No.000156 Dual Centering Mechanism

Good IDEA!

74

Selection criteria

It has the suitable radial clearance and accuracy.

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Available sizes

■Linear Guides

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
Dimension tolerance of H		±100	±40
Pair variation of H		20	15
Dimension tolerance of 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	Co (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

■Linear guide life calculations

●Life

When linear guides operate in linear motion while supporting loads, repeated stresses apply on the rolling elements (balls) and raceways (rails), eventually causing scale-like flaking due to material fatigue. The total run distance until this flaking appears is defined as linear guide's "Life".

●Rated Life.

Rated life is a total distance 90% of linear guides reach without flaking when a group of the same guides are run under the same condition. The rated life can be calculated with basic dynamic load rating and the load applied on the guides as follows.

When using linear guides, load calculations are initially needed. It is not easy to calculate the loads during linear motion due to vibrations and shocks, as well as load distribution on the guides. Furthermore, operating environment temperature has large effect on life. When these conditions are taken in consideration, the calculations would 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)

In using linear guides, the shaft that balls contact must have sufficient hardness, If adequate hardness cannot be obtained, load rating decreases and life will be reduced as a result.

●Temperature factor (fT)

When the temperature of linear guides exceed 100°C, hardness of blocks and rails will be reduced, causing reduction of life. Please compensate the life rating with temperature factor.
* Please use linear guides within temperature shown on product pages.

●Contact factor (fC)

Table-1. Contact Factor

Number of blocks installed on one rail and 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 2 or more blocks on 1 rail. In such case, load applicable on each block would not be uniform due to machining variations. As the result, allowable load rating on each block would vary depending on the number of blocks used per rail. Please compensate the life rating with contact factor shown on Table-1.

●Load Factor (fW)

Table-2. Load Factor

Application condition	fw
No external shocks or vibrations and speed is low 15m/min or less	1.0-1.5
No significant shocks or vibration and med. speed 60m/min or less	1.5-20
External shocks and vibrations exist and the speed is high 60m/min or over	2.0-3.5

When calculating loads applicable on linear guides, other than the weight of the object, inertial force due to motion speeds, moment loads, and variations of each over time must also be obtained accurately. However, accurate calculation would be difficult due to repeated starts and stops and various shocks and vibrations. Therefore, the Load Factors shown in Table-2 are used to simplify the life calculations.

●Applicable load calculation method

When moment loads apply a block, use the following formula to convert the moment load to applicable load.

• P: Applied Load (N)
• F: Downward Load (N)
• Co: 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

Material	Hardness	Surface Treatment
EN 1.7220 Equiv.	40-45HRC	Black Oxide
		Electroless Nickel Plating
EN 1.4006 Equiv.		-

■Sizes and Dimensions

Thread Dia. (Coarse)	Thread Dia. (Fine)	Length in 5 mm increments
M3 x 0.5	-	10-30
M4 x 0.7	M4 x 0.5	15-60
M5 x 0.8	M5 x 0.5	15-60
M6 x 0.75	M6 x 0.75	20-60
M8 x 1.25	M8 x 0.75	25-60
M10 x 1.5	M10 x 1.0	30-70
M12 x 1.75	M12 x 1.0	35-80

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