Manufacturing glossary.
Plain-English definitions of the manufacturing and engineering terms you\'ll meet when sourcing precision parts — from anodizing to work hardening.
Anodizing
An electrochemical finish that grows a hard, corrosion-resistant oxide layer on aluminium (and titanium). Type II accepts colour dyes; Type III (hardcoat) is thicker and more wear-resistant. See anodizing guide.
Bead blasting
A finishing process that propels fine glass beads at a surface to produce a uniform matte texture, removing tool marks before anodising or as a final finish.
Bend allowance
The arc length of material consumed in a sheet-metal bend, used to calculate the flat-pattern length. It depends on thickness, radius, angle and K-factor — compute it in our bend calculator.
Bend radius
The inside radius of a sheet-metal bend. Keep it at or above the material thickness to avoid cracking. See the bending guide.
CAM
Computer-Aided Manufacturing — software that converts a CAD model into the toolpaths and G-code a CNC machine follows to cut the part.
Casting
A process where molten metal is poured into a mould and solidified. Common types include sand, investment (lost-wax) and die casting.
Chamfer
An angled (bevelled) transition that breaks a sharp edge, easing assembly and removing burrs. Usually called out as a distance and angle, e.g. 0.5 × 45°.
CMM
Coordinate Measuring Machine — a precision device that probes a part to verify dimensions and GD&T against the drawing. See CMM inspection.
CNC machining
Computer Numerical Control machining — a subtractive process that removes material from a solid block or bar with software-guided rotating tools. See CNC materials.
Counterbore
A flat-bottomed enlargement at the top of a hole that lets a socket-head cap screw sit flush or below the surface.
Countersink
A conical enlargement at the top of a hole that lets a flat-head screw sit flush with the surface.
Datum
A theoretically exact reference point, axis or plane on a part, used as the origin from which GD&T controls are measured. See GD&T basics.
DFM
Design for Manufacturability — shaping a part so it is easy and economical to make without compromising function. We provide free DFM feedback with every quote; see DFM for CNC.
Die casting
A high-pressure casting process that injects molten metal (often aluminium or zinc) into a steel die for fast, repeatable, thin-walled parts.
Draft angle
A slight taper (typically 1–2°) on the vertical faces of a moulded or cast part that lets it release cleanly from the tool.
EDM
Electrical Discharge Machining — removes material with controlled electrical sparks, used for hardened steels, sharp internal corners and intricate cavities that tools cannot cut.
Fillet
A rounded internal corner that reduces stress concentration and, in machining, lets a standard round tool reach the corner. The opposite of a sharp corner.
First Article Inspection
FAI (report: FAIR, standard AS9102) — a full dimensional verification of the first part from a process, proving it meets every drawing requirement. See FAI vs PPAP.
Five-axis machining
CNC machining that moves the tool or part along five axes simultaneously, cutting complex contoured geometry in a single setup. See 5-axis machining.
Forging
Shaping metal under compressive force (hammering or pressing), which aligns the grain flow for high strength. See forging processes.
GD&T
Geometric Dimensioning and Tolerancing — a symbolic language (ASME Y14.5 / ISO GPS) that defines the form, orientation and location of features and how they relate. See GD&T basics.
Hardness
A material's resistance to indentation, measured on scales such as Rockwell (HRC) or Brinell (HB). Heat treatment and alloy choice set the achievable hardness.
Heat treatment
Controlled heating and cooling (annealing, hardening, tempering, etc.) that tunes a metal's hardness, strength and toughness. See heat treatment guide.
Injection molding
A high-volume process that injects molten plastic into a steel mould cavity. Economical at scale once tooling is amortised. See molding design.
ISO 2768
An international standard for general (unspecified) tolerances, with fine (f), medium (m), coarse (c) and very coarse (v) classes. See the tolerance chart.
K-factor
The ratio locating the neutral axis within sheet thickness during bending (typically 0.33–0.45). It drives the bend allowance and flat-pattern length.
Knurling
A turning operation that rolls a textured (often diamond) pattern onto a cylindrical surface for grip, on knobs and fasteners.
Lead time
The time from order to delivery. At MechPart, prototypes ship in about 5–10 business days and small batches in 2–3 weeks, with expedited options.
Machinability
How easily a material can be cut — affecting tool wear, speed, finish and cost. Free-machining alloys like 6061 aluminium and 303 stainless rate highest.
MMC
Maximum Material Condition — the state in which a feature contains the most material (largest pin or smallest hole). Applying it to position tolerance earns bonus tolerance as the feature departs from MMC.
MOQ
Minimum Order Quantity — the smallest order a supplier accepts. MechPart has no minimum: from a single prototype to full production.
NDT
Non-Destructive Testing — inspecting a part for internal or surface flaws (ultrasonic, dye-penetrant, X-ray) without damaging it, common on safety-critical forgings and castings.
Neutral axis
The layer within a bent sheet that is neither stretched nor compressed; its position (set by the K-factor) determines bend allowance.
Passivation
A chemical treatment that removes free iron and enhances the protective oxide layer on stainless steel, improving corrosion resistance — standard for medical and food parts.
Powder coating
A durable finish where electrostatically charged powder is applied and cured into a hard, even, corrosion-resistant film, common on steel and aluminium.
PPAP
Production Part Approval Process — an automotive documentation package demonstrating a process can make conforming parts repeatably at volume. See FAI vs PPAP.
Prototyping
Making early sample parts to validate form, fit and function before committing to production. CNC, 3D printing and bridge tooling each suit different prototype needs.
Ra
Arithmetic average roughness — the standard surface-finish parameter, in µm or µin. Standard CNC finish is ~Ra 1.6–3.2 µm. See the roughness chart and Ra vs Rz.
Reaming
A finishing operation that lightly enlarges a drilled hole to a precise diameter and fine finish.
Rz
Average maximum height of the surface profile — more sensitive than Ra to individual deep scratches; used on sealing and fatigue-critical faces.
Sheet metal gauge
A numbering system for sheet thickness; the same gauge maps to different thicknesses for steel, stainless and aluminium. See the gauge chart.
Sink mark
A surface depression over a thick section (e.g. behind a rib or boss) in a moulded part, caused by uneven cooling and shrinkage.
Springback
The slight elastic recovery of metal after a bend, opening the angle. Shops overbend to compensate; it grows with material strength and thickness.
Surface finish
The texture of a machined surface, specified by roughness parameters (Ra, Rz) and any coating or treatment applied. See finishes guide.
Swiss machining
Turning on a Swiss-type lathe, where the bar is supported close to the tool — ideal for long, slender, high-precision small parts in volume.
Tap / Tapping
Cutting internal threads in a hole with a tap. The hole is first drilled to a specific tap-drill size; see the tap & drill chart.
Threading
Producing helical threads, either external (on a shaft) or internal (in a hole), by tapping, single-point turning or thread milling. See threads guide.
Tolerance
The permissible variation on a dimension. Unspecified dimensions follow a general standard (ISO 2768); tight tolerances add cost, so reserve them for features that mate or seal.
Tolerance stack-up
The accumulation of individual tolerances across a chain of features or an assembly. See stack-up analysis.
Tool steel
High-carbon, alloy-rich steels (D2, A2, H13, M2) that harden to high wear resistance for dies, moulds and cutting tools. See tool steel.
Turning
A machining process where the workpiece rotates against a stationary cutting tool on a lathe, producing cylindrical features. See turning vs milling.
Undercut
A recessed feature that a standard tool cannot reach straight on — requiring specialty cutters in machining or side-actions in moulding.
Wall thickness
The thickness of a part's walls. Minimums vary by process; uniform walls prevent warp and sink. See the wall thickness guide.
Work hardening
The increase in a metal's hardness and strength caused by plastic deformation during machining or forming — pronounced in stainless steel and titanium.
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