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Selecting The Type Of Linear Motion System To Fit Your Needs

January 16, 2020

When selecting a positioning table, 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, a positioning table can be selected that will give the required performance over the life of the system.

The items below are covered in more detail on the pages referenced of the Lintech Positioning Systems Catalog.

Bearing Designs – Linear (ball, cross roller, round rail, square rail, and air) bearings, along with rotary bearings.(See pages A-10 to A-12)

Drive Mechanisms (acme screws, ball screws, belt, and worm gears). See pages (A-13 to A-15)

How to Select a Positioning Table which includes safety factors and travel life. (See page A-16)

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)

Maximum Speed of a positioning table sometimes depends on the bearing components and sometimes depends on the drive mechanism. (See page A-28)

Acceleration & Thrust Forces are parameters that can put extra stresses on positioning table components in certain situations. (See page A-29)

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)

Table Physical Size (See page A-34)

Lubrication (See page A-35)

Mounting Considerations (See page A-36)

Motor Couplings (See page A-37)

EOT (end of travel) & Home Switches (See page A-38)

Encoders (See page A-39)

Power-off Brakes (See page A-40)

Multi-Axis Systems (See page A-41)

Environments (See page A-42)

Testing (See page A-43)

Custom Systems (See page A-44)

Application Guide (See page A-45)

Motor Sizing (See pages A-46 to A-49)

Lintech Positioning Systems

Linear Motion Systems – Drive Mechanism Load Capacities

January 2, 2020

Linear positioning table drive mechanisms will have static and dynamic load capacity ratings for the acme screw, ball screw, and belt drive assembly. These values are used to help select a correct drive mechanism for a given load/life table application. For most acme screw driven positioning table applications, the screw (and not the linear bearing) is the major factor in determining the life of the table. This is due to the high friction of the nut assembly. For most ball screw driven positioning table applications, the linear bearing system (and not the screw) is the major factor in determining the life of the table. This is due to the high efficiency and high load capacity of the nut. For most belt driven positioning table applications, the linear bearing system (and not the belt) is the major factor in determining the life of the table. This is due in large part to the fact that belt driven tables usually travel lots of inches at high speeds. The use of adequate safety factors is a key element in the selection process of the drive mechanism for a given application. Selecting a system with no safety margin can lead to problems relating to performance and long-term life.

The actual (axial) load a drive mechanism “sees” needs to be determined first. Then the effects of that load on the drive mechanism can be reviewed. For both screw & belt driven positioning tables, the actual load the drive mechanism experiences will vary as the table moves. During acceleration and deceleration intervals of a positioning table, the force exerted upon the drive mechanism changes as the acceleration or deceleration rate varies. In most cases, the extra force acting upon the drive mechanism during the acceleration interval is offset by a reduced force during the deceleration interval. Therefore, using just the forces acting upon the drive mechanism during constant velocity can be used. The applied (axial) load “as seen by the screw nut or belt” depends upon the table orientation. See the equations below.

Drive Capacities

Static Loads can exert an extreme force upon the drive assembly in a non-moving state. For acme screw driven tables, if the static load rating of a particular screw is exceeded, the nut assembly can permanently be deformed, or crack outright. For ball screw driven tables, if the static load rating of a particular screw is exceeded, a localized permanent depression in the screw shaft and ball nut could cause the system to not operate smoothly or fail prematurely. For belt driven tables, if the static load rating (maximum belt tensile force) of a particular belt is exceeded, the belt will permanently stretch, or tear. To ensure proper life, external forces should never come close to the static rating. Repeated forces at or near the maximum rating can fatigue the elements causing premature failure. Some static forces will be known and can be accounted for (i.e. drilling, insertion, stamping, engraving, etc.). Other unexpected forces that are difficult to determine could come from vibrations, impacts, or inertial forces. To ensure proper life, external forces should never come close to the static rating. Repeated forces at or near the maximum rating can fatigue the elements causing premature failure. Thus, a safety factor should be considered to account for these forces. Also, by using a safety factor, extra unforeseen loads that arise within an application sometime in the future, would not affect the positioning table chosen.

Hand Wheel Lock on TRCA Carriages & Pillow Blocks

December 16, 2019

This option adds an aluminum clamping block to the end of a pillow block, which then provides for a manual lock of the bearing to the shaft. The threaded hand wheel shaft presses into a bronze insert which makes contact to provide a “pressure lock” to the shaft. The threaded steel screw will not back drive and does not make physical contact with the steel shaft (no steel to steel contact). The lock will be installed as shown below when ordered with a SLBC, SLBO, DLBC, DLBO, or TRCA series. Multiple locks can be installed onto a TRCA assembly.

P_TRCA

TRCA Lock

Profile Rail Linear Guide Converter Tool

December 2, 2019

Lintech provides a tool which will automatically convert another manufacturer’s part number with the Lintech part number.

First, go to Lintechmotion.com or type in the address below. If you’re already on the Lintech home page, highlight “Customer Service” and select “Sizing Application”. When you see the page below, click on “Competitor Conversion”.

Sizing Application

When you select Competitor Conversion, the page below is what you will see. At this point, you would select the manufacturer brand that you want to change from. Let’s say you were trying to convert an INA part number to Lintech. So, you would click on “INA”.

Converter

After you have clicked on INA, below is the page you will be looking at. The default shows a KUME style and you would replace that with the part number you have along with the 4 other options then hit “Convert”.

INA

Below is the Lintech conversion for the INA part number above.

Interchange Result

You’re all done – piece of cake! You can even price it out right from our website if you like.

Pay for The Length You Want!

November 15, 2019

When using profile rail linear guides, everyone has a preferred rail length to suit their application requirements. A specific travel length is desirable, but the overall product package size needs to be efficient to minimize waste. Waste is needless expense.

Homepage-Catalog-Profile-Rail

The manufacturing time to make linear guides can be relatively long because of the exacting specifications of the product, individual manufacturing plant capacities and many other reasons. So, in order to have product more readily available for individual needs, many guide manufacturers have chosen to stock various standardized rail lengths pre-cut to 170mm, 220mm, etc. That’s great and often helpful to the designer. However, if the length desired in a specific application is somewhere in between the standard rail lengths offered, it can cause an additional cost and time for subsequent machining to the rail. Therefore, the designer initially pays for more length than is required and pays again to cut the rail to the appropriate length.

The idea is that once a machine builder enters a production phase, they will have the “time” to plan and order the efficient rail length from the manufacturer…..at least that’s the theory.

Lintech has chosen Not to offer pre-determined lengths. Rail lengths are ordered to the nearest millimeter desired (see below).

Rail length

Lintech determines that they will have a better opportunity to utilize excess material in the form of rails which were not arbitrarily cut to standard lengths. Lintech has been able to keep lead-times very short for most sizes. Pricing is also VERY competitive.

Linear Guides with Cylindrical Rollers instead of Balls

November 1, 2019

Lintech is now offering linear guides utilizing cylindrical roller elements versus balls to support a load. The 2 linear guide series products are the ARR and HRR models.

ARR Square Rail Roller Linear GuideHRR Profile Rail Roller Linear Guide

These ultra-high capacity linear guides are designed to support a load in any direction without de-rating the capacity. Because there is more surface area supporting the load than with ball elements, these linear guides have a far greater capacity and are much stiffer than a ball element design.

The ARR and HRR have different dimensions to match other linear guide manufacturers products.

If you determine that these features would be beneficial to your organization, contact Lintech and we can assist with pricing and availability.

ARR and HRR product links are highlighted.

Infrared Inspection System

October 15, 2019

Custom Frame Aircraft

The graphic above represents a combination belt and screw driven infrared inspection system. The 16 foot (5 m) by 6 inch (150 mm) X-Y axes are mounted to a movable flexible aluminum structure. The X axis is driven by a belt, while the Y axis uses a standard screw driven positioning table.

For assistance with your custom motion system, please contact Lintech.

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