A ball screw is a unique actuator that converts rotational motion into linear motion with minimal friction. It is widely used in a variety of industrial applications where high precision and close tolerances are required. What sets this design apart from conventional lead screws or ballscrews is the fact that it practically eliminates backlash.
The unique feature of a ballscrew is the rolling balls inside the helical groove. This reduces mechanical contact within the screw assembly and replaces sliding friction with rolling friction.
The threaded shaft creates a helical raceway for ball bearings, which have the advantage of being able to apply or withstand high thrust loads with minimal internal friction.
The linear motion of the ballscrew is established by the set of bearings at an angle to the rod. The angle between these bearings and the rod determines the linear motion. This results in a smooth and precise linear motion without the issue of backlash.
At Balaji Engineering Works, we understand the importance of high-quality ballscrews. Therefore, we only supply premium quality ballscrews. Our ball screws are made from high-quality materials and are manufactured to strict tolerances to ensure maximum precision and durability. We offer a wide range of ball screws to suit various industrial applications.
In conclusion, if you require high-precision linear motion with minimal friction and no backlash, a ballscrew is the ideal actuator for your application. Trust Balaji Engineering Works for your ballscrew needs and experience superior performance and reliability.
Components of the Ball Screw
Screw Shaft
Ballscrew have a screw shaft that receives rotational force from the shaft, which in turn is translated into linear motion. The power to rotate this shaft is provided by the motor that is situated on its end. Screw shafts are long cylindrical shafts with a continuous groove, known as the ball groove, running continuously around their length, which is referred to as the screw thread. A ball screw has a semicircular or gothic arc ball groove which serves as the pathway for the rolling ball bearings. Gothic arc groove profiles have ogival shapes formed by two arcs, while semicircular arc grooves are formed by a single arc. They differ on the areas of point of contact where they touch the ball. When the groove on the shaft of a ball screw runs clockwise and slants to the right, it is a right-hand ball screw, while if it runs counterclockwise and slants to the left, it is a left-hand ball screw.
Nominal Diameter
A screw shaft’s nominal diameter is its maximum diameter, excluding the ball bearings.
Ball Circle Diameter
The diameter of a ball circle (also known as the pitch circle diameter) refers to the center-to-center distance between two opposite balls when the ball bearings are in contact with the grooves.
Root Diameter
In screw shafts, root diameter corresponds to the distance between the bottommost section of the groove and the bottommost section of the opposite groove. This is the minimum diameter of the screw shaft.
Pitch
In ballscrew, pitch is the axial distance between two threads adjacent to each other.
Lead
Lead is a specification of a ball screw that determines linear travel, speed, and load capacity since it covers the distance covered by one complete rotation (360°). Increased lead length increases the linear distance and speed of ball screws; however, less balls are accommodated around the screw shaft, resulting in a decrease in load carrying capacity.
Start
A screw has a start in the form of an independent helical ring around the shaft. Screws typically have one, two, or four helices, with the lead equaling the pitch multiplied by the number of helices. One of the most common types of screws is the single start screw. In this type of
screw, the lead is equivalent to the pitch. Multiple start screws are used for rapid linear movements with fewer rotations or high load capacities.As a result, higher leads have fewer consequences. For instance, double- start screws have lead equivalent to twice its pitch; this means that for one full rotation, the screw will cover two-pitch units. A higher number of starts results in a greater linear distance covered in a revolution.
Nut
A ball screw nut is a cylinder containing the ball bearing and its recirculation system. The internal surfaces of the nut are grooved to match the grooves in the screw shaft.
Circuit
The circuit of a ball nut refers to the closed path of the recirculating system. Ball nuts with multiple circuits can carry heavier loads than ones with single circuits.
Turn
Depending on the type of recirculation used with a ball screw, the turn of the circuit depends on the number of trips the ball makes before being recirculated in the circuit. In the nut, balls are returned to their starting position through a ball recirculation system, which uses deflectors, return tubes, and end caps to help return the ball to where it began.
Ball Bearings
Among the most prominent parts of the ball screw are the ball bearings, or balls, which move between the clearance between the nut and the shaft of the ball screw. These balls are used in screw assemblies to reduce friction generated by the moving screw and the nut. Without them, the friction would be too great. Balls with steel cores are generally used. There is contact between the ball and the screw shaft and nut. These contact points are distinguished by the groove profiles on the two components where the ball touches. Gothic and circular grooves are the most common groove profiles.
Gothic Arc Profile.
As the name implies, it is a groove profile consisting of two intersecting arcs. In this groove profile, the ball has two points of contact with the shaft and two points with the nut. It is the most common type of groove profile.
Semi-Circular Arc Profile.
The groove profile has a semicircular shape. Using this profile, the ball would have one point of contact on the screw shaft and one point of contact on the nut. Both profiles have an arc with a larger radius than the ball used. This design results in clearance between the ball and the ball screw which causes backlash; this clearance can be eliminated by preloading the ball screw.
Seal
Seals are minor components of ball screws that protect the entire ballscrew assembly.By preventing contaminants from entering the gap between the ball and the nut, it maintains the ball screw’s efficiency, as well as maintaining lubrication.
