BS ISO 16287:2021 pdf free

BS ISO 16287:2021 pdf free.Plain bearings – Thermoplastic bushes – Dimensions and tolerances.
Thermoplastics shall be in accordance with Iso 6691, e.g. PA, PET, PE, POM.
For modified or other materials, details shall be subject to agreement between the supplier and the purchaser.
NOTE Thermoplastics have a higher coefficient of linear thermal expansion than metals. PA absorbs more moisture than the other materials given and thus, in addition, will alter in volume.
With the tolerance zones and fits specified in this document, these properties are taken into account under the following conditions:
a) the bearing clearance is designed for an operating temperature of the bush of—lO °C to +50 °C and a relative ambient humidity of 20% to 95 %;
b) interference fit in the housing is achieved by the insertion interference (limit deviation of DcJ and is also maintained at operating temperatures of—lO °C to +50 °C;
For other operating conditions than those given above, the bearing clearance and the type of fixing shall be reviewed and validated. The tolerances are applicable in the conditioned state of the bushes, i.e. they shall have the temperature (23 °C) and the moisture content (SO %) resulting at a standard atmosphere in accordance with Iso 554 (23/50).
To maintain their dimensions, bushes made of PA shall be stored in the above given standard atmosphere or in a suitable hermetically sealed condition.
The surface finish and tolerance classes shall be in accordance with Table 5. for group A or B.
The edges shall be free from flash or burrs.
Due to the large insertion interference, the leading edge of the housing bore shall be suitably chamfered or rounded in order to avoid damage during insertion (see Figure 3 in Clause 9).
The standard bearings (type C and type F) shall have a minimum of one outside diameter chamfer and one inside diameter chamfer at opposite ends. By agreement, additional chamfers may be provided.
The dimensions of the bush shall be tested in the conditioned state (see also the Note in Clause 6).
8.2 Outside diameter, D0
a) Check the outside bush diameter with two ring gauges.
The GO ring corresponds to the maximum D0 size limit and the NO GO ring to the minimum D0 size limit according to Tables 1 to 4 or supplier specification for special thermoplastic compounds.
b) Measure the outside diameter in free condition, determined as the arithmetic mean of at least two measurements (see ISO 12301).
Inside diameter, D1
a) Check the inside bush diameter with two ring gauges.
Insert the bush successively into two gauging rings, one corresponding to the maximum size limit and the other to the minimum size limit of the housing tolerance class H7.
The inside bush diameter shall not exceed the bottom limit of the specified tolerance class according to Table 5, when inserted into the gauging ring having the minimum housing tolerance limit.
The inside bush diameter shall not exceed the upper limit of the specified tolerance class when inserted into the gauging ring having the maximum housing tolerance limit.
The inside maximum and minimum bush diameter shall be checked with a GO and NO GO plug gauge or measured with a 3-point measuring instrument.
b) Check the inside bush diameter with one ring gauge, in accordance with ISO 3547-2, test C for wrapped bushes
Press the bush into a ring gauge. the size of which is made up of D0 and the rounded average value of the tolerance class H7.
The inside diameter of the hush when it is pressed into the ring gauge DICh shall be checked with a GO and NO GO plug gauge or measured with a 3-point measuring instrument.
The width of the gauging ring shall be greater than the width of the bush.
There are tolerance differences between checking the inside diameter of the bush in two ring gauges corresponding to the H7 limit sizes [see 8.3. a)J and checking the inside bush diameter in one ring gauge with the average value of H7 Isee fl3.. b)J. There are further tolerance differences between gauging and measuring the inside bush diameter. Therefore, checking details shall be subject to agreement between the supplier and the purchaser.BS ISO 16287 pdf download.