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Linear Bearing Life Calculator

August 15, 2022

There are many factors which impact how long a bearing of any type is going to survive. Like many materials, however, after a number of times that it is stressed, it will fail. This is your starting point when trying to calculate a reasonable travel life. It is not an exact calculation but a “reasonable expectation”.

There are many ways in which linear bearings will be utilized. Often, a linear rail may have more than one bearing block to support a given load. Lintech provides the tools to calculate estimated life for all kinds of loading in catalogs and online. However, Lintech also offers an online calculator for “quickly” determining the expected life of a linear rail with 2 blocks on it.

Any life calculations available for bearings help to predict how long a particular arrangement will survive the steel “flexing”. However, then it is helpful to examine factors beyond the calculation which could reduce that predicted life. Factors such as contamination, environmental conditions, misalignment, vibration, electrical currents, improper lubrication, temperature extremes, etc. Having any of these factors present eliminates reasonably predicting life. So, it is best to examine the potential conditions of an application and to reduce or eliminate any factor which could negatively impact the bearing life.

Linear Table Speed Limits

August 1, 2022

For each table series, Lintech provides a table in the catalog which reflects the Maximum Safe Table Operating Speed. These listed speeds are a mechanical limitation. The maximum speed of a positioning table depends upon the screw diameter, screw lead, screw length, and the screw end bearing support configuration. Lintech typically utilizes a fixed-simple screw end bearing support configuration in its positioning tables. The correct motor and drive system needs to be selected in order to reach the rated maximum table speeds. Below is the table for the 160 & 170 series tables.

It is possible to increase the speed limitation a little bit beyond the listed limit IF the end support configuration is modified to a rigid-rigid design. This configuration increases the screw rigidity by changing the bearing arrangements on each end and therefore enables the screw to rotate at a bit higher speed before whipping will occur.

Lintech actually chose to offer the rigid-rigid design as a “standard” on the 610 linear table series. This is a little more expensive but enables the 610 series tables to have a somewhat higher speed rating.

If you want to use a ball screw driven table and need to push the envelope a little for some reason, contact Lintech for ideas.

Lintech – Niche for providing Tailored Solutions

July 15, 2022

Lintech manufactures many different variations of screw driven and belt driven linear tables. A common thread though, over the years, is that frequently the particular linear table provided by Lintech has been customized in one or more ways.

Lintech does “customization” well – often when the requirement is just for 1 unit. Obviously, not all linear slide manufacturers are set-up to accommodate custom solutions. However, it has been our history and has helped to create our niche.

As simple as providing a little additional machining or a solution where framing, motors, controls, sizing, etc. are included. Communication is clean and timely which is a key component to customer satisfaction.

Lintech 100 Series Screw Driven Table

July 5, 2022

One of the original Lintech screw driven tables is the 100 series. It is relatively compact in size at 2.375” tall x 3.5” wide. However, it has a load capacity of up to 3100 lbs. depending upon how many bearings are chosen to support the load – yes, you can choose!

Lintech 100 series with top/side covers

As with all of the Lintech tables, there are an incredible number of standard options available to choose from. “Standard” meaning they are generally available in the 2-4 week typical lead-time. Of course, you are not limited to these options offered. Lintech will consider any application requirement needed and is very accommodating. Take a look at the 100 series for your next application.  

Round Rail Linear Ball Bushing Bearings

June 1, 2022

The closed LBC and the open LBO are super linear ball bushing, inch series self-aligning bearings. These ball bushing versions are suited for the Lintech SL series class L shafting. These products are utilized together to form a precision linear positioning system that can handle large load requirements. These products will also perform well in applications where there is slight misalignment between a pair of shafts. Sometimes, due to other limitations, it is very difficult to maintain a high degree of parallelism between shafts and ball bushings with SL shafting can help to prevent the linear system from binding. The closed LBCA and the open LBOA are all steel plain type linear bearings that work with Lintech SS series class S precision shafting to form a positioning system that can operate in a high temperature environment.

Metric Ball Bushing Configurations:

When considering metric ball bushings, there are two standards available. There are Asian as well as European standards which maintain slightly different tolerances. The closed LBCM and the open LBOM are Asian style self-aligning ball bushings that should be matched with Lintech’s SM metric precision shafting to form a positioning system where Asian metric standards are required. The closed LBCME and the open LBOME are European style super linear ball bushings that also should be matched with SM metric precision shafting to form a positioning system where European metric standards are required.

Ball Bushing Configurations

Ball Screw Maximum Compression Load

May 2, 2022

A compression load is a force that tends to compress, or buckle a ball screw shaft. If a compressive force is applied to a screw that exceeds its column strength, the ball screw will bend and cause premature or permanent failure. This can happen in either horizontal or vertical applications. In some cases, you may have to select a more rigid end support housing arrangement, and/or a larger diameter screw in order for the ball screw assembly to withstand your compression load. Refer to Lintech’s Positioning Component catalog specification section for the maximum compression load for a particular ball screw model number.

If a sufficiently heavy load is applied to a nut with a long ball screw in a horizontal application, the ball screw could buckle. In a vertical application, if a fixed or rigid motor driven housing is mounted below the ball screw, the ball screw weight and load weight could buckle the screw. Therefore, in a vertical application, installing the motor driven support housing above the ball screw puts the ball screw assembly in a tension mode, while the bottom end support bearing is free to “float axially” and is used only to guide the end of the screw. By loading the screw in tension, most of the time you avoid any compression load issues, and only need to be concerned with the load capacity of the nut and end support bearings. However, in some vertical applications with the ball screw mounted in a tension mode, you will have to be concerned about compression loads if you have a reversing force that exceeds the load weight being moved.

Encoders – Within the motor, separately attached to the end of a ball screw, or directly measuring linear motion by sensing the actual carriage position?

April 15, 2022

There are several ways to track the position of a load being transported. If the encoder is within the motor, it is measuring motor rotation – an indirect method of measuring ball screw rotation.

If a discrete rotary encoder is supplied by Lintech, it is shipped attached to the ball screw assembly or linear table opposite the motor mount end. This rotary encoder is shaftless and is physically mounted to the screw shaft extension. So, it measures screw rotation. WARNING – It is important NOT to remove the rotary encoder from the ball screw assembly. Removing it will void its warranty. The glass disk is pre-aligned by Lintech for proper operation. Removing the encoder could affect its performance. The encoder is protected with a sheet metal cover, which is not totally sealed. Therefore, if splashing fluid or other materials is present, precautions should be made to redirect these items away from the encoder housing since contaminants which penetrate the housing can cause encoder failure.

With the methods utilized above, they are both indirectly measuring the position of the load being transported. A linear scale can also be used to directly measure the load position. The scale is attached to the table and tracks the actual linear position of the load.

There are different accuracy grades and prices for each of these options. All have associated positives and negatives. Individual application requirements will dictate which is the best choice. Lintech can recommend and supply any of these options after discussing the application.

Profile Rail Linear Guide Interchangeability

April 1, 2022

Many companies use linear guide profile rails (square rails) in applications to obtain precision linear motion. The initial design selection process in choosing the correct rail solution can often entail a long study of different products, sizes and configurations to obtain the most efficient product for the particular application.  Some linear motion applications are less demanding or may be less critical and do not require the long testing process leading up to selection. Anyway, companies sometimes get to the point where they may want to try alternatives or they feel forced to do so due to price, availability, or an application problem requiring a better solution.

There are some basic critical elements to review before selecting an interchange. These are as follows:

  • Rail and block height dimensions
  • Bolt hole size and spacing on the block and rail
  • Load capacity in all critical orientations – load is based upon a given life which varies by manufacturer.

The above bullets determine the basic pass/fail for an interchange. Beyond that, you need to understand the desire for change and how it might be solved with the replacement chosen.

Lintech offers HRC, ARC & MR linear guides. These guides are very well priced, have a myriad of options which can be utilized to solve application problems, and the lead-time is very short. They often match up with the 3 basic pass/fail elements with respect to other manufacturer’s linear guides.

If you have some motivation to solve an application problem, want to have better product availability or you would like to investigate lower cost alternatives for linear guides, contact Lintech.

Lintech 550 Series Belt Driven Tables

March 15, 2022

The 550 series is one of the most popular belt drives for many reasons.

Lintech can even offer these systems in “segments” that enable easier shipping, installation in limited spaces, etc. Quite a few of these segmented systems have been manufactured over the years. In addition, 360 inches of travel is NOT the maximum length. Longer systems have been built.

Multi-Axis Mounting Configurations

March 1, 2022

Lintech provides standard or custom mounting brackets to mount multiple axes together in an assortment of configurations. In some cases one table can be mounted directly on top of another. However, often some sort of intermediate bracket is required in order to obtain the necessary orientation.

Since Lintech tables are used for high precision and significantly loaded applications, the brackets for different mounting arrangements need to be very strong and very accurate, not just a plate to which the tables can be attached. Hence, they represent a significant cost. Having many pre-configured standard designs allows for more efficient pricing.

Lintech will also perform the actual mounting of multiple axes to make sure all axes are aligned properly. In addition, they can also add motors, controls, switches, and etcetera, to complete the entire motion control system.

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