MGB EN

MGB | Data sheet

■ Calculating the Nominal Life The nominal life (Lkm) is calculated using the basic dynamic load rating (C100) and the calculated load (P) acting on the MGB guide. For this calculation, the basic dynamic load is based on a nominal life of 100 km. During operation, an MGB rail may be exposed to vibrations, shocks, and fluctuating loads, which are often difficult to quantify. Additionally, operating temperature and block arrangement (especially when blocks are placed directly in line) have a decisive influence on service life. Taking these factors into account, the nominal life (L km ) can be calculated according to the following formula.

L km : Nominal life (km) C 100 : Basic dynamic load rating (N) P: Calculated load (N) f C : Contact factor f W : Load factor

Note: This nominal life formula may not apply when the stroke length is less than or equal to twice the length of the MGB block.

The equivalent load P corresponds in its effects to the sum of the forces and moments working simultaneously on a sli der. If these different load components are known, P results from the equation below:

Once the nominal life (L km ) has been obtained, the service life time can be obtained using the following formula if the stroke length and the number of cycles are constant.

L h : Service life time (h) l s : Stroke length (mm) n 1 : Cycles per minute (min -1 )

f C : Contact factor When multiple blocks are installed in close contact with each other, it is difficult to achieve uniform load distribution because of moment loads and mounting surface accuracy. When multiple blocks are used in close contact, multiply the basic load rating (C or C₀) by the corresponding contact factor shown in Tab 25. ‘Close contact’ refers to a center distance between blocks that is less than twice the block length L. Note: If uneven load distribution is expected in large machines, apply the corresponding contact factor from Tab 25. f W : Load factor In general, reciprocating machines are subject to vibrations or impacts during operation. It is difficult to accurately quantify vibrations generated at high speeds and impacts occurring during frequent starts and stops. Therefore, when the effects of speed and vibration are significant, divide the basic dynamic load rating (C) by the load factor (f v ) corresponding to Tab 26, based on empirically obtained data.

Contact factor f C

Number of blocks used in close contact

2

0.81

3

0.72

4

0.66

5

0.61

6 or more

0.6

Normal use

1

Tab.25

f W

Speed (V)

Vibrations/ impacts

Very low V≤0.25 m/s

Faint

1 to 1.2

Low 0.25 m/s < V ≤ 1 m/s

Weak

1.2 to 1.5

Medium 1 m/s < V ≤ 2 m/s

Medium

1.5 to 2

High V>2 m/s

Strong

2 to 3.5

Tab.26

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25