311 2Operating Life When Linear Guide is loaded in linear reciprocating motion, scaly damages called flaking appear due to material fatigue as the stress works on the rolling elements and rolling contact surfaces constantly. Total travel distance until the first flaking occurs is called Life of Linear Guides. Rated life is the total travel distance that 90% of linear guides of the same type can reach, under the same conditions, with no occurrence of flaking damage. Rated life can be obtained from the Basic Dynamic Load Rating and the actual load applied on the linear bushings, as shown below. 2Rated Life Load must be calculated before actually using Linear Guides. To obtain load during linear reciprocating motion, it is necessary to fully consider vibration and impact during motion, and also distribution status in relation to Linear Guides. So, it is not easy to obtain load by calculation. Operating temperature also critically affects life. All these conditions considered, the above-mentioned calculation formula is as follows. L : Rated Life (km) fH : Hardness Factors (See Fig. 1) fT : Temperature Factors (See Fig. 2) fC : Contact Factors (See Table-1) fW : Load Factors (See Table-2) C : Basic Dynamic Load Rating (N) P : Applied Load (N) t Hardness Factor (fH) For Linear Guide applications, sufficient hardness is required for ball contact shafts. Insufficient hardness causes less allowable load, resulting in shorter life. Please correct the rated life according to the hardness factors. t $POUBDU 'BDUPS GC) For actual applications, more than 2 blocks are generally used per shaft. In this case, load applied to each block varies depending on machining precision but is not uniformly distributed. As a result, per-block allowable load varies depending on per-shaft Linear Guide quantity. Please correct the rated life according to Table-1 Contact Factor. t -PBE 'BDUPS GW) To calculate load applied to the Linear Guides, in addition to object weight, it requires inertia force attributed to motion velocity or moment loads. Further, it is necessary to accurately determine the temporal change of each. It, however, is difficult to attain accurate calculations due to potential vibration and impacts caused during reciprocating motion, other than repeated start-stop motions. Table-2 Load Factor helps simplify operating life calculation. t 5FNQFSBUVSF 'BDUPS GT) If the Linear Guide temperature exceeds 100°C, the Linear Guide and shaft hardness decreases, resulting in less allowable load and shorter life than used at a room temperature. Please correct the rated life according to the temperature factors. * Please use Linear Guides under the allowable temperature shown on each product page. Condition of Use fw No shocks/vibrations, low speed: 15m/min. or less 1.0~1.5 No significant shocks/vibrations, medium speed: 60m/min. or less 1.5~2.0 With shocks/vibrations, high speed: 60m/min. or more 2.0~3.5 Table-2. Load Factor F Lr F Ly F Lr F Lp t "QQMJFE -PBE 1 $BMDVMBUJPO .FUIPE When load is applied to the a block, convert moment load into applied load by the following formula. t Horizontal Installation t Lateral Installation P: Applied Load (N) F: Downward Load (N) Co: Static Load Rating (N) MA: Allowable Static Moment - Pitch Direction (N t m) MB: Allowable Static Moment - Yaw Direction (N t m) MC: Allowable Static Moment - Roll Direction (N t m) Lp: Distance from Block Center to Load Center in Pitch Direction (m) Ly: Distance from Block Center to Load Center in Yaw Direction (m) Lr: Distance from Block Center to Load Center in Roll Direction (m) Fig. 1. Hardness Factor 60 50 40 30 20 10 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Hardness Factor fH Raceway Hardness HRC 100 150 200 250 0.5 0.6 0.7 0.8 0.9 1.0 Fig. 2. Temperature Factor Temperature Factor fT Linear System Section Temperature °C Table-1. Contact Factor Number of Linear Guide on One Shaft Contact Factor fc 1 1.00 2 0.81 3 0.72 4 0.66 5 0.61 P=F+ Co MC x(FxLr)+ Co MA x(FxLp) P=F+ Co MC x(FxLr)+ Co MB x(FxLy) C 3 L= t 50 P ( ) ( ) fH t fT t fC C 3 L= t t 50 fW P Linear Guide Operating Life Calculation for Linear Guides
RkJQdWJsaXNoZXIy MTc2MTk0OA==