Manufacturing glossary

100 terms engineers, buyers and reps use every day, defined in a sentence or two: tolerancing and GD&T, molding and stamping vocabulary, sourcing and quality paperwork like PPAP and FAI, and the language of the rep business such as principal, line card and territory.

100 terms

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2D drawingEngineering drawing, Print: A 2D drawing is a dimensioned engineering drawing, usually a PDF, that defines a part's tolerances, datums, material, finish, and inspection requirements. The 3D model shows shape; the drawing controls what gets measured and accepted. Most quality agreements make the drawing the governing document when the two disagree.

A

Amortized tooling: Amortized tooling is tooling whose cost is spread across the piece price of a set quantity of parts instead of being paid up front. It lowers initial cash outlay, but the buyer usually pays a financing markup, and the terms must state what is owed if volume falls short.
APQPAdvanced Product Quality Planning: APQP is Advanced Product Quality Planning, the AIAG framework automotive suppliers use to plan a new part from concept through launch. Its five phases cover planning, product design, process design, validation, and feedback, with outputs such as the PFMEA, control plan, and PPAP submission.
AS9100: AS9100 is the quality management system standard for aviation, space, and defense suppliers. It adds requirements to ISO 9001 for configuration management, product safety, counterfeit part prevention, and first article inspection per AS9102. Many aerospace primes require it from suppliers of flight hardware.

B

Blank: A blank is the flat piece of sheet metal cut from coil or sheet before it is formed, drawn, or pierced. Blank size and nesting drive material usage, which is often the largest cost in a stamped part. Blanks are produced by blanking dies, shearing, or laser cutting.
Blanket POBlanket purchase order, Blanket order: A blanket PO is a purchase order that commits to a total quantity or dollar amount over a set period, usually 12 months, with releases issued against it as parts are needed. It gives the supplier volume visibility for material buys and gives the buyer fixed pricing.
Bridge toolingPrototype tooling, Soft tooling: Bridge tooling is lower-cost, faster tooling, often aluminum or unhardened P20 steel molds and soft dies, used to make production-intent parts while hardened production tooling is built. It covers pilot builds, launches, and early sales at volumes from hundreds to tens of thousands of parts.
Burr: A burr is the raised, sharp edge of material left on a part after shearing, punching, or machining. Stamping drawings often allow burr height up to 10% of material thickness and state which side the burr may fall on. Removing burrs adds a secondary operation and cost.

C

Cavity: A cavity is the hollow in a mold that forms the part's shape, typically the outside or cosmetic side. A mold may have one cavity or many; a 4-cavity mold makes four parts per cycle. More cavities raise tooling cost and lower piece price.
Chatter: Chatter is a self-sustaining vibration between a cutting tool and the workpiece that leaves a wavy, patterned surface and shortens tool life. It comes from long tool stick-out, thin walls, weak workholding, or the wrong speed and feed. Chatter marks usually fail surface finish callouts.
Closed-die forgingImpression-die forging: Closed-die forging is a forging process that presses or hammers heated metal between two shaped dies until it fills the die impression. It produces near-net parts with continuous grain flow and high fatigue strength, such as connecting rods, yokes, and wrench bodies. Excess metal escapes as flash and is trimmed.
CNCComputer numerical control, CNC machining: CNC is computer numerical control, the use of programmed instructions to drive machine tool motion. CNC mills and lathes cut parts from solid stock to typical tolerances of ±0.005 in (±0.13 mm), and ±0.0005 in (±0.013 mm) on critical features. It suits prototypes and low-to-medium production.
Coining: Coining is a stamping operation that squeezes metal under very high pressure so it flows into fine die detail or reaches a precise thickness. It is used for sharp embossed features, flattening, and sizing critical dimensions. Coining needs far more tonnage than bending or blanking the same part.
Cold runner: A cold runner is an unheated channel system in an injection mold that carries molten plastic from the sprue to the gates. The runner solidifies with each shot and is ejected with the parts, then scrapped or reground. Cold runner molds cost less than hot runner molds but waste more material.
Cold shut: A cold shut is a casting defect where two streams of molten metal meet but fail to fuse, leaving a visible seam or weak line. It comes from low metal temperature, slow fill, or poor gating. In die casting, cold shuts often appear far from the gate on thin sections.
Commission: Commission is the percentage of invoiced sales a principal pays a manufacturers' representative for business the rep develops and services in a territory. Rates vary by industry, product, and deal size. Commission is usually paid monthly or quarterly after the customer pays the principal.
Compaction: Compaction is the powder metal step where metal powder is pressed in a rigid die, typically at 30–60 tons per square inch (415–830 MPa), to form a green part. Compaction pressure sets green density, which drives final strength. Part height and press tonnage limit what can be compacted.
Compression set: Compression set is the permanent deformation left in a rubber part after it is held compressed for a set time and temperature, expressed as a percentage of the original deflection. Lower is better for seals and gaskets. It is typically tested per ASTM D395 Method B.
Contract manufacturerCM: A contract manufacturer is a company that builds parts or finished products to another company's design, sold under that company's brand. Some make components; others do full box builds with assembly, testing, and packaging. The customer owns the design, and the contract manufacturer owns the process.
Core: A core is the half or insert of a mold that forms a part's inside features, such as the interior of a housing or a hole. In injection molding the core usually sits on the moving half, and the part shrinks onto it, so ejection happens from the core side.
Cost-down: A cost-down is a project to lower a part's price without lowering its function, through design changes, material substitution, process changes, more cavities, or moving production. Many OEMs ask suppliers for annual cost-downs. The best targets are high-volume parts designed before their current volume was known.
Cycle time: Cycle time is the time needed to complete one full production cycle, such as one mold shot, one press stroke, or one machined part. It sets machine hours per part, so it is a primary input to piece price. In injection molding, cooling usually takes most of the cycle.

D

Datum: A datum is a theoretically exact point, axis, or plane, established by a real feature on a part, from which other features are located and measured. Drawings list datums in order of precedence (primary, secondary, tertiary), which tells inspection how to fixture the part.
DDPDelivered Duty Paid: DDP is Delivered Duty Paid, the Incoterm under which the seller delivers goods to the buyer's named place, cleared for import, with freight, duties, and taxes paid. It puts the most responsibility on the seller and gives the buyer the closest thing to a true landed price.
DFADesign for assembly: DFA is design for assembly, the practice of designing parts so products go together faster, with fewer parts, fewer fasteners, and fewer ways to assemble them wrong. Typical moves include snap fits, self-locating features, and combining parts. DFA pairs with DFM, which targets each part's manufacturability.
DFMDesign for manufacturability, Design for manufacturing: DFM is design for manufacturability, the review of a part design against the limits of the process that will make it, before tooling is cut. It checks wall thickness, draft, radii, tolerances, and material choice. DFM changes are cheap before steel is cut and expensive after.
Draft angleDraft: Draft angle is the taper applied to part walls parallel to the direction of mold opening so the part releases without dragging. Injection molded parts typically need 1–2° of draft, plus about 1–1.5° more per 0.001 in (0.025 mm) of texture depth. Die castings typically need 0.5–2°.
Draw ratioLimiting draw ratio, LDR: Draw ratio is the ratio of blank diameter to punch diameter in a deep drawing operation. It sets how far one draw can reduce a blank before the metal tears. A first draw in steel is typically limited to about 1.8–2.2, so deeper parts need redraw stations.
Dual sourcing: Dual sourcing is qualifying two suppliers for the same part so production can continue if one has a capacity, quality, or supply problem. It usually costs more than single sourcing because of duplicate tooling and split volume, and buyers weigh that cost against supply risk.
DurometerShore hardness: Durometer is a measure of hardness for rubber and plastics, read on Shore scales with an indenter gauge. Shore A covers soft elastomers, with most seals and gaskets between 40A and 80A; Shore D covers harder materials. Durometer is typically specified with a tolerance of ±5 points.
DXFDrawing Exchange Format: DXF is the Drawing Exchange Format, an open 2D CAD file format created by Autodesk. It is the standard input for laser cutting, waterjet, and punching flat patterns. A DXF carries geometry but usually not tolerances, material, or thickness, so it should travel with a drawing.

E

EAUEstimated annual usage: EAU is estimated annual usage, the number of parts a buyer expects to order in a year. Suppliers use EAU to choose the process, tooling, cavity count, and material buys, so it moves the quote more than almost any other RFQ field. Overstated EAUs lead to overbuilt tooling and disputes.
Ejector pin: An ejector pin is a hardened steel pin in a mold that pushes the finished part off the core when the mold opens. Ejector pins leave small round witness marks, so designers place them on noncosmetic surfaces. Too few pins, or too little draft, can distort or crack parts.
Extrusion die: An extrusion die is a hardened steel plate with an opening shaped to the profile being extruded. Rubber, plastic, or aluminum is forced through it to form continuous lengths. Rubber profile dies typically cost a few hundred to a few thousand dollars and are quick to modify.

F

Family mold: A family mold is an injection mold that makes two or more different parts in the same shot, such as a housing top and bottom. It saves tooling cost at low to medium volumes, but the parts must share a material and color, and balancing fill across different cavities is harder.
First article inspectionFAI, First article: First article inspection is the full dimensional and documentation check of the first production parts against every drawing requirement before production is released. Results are recorded against a ballooned drawing. In aerospace it follows AS9102; in automotive, dimensional results are part of the PPAP.
FixtureWorkholding: A fixture is a custom workholding device that locates and clamps a part in a repeatable position for machining, welding, assembly, or inspection. Good fixtures locate from the drawing's datums. Fixture cost is usually a one-time charge on the quote, separate from piece price.
Flash: Flash is excess material that escapes past the parting line or between die halves and hardens as a thin fin on the part. In molding and die casting it signals worn tooling, low clamp force, or excess pressure. In forging, flash is designed in on purpose, then trimmed off.
Flatness: Flatness is a GD&T form control that requires every point of a surface to lie between two parallel planes a specified distance apart. It does not reference a datum. Flatness is common on sealing faces, mounting pads, and machined plates, and very tight callouts often need grinding or lapping.
FOBFree On Board: FOB is Free On Board, an Incoterm for sea and inland waterway freight under which the seller's responsibility ends when goods are loaded on the vessel at the named port. In US domestic trade, FOB origin or FOB destination instead sets where title and freight risk transfer.
FourslideMultislide, Four-slide: Fourslide is a forming process that uses four tool slides moving in from different directions to bend wire or flat strip into complex shapes in one machine cycle. It suits clips, wire forms, and small stampings with multiple bends, and its tooling usually costs less than a progressive die.
Free length: Free length is the overall length of a spring with no load applied. For compression springs it is measured end to end; for extension springs it is usually measured inside the hooks. Free length, spring rate, and solid height together define how the spring works in an assembly.

G

Gate: A gate is the opening where molten plastic or metal enters the mold cavity from the runner. Gate type, size, and location affect fill, knit lines, sink, and the mark left on the part. Common types include edge, submarine, pin point, and valve gates.
GD&TGeometric dimensioning and tolerancing: GD&T is geometric dimensioning and tolerancing, the symbol system defined in ASME Y14.5 and ISO 1101 for controlling the form, orientation, location, and runout of part features relative to datums. It states functional intent more precisely than plus-minus dimensions and often allows larger tolerances where they do not matter.
Green partGreen compact: A green part is a powder metal part after compaction and before sintering. It holds its shape but has low strength, about like chalk, so it must be handled carefully. Green density, typically 6.4–7.2 g/cm³ for iron-based parts, sets final strength after sintering.

H

Hot runner: A hot runner is a heated manifold and nozzle system inside an injection mold that keeps plastic molten all the way to the gates. It eliminates runner scrap and often shortens cycle time, but it adds several thousand to tens of thousands of dollars to the mold, plus controller maintenance.
House account: A house account is a customer a principal sells to directly and excludes from its rep agreement, so no commission is paid on those sales. House accounts should be listed by name in the agreement. Disputes often start when a house account's new division or plant buys in the rep's territory.
HTS codeHarmonized Tariff Schedule code, HTSUS number: An HTS code is the 10-digit classification number under the Harmonized Tariff Schedule of the United States that sets the duty rate for an imported product. The first 6 digits follow the international Harmonized System. Wrong classification can mean overpaid duty, penalties, or missed tariff exclusions.

I

IATF 16949: IATF 16949 is the quality management system standard for automotive production and service part suppliers, published by the International Automotive Task Force. It builds on ISO 9001 and requires core tools such as APQP, PPAP, FMEA, MSA, and SPC, plus each OEM's customer-specific requirements.
IGESInitial Graphics Exchange Specification, IGS: IGES is the Initial Graphics Exchange Specification, an older neutral CAD file format for exchanging 3D surfaces and curves between systems. It still opens in almost every CAD package, but it often loses solid-body data, so STEP is the better choice for quoting and tooling.
Incoterms: Incoterms are the International Chamber of Commerce rules that define who pays for freight, insurance, and duties, and where risk passes from seller to buyer in international trade. The current set, Incoterms 2020, has 11 rules, including EXW, FCA, FOB, CIF, DAP, and DDP.
InfiltrationCopper infiltration: Infiltration is a powder metal process where molten copper is drawn into the pores of a sintered steel part by capillary action. It raises density, strength, and impact toughness and can seal parts for pressure tightness. Copper-infiltrated steels carry the MPIF FX material designation.
ISO 2768: ISO 2768 is an international standard for general tolerances that apply to dimensions without an individual tolerance on the drawing. Part 1 covers linear and angular dimensions in classes f, m, c, and v. ISO 2768-m, the medium class, is the most common title block callout.
ISO 9001: ISO 9001 is the international standard for quality management systems, covering document control, corrective action, supplier control, and continual improvement. It is the baseline certification most OEMs expect from production suppliers and the foundation for industry standards such as IATF 16949 and AS9100.
ITARInternational Traffic in Arms Regulations: ITAR is the International Traffic in Arms Regulations, the US State Department rules that control the export of defense articles and technical data on the US Munitions List. ITAR-controlled drawings cannot be shared with foreign persons without authorization, and manufacturers of defense articles must register with DDTC.

K

Knit lineWeld line: A knit line is a visible line and potential weak spot where two flow fronts of molten plastic meet and fuse inside a mold, usually around holes or bosses. In glass-filled resins, knit line strength can drop to half of the base material or less. Gate location controls where knit lines fall.

L

Landed cost: Landed cost is the total cost of a part delivered to the buyer's dock, including piece price, tooling amortization, packaging, freight, insurance, duties, tariffs, brokerage, and inventory carrying cost. Comparing offshore and domestic quotes on piece price alone understates the cost of the offshore part.
Line card: A line card is the list of principals, or manufacturers, that a manufacturers' representative sells for, usually with each principal's processes and capabilities. Buyers use it to see which sources a rep can bring to an RFQ. Reps generally avoid carrying directly competing lines.

M

Manufacturers' representativeManufacturers' rep, Independent sales rep, Rep firm: A manufacturers' representative is an independent sales firm that sells for several noncompeting manufacturers, called principals, in a defined territory and is paid commission on sales. The rep finds programs, manages RFQs, and handles communication between buyer and plant. The principal pays the rep, not the buyer.
Maximum material conditionMMC: Maximum material condition is the state where a feature of size contains the most material allowed by its tolerance: the smallest hole or the largest pin. When a position tolerance is applied at MMC, the tolerance grows as the feature departs from MMC, which is called bonus tolerance.
MOQMinimum order quantity: MOQ is minimum order quantity, the smallest run a supplier will accept for a part. It is set by setup time, material minimums such as a full coil or bag of resin, and finishing lot charges. Below the MOQ, the piece price rises steeply or the supplier declines the order.

N

Nearshoring: Nearshoring is moving production to a nearby country, for US buyers usually Mexico or Canada, to cut transit time, inventory, and tariff exposure while keeping labor costs below domestic levels. Parts that meet USMCA rules of origin can enter the US duty-free.

O

OEMOriginal equipment manufacturer: An OEM is an original equipment manufacturer, the company that designs and sells the finished product under its own brand, such as a mower, truck, or appliance. OEMs buy parts from Tier 1 and Tier 2 suppliers and set the quality and documentation requirements that flow down the supply chain.
Open-die forgingHand forging, Smith forging: Open-die forging is a forging process that shapes heated metal between flat or simple dies that do not fully enclose the workpiece, using repeated blows and repositioning. It suits large, simple shapes such as shafts, rings, and blocks at low volumes, with machining to finish.

P

Parting line: A parting line is the line on a molded or cast part where the two mold halves meet. It usually leaves a slight witness line and is where flash forms as the tool wears. Designers place it on an edge or noncosmetic surface and set draft away from it.
Porosity: Porosity is voids inside a cast or sintered part, caused by trapped gas or by shrinkage as metal solidifies. In die castings it can cause leaks and weaken machined surfaces. It is controlled with gating, venting, and vacuum assist, and pressure-tight parts are sealed by vacuum impregnation.
PPAPProduction Part Approval Process: PPAP is the Production Part Approval Process, the AIAG method automotive suppliers use to prove a production process makes parts that meet every requirement at the quoted rate. A submission can include up to 18 elements, such as dimensional results, material certs, PFMEA, and control plan. Level 3 is the default.
Principal: A principal is a manufacturer that contracts a manufacturers' representative to sell its products or capabilities in a territory. The principal quotes, builds, ships, and invoices the parts, and it pays the rep commission on sales. A rep firm's principals make up its line card.
Progressive die: A progressive die is a stamping die with a series of stations that pierce, form, and cut a part in sequence as a metal strip feeds through the press. One finished part drops with each stroke. It is the lowest piece-price option for high-volume small and medium stampings.

R

Reshoring: Reshoring is moving production that had been offshore back to the buyer's home country. Buyers reshore to shorten lead times, cut inventory, reduce tariff and freight exposure, and protect intellectual property. It pays off when quotes are compared on landed cost, not piece price.
RFIRequest for information: An RFI is a request for information, a document buyers send potential suppliers to learn their capabilities, capacity, certifications, and equipment before asking for prices. It narrows the supplier list so the RFQ goes only to shops that fit the program.
RFQRequest for quote, Request for quotation: An RFQ is a request for quotation, the package a buyer sends suppliers to get prices for a specific part. A complete RFQ includes a 3D model, 2D drawing, material, finish, annual volume, release quantities, and required certifications. Missing details lead to padded or non-comparable quotes.

S

Safety stock: Safety stock is extra inventory held above expected demand to cover supplier delays, quality holds, and demand spikes. It is often set in weeks of usage. Longer or less predictable supply chains, including most offshore sources, need more safety stock, which adds carrying cost.
Screw machineAutomatic screw machine, Multi-spindle screw machine: A screw machine is an automatic lathe that turns small, round parts from bar stock at high speed, with several tools cutting at once. Cam-driven multi-spindle machines make high-volume parts such as fittings and pins in seconds each, while CNC screw machines shorten setups for smaller lots.
SetupChangeover, Make-ready: Setup is the work needed to prepare a machine to run a specific part: loading tooling, fixtures, and programs, then running and inspecting first pieces. Setup cost is fixed per run, so it is spread over the lot size and is a main driver of MOQ.
Short shot: A short shot is an injection molded part that is incomplete because plastic froze before filling the whole cavity. Causes include low shot size or pressure, blocked vents, thin walls, and long flow lengths. Molders often run short shots on purpose during mold trials to study fill.
Shot size: Shot size is the volume or weight of material injected into a mold in one cycle, including parts and runners. Molders typically want a shot to use about 20–80% of a press's barrel capacity to avoid degraded resin or inconsistent fill. In die casting, shot size drives machine and shot sleeve selection.
Should-costShould-cost model, Cost model: Should-cost is an estimate of what a part should cost to make, built bottom-up from material, machine time, labor, overhead, tooling, and margin. Buyers use should-cost models to judge quotes and find cost-down targets, and suppliers use them to explain where a price comes from.
Sink mark: A sink mark is a shallow depression on the surface of a molded part over a thick section, rib, or boss, caused by the thick area shrinking as it cools. Keeping ribs at 50–60% of the adjacent wall thickness is the usual design fix, along with coring out thick sections.
Sintering: Sintering is heating compacted metal powder below its melting point, typically around 2,050 °F (1,120 °C) for iron-based parts, in a controlled atmosphere so the particles bond metallurgically. It turns a fragile green part into a strong, finished component. Parts may then be sized, machined, or heat treated.
Solid height: Solid height is the length of a compression spring when it is compressed until all coils touch. A design should never drive a spring to solid in service, and most designs keep maximum working deflection to about 80–85% of the travel available before solid height.
SPI finishSPI mold finish: SPI finish is a mold surface finish grade defined by the Society of the Plastics Industry, now the Plastics Industry Association. Grades run from A-1, a diamond-buffed mirror, through B paper and C stone finishes to D bead-blasted textures. Glossy grades cost more to polish and maintain.
Split commission: A split commission is a commission divided between two or more reps when the design influence and the order happen in different territories, such as engineering at one site and purchasing at another plant. Rep agreements usually state the split by percentage for the design, purchasing, and delivery locations.
Spring rateSpring constant: Spring rate is the load needed to deflect a spring one unit of distance, expressed in lb/in or N/mm. It depends on wire diameter, coil diameter, active coils, and material. On commercial-grade compression springs, load at a set height is typically held to about ±10%.
Springback: Springback is the partial elastic return of formed metal toward its original shape after the forming load is removed. It means bends must be overformed to hit the final angle. Higher-strength steels, stainless, and aluminum spring back more than mild steel does.
STEPSTP, ISO 10303: STEP is a neutral 3D CAD file format defined by ISO 10303, saved as .step or .stp. It carries exact solid geometry that any CAD, CAM, or quoting system can read, which makes it the preferred file for RFQs, tooling design, and machining.
STL: STL is a 3D file format that describes a part surface as a mesh of triangles. It is the standard input for 3D printing, but it approximates curves and carries no exact geometry, so it cannot support accurate machining or tooling quotes. Send STEP for those.
Surface roughness (Ra)Ra, Roughness average: Surface roughness (Ra) is the arithmetic average of a surface profile's deviations from its mean line, reported in microinches or micrometers. Typical machined surfaces run 63–125 µin (1.6–3.2 µm) Ra, ground surfaces 16–32 µin (0.4–0.8 µm), and seal surfaces often 16 µin (0.4 µm) or finer.
Swiss turningSwiss machining, Swiss-type lathe: Swiss turning is a lathe process where bar stock feeds through a guide bushing so the cut always happens right next to support. That lets it turn long, slender parts to tolerances of ±0.0002–0.0005 in (±0.005–0.013 mm). It suits small precision parts up to about 1.25 in (32 mm) diameter.

T

T1 sampleT1, First shots: A T1 sample is a part from the first trial run of a new mold or die, used to check fill, dimensions, and fit before the tool is finalized. T1 parts often need tool adjustments; later trials are T2, T3, and so on until parts are approved for PPAP or first article.
TariffDuty: A tariff is a tax on imported goods, collected in the US by Customs and Border Protection and set by the product's HTS code and country of origin. Beyond base duty rates, added tariffs such as Section 232 and Section 301 duties can change with little notice.
Territory: A territory is the geographic area, customer list, or market a manufacturers' representative is contracted to cover for a principal. Commission is typically paid on orders shipped to or placed from the territory. Clear territory lines prevent split-commission disputes.
Tier 1Tier 1 supplier, Tier one: Tier 1 is the supplier level that sells components or systems directly to an OEM, such as a seat, brake, or wiring harness maker selling to an automaker. Tier 1 suppliers manage their own sub-tier suppliers and carry OEM quality requirements down to them.
Tier 2Tier 2 supplier, Tier two: Tier 2 is the supplier level that sells parts to a Tier 1 rather than directly to the OEM, such as a stamper or molder supplying brackets to a seat maker. Tier 2 suppliers usually work to the Tier 1's flowed-down requirements, including PPAP and often IATF 16949.
Tolerance: Tolerance is the total amount a dimension is allowed to vary from its nominal value, such as ±0.005 in (±0.13 mm). Tighter tolerances raise cost through slower processes, extra operations, and added inspection. Hold them only on features that affect fit or function.
Tonnage: Tonnage is the force a press can apply, rated in tons, and the force a job requires. Stamping tonnage is estimated from cut length, material thickness, and shear strength. In molding and die casting, clamp tonnage must exceed cavity pressure times projected area to keep the tool closed.
Tooling ownership: Tooling ownership is the legal title to molds, dies, and fixtures, and the right to control them. Customer-owned tooling is paid for by the buyer and can be moved to another supplier; supplier-owned tooling stays put. Ownership, maintenance, and transfer terms belong in writing before the tool is built.
Transfer die: A transfer die is a stamping setup where separate stations each perform one operation and mechanical fingers move the part between them after it is cut from the strip. It handles larger or deeper parts, such as deep drawn shells, that cannot stay attached to a carrier strip.
Trim die: A trim die is a press tool that shears flash, gates, runners, and overflows off a die casting or forging after it leaves the machine. Trim dies are a separate tooling line item, and complex parts can need more than one. Trimming leaves a slight witness line at the edge.
True positionPosition tolerance: True position is a GD&T location control that defines a tolerance zone, usually cylindrical, around the theoretically exact location of a feature such as a hole, relative to datums. A diameter-zone position callout gives about 57% more tolerance area than the equivalent plus-minus square zone.