A “Straight” Forward Reference on Linear Guides

Linear guides are mechanical systems used to support and carry loads, while also ensuring straight and level linear movement of components within a wide variety of devices and machinery. While there are many types of linear guides, the goal of any linear guide system is the same: to provide smooth, low-friction motion in applications that require highly precise, straight-line movement. Here, we will explore the types of linear guides, the advantages of using them and several common applications.

Types of Linear Guides

Because the role of a linear guide is to contain motion along a single axis and allow for precise linear movement, they are often used in machinery and equipment where deviation from the assigned path is not favorable. Typically, linear guides include a linear base, a slider and ball or roller bearings. The slider is attached to the moving component and the linear base is mounted to a stationary surface.

The ball or roller bearings permit low-friction movement between the slider and the linear base. There are many available designs to enable use in applications that require attributes such as high-strength, ultra-high precision and accuracy to micrometers; however, the most common types of linear guide rails include:

Ball Bearing Linear Guides: These linear guides contain ball bearings that run along the length of the rail. Ball bearings permit low friction, high speed and high precision. Many manufacturers, such as Accu Tech USA, offer full-ball, heavy-load types that are engineered with low-friction coefficients to enable smooth motion, even under strenuous loads. Anti-friction bearings allow for high repeatability and positioning to sub-micron accuracies.

Recirculating Ball Linear Guides: This type of linear guide contains linear ball bearings, carriages and guideways to enable large distances between support points and allow for unlimited travel. They are suitable for applications that require high-load capacity. Reputable manufacturers like Accu Tech USA, provide models with low friction resistance that can withstand loading in all four directions (tension, compression and side to side).

Ball Chain Linear Guides: In this type of linear guide, the ball track and ball chain system ensure the balls don’t contact each other, reducing friction and noise while allowing precise, high-speed linear motion. Accu Tech USA can provide several versions of this type of linear guide.

The Advantages of Linear Guides

While linear guides can be more expensive than other types of guides, they offer several advantages that make them worth the investment in applications that require straight, smooth, low-friction motion, high speeds and high accuracy. No matter which type of linear guide is selected, you can expect:

  • A very accurate and repeatable motion profile
  • Rigidity, robustness and low vibration that makes them suitable for high-speed applications
  • High-loading capabilities that fully support the load along the length of travel
  • Low friction that requires less energy for the motion in the application. As they are designed to roll loads across rails, less work is needed to drive the system to move the load, making them very efficient
  • High strength that makes them essential when guiding heavy loads

5 Common Applications for Linear Guides

Because the primary purpose of a linear guide is to provide support, guidance and linear, or straight-line, motion with very little friction, they are found in a variety of devices, equipment and machinery, including material handling machinery, factory automation, packaging machinery, medical equipment and smaller devices such as inspection equipment and optical instruments. Typically, linear guides are used in applications where precise and reliable linear motion is required, but where the component must be robust and able to provide high levels of precision and accuracy along with repeatability. They may also be used in applications where the entire weight of an object must be supported while moving in a straight line. Five of the most common uses include:

  1. CNC Machines: Linear guides are used in Computer Controlled Numerical (CNC) machines to keep the cutting tool in a straight line to facilitate precise, repeatable cuts.
  2. 3D Printers: Because 3D printers must be very precise, linear guides are often employed to keep the print head moving in a straight line, encouraging accuracy of the finished object.
  3. Robotics: Linear guides are widely used as components within industrial robots. For example, linear guides may help cartesian robots move with more accuracy and provide a smoother motion profile. They are also found in end-of-arm tooling, such as grippers, to allow them to move with more precision, making it easier to pick and place objects. They are often employed in gantry robots that move along overhead rails, as well.
  4. Material Handling Equipment: Equipment such as conveyor systems, material handling machinery and assembly lines often employ linear guides because they enable robust, sturdy and reliable low-friction movement.
  5. Medical Devices: Surgery tables, X-ray machines, hospital beds and exam tables all require smooth motion and precise positioning to best serve patients and healthcare staff. MRI machines and CT scanners also rely on linear guides to provide smooth motion to enable more precise scans. Linear guides may also be found in devices such as blood pressure monitors and medical pumps to allow highly accurate, repeatable and smooth motion.

How to Select a Linear Guide

No matter the application, when looking to select and specify a linear guide there are several important considerations, including:

Load CapacityThe load capacity refers to the amount of weight that the guide can safely support. It’s essential that the selected linear guide can manage the weight of the heaviest object that will be moving along the guide. Static and dynamic load capacities are both critical specifications. Keep in mind that manufacturers, including Accu-Tech USA, offer heavy-duty linear guides in a variety of styles.
Travel LengthThe size of the application and required amount of travel will dictate the length of the linear guide.
SpeedHow long will it take the component to travel at the force that is required in the application? This is an important consideration in many applications, including material handling and robotics applications that demand efficiency.
Accuracy and PrecisionThis is an important consideration in applications that require high levels of accuracy and precision, such as CNC machines, 3D printers and medical devices.
RepeatabilityThe ability to repeat the motion profile each and every time is essential in applications such as CNC machines, 3D printers, optical equipment and medical devices.
Duty CycleThe duty cycle requirements need to be considered also, will the linear guide cycle only a few times per day, or many times per minute?  This needs to be taken into consideration when selecting a linear guide to ensure it will have a long and trouble-free service life.
EnvironmentLinear guides are available with optional materials of construction and seals.  Choosing the correct combination suited for the environment it will be installed in can make the difference between a linear guide that runs trouble free for many years and one that fails within a few weeks.

For “straight” forward information on how linear guides can support your motion control application, please reach out to a specialist at JHFOSTER who can assist you with finding the most suitable linear guide from Accu Tech USA or another reputable manufacturer.