Sliding Block

IKO Guide Rail
IKO Guide Rail is a type of safety barrier system that is used on roads and highways to prevent vehicles from leaving the roadway and crossing over into opposing traffic or off the road. It is a highly durable and effective system that is made of galvanized steel or aluminum and is installed along the edge of the roadway.
The purpose of the IKO Guide Rail is to protect drivers and passengers from accidents caused by cars and trucks leaving the road. The barrier system is designed to absorb the impact of a vehicle and prevent it from crashing through the barrier and causing further damage or injury.
The IKO Guide Rail system is available in various designs and configurations to meet the needs of different roadways. It is typically installed in regions where high-speed traffic is common, or where the edge of the roadway is close to a steep drop off or other hazardous condition.

THK Guide Rail
THK guide rails are linear motion products that are used to provide precision movement and support in industrial and manufacturing applications. These guide rails are designed with a series of precisely machined grooves on their surface that allow linear bearings and other rolling elements to roll smoothly and accurately along the length of the rail.
These guide rails are typically made from high-quality materials such as hardened steel or aluminum and are available in a variety of sizes and configurations to suit specific applications. THK guide rails are renowned for their durability, precision, and reliability and are used in a variety of industries, including automotive, aerospace, robotics, and medical equipment.
THK guide rails are easy to install and require minimal maintenance, making them a popular choice for industrial and manufacturing applications. They are also designed to operate smoothly and quietly, minimizing noise and vibration in the manufacturing process.

INA Guide Rail
An INA guide rail is a type of guide rail system used on highways, roads and bridges to provide a physical barrier and prevent vehicles from colliding with roadside hazards such as slopes, drainage ditches, or trees.
The INA guide rail system consists of posts, blocks, and rails, all made of galvanized steel. The posts are anchored in the ground and spaced about 6 feet apart. The blocks, which are placed on top of the posts, have slots that hold the rails in place, creating a continuous barrier.
The purpose of the rails is to absorb the impact of a vehicle and redirect it back onto the road, reducing the risk of serious injuries or fatalities. The INA guide rail system has been designed to meet federal safety standards and has been extensively tested to ensure its effectiveness.

ROLLWAY Guide Rail
Rollway Guide Rail is a system used to guide rollers and keep them aligned properly, commonly used in conveyor applications. It is made up of a metal rail that typically has a channel shape and features small guiding wheels, which are placed inside the channel. The rollers are then positioned onto the wheels, allowing them to move smoothly over the rail. The Rollway guide rail system can help reduce friction, minimize wear and tear on the conveyor, and prevent damage to the equipment. It is also an effective way for maintaining proper speed and alignment of conveyor rolls or products being transported on the conveyor.

NSK Guide Rail
NSK guide rail is a linear guide system that contains a rail and a block. The linear rail is made up of a hardened steel material with precise linear guide grooves on its surface to provide a guidance channel to the block. The block slides along the rail as a guided load, with little to no friction in motion, ensuring precise control of movement.
The NSK guide rail system is designed with a high load capacity and rigidity for precision machining applications. It is capable of performing various complex motion control tasks while eliminating the problem of bearing wear or other mechanical malfunctions that would impede machine performance.

SCHNEEBERGER Guide Rail
Schneeberger is a company that produces high-quality guide rails for a variety of industrial applications. These guide rails are designed to provide smooth, precision movement for linear motion systems, such as machine tools and robotics.
The Schneeberger guide rail is made from high-quality materials, such as hardened steel or stainless steel, and features advanced lubrication systems to ensure optimum performance and longevity. The guide rail is designed to provide minimal friction, reducing wear and tear on the system and minimizing the need for maintenance.

HIWIN Guide Rail
HIWIN guide rails are precision linear motion components used in a variety of industrial and automation applications. They are designed to provide accurate, smooth, and reliable linear motion control while minimizing drive force, maintaining high rigidity, and reducing noise levels.
HIWIN guide rails are made of high-quality stainless steel or aluminum alloys to withstand the harshest environments and ensure long-lasting performance. They come in various sizes and configurations to fit different applications, from small instrumentation and medical devices to heavy-duty machine tools and automation systems.
HIWIN guide rails function based on the recirculating ball bearing motion principle. The guide rail has a linear groove where the ball bearings recirculate as the carriage moves back and forth along the rail. This allows for low friction and high precision linear motion while reducing wear and increasing lifespan.

Rexroth Guide Rail
Rexroth guide rails are precision rails that are used in linear motion systems. They are made from high-quality materials and are manufactured to very tight tolerances to ensure accuracy and reliability in operation. Rexroth guide rails are designed to guide linear movement along a fixed path, offering smooth and precise motion control across a range of applications, from factory automation to semiconductor manufacturing.
The Rexroth guide rail system consists of a guide rail and a linear ball bearing or roller bearing carriage that is mounted on the rail. The bearings roll along the surface of the rail, providing low-friction movement. The guide rail provides the necessary support for the bearings, keeping them aligned and stable as they move along the rail.

The lead screw itself is a small component in many complex assemblies. But even a basic lead screw can be broken down into three main components/features. These are:

• Screw shaft
The screw shaft is a cylindrical rod with threads or grooves along its length. At times, it may be referred to as an ACME rod, buttress rod or square-threaded rod as per the thread geometry. The most common materials used for lead screw shafts are carbon steel, stainless steel and aluminum. PTFE-based coatings are often used in harsh environments for durability and to remove the need for oil and grease.

• Threads
The threads are present on the screw shaft and the nut. Although it is not a separate component in itself, the thread's structure is responsible for converting rotational motion into linear motion. The external threads are in direct contact and mesh with the nut's internal threads.

• Nut
The nut is a fairly simple component but does not offer much use by itself. Typically, it will have some means, such as tapped or through holes, to connect it to supporting components like a clamp. The clamp connects the nut to a guide rail, restricting the nut's rotation and only allowing linear motion. Nuts can be made from plastic or bronze to add self-lubricating properties.

Apart from these components, lead screws may require additional parts depending on the function. For instance, to control backlash, precision lead screws are fitted with loaded springs that create an axial load to prevent unintended axial movements.

Balls screws also offer higher levels of efficiency because rolling contact provides a lower coefficient of friction than sliding contact. The efficiency of ball screws is relatively constant and is typically better than 90%. The efficiency of lead screws, on the other hand, typically ranges between 20% and 80%. The efficiency of a lead screw is highly dependent upon its helix angle.
As a general rule, higher helix angles mean higher efficiency. A higher helix angle is more efficient because less of the energy used to drive the lead screw goes into overcoming friction. This is because the number of times the screw must rotate to achieve the same linear displacement is reduced on a high helix screw. A disadvantage of a high helix angle is that more torque is required to turn the screw. 

Lead screws use the helix angle of the thread to convert rotary motion to linear motion. The performance of a lead screw depends on the coefficient of friction between the nut and the screw, which in turn depends on the material used for the nut and screw.

Load capacity
Begin by looking at the required load capacity. Plastic nuts are typically used for light loads of less than 100 lbs, although plastic nut designs for 300 lbs and beyond are possible. Bronze nuts, on the other hand, can be used for applications in excess of several thousand pounds.

Pressure-velocity factor
The pressure-velocity, or PV factor, is the product of the pressure and velocity between the nut and screw. It helps determine the load, speed and duty cycle that the nut can handle. Plastic materials have an intrinsic PV rating, the point at which frictional heat causes permanent deformation of the plastic. So the more load applied to a lead screw assembly, the slower it must be turned to avoid exceeding the nut's PV limit. Likewise, the faster the nut is turned, the lower the available load capacity. The primary modes of failure for plastic nuts are wear and PV. By designing within the PV envelope, failure occurs as a result of wear. Wear failure occurs more slowly than a PV failure and can be accounted for through application of case studies and testing.

Efficiency
The efficiency of lead screws typically ranges between 20 and 80% and depends on its helix angle. As a general rule, higher helix angles mean higher efficiency. A higher helix angle is more efficient because less of the energy used to drive the lead screw goes into overcoming friction. This is because the number of times the screw must rotate to achieve the same linear displacement is reduced on a high helix screw. A disadvantage of a high helix angle is that more torque is required to turn the screw.
It's important to note that when the efficiency of a lead screw exceeds 50%, the lead screw becomes back-drivable, which means it can be driven backwards by the load. Back-drivability is a disadvantage in many applications because a brake may be needed to support the load if the lead screw is mounted in a vertical orientation. On the other hand, back-drivability is a plus in some applications.

Speed
Lead screws come in a wide range of leads, from under 0.050 in. to 2.00 in./rev or more. The use of a wide range of leads can deliver a wide variation in jog speeds up to 70 in./sec. This lead screw feature can provide advantages in many applications. For example, devices that need to be positioned with a high level of accuracy can use a lead screw with a low helix angle to obtain high positioning resolution. Other applications benefit from fast jog speeds and low screw rpm, providing quiet operation and long life. The maximum rpm of a lead screw is limited by the critical speed of the screw (speed at which resonance occurs). Lead screw nuts can be driven at high rpm, but depending on the load applied, heat buildup may occur and limit duty cycle.

Duty cycle
Plastic and stainless steel lead screw assemblies are typically limited to a duty cycle of 50% under the rated load. Lead screw assemblies that use bronze nuts have higher load capacities, but these heavier loads increase frictional heat so their duty cycles must be lower, often as low as 10%. This can be calculated more accurately using the PV factor. Lead screws can operate at 100% duty cycle at light loads and moderate speeds, or they can run at lower duty with either high load and low rpm or low load and high rpm, but not both. High load and high rpm relative to a given thread size and nut design will result in overheating and failure.

Backlash
Backlash is another significant consideration in applications where positioning accuracy is important. Standard lead screw configurations typically have backlash ranging from 0.002 in. to 0.010 in. Anti-backlash lead nuts eliminate freeplay and increase repeatability. Most designs place a compression spring or other compliant member between two nut halves to remove radial clearance. Preload between the nut halves must equal or exceed the applied axial load in the direction in which the assembly is loaded through the take-up mechanism to prevent lost motion. The result is a higher torque requirement which typically necessitates a larger motor.

Life
There is no reliable closed-form solution for calculating the life of a lead screw because friction wear can be non-linear. A single wear coefficient is often insufficient to predict performance throughout the life of a lead screw assembly. Life is estimated by case study under controlled operating conditions. In the case where the combination of loading, speed and duty cycle exceeds a certain limit, failure is predictable and will occur rapidly. For applications that operate near the recommended design load at greater than 500 rpm, check with the engineering department of your lead screw supplier. They can calculate the PV factor, which is a key design factor in proper sizing and selection of lead screw assemblies that use polymer nuts.

Lubrication
Lead screw mechanisms using bronze nuts also need a lubricant, usually a thick damping grease. Lead screw assemblies with plastic nuts can run well without lubricant due to the internal lubricants in the nut material, but the use of a gel type lubricant will help increase allowable loading and extend life by reducing friction between the nut and screw. If particulate is present, the screw should be cleaned before re-applying lubricant. Re-apply when there is no visible film remaining on the flanks of the screw thread.
Grease should not be used in environments with significant particulate or debris that can load the grease and cause it to become an abrasive slurry. In this type of application, dry film lubricant should be used instead. PTFE coating is a dry film that creates a lubrication barrier between a metal substrate and a polymer bushing or lead nut. It is well suited for use with plastic nuts and stainless steel lead screws. Lubrication maintenance intervals can be eliminated and the coating does not attract particulate like a gel lubricant.

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Brands covered include: Nsk, skf, ntn, fag, ina, koyo, ezo, nmb, iko, thk, timkne, nachi, mcgill, elges, fyh, asahi, ijk, east, rollway, samick, hrb, zwz, lyc, tr, but, zhbr, yfa, hzy, qcs, and other well-known domestic and foreign brands.