紧固件 技术交货条件 用于螺栓/螺母组件的弹簧垫圈

Fasteners

Technical delivery conditions
Steel spring washers for bolt/nut assemblies

DIN 267
Part 26

Mechanische Verbindungselemente; technische Lieferbedingungen;
Federelemente aus Federstahl für Schraubenverbindungen

In keeping with current practice in standards published by the International Organization for Standardization (ISO), a comma has been used throughout as the decimal marker.

1 Scope and field of application

This standard applies to steel spring washers for use with bolt/nut assemblies and dealt with in the following standards:

• DIN 127 Spring lock washers with tang ends and square ends
• DIN 128 Curved and wave spring lock washers
• DIN 137 Curved and wave spring washers
• DIN 6796 Conical spring washers for bolt/nut assemblies
• DIN 6904 Spring washers for screw assemblies
• DIN 6905 Spring lock washers for screw assemblies
• DIN 6908 Conical spring washers for screw assemblies
• DIN 6913 Spring lock washers with safety ring
• DIN 7980 Spring lock washers for cheese head bolts

It is recommended that this standard also be applied for steel spring washers for bolt/nut assemblies which have not been standardized.

Spring washers made from materials other than spring steel are not the subject of this standard.

Note. Steel spring washers serve to counteract the loss in inherent tension caused by setting or creep of a bolt/nut assembly provided that they are sufficiently resilient to increase the overall resilience of the assembly and that their inherent springiness can compensate for any loss in tension so that the clamping force required to ensure the reliability of the assembly is maintained.

There may be a relative movement between bolt and nut if the friction between the clamped components is overcome by transverse forces. If this does occur, loosening of the assembly cannot be prevented by spring washers.

Thus, when using these components, it should be checked whether the spring washers may usefully be applied as the elements maintaining the clamping force.

2 General requirements

The effectiveness of spring washers in bolt/nut assemblies depends on the material (see clause 3) and on whether the test criteria specified in clause 4 are complied with.

Spring washers shall have a smooth surface and be free from scale and burrs. The surface roughness should be specified in the product standards where required. In the as delivered condition, spring washers shall have a rust protection.

DIN 267 Part 1 shall apply for the surface finish of spring washers in the as delivered condition, unless otherwise specified in the relevant product standard (e.g. by specifying "phosphated and oiled", denoted by Znphr . . . f), or particular agreements have been made.

DIN 267 Part 9 shall apply for electroplated coatings.

Note. Hydrogen-induced embrittlement cannot be ruled out when employing current methods of applying metal coatings from aqueous solutions (see DIN 267 Part 9). As there is even an increased risk of embrittlement in the case of components with a hardness of 400 HV or more, particular care is to be taken when selecting the material, and in connection with heat treatment and surface treatment.

3 Material

Spring washers shall be made of spring steel (FSt) complying with the specifications of DIN 17 221 or DIN 17 222, or of spring steel with equivalent properties, the grade being at the manufacturer's discretion. This requirement shall also apply where the documentation does not specify any material. Spring washers for bolt/nut assemblies, in the hardened and tempered condition, shall have a hardness as specified in table 1.

Table 1. Hardness

Type of spring washer	Hardness
Spring lock washers	HV 430 to 530
Spring washers	HV 430 to 530
Conical spring washers	HV 420 to 510

4 Testing

4.1 Testing for accuracy to size and finish

The specifications of DIN 267 Part 5 shall apply for acceptance inspection with respect to the accuracy to size of spring washers.

Table 2 shall apply for the characteristics and the AQL values.

Table 2. AQL values

Characteristic	AQL value
Internal diameter Width of spring lock washers Washer thickness Free height External diameter of spring washers and conical spring washers	1,5

Continued on pages 2 to 10

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4.2 Testing the mechanical properties and materials

The mechanical properties shall be tested as specified in subclauses 4.2.1 to 4.2.5.

4.2.1 Hardness testing

DIN 50 133 shall apply for the Vickers hardness test, DIN 50 103 Part 1 for the Rockwell hardness test, and DIN 50 150 for the conversion of hardness values.

In the case of spring washers, the value shall be measured, where possible, in the middle of the washer surface at the point of contact with the supporting surface.

In the case of conical spring washers, the value shall be measured, where possible, in the middle of the washer surface. The supporting surface on which the measurement is made shall be hard.

In the case of spring lock washers, a number of washers shall be threaded, with the gap facing downwards, on a bolt, and clamped. The spring lock washer assembly shall then be placed in a V-block and ground down in preparation for hardness testing.

4.2.2 Test for permanent set

The spring washer to be tested shall be compressed between hardened, flat ground washers (with a hardness of not less than 60 HRC) for two minutes using the compression loads specified in tables 3 to 5 (and determined in accordance with VDI 2230 Part 1, assuming a coefficient of friction in the thread, μ_G, of 0,12), and applying

• proof loads corresponding to those for bolts of property class 6.8 in the case of spring lock washers,
• proof loads corresponding to those for bolts of property class 5.8 in the case of spring washers, and
• proof loads corresponding to those for bolts of property class 8.8 in the case of conical spring washers.

The free height of the washers (height after release of pressure) shall not be less than the values specified in tables 3 to 5.

4.2.3 Permanent load test for spring lock washers and spring washers

Ten spring lock washers or spring washers, threaded on a bolt and separated from one another by parallel-faced washers (hardened to at least 500 HV), shall not be fractured or cracked after 48 hours conditioning at ambient temperature under the compression loads specified in tables 3 and 4.

Table 3. Test for permanent set of spring lock washers

Nominal size (= bolt thread size)	2	2,5	3	3,5	4	5	6
Compression load, in N	700	1 160	1 760	2 370	3 050	5 050	7 050
Minimum free height, in mm	DIN 127	0,8	1	1,3	1,3	1,4	1,9	2,6
	DIN 128 (type A)	0,6	0,7	0,85	0,85	0,95	1,2	1,5
	DIN 69051)	–	0,7	0,85	0,85	0,95	1,2	1,5
	DIN 6913	2)	2)	2)	2)	2)	2)	2)
	DIN 7980	–	–	1,6	1,6	1,9	2,5	2,6

Nominal size (= bolt thread size)	7	8	10	12	14	16	18
Compression load, in N	9 000	12 900	20 600	30 000	41 300	56 300	69 000
Minimum free height, in mm	DIN 127	2,6	3,2	3,5	4	4,8	5,6	5,6
	DIN 128 (type A)	1,5	2	2,25	2,65	3	3,6	3,6
	DIN 69051)	1,5	2	2,25	–	–	–	–
	DIN 6913	2)	2)	2)	2)	2)	2)	2)
	DIN 7980	–	3,2	4	4	4,8	5,6	5,6

For 1) and 2), see page 3.

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Table 3 (concluded).

Nominal size (= bolt thread size)	20	22	24	27	30	33	36
Compression load, in N	88 000	110 000	127 000	167 000	204 000	255 000	298 000
Minimum free height, in mm	DIN 127	6,4	6,4	8	8	9,6	-	9,6
	DIN 128 (type A)	4,2	4,2	5,3	5,3	7,6	-	7,6
	DIN 69051)	-	-	-	-	-	-	-
	DIN 6913	2)	2)	2)	2)	2)	2)	2)
	DIN 7980	7,2	7,2	8	8	9,6	9,6	9,6
1) As a deviation from the specifications of the product standards for washers and lock washers for screw assemblies, the bolt thread size instead of the inside diameter shall be used as the relevant nominal size.
2) No values specified at present.

Table 4. Test for permanent set of spring washers

Nominal size (= bolt thread size)	3	3,5	4	5	6
Compression load, in N	1540	2070	2700	4400	6150
Minimum free height, in mm	DIN 137 (type B)	0,8	0,9	1	1,1	1,3
	DIN 69041)	0,9	1	1,5	1,6	1,85

Nominal size (= bolt thread size)	7	8	10	12	14	16	18
Compression load, in N	9000	11 300	18 000	26 300	36 100	49 200	60 000
Minimum free height, in mm	DIN 137 (type B)	1,5	1,5	2,1	2,5	3	3,2	3,3
	DIN 69041)	2,2	2,2	2,4	2,9	-	-	-

Nominal size (= bolt thread size)	20	22	24	27	30	33	36
Compression load, in N	78 000	97 000	111 000	146 000	178 000	223 000	261 000
Minimum free height, in mm	DIN 137 (type B)	3,7	3,9	4,1	4,7	5	5,3	5,8
	DIN 69041)	-	-	-	-	-	-	-
For 1), see table 3.

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4.2.4 Permanent load test for conical spring washers

Ten conical spring washers, threaded with alternating orientation on a bolt and separated from one another by parallel-faced washers (hardened to at least 500 HV), shall not be fractured after 48 hours conditioning at a temperature of + 100 °C under the compression loads specified in table 5, nor shall the free height be more than 2 % below the values specified in table 5.

Table 5. Test for permanent set of conical spring washers

Nominal size (= bolt thread size)	2	2,5	3	3,5	4	5	6
Compression load, in N	920	1540	2350	3160	4050	6700	9400
Minimum free height, in mm DIN 6796	0,5	0,6	0,7	0,9	1,1	1,3	1,7
DIN 69081)	-	1	1,2	1,2	1,5	1,8	2

Nominal size (= bolt thread size)	7	8	10	12	14	16	18
Compression load, in N	13 700	17 200	27 500	40 000	55 000	75 000	95 000
Minimum free height, in mm DIN 6796	2	2,2	2,8	3,4	4	4,6	5,1
DIN 69081)	2,3	2,8	2,8	3,3	-	-	-

Nominal size (= bolt thread size)	20	22	24	27	30
Compression load, in N	122 000	152 000	175 000	230 000	280 000
Minimum free height, in mm DIN 6796	5,6	6,1	6,8	7,3	8
DIN 69081)	-	-	-	-	-
For 1), see table 3.

4.2.5 Twist test for spring lock washers

Spring lock washers shall not fracture when twisted through 90° (see figure 1).

Figure 1.

Figure 2.

Bend the spring lock washer slowly and gradually, taking precautions to prevent injuries from any flying splinters. The clamping jaws shall be approximately 0,5 d₂ apart, their edges shall be slightly rounded (see figure 2).

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4.2.6 Spring force test

A spring force test may be carried out in order to assess the springiness of spring washers, this test permitting the residual spring force to be determined.

Place the washer to be tested in a test device and apply the compression load specified in table 7, 8 or 9, the test device being designed to permit as uniform an application of the load as possible. The pressure platen shall have a surface hardness of at least 60 HRC. After two minutes, the load applied to the spring washer shall be slowly and steadily released through a travel of 20 μm, which shall be measured using a precision measuring device (see Explanatory notes).

The residual spring force shall reach the values specified in table 7, 8 or 9, due allowance being made for any deformation of the test device.

The Explanatory notes describe a suitable test device and include examples of spring characteristics.

The residual spring force values represent provisional specifications, with which experience has to be gained. Table 6 summarizes the residual spring forces required for all washer types.

Table 6.

Type of washer	As specified in	Compression load corresponding to the proof load for property class	Residual spring force after release through travel of 20 μm, as a percentage of the compression load
Spring lock washer	DIN 127 DIN 128, type A DIN 6905 DIN 6913 DIN 7980	6.81)	20% for nominal sizes 4 to 5 30% for nominal sizes 6 to 12 40% for nominal sizes 14 to 20 50% for nominal sizes above 22
Spring washer	DIN 137, type B DIN 6904	5.8	10% for nominal sizes 4 to 6 15% for nominal sizes 7 to 12 25% for nominal sizes above 12
Conical spring washer2)	DIN 6796 DIN 6908	8.8	35% for nominal sizes 4 to 5 45% for nominal sizes 6 to 16 60% for nominal sizes 18 to 22 70% for nominal sizes above 22
1) Spring lock washers which are only intended for bolt/nut assemblies involving fasteners of a property class less than 6.8 are also to be tested at compression loads corresponding to property class 6.8 proof loads.
2) The residual spring force values have been determined on conical spring washers complying with DIN 6796.

Table 7. Spring lock washers as specified in DIN 127, DIN 128 (type A), DIN 6905 *), DIN 6913, DIN 7980

Nominal size	4	5	6	8	10	12	14	16	18
Compression load1), in N	3050	5050	7050	12 900	20 600	30 000	41 300	56 300	69 000
Minimum residual spring force, in N	600	1000	2100	3 900	6 200	9 000	16 500	22 500	27 600

Nominal size	20	22	24	27	30	332)	36
Compression load1), in N	88 000	110 000	127 000	167 000	204 000	255 000	298 000
Minimum residual spring force, in N	35 200	55 000	63 000	83 000	102 000	127 000	149 000
1) Corresponding to property class 6.8.
2) Nominal size not included in DIN 127 and DIN 128 (type A).

*) As a deviation from the specifications of the product standards for washers and lock washers for screw assemblies, the bolt thread size instead of the washer or lock washer inside diameter shall be used as the relevant nominal size.

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Table 8. Spring washers as specified in DIN 137 (type B), DIN 6904 *)

Nominal size	4	5	6	7	8	10	12	14	16
Compression load 1), in N	2700	4000	6150	9000	11 300	18 000	26 200	36 100	49 200
Minimum residual spring force, in N	270	400	615	1350	1 700	2 700	3 900	9 000	12 300

Nominal size	18	20	22	24	27	30	33	36
Compression load 1), in N	60 000	78 000	97 000	111 000	146 000	178 000	223 000	261 000
Minimum residual spring force, in N	15 000	19 500	24 200	27 800	36 500	44 500	55 700	65 200
1) Corresponding to property class 5.8.

Table 9. Conical spring washers as specified in DIN 6796, DIN 6908 *)

Nominal size	4	5	6	7	8	10	12	14	16
Compression load 1), in N	4050	6700	9400	13 700	17 200	27 500	40 000	55 000	75 000
Minimum residual spring force, in N	1400	2300	4200	6 200	7 700	12 400	18 000	25 000	34 000

Nominal size	18	20	22	24	27	30
Compression load 1), in N	95 000	122 000	152 000	175 000	230 000	280 000
Minimum residual spring force, in N	57 000	73 000	91 000	122 000	161 000	196 000
1) Corresponding to property class 8.8.

5 Form of supply

Steel spring washers shall be packed to give adequate protection against mechanical damage during transport. The packages shall be marked with the standard designation specified in the relevant product standard, e.g.:

DIN 127 – A 8 – FSt

The number of units in the package and the manufacturer's symbol shall also be stated on the package.

*) As a deviation from the specifications of the product standards for washers and lock washers for screw assemblies, the bolt thread size instead of the washer or lock washer inside diameter shall be used as the relevant nominal size.

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