and excellent wear resistance. They are used in applications that require sub-micron positioning accuracy, such as semiconductor manufacturing and aerospace systems.
Miniature ball screws
Miniature ball screws are designed for small space applications or applications that demand high accuracy with limited space. They are available in various diameters ranging from 3mm to 16mm with small lead pitches. They offer low friction and high precision with relatively low load capacity. Miniature ball screws are used in medical devices, laboratory equipment, and microelectronics.
Stainless steel ball screws
Stainless steel ball screws are made of corrosion-resistant and high-strength material, making them suitable for applications that require high durability and resistance to harsh environments. They can withstand high temperatures and humidity and offer high reliability and stability. Stainless steel ball screws are used in the food, beverage, chemical, and marine industries.
How to Choose the Best Ball Screw for Your Application
Axial load
Axial load depends on the orientation of the application. Axial load in vertical applications is the actual weight of the load. In horizontal orientations, axial load is the actual weight of the load multiplied by the load support bearings' coefficient of friction.
Design life objective
The design life objective is the distance in inches the nut will travel during its lifecycle. A ball screw requires an adequate dynamic load rating to accommodate the inches it will travel.
Critical speed
Critical speed is the intended operating speed within the ball screw's safe limits. Determine the critical speed using screw length, screw diameter, and end mounting rigidity.
Safe compression load
The compression load prevents the screw from buckling under a heavy load. Determine the safe compression load using the distance between the load and the ends of the bearings, the rigidity of the mounting ends, and the load itself.
What to Look for When Choosing a Precision Ball Screw
The manufacturing process
Manufacturing a high quality precision ball screw begins with selecting the right steel. During the processing of steel, microscopic inclusions can form in the material which will eventually lead to the propagation of cracks and other surface fatigue that shorten the ball screw’s useful life. Steel production technology has evolved to the point where the number and size of inclusions can be significantly reduced. However, these higher quality steels do cost more. Typically, the best material is a vacuum-degassed purified alloy steel.
Examining design
Proven ball screw designs use tubes or deflectors for ball recirculation and, most recently, systems of internal ball recirculation. This latest approach allows the ball screw nut to be smaller. And because there are no tubes or deflectors, the balls will run quieter and faster, allowing higher operating speeds and lower noise levels than more conventional methods of recirculation.
Accuracy grades
For precision ball screws, there are a number of standards which set forward basic specifications for everything from materials to mathematical tolerances. These include the ANSI-B5.48, DIN 69051, ISO 3408, and JIS B1191 standards.The most important specification for any ball screw is the lead error and lead accuracy. Lead error is the difference between a specified distance and the actual travel distance of the lead screw nut. This parameter, expressed as an error over a specified travel distance, helps determine the accuracy rating of the ball screw.
Ball Screw Physical Specifications
The design arrangement can be English or metric. Some suppliers specify both.
The length of the screw is the most important dimension to consider.
The outer screw diameter is the largest diameter value of the screw.
Screw lead is the axial distance a screw travels during one revolution, measured in inch/turn. Screw lead accuracy is represented as a percentage.
The dynamic load rating is the load that can be sustained while the assembly is moving.
The maximum static capacity is the load that can be sustained, measured while the load is stationary.
Ball Screw Design Features
Backlash is the axial free motion between the nut and screw. It is a measure of the stiffness of the assembly.
Right hand thread specifies that the direction of the threads on the screw shaft causing the ball nut to travel away from the end viewed when rotated is clockwise.
Left hand thread specifies that the direction of the threads on the screw shaft causing the ball nut to travel away from the end viewed when rotated is counter-clockwise.
Lead is the axial distance a screw travels during one revolution.
Twin leads are useful in opposing dual motion using a single drive system. This design features both the left and right hand threads.
Common nut materials for ACME screws include plastic and bronze.
Ball Screws and Lead Screws Comparison Chart
|
Ball Screws |
Lead Screws |
|
|
Mechanism |
Recirculating ball bearings |
Threaded screw with plastic or metal nut |
|
Industries and Applications |
Large, industrial-scale applications |
Smaller OEM applications |
|
Capacity |
Higher load capacity |
Lower load capacity |
|
Design |
Complex design |
Simple design – easy to customise for applications |
|
Operation |
High efficiency, accuracy, precision. |
Efficiency, accuracy, and precision are not as high. |
4 Tips for Increasing the Life Span of a Ball Screw
Proper machining alignment
The installation of the ball screw must be correct. Improper machining alignment is the fastest way to degrade the ball screw and increase wear, decreasing its life span and increasing expenditure.The result of an improperly aligned ball screw could also cause damage to the corresponding machine and result in costly repair or replacements. Ensure a trained and certified engineer installs the ball screw and performs any repairs to maintain alignment demands. Consider having the same engineer perform all alignment maintenance regularly.
Environmental cleanliness
It’ s vital to ball screws that their environment is clean and well maintained. This includes the workspace, machining area, and team members’ designated areas. An unclean workspace poses a significant risk to all involved, including the ball screw.Dirt, debris, and dust are unavoidable in machining processes. Implementing a safety and sanitization checklist for designated work areas is essential to ensure team members are doing their part to combat this issue. When ball screws pick up an excess of debris, they become inefficient and can throw entire machines into failure.
Adequate lubrication measures
Lubrication plays a significant role in the overall health and viability of ball screws. It' s vital to use adequate lubrication upon installation and perform routine exams to ensure the lubrication is intact. When the ball screw begins showing inadequate lubrication, it' s best to reapply more to help avoid costly damages.Without lubrication, ball screws risk heat damage, alignment issues, grinding in the threading, and poor accuracy. Partner with a certified ball screw manufacturer to ensure you use the correct lubrication for your ball screw, machining, and environment.
Pre-installation care and handling
Before installation, most ball screws should arrive at a given facility in secure, protective packaging. Ensuring this packaging is intact and that the storage location is viable for the ball screw is critical to its performance and life span. When a new ball screw experiences increased environmental pollution or abrasion, you risk its integrity and put its vital components, such as threading or nuts, at risk of avoidable defects.
Our factory
Wenzhou Xionglian Hardware Machinery Co., Ltd. is a member of China Machinery General Parts Industry Association. The company was founded in 1988, is a modern manufacturer integrating production, R&D, manufacturing and sales. The company focuses on the production of fasteners, stamping parts and special kinds of fasteners. Our products are widely used in machinery, automobile, military, aerospace, metallurgy, mining, industrial automation and others.
Our Certificate
Asked Question
Q: What are the requirements for ball screws?
Q: What are the possible failures of ball screws?
Q: What is the life expectancy of a ball screw?
Q: How much load can a ball screw hold?
Q: Does ball screw need maintenance?
Q: What are the reasons to use a ball screw?
Q: Why are ball screws so expensive?
Q: What is the most accurate ball screw?
Q: What is the critical speed of a ball screw?
Q: Can you backdrive a ball screw?
Q: Can ball screws be back driven?
Q: What is an alternative to ball screws?
Q: Do ball screws need lubrication?
Q: How often do you grease ball screws?
Q: What is the lock nut on a ball screw?
Q: Are ball screws self locking?
Q: What temperature should ball screws be?
Q: What is the difference between rolled and ground ball screw?
Q: What is the difference between single and double ball screws?
Q: What steel are ball screws made of?