No.000116 Pusher Overload Detection Mechanism

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34

Selection criteria

Ensure running straightness.

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Available sizes

■Miniature Linear Guides Standard Blocks, Light Preload, Precision Class L Configurable Type

Material	Hardness
440C Stainless Steel	56HRC-
Carbon Steel (Alloy Steel including SCM)	58HRC-

■Sizes and Dimensions.

Number of Blocks	Block Width	Block Length	Overall Height	Rail Length
1	17	23.6	8	40-130
	20	30	10	35-275
	27	33.9	13	45-470
	32	42.4	16	70-670
	40	50	20	100-700
2	17	23.6 x 2pcs.	8	70-130
	20	30 x 2pcs.	10	95-275
	27	33.9 x 2pcs.	13	120-470
	32	42.4 x 2pcs.	16	150-670
	40	50 x 2pcs.	20	160-700

* 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 Reference (Standard Blocks / Light Preload / High Grade).

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Performance info.

Load Rating of Linear Guides (Standard block / Light Preload / High Grade).

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Technical Calculations

Operating Life Calculation for Linear Guides

Operating Life.

When the 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 (steel balls) and the rolling contact surfaces (rails) constantly.Total travel distance until the first flaking occurs is called Life of Linear Guides.

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 calculation the loads.In addition, the factors as operating temperature also significantly affect 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 Guide applications, sufficient hardness is required for ball contact shafts. Inappropriate hardness causes less allowable load, resulting in shorter life.
Please correct the rated life with the hardness factor.

Temperature factor (fT)

When the temperature of linear guides exceeds 100 C, the hardness of guides and shafts will be reduced, and the allowable loads will also be reduced compared to being used at room temperature, causing a reduction of life.Please correct the rated life according to the temperature factors.
* Please use Linear Guides at within the heat resistance temperature ranges 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

For actual applications, more than 2 blocks are generally used per shaft.In this case, the load applied to each block varies depending on machining precision and is not uniformly distributed.As a result, per-linear guide allowable load varies depending on the number of linear guides per rail. Please compensate the rated life with contact factors on table - 1.

Load factor (fW).

Table-2. Load factor.

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	1.5-20
With shocks/vibrations, high speed: 60m/min. or more	2.0-3.5

To calculate load applied to the Linear Guides, in addition to object weight, it requires inertia force attributed to motion velocity or moment loads.However, it is difficult to calculation the load accurately due to potential vibrations and shocks caused by other element than repeated start-stop motions during reciprocating motion.Thus, table-2 load factor helps simplify the life calculation.

Applicable load calculation method.

When load is applied to the a block, convert moment load into applied load by the following formula.

• P: Applicable 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

Select a groove type of spring which is capable of preventing the shift to the hook attachment of extension spring

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Available sizes

■Spring Anchors - Flat Head Screwdriver Type, with Groove

Material	Surface Treatment	Accessory
1045 Carbon Steel	Black Oxide	Nut one pc (JIS Class 1)　 Steel
303 Stainless Steel	−	Nut one pc (JIS Class 1)　 304 Stainless Steel

■Sizes and Dimensions.

O.D.	Overall Length									Threaded Section Length (overall length - shown below)	Screw Dia. (Coarse)	Spring Latch Shaft Dia.
	10	15	20	25	30	35	45	55	65
φ3	○	○	○	○	-	-	-	-	-	4	Ｍ3	φ1.8
φ4	○	○	○	○	○	-	-	-	-	4.2	Ｍ4	φ2
φ5	-	○	○	○	○	○	-	-	-	6	Ｍ5	φ3
φ6	-	-	○	○	○	○	○	-	-	7	Ｍ6	φ3.6
φ8	-	-	-	○	○	○	○	○	○	7	Ｍ8	φ5
φ10	-	-	-	-	○	○	○	○	○	7	Ｍ10	φ6
φ12	-	-	-	-	-	○	○	○	-	8	Ｍ12	φ6.5

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Selection criteria

In order to set the abnormal load limit

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Available sizes

■Tension Spring - Standard Lengths

Load Type	Material		O.D. range	Free length range	Both ends hooked
	Spring Steel (ASTM A228)	304 Stainless Steel			S-shape	90 degree S
Ultra light load	○	○	φ2 - 12	10 - 100	○	-
Light Load	○	△	φ2 - 20	10 - 175	○	△
Light/Medium Load	○	△	φ2 - 20	10 - 175	○	△
Medium Load	○	△	φ2 - 24	10 - 200	○	△
Medium and Heavy Load	○	-	φ2 - 12	10 - 100	○	-
Heavy Load	○	△	φ3 - 24	10 - 200	○	△

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Performance info.

■Load info. on tension spring.

Load Type	Reference load (N)
	Minimum	Max.
Ultra light load	0.69	19.6
Light Load	1.86	78.45
Light/Medium Load	2.45	98.07
Medium Load	3.53	225.55
Medium and Heavy Load	6.47	83.36
Heavy Load	8.8	430.51

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Technical calculations

■Tension spring load calculations.

P　＝　Pi　+　（k × F）.

P: Load (N).
Pi: Initial Tension (N).
k： Spring Constant(N/mm).
F: Deflection (mm).

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