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Lintech Application Tools

March 30, 2017

Lintech offers many online options and tools enabling the designer to get the necessary answers to application questions. There is a “Sizing Apps” page which helps with many types of motor sizing for all Lintech tables. There are also tools for determining if an application load will back-drive when power is off, one to determine the maximum safe operating speed for a ball screw, calculating linear bearing life, etc.

Once the designer chooses a table series which seems like it will be suitable, there is a page to calculate the price for the table with all of the desired options. Although it is possible to obtain better pricing for higher quantities or other situations, the price online enables the designer to get a good starting reference point for cost. Sometimes, slightly changing various components can help reduce cost so it can be beneficial to contact Lintech to review the selection parameters before purchasing online.

Sizing Apps Page

Lintech Custom Positioning Systems

March 15, 2017

Custom X, XY and XYZ linear positioning tables:

Sometimes a standard mechanical assembly, linear slide linear actuator or positioning system is not the right choice for a particular motion control application. It may also be impossible, or not practical, to have the system built in house by your own design team. Let Lintech take a look at your special requirements. We have been designing and building custom assemblies and positioning systems for over 45 years. We have the design engineering staff, a versatile machine shop, and the experienced assembly team to create that custom mechanical positioning system. We can use our many years of experience to help you select the right approach to a unique motion control problem.

Lintech has built positioning systems for OEM’s and Users for use in a wide range of markets. From fortune 500 companies down to 1 person shops. Contact Lintech with your requirements.

Lintech Custom Positioning Systems

Accuracy and Repeatability in a Motion System

March 1, 2017

Accuracy is described as how well a positioning system makes a true relative move in reference to an absolute 3D location. Repeatability is a drive mechanism’s ability to return to the same position multiple times under identical conditions.

Accuracy & Repeatability

In essence, if we lived in a perfect world, when a positioning system makes a 1.0 inch (25.4mm) move, it truly moves 1.0 inches (25.4mm). However, there are mechanical errors associated with every positioning system which may have to do with the linear bearings, structure, drive mechanism or other components. These errors will cause the positioning system to be less than perfect when making moves. This will result in move distances that will be something different than what is truly desired.

The linear bearing and structure inaccuracies can cause a positioning system to move something other than what is desired. Therefore, Lintech provides these errors in the overall “position accuracy” catalog values for a given table. Lintech also provides flatness and straightness specifications for each table series. These values can be used as a general gauge to the overall linear bearing and structural quality of a positioning table. The better these values are, the better the accuracy and repeatability of the positioning table.

The difference between accuracy and repeatability is widely misunderstood. Accuracy in a positioning system is much harder to achieve than repeatability, and it is also more expensive to accomplish. Applications like part insertion pick & place, and simple inspection stations require good repeatability, not necessarily accuracy. Why? Because once you have programmed the electronic motion controller and mechanical positioning table to position a load to a given location, you are typically more concerned as to how well the system can return to that location. Repeatability of the overall system becomes important for the application. The inaccuracies in the above systems can be offset by instructing the electronic motion controller to move a little bit more, or a little bit less. On the other hand, microscope X-Y inspection stands, semiconductor wafer probing machines, and coordinate measuring machines require both good repeatability and high accuracy. Why? Because for these applications to be successful, they need to be very accurate (in the truest sense) when making a move from one location to another. Many positioning system applications in the real world require high repeatability, not necessarily high accuracy.

Contact Lintech for guidance on selecting components for targeting accuracy and/or repeatability goals.

Linear Table Speed Limits

February 15, 2017

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.

170-speed-limit

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.

Ball Screw Assemblies From Lintech

January 30, 2017

For designers building their own linear motion systems, the choice may be made to utilize a ball screw as the drive mechanism. There are a variety of companies offering ball screws of different diameters and leads, but many do not offer the accessories to simplify the integration of the screw into the motion system. For instance, the screw needs to be held in place, the load needs to be connected to the ball nut, etc. Lintech offers some options to assist in the integration process by offering ball screw support assemblies, brackets to enable the attachment of the load to the nut as well as many other items which will be needed in a motion system.

ball-screw-integration

When selecting a ball screw from Lintech, the part number configurator leads you through the selection of components for the assembly and not just the screw and nut. Of course, if the design does not enable selection of these pre-engineered accessories, Lintech can supply the basic screw and nut only.

Linear Guides – Avoiding Premature Failures

January 16, 2017

When initially selecting a linear guide the idea, of course, is to select a component which will last what you determine to be an acceptable “life”. That may be some number of cycles, millions of inches of travel, etc. To get the life you desire, you would initially select a catalog product with appropriate load ratings. However, In order to achieve the rated catalog load/life, you may need to dodge or lessen the impact of potential linear guide life shortening circumstances.

What are some of those circumstances? Common causes are contamination, corrosion, excessive or incorrect loading, lubrication failure, vibration, improper mounting and excessive temperatures. When one of these circumstances is present, it can often develop into other problems. For instance, a lubrication failure will lead to high temperature, as you might imagine.

Since the designer does not often have total control over the conditions to which the linear guide is subjected, the goal would be to minimize the degree of those conditions. Contamination is probably the most common cause of premature failure. You would not want to operate linear bearings in an environment as depicted below. However, if you had a degree of contamination in your application that is out of your control, maybe there is a better sealing option which would minimize contamination.

lintech-contamination-failure-example

Likewise, if you had an environment which was very humid, you might select bearings which were stainless or plated. If there were “high” temperatures, possibly selecting lubrication rated for higher temperatures would be helpful and/or blowing cool air on the linear guide.

The point is that linear guides have the best potential of achieving their rated life if the common causes of premature failure are recognized and an attempt is made to minimize those causes of premature failure.

When Lintech has the opportunity to be considered for a new application, we have a worksheet which reminds us to inquire into the application environment as well as all of the standard application specifications. If you would like assistance selecting components for a new linear motion application, please contact http://www.LintechMotion.com.

Basics – Motion Device Selection Options(con’t from 12/15)

December 30, 2016

When selecting a positioning table, in addition to the topics to consider from the December 15th post, each of the following items should be reviewed thoroughly by the user. Some items will not be of major importance for a specific application. However, by reviewing each and every item(explained in more detail in the Lintech Positioning Systems Catalog), a positioning table can be selected that will give the required performance over the life of the system.

Items to review:

  • Bearing Designs – Linear (ball, cross roller, round rail, square rail, and air) bearings, along with rotary bearings. Different linear bearing types offer advantages and/or disadvantages(See pages A-10 to A-12 of the Positioning Systems catalog)
  • Drive Mechanisms (acme screws, ball screws, belt, and worm gears). See pages (A-13 to A-15 of the Positioning Systems catalog)
  • How to Select a Positioning Table which includes safety factors and travel life. (See page A-16 of the Positioning Systems catalog)
  • Load Capacities of all the critical elements of a positioning table need to be thoroughly reviewed in order to select the proper table for a given application. This includes capacities for bearings, drive mechanisms, and table structures. (See pages A-17 to A-27 of the Positioning Systems catalog)
  • Maximum Speed of a positioning table sometimes depends on the bearing components and sometimes depends on the drive mechanism. (See page A-28 of the Positioning Systems catalog)
  • Acceleration & Thrust Forces are parameters that can put extra stresses on positioning table components in certain situations. (See page A-29 of the Positioning Systems catalog)
  • Accuracy & Repeatability are two of the most misunderstood parameters when selecting a positioning table. By determining what it is you really need, will help you select a cost effective positioning system. (See pages A-30 to A-33 of the Positioning Systems catalog)
  • Table Physical Size (See page A-34 of the Positioning Systems catalog)
  • Lubrication (See page A-35 of the Positioning Systems catalog)
  • Mounting Considerations (See page A-36 of the Positioning Systems catalog)
  • Motor Couplings (See page A-37 of the Positioning Systems catalog)
  • EOT (end of travel) & Home Switches (See page A-38 of the Positioning Systems catalog)
  • Encoders (See page A-39 of the Positioning Systems catalog)
  • Power-off Brakes (See page A-40 of the Positioning Systems catalog)
  • Multi-Axis Systems (See page A-41 of the Positioning Systems catalog)
  • Environments (See page A-42 of the Positioning Systems catalog)
  • Testing (See page A-43 of the Positioning Systems catalog)
  • Custom Systems (See page A-44 of the Positioning Systems catalog)
  • Application Guide (See page A-45 of the Positioning Systems catalog)
  • Motor Sizing (See pages A-46 to A-49 of the Positioning Systems catalog)
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