Brochure

Calculation of Guide Load Factor
Maximum Allowable Moment/Maximum Load Weight
Model
MY1B
Bore size
[mm]
25
32
40
Maximum allowable moment [N·m]
M1 M2 m2M3 m3
Maximum load weight [kg]
m1
Moment [N·m]
1. We recommend an external shock ab-
sorber be installed when the cylinder is
combined with another guide (connection
with floating bracket, etc.) and the maxi-
mum load weight is exceeded.
2. Load factor of 0.5 or less
When the load factor is high against the
cylinder output, it may adversely affect the
cylinder (condensation, etc.) and cause
malfunctions. Select a cylinder to make
the load factor 0.5 or less. (Mainly when
using an external guide)
When using it as a load balancer, please
contact SMC sales representatives.
3. Consider uncalculated loads such
as piping, cableveyor, etc., when
selecting a load moment
Calculation does not include the external
acting force of piping, cableveyor, etc.
Select load factors taking into account the
external acting force of piping, cablevey-
or, etc.
4. Accuracy
Mechanically jointed rodless cylinders do
not guarantee traveling parallelism. When
accuracy in traveling parallelism and inter-
mediate stroke position is required,
please contact SMC sales representa-
tives.
1) Maximum load weight (1), static moment (2), and dynamic moment (3) (at the time of impact with stopper) must be examined for the
selection calculations.
∗ To evaluate, use υa (average speed) for (1) and (2), and υ (collision speed υ = 1.4υa) for (3). Calculate m max for (1) from the maximum
load weight graph (m
1, m2, m3) and M max for (2) and (3) from the maximum allowable moment graph (M1, M2, M3).
υ
L1
ME
δ
g
: Collision speed [mm/s]
: Distance to the load center of gravity [M]
: Dynamic moment [N·m]
: Bumper coefficient
With air cushion = 1/100
With shock absorber = 1/100
: Gravitational acceleration (9.8 m/s
2
)
Sum of guide
load factors
Load weight [m]
Maximum load weight [
m max]
Static moment [
M]
Note 1)
Allowable static moment [M max]
Dynamic moment [
M E ]
Note 2)
Allowable dynamic moment [M E max]
Σα =
+
+
≤1
Note 1) Moment caused by the load, etc., with cylinder in resting condition
Note 2) Moment caused by the load equivalent to impact at the stroke end (at the time of impact with stopper)
Note 3) Depending on the shape of a workpiece, multiple moments may occur. When this happens, the sum of the load factors (
Σα) is the total of all such moments.
Load weight [kg]
Caution on Design
m1
M1 = F1 x L1
F1
L
1
F2
L
2
M2 = F2 x L2
m2
L
3
M3 = F3 x L3
F3
m3
: Load weight [kg]
: Load [N]
: Load equivalent to impact
(at the time of impact with stopper) [N]
: Average speed [mm/s]
: Static moment [N·m]
10
20
40
1.2
2.4
4.8
3.0
6.0
12
29
40
53
5.8
8.0
10.6
5.4
8.8
14
The above values are the maximum allowable values for moment and load weight. Refer to each graph
regarding the maximum allowable moment and maximum load weight for a particular piston speed.
2) Reference formula [Dynamic moment at the time of impact]
Use the following formulae to calculate dynamic moment when taking stopper impact into consideration.
m
F
F
E
υa
M
υ = 1.4υa [mm/s] FE = 1.4υa·δ·m·g
∴ME = ·FE·L1 = 4.57υaδmL1 [N·m]
Note 4) 1.4υaδ is a dimensionless coefficient for calculating impact force.
Note 5) Average load coefficient (= ): For averaging the maximum load moment at the time of impact with stopper according to service life calculations.
3) For detailed selection procedures, refer to page 3.
Note 4)
Note 5)
1
3
1
3
Series MY1B
Prior to Use 1
FE
ME
m
L
1
υ
1