Marking Standard Description Mechanical Properties Property lbf/in2 Mpa Bolts AS/NZS 2451 Hexagon BSW Mild Steel Tensile Strength 62720 (432.5) Yield Stress 35840 (247) Proof Load Stress - - AS/NZS 1111 Hexagon ISO Metric Commercial 4.6 Tensile Strength (58015) 400 Yield Stress (34809) 240 Proof Load Stress (32634) 225 AS/NZS 1393 Hexagon ISO Metric Coach Screws 4.6 Tensile Strength (58015) 400 Yield Stress - - Proof Load Stress - - AS/NZS 1110 Hexagon ISO Metric Precision 8.8 Tensile       M5 - 15 Strength     M20 - 39 (116030) (120382) 800 830 Yield          M5- 16 Stress       M20 - 39 (92824) (95725) 640 660 Proof Load  M5 - 16 Stress         M20 - 39 (84122) (87023) 580 600 AS/NZS 1110 Hexagon ISO Metric Precision 10.9 Tensile Strength (150840) 1040 Yield Stress (136336) 940 Proof Load Stress (120382) 830 AS/NZS 2465 Hexagon Unified High Tensile UNC/UNF SAE Grade 5 Tensile   1/4" - 1" Strength 1 1/8-1 1/2 120000 105000 (827) (724) Yield       1/4" - 1" Stress     1 1/8-1 1/2 92000 81000 (634) (558) Proof Load 1/4" - 1" Stress     1 1/8-1 1/2 85000 75000 (586) (510) AS/NZS 2465 Hexagon Unified High Tensile UNC/UNF SAE Grade 8 Tensile Strength 150000 (1034) Yield Stress 130000 (896) Proof Load Stress 120000 (827) A.S.B. 108 ANSI B 18.5 Cup Square BSW Mild Steel Tensile Strength 58240 (402) Yield Stress 29120 (201) Proof Load Stress - - AS/NZS 1390 Cup Square ISO Metric 4.6 Tensile Strength (58015) 400 Yield Stress (34809) 240 Proof Load Stress (32634) 225 Nuts AS/NZS 2451 Hexagon BSW Mild Steel Nuts Proof Load Stress 62720 (432.5) AS/NZS 1112 Hexagon ISO Metric Nuts Prop. Class 5 Proof Load Stress (88473) 610 (Alternative marking can be 5 on one face or Hex flat) AS/NZS 1112 Hexagon ISO Metric Nuts Prop. Class 8 Proof Load Stress (124733) 860 (Alternative marking can be 5 on one face or Hex flat) AS/NZS 2465 Hexagon Unified High Tensile UNC/UNF Nuts SAE Grade 5 Proof Load Stress Up to 1" UNC UNF 120000 109000 (827) (751) Over 1" UNC UNF 105000 94000 (724) (648) AS/NZS 2465 Hexagon Unified High Tensile UNC/UNF SAE Grade 8 Proof Load Stress 150000 (1034) The following three charts compare approximate indices of buying prices, application 'in-place' costs and product weights for bolts of different diameters and strength grades but having similar mechanical capabilities. The 'in-place' costs give consideration to such factors as: relative numbers of fasteners for a given joint. hole preparation labour and consumables. insertion and tightening labour. user handling, freight, warehousing (stainless examples also considered cost penalties for increased flange diameter to accommodate larger diameter fasteners). These charts are not intended to accurately reflect a range of applications but simply to demonstrate that higher strength, smaller diameter, lighter products will normally provide a similar clamp load result at a somewhat lower 'in-place' cost. As always the design engineer will take many other factors into consideration when selecting the appropriate fastener for a given application. Cold Heading Below is a cold headed part formed from the diameter of wire shown to the right. Unbroken metal flow lines (grain) greatly increase fatigue life and enhance load-carrying ability. Machining Illustrated below is a representation of a bolt produced by machining a large diameter bar or wire. Grain or metal flow lines are broken through the head and washer section, which creates planes of weakness. Thread Rolling No metal is cut away, the grain flow lines are unbroken and curve around the thread profiles. The cold rolling stresses the roots in compression, significantly increasing fatigue strength. Smooth roll dies create burnished roots and smooth flanks free from cutter tool marks, reducing potential galling and stress risers. Thread Cutting The grain flow lines are cut and planes of weakness are created.     Click here to download the complete Training Manual. (588kb)   You will need Adobe Acrobat to view this file. Click the logo for a free download