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igus® Ltd.

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iglidur® M250 - Material data

The most important specifications at a glance

Extremely resistant to edge pressure
Very resistant to shocks and impacts
Particularly resistant to dirt and dust
Fogging behaviour according to DIN 75201-B

M250 material specifications

When do I use this material?

When the bearings are exposed to severe
dirt
When high vibration dampening is necessary
For low to medium speeds
When mechanical reaming of the bore is necessary
Resistant to edge pressure
High impact resistance
Thick walled according to DIN 1850

When do I use a different material?

For applications in wet areas iglidur®
H, sleeve bearing, mm
When very high precision is required
iglidur® P, sleeve bearing, mm
For very smooth shafts
iglidur® J, sleeve bearing, mm
When a cost-effective bearing with maximum
wear resistance is required
iglidur® R, sleeve bearing, mm

Maximum surface speed

m/s	Rotating	oscillating	Linear
Constant	0,8	0,6	2,5
Short-term	2	1,4	5

Table 02: Maximum surface speeds

Permitted surface speeds

As a standard, iglidur® M250 is manufactured as a thick-walled bearing. iglidur® M250 is best suited for low to medium surface speeds. The maximum permitted surface speeds in the dry operation are 0.8 m/s (rotating) and 2.5 m/s (linear) respectively. In practice these limit values are not always reached due to interactions.

p x v value and lubrication

Figure 04: Coefficients of friction dependent on the surface speed, p = 0,75 MPa

X = Surface speed [m/s]
Y = Coefficient of friction μ

Figure 05: Coefficients of friction dependent on the load, v = 0,01 m/s

X = Load [MPa]
Y = Coefficient of friction μ

Friction and wear

The coefficient of friction µ of a bearing is, among other things, influenced by surface speed and load (Fig. 04 and 05).

iglidur® M250	Dry	Grease	Oil	Water
Coefficients of friction µ	0,18 - 0,40	0,09	0,04	0,04

Table 04: Coefficients of friction for iglidur® M250 against steel (Ra = 1 μm, 50 HRC)

Coefficients of friction

Wear resistance

Shaft materials

The friction and wear are also dependent, to a large degree, on the counter partner. If you observe the coefficient of friction, then the ideal shaft surface finish for iglidur® M250 bearings is Ra = 0.6mm. Diagrams 06 and 07 display a summary of the results of tests with different shaft materials executed with plain bearings made of iglidur® M250. Up to loads of 2MPa the shaft material plays a relatively small role for rotational movements. Therefore, a suitable shaft material must be considered for higher loads. These are hardened shafts, such as Cf53 or hard-chromed. Diagram 07 shows that iglidur® M250 is much better suited for rotational motion than for pivoting movements. However, it must be mentioned that pivoting movements often cause high vibrations, which act on the bearing. This is where iglidur® M250 can show off its special dampening specifications. In our test, these vibrations are excluded for clarity so that the comparison between rotation and pivoting operation is accurate.Shaft materials

Fig. 07

Figure 06: Wear, rotating application with different shaft materials, p = 1 MPa, v = 0.3 m/s

Y = wear [μm/km]

A = Aluminum, hard-anodized
B = machining steel
C = Cf53
D = Cf53, hard chrome-plated
E = St37
F = V2A
G = X90

Wear in pivoting and rotating applications

Diagram 07: Wear in pivoting and rotating applications with various shaft materials, p = 2MPa

Y = wear [μm/km]

A = CF53
B = hard-chromed
C = 304 SS
D = HR carbon steel

blue colour = rotating
pink colour = oscillating

Diameter d1 [mm]	Shaft h9 [mm]	iglidur® M250 D11 [mm]	Housing H7 [mm]
Up to 3	0 - 0,025	+0,020 +0,080	0 +0,010
> 3 to 6	0 - 0,030	+0,030 +0,105	0 +0,012
> 6 to 10	0 - 0,036	+0,040 +0,130	0 +0,015
> 10 to 18	0 - 0,043	+0,050 +0,160	0 +0,018
> 18 to 30	0 - 0,052	+0,065 +0,195	0 +0,021
> 30 to 50	0 - 0,062	+0,080 +0,240	0 +0,025
> 50 to 80	0 - 0,074	+0,100 +0,290	0 +0,030

Table 07: Important tolerances for iglidur® M250 bearings according to ISO 3547-1 after the press-in.

Installation tolerances

iglidur® M250 bearings require relatively large bearing clearances for optimum performances. These ensure that the bushings work reliably even with thermal expansion and water absorption. The disadvantages of the bearing clearance are again compensated by the vibration dampening properties. The bearings are designed for press-fit in a housing with h7 tolerance. After the installation in a housing with nominal diameter, the inner diameter of the bearing automatically adjusts to the D11 tolerance. The shaft should have at least an H9 tolerance.

Additional properties

Medium	Resistance
Alcohols	+ to 0
Hydrocarbons	+
Fats, oils, without additives	+
Fuels	+
Diluted acids	0 to -
Strong acids	-
Diluted bases	+
Strong bases	0

+ resistant 0 partially resistant - non-resistant
All specifications at room temperature [+20℃]
Table 05: Chemical resistance of iglidur® M250

Electrical properties
iglidur® M250 bearings are electrically insulating.

Specific forward resistance	> 10¹³ Ωcm
Surface resistance	> 10¹¹ Ω

Chemical resistance

iglidur® M250 bearings have a good resistance against chemicals. They are resistant to most lubricants. The iglidur® M250 is not affected by most weak organic and inorganic acids.

Radioactive rays

Bearings made of iglidur® M250 are conditionally usable under radioactive radiation. They are resistant up to a radiation intensity of 1 · 10⁴ Gy.

UV-resistant

iglidur® M250 bearings are permanently resistant against UV rays.

Vacuum

In vacuum, iglidur® A250 plain bearing degases. The relatively high humidity absorption of the bearing therefore permits the bearing to be used in vacuum only restrictedly.

Typical application areas

Agricultural machinery

Agricultural engineering

Furniture

Furniture and industrial design

Textile industry

Textile industry

Consulting

I would be happy to answer your questions

Rob Dumayne

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