Manufacturing Glossary

A glossary is only useful when each term is grounded in the standard or process it comes from. This page defines the manufacturing terms used across the site, grouped by domain: machining and tolerances, sheet metal and forming, additive manufacturing, materials and properties, finishing, and file format and quality. Each entry ties a word to the number, standard, or process behavior behind it, so a reader can move from the term to the decision it drives.

The terms overlap across processes. Tolerance applies to a CNC pocket and a laser cut; surface finish applies to a milled face and a printed wall; kerf and the heat-affected zone shape both cutting and welding. Read the entries as a shared vocabulary, not a set of isolated definitions, and use the cross-references to follow a term into the process where it matters most.

Machining and tolerances

Processes and general tolerances

• CNC machining. Computer-controlled subtractive machining, milling and turning, that removes material from a solid blank to hit a programmed dimension. It is the default choice when a part needs a tight tolerance on a mating face or a fine surface that additive or cut sheet cannot reach.
• Tolerance. The allowed variation in a dimension, the band inside which a part is accepted. For machined metals, general tolerances follow ISO 2768-1, with class f, or fine, at plus or minus 0.05 millimeters for a 0.5 to 3 millimeter dimension and class m, or medium, at plus or minus 0.10 millimeters. A tighter tolerance costs more time and finer tooling, so it is specified only where the function demands it.
• ISO 2768. The general-tolerance standard for machined parts, split into ISO 2768-1 for linear and angular dimensions and ISO 2768-2 for geometric tolerances. It lets a drawing carry a default tolerance class, such as class f and grade K, instead of writing a tolerance on every dimension.

GD&T and datums

• GD&T. Geometric Dimensioning and Tolerancing, a symbolic system, governed by ASME Y14.5 and ISO 1101, that controls form, orientation, location, and runout rather than size alone. A flatness or position callout in GD&T says what a face or hole must do, not merely how wide it is, which captures functional intent that plus or minus tolerancing misses.
• Datum. A reference feature, a plane, axis, or point, that everything else on a part is measured from. Datums are the anchors of GD&T, because a position or perpendicularity callout is meaningless until the datum it is measured against is fixed on the drawing and on the inspection setup.

Surface and feature terms

• Ra, surface finish. Roughness average, the standard measure of surface smoothness per ISO 21920-2, where a lower Ra is smoother. As-machined metal sits around Ra 3.2 micrometers, or 125 microinches, a fine-machined surface around Ra 1.6, and a ground surface around Ra 0.4 micrometers, or 16 microinches. Ra is set against what the face must do, since a smoother finish takes a finer tool and a slower pass.
• Chamfer and fillet. A chamfer is a beveled edge that transitions between two faces at an angle, usually 45 degrees, while a fillet is a rounded inside radius that blends them. Chamfers break a sharp edge for handling and assembly, and fillets remove the inside corner that would otherwise concentrate stress and crack under load.
• Pitch. The distance from one point on a thread or tooth to the same point on the next, the spacing that defines a screw thread or a gear. Pitch is paired with the tap or die that cuts it, so a hole tapped for an M8 by 1.25 thread takes a bolt with a 1.25 millimeter pitch.
• Tap and drill. To tap is to cut internal threads in a drilled hole with a tap, and the drill size is the hole drilled first, sized just under the thread’s minor diameter. A tap drill chart gives the right drill for each thread, because an oversize hole leaves shallow threads that strip and an undersize hole breaks the tap.
• Gauge. A standard thickness for sheet metal, where a lower gauge number means a thicker sheet, so 16 gauge steel is thicker than 18 gauge. Gauge predates metric thickness in much of North American sheet metal work, and because gauge differs between steel, aluminum, and stainless, the metric thickness, in millimeters, is the unambiguous value to put on a drawing.

Sheet metal and forming

Cutting terms

• Kerf. The width of material a cutting process removes, the slot the beam or abrasive stream leaves behind. Fiber laser kerf runs about 0.15 to 0.30 millimeters and waterjet kerf about 0.75 to 1.15 millimeters, so nesting software offsets each cut path by half the kerf to land the part on size.
• Heat-affected zone, HAZ. The band of metal next to a thermal cut, laser or plasma, whose metallurgy has changed from heat input, often softer or harder and less corrosion-resistant than the parent metal. Fiber laser leaves a HAZ of about 0.10 to 0.25 millimeters on steel, while waterjet, a cold cut, leaves none.

Bend calculation terms

• Bend allowance. The length of the neutral axis through a bend, the arc length the metal travels as it folds, used to calculate the flat blank size that folds to the wanted flange. It is derived from the K-factor, the material thickness, and the bend angle.
• Bend deduction. The amount subtracted from the sum of the two flange lengths to get the flat blank length, the correction for the material that compresses inside the bend. It is calculated as the K-factor times thickness times the quantity 180 degrees minus the bend angle, times 0.01745.
• K-factor. The ratio that locates the neutral axis within a bend as a fraction of the material thickness, the value that links bend allowance and bend deduction. It is typically 0.40 to 0.45 for most materials (PC-070).

Bend behavior and cut quality

• Springback. The elastic recovery of sheet metal after a bend, the amount the flange springs back toward flat when the press releases, so the tool must overbend to hit the final angle. Soft aluminum springs back about 1 to 3 degrees, carbon steel 3 to 10 degrees, and stainless steel 5 to 12 degrees.
• Minimum bend radius. The smallest inside radius a material will fold through without cracking, typically at least half the material thickness for ductile metals. A sharper radius concentrates strain at the outside of the bend and risks a tear, so the radius is set by both the material and the die.
• ISO 9013-1. The standard that classifies thermal cut quality, from Level 1 for aerospace and medical precision up to Level 5 for flame-cut thick plate. It grades the cut edge on perpendicularity, dross, and surface roughness, so a Level 2 or 3 cut is the typical fiber-laser target for industrial work.

Additive manufacturing

Process and layer terms

• Layer height. The thickness of each slice in a fused-deposition print, the value that trades surface quality against build time. A 0.1 millimeter layer prints smooth but slow, a 0.3 millimeter layer builds fast but shows ridges, and most engineering parts land around 0.15 to 0.2 millimeters.
• Support. The sacrificial structure a printer builds under an overhang or bridge, removed after the build to leave the part behind. Supports cost material, cost time, and leave marks, so a part is oriented or chamfered to need as few as possible, often none below a 45-degree overhang.
• Anisotropy. Direction-dependent properties, the trait that makes a printed part weaker across its layers than within them. A fused-deposition part is about 20 to 30 percent weaker along the Z, or build, direction than in the XY plane, so load-bearing parts are oriented with the load along the layers.

Materials and standards

• Sintering. The process of bonding powder into a solid by heating it below the melting point, used in metal powder-bed fusion and in selective laser sintering of nylon. Sintering leaves a slightly rough, porous surface that usually needs post-machining on a mating face.
• Photopolymer. A resin that cures from liquid to solid under light, the feedstock for SLA and similar vat-printing processes. Photopolymers give a smooth, detailed surface but tend to be brittle and to weaken in sunlight and heat, so the resin is chosen against the part’s working environment.
• ISO/ASTM 52900. The standard vocabulary for additive manufacturing, the source of the process names, fused deposition modeling, selective laser sintering, and powder-bed fusion, used consistently across the site. It fixes the terminology so a term means the same process on every page.

Materials and properties

• Tensile strength. The maximum stress a material takes before it breaks, the peak of the stress-strain curve. Aluminum 6061-T6 reaches about 310 megapascals, stainless 304 about 500 to 600, and titanium grade 5 about 895 to 1105, so tensile strength sets the ceiling a part can approach before failure.
• Yield strength. The stress at which a material stops deforming elastically and takes a permanent set, the practical design limit for a loaded part. Aluminum 6061-T6 yields at about 276 megapascals, well below its 310 megapascal tensile strength, because a bracket that yields has already failed in service even if it has not broken.
• HDT, heat deflection temperature. The temperature at which a polymer bends under a defined load, the practical upper temperature for a plastic part. PLA deflects around 55 degrees Celsius, PETG around 70, and ABS around 95, so HDT sets which filament a warm-environment part can use.
• Shore hardness. A durometer scale for soft polymers and elastomers, where Shore A runs from flexible rubber at the low end to hard rubber at the high. TPU filament, the common flexible print material, spans Shore A 60 to 95, and the grade is chosen against how stiff or rubbery the part must feel.
• Anisotropy in metals and polymers. Direction-dependent behavior that appears in rolled sheet, drawn tube, fiber-filled filament, and printed layers. A fiber-filled nylon is stiffer along the fiber direction, and a cold-rolled steel sheet bends differently with and across the grain, so the material’s direction is part of the design.
• Hygroscopy. A material’s tendency to absorb moisture from the air, which shifts its dimensions and, in printing filament, weakens the part and causes stringing. Nylon PA6 absorbs about 9 percent water by weight and PA12 about 1 percent, so nylon is dried before printing and stored dry after.
• Passivation. A chemical treatment, usually acid, that removes free iron from a stainless steel surface and lets the chromium oxide layer form fully, raising corrosion resistance without changing the dimensions meaningfully. It is standard for stainless parts in food, medical, and marine service.
• Anodizing. An electrolytic conversion that grows a hard aluminum oxide layer on an aluminum surface, Type II for color and corrosion resistance and Type III, hardcoat, for wear. Anodizing removes about 10 to 15 micrometers from the surface while building the oxide, so a tight fit is adjusted for the net change.
• Powder coat. A dry-polymer finish electrostatically sprayed onto a metal part and baked to a tough, continuous film about 60 to 120 micrometers thick. It gives color and corrosion protection in one coat, but because it adds thickness, a powder-coated dimension must allow for the film or the parts will not assemble.
• Electropolishing. A reverse-plating process that removes a thin, uniform layer from a stainless steel surface to leave a mirror finish around Ra 0.1 to 0.2 micrometers. It smooths, cleans, and passivates in one step, which is why it is common on medical and food-contact parts.
• DFM, design for manufacturing. The practice of shaping a part, choosing its features, and writing its drawing so that it can be made reliably and economically by the chosen process. DFM is the umbrella over every entry on this page, because a tolerance, a radius, or a file format chosen without the process in mind becomes scrap.

File format and quality

• STEP. The STandard for the Exchange of Product data, the file format, .step or .stp, that carries boundary-representation geometry with tolerances and assembly structure. STEP is the primary 3D format for CNC machining and sheet metal, because it preserves the surfaces and datums a CAM system needs.
• STL. The stereolithography mesh format, a tessellated surface with no tolerance, unit, or assembly data, accepted for 3D printing but not for CNC. STL is universal and simple, but because it carries no units, a file without explicit units is the most common and most expensive file-format error in custom manufacturing.
• DXF. The Drawing eXchange Format, the standard 2D vector format for laser, waterjet, and plasma cutting, carrying the cut profile as lines, arcs, and polylines. A DXF cut path must use continuous lines, because hidden or dashed lines are ignored by the cutting software.
• DWG. The AutoCAD native 2D and 3D format, accepted by many suppliers but less universally interoperable than DXF. For cutting, DWG is converted to DXF at the supplier, so sending DXF directly removes a conversion step.
• Units and the 25.4 scale error. The units, millimeters or inches, that a file is drawn in, which must be stated in the file or the filename because STL and some DXF files carry no unit metadata. A millimeter file read as inches, or the reverse, produces a part at 25.4 times the intended scale, so confirming the units in the order is the single most effective file-format check.

How to use this glossary

Treat these definitions as the shared vocabulary behind every process and material page on the site. When a page mentions a tolerance class, a surface finish, or a file format, the entry here gives the standard and the number it rests on, and the related pages below carry the term into the process where it applies. Read across the groups rather than down one, because the same term, tolerance, finish, kerf, anisotropy, appears in machining, cutting, bending, and printing, and the decision it drives is the same wherever it shows up.