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Plastic linear bearings are softer, more affordable, and exhibit a lower coefficient of friction compared to metal bearings. Common plastics used in these bearings include nylon, polyethylene, and PVDF, often coated with self-lubricating materials like PTFE. They may also be reinforced with fibers and fillers to improve their load-bearing capabilities. While plastic bearings can work with softer shaft materials, they typically have lower load capacities and are limited to use within room temperature ranges.

V-type roller bearings feature a V-shaped track with a 90° angle for the carriage. Each side of the V-profile accommodates a row of cylindrical or needle rollers.

Electric actuators are devices capable of creating motion of a load, or an action that requires a force like clamping, making use of an electric motor to create the force that is necessary...

Linear slides, also referred to as linear guides or linear-motion bearings, are types of bearings that allow smooth and near-frictionless motion in a single axis. Machine tools, robots, actuators, sensors, and other mechanical equipment often require moving components in a straight line in any of the three-dimensional axes...

In a circular arc profile, the ball contacts the raceway at two points—one on the bearing groove and one on the guide rail groove. This design results in reduced differential slip and lower friction compared to the gothic arc profile. However, the circular arc profile typically offers lower load capacity than the gothic arc profile.

Air linear bearings are classified into two types: hydrodynamic and hydrostatic, based on their method of generating the supporting film. Both types use a gaseous medium, typically air, to support loads. In environments where air quality is a concern—such as in clean rooms—alternative gases like nitrogen may be used to avoid issues like moisture-induced corrosion.

In a gothic arc profile, the ball makes four contact points with the raceway—two points each on the bearing and guide rail grooves. This profile is more compact and can handle higher moments and heavier loads compared to the circular arc profile with the same raceway size. However, it also experiences greater differential slip, which increases friction. Differential slip occurs due to the varying circumferential lengths between the inner and outer contact diameters, leading to different rolling speeds and resulting in slippage. Consequently, driving the ball bearing requires a greater force to counteract this effect.

These bearings offer high load capacities and operate with minimal noise, making them ideal for high-speed and high-precision applications. However, they are generally more expensive and require more maintenance compared to other linear bearing types. Their performance can be affected by fluid leakage or exposure to extreme temperatures.

Air bearings can achieve higher speeds and accelerations because they do not have recirculating elements. They offer exceptionally precise motion with minimal scale errors. The fluid film fully supports the load, providing high stiffness and accuracy.

When I do a lot of interior work with an ultra wide angle, I generally use f8 or f11 as I know this will suffice for the image quality I need with this lens.

I have always found "depth of field" a strange term, why not simply call it Depth of Focus? Anyway, it matters not, what does matter is how it affects your photography and how you can use it to your benefit.

We have covered various types of linear bearings, their construction materials, and how these factors influence load capacity, speed, and service life. Here are additional considerations for selecting, operating, and maintaining linear bearings:

Lubrication presents another challenge in cleanroom environments. External lubricants like oil and grease must be kept to a minimum to avoid contaminating the cleanroom products. Thus, bearings made from plastic or composite materials are favored. Additionally, any lubrication used must be compatible with cleanroom standards and the washdown or clean-in-place systems used within the cleanroom.

The aperture setting has the largest factor in determining the depth of field of your images. Just remember that f4, 3.5 or 2.8 (or larger) will have shallow or little DOF. Whereas F8, 11, 16 or smaller, will have greater DOF. This is particularly true if you are doing close up work, a large (wide) aperture close up will have very little in focus.

High-precision, linear motion goods are essential components at the core of several items which are generally used in machine tools and equipment for manufacturing semiconductors. These items are utilized...

Linear ball bearings, also known as ball bearings, feature spherical rolling components such as steel balls. They are favored for their low friction, extended lifespan, and high precision. As one of the most common types of rolling linear bearings, their spherical design makes them versatile for various linear bearing applications.

DualVee guides are designed for harsh and challenging conditions where other systems may fail. Their long length, low noise, and smooth operation provide superior performance and stability in stressful environments.

For the second shot, the leaf was brought inside, rain water and all. I set it up in a similar way. This time however, I used natural low lighting which meant that with an aperture of F29, I needed 30 seconds to make the correct exposure. Remember that when you open or close the aperture, you or the camera has to adjust the shutter speed to compensate. If you close the aperture right down for good depth of field, check the shutter speed as it may become slow and "non-hand-hold-able".

Cylindrical rolling elements are another type used in linear bearings. These bearings offer greater load capacity, rigidity, and resistance to shocks and impacts compared to ball bearings. However, they tend to have higher friction due to the increased contact area and are more susceptible to misalignment issues.

Plain linear bearings operate through direct sliding contact between two surfaces, without the use of rolling elements. Compared to roller linear bearings, they feature a simpler construction and operating mechanism, making them more cost-effective. The larger contact area results in lower surface pressure, allowing them to support higher loads, weigh less, and better absorb shocks and dampen vibrations.

Ceramic linear bearings are commonly made from materials such as silicon nitride, aluminum oxide, zirconium oxide, and silicon carbide. These bearings offer high rigidity, ensuring precise travel and accuracy even at high speeds. Their hardness enhances service life and abrasion resistance while minimizing particle generation from component friction. Ceramic bearings are also suitable for use in vacuum environments and with electrostatic discharge (ESD)-sensitive equipment.

In a face-to-face configuration, the balls or rollers make inward-facing contact with the guide rails, forming an X-pattern. This setup provides uniform load capacities in all directions but has a lower resistance to applied moment loads.

In a non-recirculating linear bearing, individual rollers are fixed in place within a frame known as the cage, which is housed inside the bearing. These rollers are spaced at equal intervals by a retainer or separator, preventing direct metal-to-metal contact between them. Cages can be constructed from either metal or plastic materials.

Box-way slides are a type of linear bearing featuring a T-shaped profile formed by a stationary base and a moving saddle. The base acts as the guide rail, while the saddle serves as the carriage. Adjustable gib plates are placed between the base and saddle to apply preload and eliminate clearance. Box-way slides offer increased load capacity due to the larger contact area between the saddle and base.

Ball spline is a variant of the linear ball bushing. It features a shaft with axial grooves that align with corresponding grooves in the spline nut. These grooves prevent shaft rotation and enable torque transmission. Ball splines are designed to handle greater moment loads and are capable of supporting overhung loads effectively.

Non-recirculating linear ball bearings feature metal balls that are secured within a cage. The corresponding grooves on the bearing and guide rail may have either a circular or gothic arc track geometry.

Lastly, this image below shows the other extreme. I used a Canon EF 50mm standard lens to get this shot of Dillon. You can see that the background is completely out of focus with virtually no depth of field. In fact the depth of field is so shallow that even though his head is only slightly turned, one eye is in focus and the other isn't! You can see a larger and clearer version of this image by clicking on it.

Ag bearings

The camera was on a tripod and I used 2 studio lights closely positioned, and pre-focussed on the point where I would drop the milk.

Linear sleeve bearings, or plain linear bushings, are hollow cylinders that support the journal (shaft guide rail) sliding along their inner surface. This surface is often coated with self-lubricating materials, such as PTFE. These bearings can accommodate both axial and radial loads but generally offer lower load capacity and stiffness compared to box-way and dovetail slides. They are commonly used in light to medium-duty applications.

Non-Contact Linear Bearings operate without direct contact between the carriage and guide rails, resulting in reduced friction. This design leads to longer service life and the capability for higher speeds. There are two main types of these bearings:

Personally, I normally set my camera to Av or "aperture priority" 95% of the time for more control over sharpness. For the kind of work I do, the depth of field is more important to me than shutter speed. Although, if I need a fast shutter speed, I can just quickly and easily whack the aperture right open. This gives me the fastest speed available in that light.

PV rating refers to a specification that indicates the maximum allowable combination of surface pressure and sliding velocity a linear bearing can handle while operating effectively. This rating accounts for heat and wear generated by friction. For example, higher speeds can decrease the maximum permissible load capacity of a linear bearing. The PV value, which is the product of the operating surface pressure and speed, must always be lower than the PV rating.

Magnetic linear bearings use magnetic force to levitate the carriage above the guide rail, allowing for smooth, frictionless motion. They offer high load capacities due to the strength of the magnetic forces. However, the electromagnets used in these bearings can pose a risk to nearby electronic components by potentially causing interference or damage.

Linear Rails are ideal for moving items through a production process with great precision and as little friction as possible if creating, packing, and distributing products. Linear Rail is a type of gadget that...

The geometry of the track in a linear bearing influences the number of contact points between the balls or rollers and the raceway, affecting both the load capacity and friction generated by the bearing.

Linear bearings are primarily categorized into two types: rolling linear bearings and plain linear bearings. The following sections will explore the components, operational principles, and design considerations of each type in detail.

Bronze, an alloy primarily made of copper and zinc, with additional elements like manganese and phosphorus, is a softer metal. Bronze linear bearings offer a higher load capacity compared to plastic bearings. However, due to metal-to-metal contact, they generate more friction, which requires regular maintenance to ensure adequate lubrication.

Bearings

A linear actuator actuates, moves, in a linear, straight, line to complete or start a process. There are a variety of terms used to describe a linear actuator such as ram, piston, or activator. They are very common in...

The main advantage of air linear bearings is the elimination of friction, wear, and heat generation due to the lack of mechanical contact between rotating and stationary surfaces. This absence of contact means that lubrication is unnecessary, reducing particle generation and producing less noise compared to rolling or sliding bearings.

However, they have higher friction. Friction limits the speed of the linear guide and increases its wear. Hence, lubrication needs to be maintained. Different sliding materials or materials with a self-lubricating coating are frequently used to reduce the coefficient of friction. They also have lower travel accuracy, which makes them unfit for high precision systems.

In a back-to-back arrangement, the balls or rollers contact the guide rails facing outward, forming an O-pattern. This configuration provides increased leverage on the guide rail, offering enhanced resistance to applied moment loads, as well as greater stiffness and rigidity.

Hydrostatic linear air bearings utilize a positive air pressure supply to create a gap between the rotating and stationary surfaces. Like hydrodynamic bearings, hydrostatic linear air bearings are classified as fluid film bearings.

Needle linear bearings utilize cylindrical rollers, known as needles, with a length-to-diameter ratio ranging from 3:1 to 10:1. These bearings offer superior rigidity and load capacity compared to ball or cylindrical bearings because the load is spread across a larger number of smaller rollers. The reduced size of the rollers enhances the contact area and minimizes deformation.

Crossed roller bearings feature cylindrical rollers arranged so that each roller's axis intersects at a 90° angle with the adjacent ones, creating a crisscross pattern. This design provides increased load capacity, enhanced resistance to vibration and shock, and a longer service life. However, their assembly can be challenging.

Outgassing refers to the release of trapped gases and vapors from solid materials through vaporization or sublimation at low pressures. This phenomenon can increase the pressure in a material's surrounding environment and disrupt the ability to create or maintain low pressures in a vacuum. Common materials that outgas include plastics, ceramics, porous metals, elastomers, and certain lubricants.

My favourite time-saving plug in for large photo editing projects such as weddings or commercial shoots. Autoloader saves me HOURS!

Linearguide

To illustrate these points, have a look at these 2 pictures. I was testing the Sigma 105mm Macro Lens and wanted to check the sharpness at close quarters. The shot on the left was taken by dropping a small amount of milk into a larger container (click for larger versions).

A roller table is a small, stiff, limited linear guide device with an integrated cross-roller guide. Electrical or mechanical drive systems are frequently used to move a roller table, making it easy to transfer heavy loads...

Let's say you are photographing your subject sitting on a wall about 20-30 meters away (or more) and you are using a wide angle or standard lens. You can almost guarantee that a lot of your image will be in focus whatever the aperture (within reason). However, bring the subject closer to say 2 meters, and that changes. The camera will focus on the subject but will more than likely throw the background into blurry "oblivion".

These bearings come in various forms, including rolling elements and fluid-based devices, to minimize friction. They ensure high precision, stable mounting, and smooth motion. Linear bearings find applications in 3D printers, sliding doors, and other automated systems that require precise rail movement.

Hydrodynamic linear bearings use a thin film of fluid or air to support rotating components, often referred to as fluid film bearings. This design minimizes friction and wear by maintaining a separation between the stationary and rotating surfaces, which extends the lifespan of the bearings.

These roller and track components can be integrated into machine frames with limited space. The adaptable design allows for various configurations to optimize support and performance based on the load's position.

A linear bearing is a critical component of a linear guide assembly. Its applications are found on cutting machinery, XY positioning tables, machine slides, industrial robots, and instrumentation systems. Either a motor driven ball screw, lead screw, pneumatic cylinders, hydraulic cylinders, or manual force can be used to drive the motion with single axis motion limited in the X-Y plane. Hydraulic and pneumatic cylinders are widely used as the basis of the XY bed of computer numeric controlled (CNC) milling machines.

The diameter of the balls or rollers affects the speed of the linear guide: larger diameters generally allow for higher speeds. Additionally, the contact angle—measured horizontally—impacts the bearing’s load capacity in various directions. A contact angle of 45° offers balanced support for loads in radial, reverse radial, and lateral directions, with the angle influencing radial load capacity positively and lateral load capacity negatively.

Aluminum is a lightweight, high-strength metal known for its corrosion and chemical resistance. It is softer and more cost-effective than steel. While aluminum linear bearings have a lower load capacity compared to steel bearings, they still offer smooth and precise motion.

A dovetail slide is a linear bearing featuring a base with a V-shaped tongue that fits into a matching saddle, providing full contact between the two components. Dovetail slides offer a high load capacity but do not allow for preloading. Instead, gib plates can be installed along the saddle's length to adjust for any clearances.

Round rail profile linear guides use cylindrical shafts as guide rails and require linear bushings. A linear ball bushing, commonly referred to as a linear bushing, features a cylindrical structure that encases recirculating balls moving along the cylindrical shaft guide rail. The bearing includes a cage to manage the balls' movement. Its straightforward design, compact size, and ease of installation make it a practical choice.

The linear guide profile defines the cross-sectional shape of the guide rails, which in turn influences the design of the bearing employed in the linear guide system.

Linear motion in these bearings is confined to the bearing's length. The rolling elements contribute to linear movement by rotating solely around their own axes. This constrained motion allows non-recirculating linear bearings to offer high load capacity and stiffness, along with smooth operation and precise travel accuracy.

Hydrostatic bearings are known for their high stiffness and long service life, making them suitable for precision machinery. Since they do not depend on lubrication for maintaining relative motion, they can support heavier loads at lower speeds and offer direct control over stiffness and damping coefficients.

Steel, an alloy mainly consisting of carbon and iron, is the most commonly used material for linear bearings. Steel bearings are valued for their excellent mechanical properties, including high strength and rigidity, which enable them to support heavy loads and ensure smooth, precise motion. Carbon steel and stainless steel are typical types used in these bearings. Higher carbon content in steel enhances its hardness, which can influence the performance of the linear bearing.

A lead screw is a kind of mechanical linear actuator that converts rotational motion into linear motion. Its operation relies on the sliding of the screw shaft and the nut threads with no ball bearings between them. The screw shaft and the nut are directly moving against each other on...

ThomsonBearing

A linear actuator is a device that transforms rotational motion into push or pull linear motion, which can then be used to lift, lower, slide, or tilt machinery or materials. They offer effective, maintenance-free motion control...

Ball screws are mechanical linear actuators that consist of a screw shaft and a nut that contain a ball that rolls between their matching helical grooves. The primary function of ball screws is to convert rotational motion to linear motion. Ball nuts are used in...

Flat-type roller bearings use cylindrical or needle rollers arranged horizontally within the cage. The rollers' axes are oriented perpendicular to the direction of linear motion.

A cleanroom is a controlled environment designed to minimize airborne pollutants, contamination, and particulates. It is used for the manufacturing of products such as food, beverages, pharmaceuticals, semiconductors, electronics, and medical devices.

So when you are out and about next, instead of setting the camera to auto, experiment with depth of field. Get creative. Used in the right context a large or very shallow DOF can be very effective.

Linear bearings are designed to support the load of a carriage during its movement along a single axis, providing a low-friction surface for smooth sliding along guide rails. In a linear guide system, the carriage moves in a straight or curved path along the guide rail, which is integrated into the linear bearing.

To mitigate outgassing, it is beneficial to use linear bearing materials that have undergone a bake-out process. Bake-out involves heating the materials to around 200°C for several hours to drive off volatile substances. However, not all materials can tolerate this temperature. Additionally, lubricants may outgas as well, so employing self-lubricating coatings and solid lubricants that are compatible with vacuum environments is essential.

It’s all to do with how much light enters your camera and the type of lens that you use. Basically, there are 3 factors that determine the depth of field in your images;

Fluid linear bearings utilize a thin layer of rapidly moving pressurized fluids, such as oil, air, or water. There are two primary types: hydrostatic fluid bearings, which use pumps to pressurize the fluid and lift the carriage off the guide rail, and hydrodynamic fluid bearings, which rely on the high-speed motion of the carriage to generate the necessary fluid pressure.

Rolling linear bearings are widely used for linear motion due to their low friction characteristics. These bearings incorporate balls or rollers that are situated between the grooves of the bearing and the guide rails, facilitating smooth movement.

Rolling linear bearings come in various designs, each offering different classifications based on their structural characteristics.

It is common to use different materials for the bearing and the guide rail. The guide rail material is typically more resistant to friction reduction. Wear is primarily focused on the contact surface of the linear bearing, which is the softer component. In contrast, guide rails, shafts, and bases (for plain linear bearings) are often made from harder materials like hardened steel, ground steel, or anodized aluminum.

A linear actuator is a means for converting rotational motion into push or pull linear motion, which can be used for lifting, dropping, sliding, or tilting of machines or materials. They provide safe and clean...

Air linear bearings differ from conventional mechanical linear bearings, which rely on rolling or sliding elements. Instead, they use a pressurized air or oil film to support loads, eliminating mechanical contact that can produce friction or heat. These bearings are particularly suited for applications demanding high precision and rigidity.

Composite bearings feature a metal backing combined with a plastic sleeve or a PTFE liner. The polymeric component eliminates metal-to-metal contact, reducing friction while retaining the bearing's high load capacity. The metal backing helps with heat dissipation.

In a recirculating linear bearing, balls circulate continuously within a looped raceway, enabling the carriage to move smoothly along the guide rail's length. This design allows for movement across any length of the guide rail. Recirculating linear bearings typically feature multiple raceways to support this function.

The raceway is the straight channel through which the balls or rollers move. The configuration of the raceway in a linear bearing plays a crucial role in how the bearing responds to applied torsional forces and impacts the overall performance of the linear guide.

The rollers are designed to resist contamination, as they are sealed to protect the ball path and remain isolated from the track. Contaminants between the track and roller are displaced as the roller moves, with the inner part of the roller moving slower than the outer part, helping to push debris away from the guide rail.

Vee linear guide systems are ideal for straightforward linear movements. They are easy to integrate, assemble, and maintain, making them suitable for demanding environments where contamination is unavoidable.

This is because my 50mm lens has a maximum f-stop of just 1.4 and this was taken at that aperture. I like this effect and use it a lot for portraits. It draws your eye to theirs with no other distractions.

Common types of hydrodynamic linear bearings include circumferential groove bearings, pressure bearings, and multiple groove bearings. They are utilized in various applications such as steam turbines, electric motors, cooling pumps, rock crushers, as well as clutches, blowers, and other auxiliary machinery.

Ball bearings are types of rolling-elements bearings that carry loads, reduce friction, and position moving machine parts while facilitating motion. They reduce surface contact and friction across moving planes by...

In cleanroom settings, recirculating linear bearings can produce fine dust from metal fragments due to high-speed metal-to-metal contact among rolling elements. Therefore, non-recirculating linear bearings are often preferred for cleanroom applications as they feature cages that separate rolling elements, minimizing dust generation. Plain linear bearings are also suitable.

Guide roller-based linear systems use individual ball-bearing rollers with a groove in their outer race, which run along a corresponding steel track. The track typically features a V-shaped edge, and the rollers are equipped with a matching V-groove. In some configurations, the roller groove is designed to accommodate rollers on a cylindrical shaft.

Drawer slide guide systems feature C-shaped slides and carriages made from sheet metal. Each carriage glides along its slide with the aid of two sets of intermediate ball bearings—one on each side of the carriage and slide. Unlike profile rail linear guide systems, the rolling elements in drawer slides do not recirculate but are held in place within the carriage by a ball cage.

Pillow blockbearing

Because I was using a telephoto lens and working extremely close I needed a very small aperture. Plus the fact that the lights were bright and also very close. In this case, the aperture was all the way closed at F36! It has to be said that even with this small aperture, parts of the background were blurred. This is more than likely due to "diffraction" of the light when you stop down too much. So, f16 is normally enough for good, sharp pictures. Also note that a telephoto combined with macro leaves little room for error as the depth of field is at its smallest.

In hydrodynamic linear bearings, the gap between surfaces is established by the motion of the bearings themselves. During startup, they require external pressure to prevent friction. These bearings are designed to handle both radial and thrust loads.

Square rail profile linear guides feature rolling elements positioned on two opposing sides along the length of the guide rail. In comparison to round rail profiles, square rails offer greater load capacity, enhanced stiffness, and improved resistance to shocks and vibrations. They also provide greater moment load capacity.

Please Note: The smaller the aperture you use (especially this small), the more "specs" of dust will appear on your images. This image was literally covered in them before I cleaned it up. It is a good way of testing your sensor for dust, but don't be too put off by this, it is quite normal and is easily fixed using a good editor and cloning/healing brush. If you are unsure of what you are doing please do not try and clean the sensor yourself, you may damage it and they cost a bit! Go to a reputable dealer/cleaner and get it done. Otherwise, there are many safe ways of cleaning the sensor yourself. Check out our "camera sensor cleaning" page for more information.