C100054 -A -Anglaise (Screws studs nuts - Aptitude to friction test - Me...

Equipment : The test is carried out at an ambient temperature of 23°C ± 5°C on a "tightening rig". This test equipment consists of a motor allowing tightening to be carried out at a constant speed (between 5 revs/min and 10 revs/min) and a measuring cell linked to an electronic data collection device and a PC. The motor drives the screw or nut assembly to be tested. The cell receives the element to be measured, assembly elements (support plate, cover, etc.) and the reference element. It is equipped with gauging bridges that measure the torsional moment and the compressive longitudinal deformation to which the element to be tested is submitted during tightening. These two values define the output between the total tightening moment and the compressive load in the cell (µ global)*. The data collection device processes the signals from the cell and transmits them to the PC that operates in two modes; one mode controlling the test rig and the other processing the data. Some cells are equipped with additional gauging bridges to measure the under head moment. Test procedure : Except for specific cases (studs, etc.) it is the element under test that is rotated. The tightening is carried out until an effort F ≥ 85% of Re min. of the screw quality class or 85% of the proof load is detected without resetting to zero the torque and torque under head channels. The coefficient of friction is then calculated within the measuring range between 50% and 80% of the theoretical Re min.(see some values in appendix 5) or between 50% and 80% of the proof load. Ensure that the effort window is well situated in an area where all the positioning or crushing of the washer is finalised. * The support diameters Di and Dw are the theoretical support diameters. * The screw or nut applying a load to the part to be tested, the plate or washer support surface must be new for each measurement. * The ideal statistical sample for control of the batch is 33 parts. If a lower number is used, take it into account in the uncertainty of measurement calculation. Table 1 (Appendix 3) determines the test process uncertainty in relation to the sample size. The equipment (sensors + recorders) must have an relative accuracy at least equal to the values below : • Effort (preload) :
2.2.1.2. Marking These fastening elements may present important similarities with existing standard or specific elements. For this reason, these must be identified by their specific part number and by a physical marking for which the type and location are specified on the definition documents. 2.3. SPECIAL CASE FOR STUDS AND THREADED RODS Unlike the other screw or nut fasteners, it is the element under test that is locked in the rotational sense in the measuring device. Tightening is carried out using a reference nut. Only the value of the thread µ will be taken into account. The acceptance values are specific : 0,10 – 0,20 for FN and 0,05 – 0,10 for FF.
OR : 11/09/1996 A : 01/08/2001
General use
PSA PEUGEOT - CITROËN
SCREW STUD NUT, APTITUDE TO FRICTION
C10 0054
3/13
3. EQUIPMENT AND PROCEDURE FOR THE APTITUDE TO FRICTION TEST
This is a translation, the French original shall be used in all cases of litigation Date of translation : 03/12/2002
CONTENTS 1. OBJECT 2. DEFINITIONS AND EXPRESSION ON DOCUMENTS 2.1. NORMAL FRICTION (FN) 2.2. LOW FRICTION (FF) 2.3. SPECIAL CASE FOR STUDS AND THREADED RODS 3. EQUIPMENT AND PROCEDURE FOR THE APTITUDE TO FRICTION TEST 4. CHARACTERISTICS OF IMPLEMENTED ELEMENTS 4.1. PREPARATION OF REFERENCE ELEMENTS 4.2. REFERENCE SCREW (TO TEST A NUT) 4.3. REFERENCE NUT (TO TEST A SCREW OR A STUD) 4.4. ELEMENT TO BE TESTED 4.5. THRUST WASHER 5. EXPRESSION OF RESULTS 6. REQUIREMENTS APPENDIX 1 APPENDIX 2 APPENDIX 3 APPENDIX 3 CONT'D APPENDIX 4 7. RECORDS AND REFERENCE DOCUMENTS 7.1. RECORDS 7.2. REFERENCE DOCUMENTS 7.3. EQUIVALENT TO : 7.4. CONFORMS TO : 7.5. KEY-WORDS 1 2 2 2 2 3 4 4 4 5 5 6 6 6 7 8 9 10 11 13 13 13 13 13 13
In order to reduce the possible variants, it is recommended to limit the targeted apparent overall mean friction to the two following cases : Normal friction “FN”, target value : 0,15 IT = ± 0,03 Low friction “FF”, target value : 0,075 IT = ± 0,015 2.1. NORMAL FRICTION (FN) Unless otherwise specified in the definition documents, it applies to all threaded fasteners for which the definition documents refer to normes C10 0020 or C20 0020. Expression on drawing (threaded fasteners without reference to the normes stated above) : “Aptitude to friction FN, 0,12/0,18, norme C10 0054”. 2.2. LOW FRICTION (FF) It applies to all threaded fastening elements, standard or non standard, when low friction is required, providing that the instructions in § “Recommendations for application of friction “FF” in production” are observed. Mandatory expression on documents : “Aptitude to friction FF : 0,06/0,09 ; norme C10 0054”. Completed if necessary by : • The required marking. • The specific definitions concerning the dimensions, geometry, thread tolerance class, of the element to be tested. 2.2.1. RECOMMENDATIONS FOR APPLICATION OF FRICTION “FF” IN PRODUCTION For threaded fastening elements “FF”, the following instructions must be mandatorily observed. 2.2.1.1. Implementation • Tightening must be carried out by rotation of the element (screw or nut) which includes the specification “FF”. The various elements (screw, nut, etc.) from a same assembly may include, without difficulty, a specification “FF”. • In the case of implementation by the torque tightening method, the relative accuracy of the recommended means of tightening must be such that :
OR : 11/09/1996 A : 01/08/2001
General use
PSA PEUGEOT - CITROËN
SCREW STUD NUT, APTITUDE TO FRICTION
C10 0054
2/13
2. DEFINITIONS AND EXPRESSION ON DOCUMENTS
1. OBJECT
This norme defines the conditions for testing screws, studs and nuts with an ISO metric thread. This test, carried out in reproducible reference conditions, verifies that the given apparent overall friction coefficient is within the tolerance range prescribed. The apparent overall friction coefficient depends upon a number of factors such as : geometry variation, surface texture, coating structure of elements facing each other, factors for which combined effects can only be measured through this coefficient. In the case of a stud or its equivalent, this norme is applicable when considering only the apparent friction coefficient of threads which must be specified on the drawing. Note : The special configuration of the assembly elements defined for this reference test, does not allow values prescribed in this document to be assigned to any assembly on a vehicle.
PSA PEUGEOT – CITROËN
C10 005TIVES
SCREWS STUDS NUTS APTITUDE TO FRICTION TEST METHOD
Page 1/13 THIS NORME REPLACES C10 0055 FOR NEW DESIGNS