Stránský a Petržík – Cylinders – Technical information

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Conditions of use and running of pneumatic cylinders Stroke tolerance of pneumatic cylinders Critical strength on piston rod, Air force	Data sheet (full information in PDF)

Conditions of use and running of pneumatic valves Contacts protecting when electromagnetic coils are used

Modified compressed air, Distribution of compressed air Mounting, operation and service of air preparation units, Recommended oils for compressed air lubricating

Compressed air consumption

Hydraulic shock absorber selection

Summary of the pneumatic symbols based on DIN ISO 1219

General conditions for pneumatic circuits

it is necessary to observe appropriate safety rules, instructions, recommendation and specifi ed parameters (temperature, pressure etc.), during setting in operation
areas, which are pressurized even after closing of main air supply, should be specially marked in pneumatic circuits
it is necessary to make allowance to product failure, eventually danger situations due to wrong operation, age or failure
we reccomend to mark with special sign whole pneumatic circuits, where the high caution during service is necessary
we do not reccomend to weld by electric arc on machinery, where pneumatic cylinders are mounted
end users must take sufficient preventive steps to prevent injuries on material and health of employees

Conditions of use and running of pneumatic cylinders

disassembly of single acting cylinders must be done very canny, because inside spring in mounted with preload
working medium is modifi ed compressed air
we reccomend to use our pneumatic oil for air lubricating, or some oil listed on recommended oil list, for renewing of lifetime grease use grease SAP-FML2A
using of other than recommended oils leads to damage of O-rings and gaskets built-in not only in cylinders, but also in other components in pneumatic circuit
if the piston rod speed if lower than 1 ms^-1 the compressed air needn‘t to be lubricated; if piston rod speed is higher, we recommend to lubricate air by lubricator and pneumatic oil (see above); we also recommend to lubricate air, when dew point of compressed air is lower than -20°C
special surface treatment, or material change (stainless steel) or using dust covers are possible options for hard conditions and aggressive surrounding
other special designs or material exchange, gaskets exchange etc. are possible after consultation with our technical dept.
it is necessaty to observe correct mounting of cylinders and correct guiding of piston rod without radial forces (insted of versions which allows radial forces e.g. guide unit H)
we recommend to use hydraulic shock absorbers, when heavy mass and high piston rod speed may occur - the machinery lifetime will be dramatically extended

Stroke tolerance of pneumatic cylinders

Stroke of cylinder may be bigger by tolerance accordingly to DIN ISO 6431, DIN ISO 6432 and VDMA 24562. The value of tolerance is due to production tolerances and depend on diameter and stroke as follows:

*) For strokes bigger than 1250 mm the tolerance is depending on agreement of producer and customer
**) This value is not listed in standard VDMA 24562, or NF E 49003.1 and it is valid only for standard DIN ISO 6431
Standard	Piston diameter [mm]	Stroke [mm]	Allowable tolerance [mm]
DIN ISO 6432	8, 10, 12, 16, 20, 25	0 to 500	+1,5
DIN ISO 6431 VDMA 24562 NF E 49003.1	32, 40, 50	0 to 500	+2,0
	32, 40, 50	501 to 1250*	+3,2**
	63, 80, 100	0 to 500	+2,5
	63, 80, 100	501 to 1250*	+4,0**
	125, 160, 200, 250, 320	0 to 500	+4
	125, 160, 200, 250, 320	501 to 1250*	+5,0**

Critical strength on piston rod (buckling length)

When stroke is big, there must be checked, if excedd of strength in buckling can‘t occur, even if cylinder should pass due to piston diameter. Fast check should be done by read the data in graph below:

Graph of critical strength on piston rod

For exact calculate, if crifitical force wasn‘t exceed use this formulae, F_K must be higher than load to prevent piston rod damage::

F_K =	Π² . E . J	Where:	F_K is critical force on piston rod [N]
			E is stress modulud 2,1*10⁵ MPa
	l² . k		J is quadratic cross section moment [mm⁴]
			l is critical length (=double stroke) [mm]
			k is safety coefficient (about 4 in practice)

Action force

Calculation of force on piston rod of pneumatic cylinder:

F = ( S_p (or S_z) . p ) - T

Where:

F is force on piston rod of pneumatic cylinder [N]
S_p is piston area at thrust [mm²]
S_z is piston area at retract [mm²]
p is working pressure [MPa]
T is friction force (about 10% inpractice)

*Table of retract force on piston rod of pneumatic cylinder [N]*
Piston diameter [mm]	Working pressure [MPa]
Piston diameter [mm]	0,1	0,2	0,3	0,4	0,5	0,6	0,7	0,8	0,9	1,0	1,1	1,2
8	4,5	9,0	13,6	18,1	22,6	27,1	31,7	36,2	40,7	45,2	49,8	54,3
10	7,1	14,1	21,2	28,3	35,3	42,4	49,5	56,5	63,6	70,7	77,8	84,8
12	10,2	20,4	30,5	40,7	50,9	61,1	71,2	81,4	91,6	102	112	122
16	18,1	36,2	54,3	72,4	90,5	109	127	145	163	181	199	217
20	28,3	56,5	84,8	113	141	170	198	226	254	283	311	339
25	44,2	88,4	133	177	221	265	309	353	398	442	486	530
32	72,4	145	217	290	362	434	507	579	651	724	796	869
40	113	226	339	452	565	679	792	905	1018	1131	1244	1357
50	177	353	530	707	884	1060	1237	1414	1590	1767	1944	2121
63	281	561	842	1122	1403	1683	1964	2244	2525	2805	3086	3367
80	452	905	1357	1810	2262	2714	3167	3619	4071	4524	4976	5429
100	707	1414	2121	2827	3534	4241	4948	5655	6362	7068	7775	8482
125	1104	2209	3313	4418	5522	6627	7731	8835	9940	11044	12149	13253
160	1810	3619	5429	7238	9048	10857	12667	14476	16286	18095	19905	21714
200	2827	5655	8482	11309	14137	16964	19791	22619	25446	28274	31101	33928
250	4418	8835	13253	17671	22089	26506	30924	35342	39760	44177	48595	53013
320	7238	14476	21714	28952	36190	43428	50666	57904	65142	72380	79618	86856

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