Mechanical drawing is a discipline that precisely represents the structural shape, size, working principle and technical requirements of machinery through drawings.
The drawing is composed of graphics, symbols, text and numbers, etc. It is a technical document used to express design intentions, manufacturing requirements and to exchange experience. It is often referred to as the language of the engineering field.
These symbols and abbreviations represent various components, processes and measurement methods used in engineering design.
What is engineering drawing abbreviations?
Engineering drawing abbreviations are standardized shorthand notations (such as “Ø” for diameter, “R” for radius, or “TYP” for typical) used to convey specific information concisely on technical drawings.
Why use abbreviations in engineering drawings?
The use of abbreviations is to reduce the amount of text required to convey the same information on drawings.
These abbreviations are commonly found in engineering drawings such as those for mechanics, electricity, plumbing, civil engineering and structures. Commonly used abbreviations include AC (alternating current), DC (direct current), FAB (manufacturing) and LD (load).
The main reasons for using abbreviations rather than full terms on engineering drawings include:
Space Saving
Drawings have limited space, and abbreviations (e.g., “⌀” for diameter, “R” for radius) prevent clutter and maintain clarity.
Efficiency
Engineers and manufacturers need to read drawings quickly; abbreviations reduce reading time and speed up production.
International Standards
Abbreviations (such as ISO or ANSI symbols) serve as a universal language, ensuring consistency in global collaboration.
Avoiding Ambiguity
Standardized abbreviations (e.g., “TYP” for “typical”) are more precise than full terms, reducing misinterpretation risks.
Common Engineering Drawing Symbols
List of Abbreviations for Engineering Drawings
Below is a complete list of all abbreviations and symbols used in engineering drawings, alphabetically arranged for easy reference. Use this as a guide to help interpret engineering drawings.
A
| AC | Across Corners |
| AF | Across Flats |
| AFF | Above Finished Floor |
| AISI | American Iron and Steel Institute |
| Al or AL | Aluminium |
| ALY | Alloy |
| AMER | American |
| AMS | Aerospace Material Standards |
| AN- | Army-Navy |
| ANN | Anneal, Annealed |
| ANSI | American National Standards Institute |
| APPROX | Approximately |
| AQL | Acceptable Quality Level |
| AR | As required |
| AS | Aerospace Standards; Australian Standards |
| AS, APS, APV, AV, APSL, AVL | Approved product supplier, approved vendor, approved-product-supplier list, approved-vendor list |
| ASA | American Standards Association |
| ASME | American Society of Mechanical Engineers |
| ASSY or ASY | Assembly |
| AVG | Average |
| AWG | American Wire Gauge |
B
| BASIC | Basic Dimension |
| BC or B.C. | Bolt Circle |
| BCD or B.C.D. | Bolt Circle Diameter |
| BHC | Bolt Hole Circle |
| BHCS | Button Head Cap Screw |
| BHN | Brinell Hardness Number |
| BoM or BOM | Bill of Materials |
| BoP or BOP | Bought Out Part |
| BP, B/P | Blueprint |
| BRZ | Bronze |
| BSC | Basic Dimension |
C
| CAD | Computer-aided design, computer-aided drafting; cadmium [plating] |
| CAGE | Commercial and Government Entity [code] |
| C-C or C-TO-C | Centre-to-centre; on centres |
| CBN | Cubic Boron Nitride |
| CDA | Current Design Activity |
| CERT or cert | Certification |
| CG | Centerless ground, centerless grinding |
| CH or CHAM | Chamfer |
| CI | Cast Iron |
| CL or ℄ | Centreline or centerline; class |
| CNC | Computer numerical control |
| CR | Controlled Radius |
| CRES | Corrosion-resistant [steel] |
| CRS | Cold rolled steel; on centres |
| C/T | Correlation / Tracking |
| C’BORE or CBORE | Counterbore |
| CSK or CSINK | Countersink |
| CTN, ctn | Carton |
D
| ⌀ | Diameter |
| D | Diameter; Delta |
| DIA | Diameter |
| DIP | Ductile iron pipe |
| DIM | Dimension, Dimensioning |
| DO, do | Ditto |
| DOD, DoD | [U.S.] Department of Defense |
| DPD | Digital product definition |
| DWG, dwg | Drawing |
E
| ED | Edge Distance |
| EO, ECO, ECN | Engineering Order |
| EQL, EQ | Equal, Equally |
| ERC | Electrical Rule Check |
| EXIST. | Existing |
F
| f | finish |
| FAO | Finish all over |
| FCF | Feature control frame |
| FD or F/D | Field of the drawing |
| FIM | Full indicator movement |
| FL | Flag note, flagnote |
| FL | Floor Level |
| FN or F/N | Flag note, flagnote; find number |
| FPSO | Floating Production Storage and Offloading |
| FS | Far side |
| FSCM | Federal Stock/Supply Code for Manufacturers |
| FTG | Fitting |
G
| GCI | Gray cast iron |
| GD&T or GDT | eometric dimensioning and tolerancing |
| GN or G/N | General note(s) |
H
| HBW | Hardness, Brinell, tungsten tip |
| HDPE | high-density polyethylene |
| HHCS | hex head cap screw |
| HRA | Hardness, Rockwell, A scale |
| HRB | Hardness, Rockwell, B scale |
| HRC | Hardness, Rockwell, C scale |
| HRS | Hot rolled steel |
| HT TR | Heat treat, heat treatment |
| H&T or H/T or HT | Hardened and tempered |
I
| IAW | In Accordance With |
| ID | Inner diameter; identity, identification number |
| IED | Insufficient Edge Distance |
| ISO | International Organization for Standardization |
J
| JIS | Japan Industrial Standard |
K
| KEY | key |
| KPSI, kpsi | kilopounds per square inch, that is, thousands of pounds per square inch |
| KSI, ksi | kilopounds per square inch, that is, thousands of pounds per square inch |
L
| LDD | limited dimension drawing |
| LH | left-hand |
| LM or L/M | list of materials |
| LMC | least material condition |
M
| MACH | Machine; machined |
| MAJ | major |
| MAX | maximum |
| MBD | model-based definition |
| MBP | measurement between pins |
| MBW | measurement between wires |
| MF or M/F | make from |
| MFD | manufactured |
| MFG | manufacturing |
| MFR | manufacturer |
| MIL- | [U.S.] Military |
| MIN | minimum; minutes; minor |
| MMC | maximum material condition |
| MOD, MoD | Ministry of Defence [U.K. and others] |
| MOP, MoP | measurement over pins |
N
| NAS | National Aerospace Standards |
| NC | National Coarse; numerical control |
| NCM | nonconforming material(s) |
| NCR | nonconformance report |
| NEC | not elsewhere classified; National Electrical Code |
| NEF | National Extra Fine |
| NF | National Fine |
| NL or N/L | notes list |
| NOM | nominal |
| NORM or NORMD | normalized |
| NPS | Naval Primary Standard[3] |
| NPT | National Pipe Taper |
| NS | National Special; near side |
| NSCM | National Stock/Supply Code for Manufacturers |
| N&T or N/T or NT | normalized and tempered |
O
| OAL | overall length |
| OC | on center(s) |
| OD | outer diameter |
| ODA | original design activity |
| OHL | over high limit |
| OPP | opposite |
| ORIG | original |
P
| pc, pcs | piece, pieces |
| PD | pitch diameter |
| PDM, PDMS | product data management, product data manager [app], product data management system [app] |
| NCR | nonconformance report |
| PH or P/H | precipitation hardening, precipitation-hardened; pilot hole |
| PHR BRZ | phosphor bronze |
| PL or P/L | parts list |
| PLM | product lifecycle management; plant lifecycle management |
| PMI | Product and manufacturing information |
| PN or P/N | part number |
| POI | point of intersection |
| P.F. | press fit |
| PSI | pounds per square inch |
| PTFE | polytetrafluoroethylene |
| PVC | polyvinyl chloride |
Q
| QMS | quality management system |
| QTY or qty | quantity |
R
| R | radius |
| RA, Ra | roughness, average; Rockwell A scale |
| RB, Rb | Rockwell B scale |
| RC, Rc | Rockwell C scale |
| REF | reference dimension |
| REQD or REQ’D | required |
| REV | revision |
| RFS | regardless of feature size |
| RH | right-hand |
| RHR | roughness height reading |
| RL | Reduced Level or Relative Level |
| RMA | return material authorization |
| RMS | root mean square |
| RT or R/T | rough turn, rough turned; room temperature |
| RTP | release to production |
S
| SAE | Formerly the Society of Automotive Engineers; now SAE International |
| SC or S/C | sharp corners |
| SF or S/F | spotfaceslip fit |
| SFACE or S/FACE | spotface |
| SHCS | socket head cap screw |
| SI | Système international [d’unités] [International System of Units] |
| SN or S/N | serial number |
| RFS | regardless of feature size |
| SOL ANN | solution anneal, solution annealed |
| SPEC or spec | specification |
| SPHER ANN | spheroidize anneal |
| SPOTFACE | Spot facing |
| SR | spherical radius |
| SS or S/S | stainless steel; supersede |
| SST | stainless steel |
| STD | standard |
| STEP | Standard for the Exchange of Product Model Data |
| STA | solution treated and aged |
| STI | screw thread insert |
| STL | steel |
| STK | stock |
T
| TAP | tapped hole |
| TB or T/B | title block |
| TCC | time-current curve |
| TDP | technical data package |
| THD or thd | thread |
| REQD or REQ’D | required |
| THRD | threaded |
| THK or thk | thickness |
| THRU | through |
| THRU ALL | Through all |
| TIR | total indicator reading; total indicated run-out |
| TOS | top of steel |
| TOL | tolerance, tolerancing |
| TSC | theoretical sharp corner(s) |
| TY | type |
U
| UAI | use as-is |
| ULL | under low limit |
| UNC | Unified National Coarse |
| UNEF | Unified National Extra Fine |
| UNF | Unified National Fine |
| UNJC | Unified National “J” series Coarse |
| UNJF | Unified National “J” series Fine |
| UNO | unless noted otherwise |
| UNS | Unified National Special; unified numbering system |
| UON | unless otherwise noted |
| UOS | unless otherwise specified |
| USASI | United States of America Standards Institute |
| USS | United States Standard; United States Steel |
| UTS | ultimate tensile strength; Unified Thread Standard |