No.000156 Dual Centering Mechanism

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29

Selection criteria

It has the suitable radial clearance and accuracy.

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Available sizes

■Linear Guides - Heavy Load

Material	Hardness
Carbon Steel (Alloy Steel including SCM)	58HRC-

■Sizes and Dimensions

Number of Blocks	Block Width	Block Length		Overall Height	Rail Length
		Standard	With Lubrication Units
1	34	57	66.6	24	100-1480
	42	67	76.6	28	160-1960
	48	83	92.6	33	160-1960
	52	57	66.6	24	100-1480
	59	67	76.6	28	160-1960
	73	83	92.6	33	160-1960
2	34	57 x 2 pcs.	66.6 x 2pcs.	24	160-1480
	42	67 x 2 pcs.	76.6 x 2pcs.	28	220-1960
	48	83 x 2 pcs.	92.6 x 2pcs.	33	220-1960
	52	57 x 2 pcs.	66.6 x 2pcs.	24	160-1480
	59	67 x 2 pcs.	76.6 x 2pcs.	28	220-1960
	73	83 x 2 pcs.	92.6 x 2pcs.	33	220-1960

* Please see the product pages for details of selectable sizes.

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Selection Steps

■Miniature linear guide selection steps

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Accuracy Info

■Preload and accuracy standards (Normal clearance type)

Normal Clearance Type.

Overall Height	Radial Clearance (µm)
24	-4－+2
28	-5－+2
33	-6－+3

Dimensional Accuracy (µm)		Standard Grade	High Grade
H Dimension Tolerance		±100	±40
Pair variation of H		20	15
Tolerance of dims. W2		±100	±20
Pair variation of W2	H24・28	20	15
	H33	30

■Running Parallelism

*The slight clearance type has clearances (play) between the rail and blocks.

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Performance info.

■Rated Load of Linear Guides for Heavy Load (Normal Clearance Type)

Overall Height	Basic Load Rating		Allowable Static Moment
	C (Dynamic) kN	C 0 (Static) kN	MA・MB N・m	Mc N・m
24	8.6	14.2	69.0	98.0
28	12.5	21.3	155.0	232.0
33	20.2	34.5	275.0	393.0

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Technical Calculations

Operating Life Calculation for Linear Guides.

Operating Life.

When the linear system is in motion with applied load, the rolling surfaces and races are subject to repeated stress. This stress can cause scale-like flaking due to material fatigue. The total run distance until the flaking appears in the "Life" of the linear system.

Rated Life.

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 calculated with the basic dynamic load rating and the actual load applied on the linear guides, as shown below.

Load must be calculated before actually using linear guides. To obtain loads during linear reciprocating motion, it is necessary to fully consider vibrations and impacts during motion as well as distribution condition of the load applied to linear guides. So, it is not easy to calculate the loads. Operating temperature also critically affects the life. Considering these conditions, the above-mentioned calculation formula will be as follows.

• L: Rated Life (Km)
• fH: Hardness Factor (See Fig.1)
• fT: Temperature Factor (See Fig.2)
• fC: Contact Factor (See Table-1)
• fW: Load Factor (See Table-2)
• C: Basic Dynamic Load Rating (N)
• P: Applied Load (N)

Hardness factor (fH)

For linear applications, the shafts and ball bearings must have sufficient hardness. If they do not, the load rating decreases and the life will be reduced.
Please correct the rated life with the hardness factor.

Temperature factor (fT)

When the temperature of the linear system exceeds 100 degrees C, the hardness will decrease and as a result, the allowable load and life will reduced.
Please correct the rated life with the temperature factor.
* Please use linear guides within temperature shown on product pages.

Contact factor (fC)

Table-1. Contact Factor

Number of blocks per rail Contact factor fC

1	1.00
2	0.81
3	0.72
4	0.66
5	0.61

In general, it is common to use two or more blocks on one rack. In these cases, the load on each block will vary depending on the machining precision and will not have equally distributed loads. As a result, the allowable load per block will vary depending on the number of blocks used on rail. Please correct the rated life with the contact factors on Table-1.

Load Factor (fW)

Table-2. Load Factor

Condition of Use	fw
No shocks / vibrations, low speed: 15 m/min. or less	1.0-1.5
No significant shocks / vibrations, medium speed: 60 m/min. or less	1.5-20
With shocks / vibrations, high speed: 60 m/min. or more	2.0-3.5

To calculate the load applied to the linear guides, in addition to the object weight, the inertia force attributed to the motion velocity, moment loads and the variations of each over time must be obtained. However, for reciprocating motion applications, it is difficult to obtain accurate calculations due to effects of the vibrations and shocks. Therefor, use Table 2 to simplify the life calculations.

Applied Load P Calculation Method

When moment load is applied to each block, convert the moment load into applied load using the following formula.

• P: Applied Load (N)
• F: Downward Load (N)
• C0: Static Load Rating (N)
• MA: Allowable Static Moment - Pitching Direction (N·m)
• MC: Allowable Static Moment - Rolling Direction (N·m)
• Lp: Load Point Distance (m) in Pitching Direction
• Lr: Load Point Distance (m) in Rolling Direction

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Selection criteria

Prevent the linear guide from overrunning.

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Available sizes

■Stopper Bolts- Hexagon Socket, Fine Thread

Material	Hardness	Surface Treatment
4137 Alloy Steel	40-45HRC	Black Oxide
		Electroless Nickel Plating
410 Stainless Steel		−

■Sizes and Dimensions

Screw Dia. (Coarse)	Screw Dia. (Fine)	Length in 5 mm increments
M3x0.5	―	10－30
M4x0.7	M4x0.5	15－60
M5x0.8	M5x0.5	15－60
M6x0.75	M6x0.75	20－60
M8x1.25	M8x0.75	25－60
M10x1.5	M10x1.0	30－70
M12x1.75	M12x1.0	35－80

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