Symbols and abbreviations

Symbols and abbreviations

1. Symbols & Abbreviations

2. There are many, many, symbols and abbreviations that are used in engineering Their purpose is to simplify the production process By looking at a symbol you can tell a great deal of things, from the material type, to the projection that the drawing is done from The American Standards Association issued the first American standards (1935), entitled “Drawing and Drafting Room Practices” BSI (British Standards Institution: 308) set guidelines, the first part published in 1984, the second in 1985, and then third 1990. These lay the standard out for our country ISO (International Standard Organisation), these standards are agreed on internationally BSI revisions are being updated progressively so that they should be in line with the ISO standard Symbols & Abbreviations

3. Lines in drawings have various meanings, this makes it easy to look at the drawing and immediately pick up information Thick lines are approximately 6mm, and thin lines are 3mm Line Meanings

4. First UK/EU convention Start from a plan view (above) located at the bottom of the page, that is “folded” over to show a side view, and flipped again either side to show front and rear views Third US convention Start from a plan view (above) located at the top of the page, that is “swung” down to show the side view, and flipped again either side to show front and rear views 1 st and 3 rd Angle

5. There are hundreds of abbreviations A small list of some is shown here on the right Abbreviations save you having to write the whole word out Having abbreviations saves space that can be better utilised by the drawing There are hundreds of abbreviations, and which ones are used are the drawers responsibility Term Abbreviations Term Abbreviations Across Corner A/C Material MATL Across Flat A/F Mechanical MECH Approved APPD Number No. Approximate APPROX Not to Scale NTS Assembly ASSY Outside Diameter OD British Standard Fine BSF Pitch Circle PC British Standard Witworth BSW Right Hand RH Cast Iron CI Rivet RVT Cast Steel CS Reference REF Case Hardened CH Screw SCR Centre line CL Sheet SH Chamfered CHMED Serial Number Sl. No. Countersunk CSK Standard STD Counter Bore C’BORE Spot face SF Cylinder CYL Specification SPEC Diameter DIA Spherical SPHERE Drawing DRG Square SQ Dimension DIM Symmetrical SYM Extruded EXTD True Position TP External EXT Traced TCD Figure FIG Unified Fine UNF Hydraulic HYD Round RD Hexagonal HEX Undercut U/Cut Horizontal HORZ Indian Standard IS Beam Inside diameter ID Channel Internal INT Number of teeth (Gear) Machine M/C Parallel Machined M/CD Tee (Structural section) Abbreviations

6. Materials are classified numerically, with the IADS defining the Aluminium standards, and AISI/SAE being used for steel Both systems are similar in function These codes have meanings, and can be read easily by someone who understands the convention This saves a very large amount of space that can be otherwise used by the drawing of the work at hand For example; An Aluminium alloy with the code 7075 is an alloy of Aluminium which contains Zinc, has no impurity control, and has at least 99.75% aluminium A Steel alloy with the code 1020 is an alloy of Steel which contains only carbon, and no other alloying elements, carbon content is approx 0.2% Material Classification

7. They are coded using the the International Alloy Designation System (IADS) standard The digit "1" as in 1xxx designates alloy free (no alloys) and is at least 99% A luminium. The Digit is interchangeable, and depending on it’s value, it means there is a different alloy that is also within the aluminium, some contain multiple major alloys, they are as follows: “2” for Copper (Cu), “3” for Manganese ( Mn ), “4” for Silicon (Si), “5” for Magnesium, “6” for Magnesium and Silicon (Mg and Si), “7” for Zinc (Zn), “8” for an unspecified alloy (including Lithium [Li]) The second part x0xx denotes the purity control of the Aluminium, where “0” is no control, and “1-9” are different controls set at the mill, these levels are set by AIDS The final part is the minimum Aluminium percentage above 99%. So xx25 means “99.25% minimum A luminium content” Aluminium Classification

8. Similar to IADS, but slightly different in that the first two digits denote the elements that are found within, and the last two is the percentage content above “0” of carbon Known as AISI/SAE Steel Classification 10XX Carbon steels Plain carbon, Mn 1.00% max 11XX Resulfurized free machining 12XX Resulfurized / rephosphorized free machining 15XX Plain carbon, Mn 1.00-1.65% 13XX Manganese steel Mn 1.75% 23XX Nickel steels Ni 3.50% 25XX Ni 5.00% 31XX Nickel-chromium steels Ni 1.25%, Cr 0.65-0.80% 32XX Ni 1.75%, Cr 1.07% 33XX Ni 3.50%, Cr 1.50-1.57% 34XX Ni 3.00%, Cr 0.77% 40XX Molybdenum steels Mo 0.20-0.25% 44XX Mo 0.40-0.52% 41XX Chromium-molybdenum steels Cr 0.50-0.95%, Mo 0.12-0.30% 43XX Nickel-chromium-molybdenum steels Ni 1.82%, Cr 0.50-0.80%, Mo 0.25% 47XX Ni 1.05%, Cr 0.45%, Mo 0.20-0.35% 46XX Nickel-molybdenum steels Ni 0.85-1.82%, Mo 0.20-0.25% 48XX Ni 3.50%, Mo 0.25% 50XX Chromium steels Cr 0.27-0.65% 51XX Cr 0.80-1.05% 50XXX Cr 0.50%, C 1.00% min 51XXX Cr 1.02%, C 1.00% min 52XXX Cr 1.45%, C 1.00% min 61XX Chromium-vanadium steels Cr 0.60-0.95%, V 0.10-0.15% 72XX Tungsten-chromium steels W 1.75%, Cr 0.75% 81XX Nickel-chromium-molybdenum steels Ni .30%, Cr 0.40%, Mo 0.12% 86XX Ni .55%, Cr 0.50%, Mo 0.20% 87XX Ni .55%, Cr 0.50%, Mo 0.25% 88XX Ni .55%, Cr 0.50%, Mo 0.35% 92XX Silicon-manganese steels Si 1.40-2.00%, Mn 0.65-0.85%, Cr 0-0.65% 93XX Nickel-chromium-molybdenum steels Ni 3.25%, Cr 1.20%, Mo 0.12% 94XX Ni 0.45%, Cr 0.40%, Mo 0.12% 97XX Ni 0.55%, Cr 0.20%, Mo 0.20% 98XX Ni 1.00%, Cr 0.80%, Mo 0.25%

9. Any Questions?