What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The main operation method of the embedded knurled copper nut of the lock nut is injection molding. After heating, it is embedded into the plastic part or directly injection molded. If injection molding is used, the melting point of P/NYLOY/PET is above 200°C. , After the embedded nut is hot melted into the plastic part, the temperature rises rapidly. After injection molding, the plastic body rapidly cools and crystallizes and hardens. If the embedded nut temperature is still at a high temperature, it may fall to the place where the copper nut contacts the plastic part. Start to loosen or crack. Therefore, copper nuts are used instead of carbon steel nuts in the injection molding of embedded nuts.
Many parts on the car need to be rubberized, which can reduce noise, especially the parts related to shock absorption. Nuts are welded on many of these parts to facilitate the installation of other parts on them. The sheet metal is generally relatively thin, and most of them are only one or two millimeters. A through hole is punched, and then the nut is placed in the hole, and then around it. Spot welding is done so that it can be fixed. After spot welding, the periphery of the screw hole on the sheet metal will not be flat due to thermal deformation, which will affect the appearance.
Most electrical appliance manufacturers only require the size and riveting gap to be tested for riveted contact components. There is no clear requirement for riveting strength. Only a few manufacturers perform torsion testing on riveting strength. The torque detection method is as follows: use a saw blade to open a one-shaped groove on the rivet head of the riveted contact element, and then insert a torque wrench into the one-shaped open groove to rotate, and measure the torque value. Because most of the electrical contacts are made of copper-silver alloy, the strength is low, and it is easy to slip during the test, and when a saw blade is used to open the one-shaped groove, the width and depth cannot be accurately positioned, so the measured value fluctuates greatly. , has always been an unsolvable technical problem in the industry.
National Standard 1 GB/T3103.3-2000 Fastener Tolerance Flat Washers 2 GB/T5286-2001 General Scheme of Flat Washers for Bolts, Screws and Nuts 3 GB/T9074.1-2002 Bolts or Screws and Flat Washers Assemblies 4 GB/ T9074.18-2002 Self-tapping screws and flat washers assembly 5 GB/T 95-2002 Flat washers C grade 6 GB/T96.1-2002 Large washers A grade 7 GB/T96.2-2002 Large washers C grade 8 GB/ T97.1-2002 Flat washer Class A 9 GB/T97.2-2002 Flat washer chamfered Class A 10 GB/T97.4-2002 Flat washer for screw and washer assemblies 11 GB/T97.5-2002 Flat Washers for self-tapping screws and washer assemblies 12 GB/T848-2002 Small washers Class A 13 GB/T5287-2002 Extra large washers Class C 14 GB/T4678.13-2003 Die-casting mold parts Part 13: Push plate washers 15 GB /T4605-2003 Rolling bearing thrust needle roller and cage assemblies and thrust washers 16 GB/T97.3-2000 Flat washers for pins 17 GB/T18230.5-2000 Flat washers for bolted structures quenched and tempered 18 GB/T9074 .5-2004 Cross recessed small pan head screw and flat washer assembly 19 GB/T9074.20-2004 Cross recessed hexagon head self-tapping screw and flat washer assembly 20 GB/T3762-1983 Sharp angle seal for tube fittings Washers 21 GB/T1231-2006 High-strength large hexagon head bolts, large hexagon nuts, and washers for steel structures Specifications 22 GB/T1230-2006 High-strength washers for steel structures 23 GB/T2861.10-2008 Die guides - Part 10 : Washers 24 GB/T5649-2008 Lock nuts and washers for pipe joints 25 GB/T94.3-2008 Technical conditions for elastic washers Saddle, wave elastic washers 26 GB/T3099.1-2008 Terms of fasteners threaded fasteners , pins and washers 27 GB/T10447-2008 Elements and tolerances of semicircular thrust washers for sliding bearings 28 GB/T94.1-2008 Technical conditions for elastic washers Spring washers 29 GB/T10446-2008 Dimensions and tolerances for full circle thrust washers for sliding bearings 30 GB/T93-1987 standard spring washer 31 GB/T94.2-1987 elastic washer technical conditions toothed, serrated lock washer 32 GB/T98-1988 stop washer technical conditions 33 GB/T849-1988 spherical washer 34 GB/ T850-1988 Cone Washer 35 GB/T851-1988 Split Washer 36 GB/ T852-1988 Square bevel washer for I-beam 37 GB/T853-1988 Square bevel washer for channel steel 38 GB/T854-1988 Single ear stop washer 39 GB/T7244-1987 Heavy spring washer 40 GB/T855-1988 Double lug Stop washers 41 GB/T7245-1987 Saddle spring washers 42 GB/T7246-1987 Wave spring washers 43 GB/T856-1988 Outer tongue stop washers 44 GB/T858-1988 Stop washers for round nuts 45 GB/T859- 1987 Light spring washer 46 GB/T860-1987 Saddle elastic washer 47 GB/T861.1-1987 Internal tooth lock washer 48 GB/T861.2-1987 Internal serrated lock washer 49 GB/T862.1-1987 External tooth Lock Washers 50 GB/T862.2-1987 External Serrated Lock Washers 51 GB/T955-1987 Wave Elastic Washers 52 GB/T27938-2011 Sliding Bearing Thrust Washers Failure Damage Terms, Appearance Features and Reasons 53 GB/T956.1 -1987 Conical Lock Washer 54 GB/T956.2-1987 Conical Serrated Lock Washer 55 GB/T28697-2012 Rolling Bearing Self-aligning Thrust Ball Bearing and Self-aligning Seat Washer Dimensions 56 GB/T9074.2-1988 Cross Groove Pan head screw and external serrated lock washer assembly 57 GB/T9074.3-1988 Cross recessed pan head screw and spring washer assembly 58 GB/T9074.4-1988 Cross recessed pan head screw, spring washer and flat washer assembly 59 GB/T9074.7-1988 Cross recessed small pan head screw and spring washer assembly 60 GB/T9074.8-1988 Cross recessed small pan head screw and spring washer and flat washer assembly 61 GB/T9074.9-1988 Cross recessed Countersunk head screw and conical lock washer assembly 62 GB/T9074.10-1988 Cross recessed half countersunk head screw and conical lock washer assembly 63 GB/T9074.11-1988 Cross recessed pocket hexagon head bolt and flat washer Assembly 64 GB/T9074.12-1988 Cross-recessed hexagon head bolt and spring washer assembly 65 GB/T9074.13-1988 Cross-recessed hexagon head bolt, spring washer and flat washer assembly 66 GB/T9074.15 -1988 Hexagon head bolt and spring washer assembly 67 GB/T9074.16-1988 Hexagon head bolt and serrated lock washer assembly 68 GB/T9074.17-1988 Hexagon head bolt, spring washer and flat washer assembly 69 GB/ T9074.26-1988 Spring washers for assemblies Ring 70 GB/T9074.27-1988 External Serrated Lock Washers for Assemblies 71 GB/T9074.28-1988 Conical Lock Washers for Assemblies 72 GB/T1030-1988 Inner Spherical Washers
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