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Predicting the Rigidity

Predicting the Rigidity

Predicting the Rigidity

Product catalog summary
Overview: The document provides guidance on selecting the appropriate radial clearance (preload) for LM Guides, which significantly impacts running accuracy, load capacity, and rigidity. It emphasizes the importance of choosing the right clearance based on application requirements, considering factors like vibrations and impacts.
Specifications: Radial clearances are categorized into normal clearance, light preload (C1), and medium preload (C0). Each type is suited for different conditions and applications, such as beam-welding machines, industrial robots, and machining centers.
Procedures: The document advises contacting THK for specific radial clearance recommendations. Preloads are adjusted before shipment for most models, eliminating the need for further adjustments.
Rigidity and Service Life: The rigidity of an LM Guide is defined as the ratio of displacement to applied load. Preload helps reduce displacement and prevent premature failure due to vibration and impact. The effect of preload can be up to 2.8 times greater than its size, but exceeding this releases the preload effect.
Radial Clearance Standards: Detailed tables provide radial clearance specifications for various LM Guide models, including SHS, SCR, SVR, SVS, and others. These tables specify the range of clearances for normal, light, and medium preloads, measured in micrometers (μm).
Recommendations: For optimal performance, select the appropriate preload based on the specific application and consult THK for guidance. Consider the impact of preload on service life and rigidity when making selections.
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Catalog excerpts

Predicting the Rigidity-1

Selection Criteria Predicting the Rigidity Predicting the Rigidity Selecting a Radial Clearance (Preload) Preload is an internal load applied in advance to the rolling elements (balls, rollers, etc.) of an LM block in order to increase its rigidity. Table 12: Types of Radial Clearance Normal clearance Clearance C1 (light preload) Clearance C0 (medium preload) ● The loading direction is fixed, ● An overhang load or moment ● High rigidity is required and impact and vibrations are miniload is applied. vibrations and impact are apmal and 2 rails are installed in ● The LM Guide is used in a plied. parallel. single-rail configuration. ● Heavy-cutting machine tools ● Ve r y h i g h p r e c i s i o n i s n o t ● Light load and high accuracy required, and the sliding resisare required. tance must be as low as possible. • • • • • • • • • Beam-welding machines Book-binding machines Automatic packaging machines XY axes of general industrial machinery Automatic sash-manufacturing machines Welding machines Flame cutting machines Tool changers Various kinds of material feeders • Grinding machine table feed axes • Automatic coating machines • Industrial robots • Various kinds of high-speed material feeders • NC drilling machines • Vertical axes of general industrial machinery • Printed circuit board drilling machines • Electric discharge machines • Measuring instruments • Precision XY tables • Machining centers • NC lathes • Grinding stone feed axes of grinding machines • Milling machines • Vertical/horizontal boring machines • Tool rest guides • Vertical axes of machine tools Since the radial clearance of an LM Guide greatly affects the running accuracy, load carrying capacity, and rigidity of the LM Guide, it is important to select an appropriate clearance according to the application. In general, the service life and accuracy are favorably affected by selecting a negative clearance (i.e., applying a preload1) while taking into account possible vibrations and impacts generated from reciprocating motion. For specific radial clearances, contact THK. We will help you select the optimal clearance according to the conditions. The clearances of all LM Guide models (except models HR, GSR, and GSR-R, which are separate types) are adjusted as specified before s

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Predicting the Rigidity-2

Service Life with a Preload Considered When using an LM Guide under a medium preload (clearance C0), it is necessary to calculate the service life while taking into account the magnitude of the preload. To identify the appropriate preload for any selected LM Guide model, contact THK. Rigidity When a load is applied to an LM Guide, the bearings and LM block will undergo elastic deformation within the allowable load range. The ratio of displacement to applied load is referred to as “rigidity.” The radial internal clearance (preload) for the LM Guide can be specified in order to reduce displacement....

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Predicting the Rigidity-3

Selection Criteria Predicting the Rigidity Radial Clearance Standard for Each Model Radial Clearances for Model SSR Radial clearance Indication symbol Light preload Radial Clearances for Models SHS and SCR Unit: m Indication symbol Light preload Medium preload Radial Clearances for Models SVR/SVS, NR-X/ NRS-X, and NR/NRS Unit: m Indication symbol Light preload Note) Model RSX includes types 5, 7, 9, 12, and 15. The Model RSX-M1 is available in models 9, 12, and 15. Radial Clearances for Model SHW Indication symbol Light preload Medium preload Indication symbol Light preload

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Predicting the Rigidity-4

Radial Clearances for Models HSR, CSR, HSR-M1, and HSR-M1VV Unit: m Indication symbol Model No. 8 Indication symbol Model No. 45 Radial Clearances for Models SR and SR-M1 Radial Clearances for Model HRW Indication symbol Model No. 15 Indication symbol Model No. 12 Radial Clearances for Models RSR, RSR-W, and RSR-M1 Unit: m Indication symbol Model No. 2

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Predicting the Rigidity-5

Selection Criteria Predicting the Rigidity Radial Clearances for Model JR Radial Clearances for Models HCR and HMG Unit: m Indication symbol Model No. 12 Light preload Radial Clearances for Model NSR-TBC Indication symbol Model No. 20 Radial Clearances for Model HSR-M2 Unit: m Indication symbol Model No. 15 Light preload Radial Clearances for Models SRG and SRN Unit: m Indication symbol Model No. 15 Super heavy preload CN2 — Note) Heavy preload and super heavy preload are available only for Model SRG-C/LC/ SLC and Model SRN-C/LC/SLC. Contact THK if you desire a heavy preload or super heavy...

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