altre abbreviazioni nelle note (O - R)


Utente Standard
Professione: ingegnere
Software: proe
Regione: veneto
OAL overall length
OC on center(s) That is, centre-to-centre; defines centre-to-centre distance of two features, such as two holes.
OD outer diameter
ODA original design activity The entity that originally designed a part. Compare to CDA, the entity that currently has design authority over the part design (definition).
OHL over high limit This abbreviation is used in a machine shop when recording nonconformances. For example, "part scrapped because ID is OHL." See also ULL.
OPP opposite See Part number > Symmetrical parts for explanation.
ORIG original
pc, pcs piece, pieces
PD pitch diameter
PDM, PDMS product data management, product data manager [app], product data management system [app] A database(s) and related application(s) that facilitate all aspects of managing data files—e.g., TDPs, TDP versions, drawings, model datasets, specs, addenda, certs, memoranda, EOs, ECOs, DCNs, RFQs, quotes, POs, e-mails, faxes, photos, word processor documents, spreadsheets. See also PLM.
PH or P/H precipitation hardening, precipitation-hardened; pilot hole
PHR BRZ phosphor bronze
PL or P/L parts list A list, usually tabular and often on the drawing (if not accompanying the drawing on a separate sheet), listing the parts needed in an assembly, including subparts, standard parts, and hardware. There is no consistently enforced distinction between an L/M, a BoM, or a P/L.
PLM product lifecycle management; plant lifecycle management See also PDM.
PN or P/N part number
POI point of intersection A point that makes easier the layout, toolpath programming, or inspection of the part. It is the intersection point of lines that may not meet on the finished part, such as the tangent lines of a curve or the theoretical sharp corner (TSC) that edge-breaking and deburring will remove. See also SC, TSC, and AC.
PSI pounds per square inch A unit of measurement for pressure. See also KSI.
PTFE polytetrafluoroethylene Also well known by the brand name Teflon.
QMS quality management system A system in place to ensure that quality of manufacture is produced and maintained; a system to prevent defective parts from being made, or, even if made, from getting into finished inventories.
QTY or qty quantity
R radius Radius of an arc or circle. Flats and reversals (falling within the dimensional tolerance zone) are tolerated unless "CR" (controlled radius) is explicitly specified.
RA, Ra roughness, average; Rockwell A scale See surface roughness; see Rockwell scale.
RB, Rb Rockwell B scale See Rockwell scale.
RC, Rc Rockwell C scale See Rockwell scale.
REF or ( )[2] reference The dimension or note is given only for reference and thus is not to be used as a part acceptance criterion (although it may be used as an aid to production or inspection). The dimension may also be surrounded by parentheses to signify a reference dimension. When a dimension is defined in one view but also mentioned again in another view, it will be given as reference in the second case. This rule prevents the mistake of defining it in two different ways accidentally; the "main" (non-reference) mention is the only one that counts as a feature definition and thus as a part acceptance criterion. See also basic dimensions, which are similar in some respects.
REQD or REQ'D required For example, "4 REQD" written next to a fastener means that four of those fasteners are required for the assembly.
REV revision Engineering drawings and material or process specifications are often revised; the usual revision control convention is to label the versions A, B, C, D, etc.; a revision block (rev block) is a tabular area on the drawing (typically in the upper right corner) that lists the revision letters, a brief description of the changes and reasons, and approval initials and dates. Revisions beyond "Z" start the alphabet over again with doubling, e.g., AA, AB, AC, AD, and so on. In the days of manual drafting, redrawing was expensive, so engineering orders (EOs, ECOs, DCNs, ECNs) were not always incorporated into a next-letter revision. They thus accompany the drawing as part of the TDP. With the dissemination of software usage (CAD, CAM, PDMSs), revision control is often better handled nowadays, in competent hands at least. In recent years the revision control of engineering drawings has even been standardized by ASME, in their standard Y14.35M.[5]
RFS regardless of feature size A material condition (or more precisely, freedom from such) in GD&T. Means that a given geometric tolerance is true in relation to a certain datum regardless of its actual size (LMC ≤ actual size ≤ MMC).
RH right-hand Referring to handedness, such as the helix handedness of screw threads or the mirror-image handedness of a symmetrical pair of parts.
RHR roughness height reading See surface roughness.
RMA return material authorization See also RTV.
RMS root mean square RMS in general is a statistical technique to define a representative value for a group of data points. With regard to surface roughness, it means that the heights of the individual microscopic peaks and valleys shall be averaged together via RMS to yield a measurement of roughness. See also herein f as a finish mark.
RT or R/T rough turn, rough turned; room temperature Rough-turned means turned on a lathe but not finished to a final machined dimension and surface roughness. Can apply to bar stock or to parts in-process. Room temperature is sometimes abbreviated "RT" within tables of specs for finishing operations (plating, painting, etc.).
RTP release to production The issuance of a drawing from the engineering/design activity to the production activity. In other words, the event when a draft becomes a completed, official document. A stamp on the drawing saying "ISSUED" documents that RTP has occurred.
RTV room-temperature vulcanizing; return to vendor 1. RTV sealants, a way to seal joints. 2. Return to vendor, send parts back to a vendor for rework or refund because they are nonconforming. Such RTV often requires an RMA.
RZ, Rz roughness, mean depth See surface roughness.