Cold-Rolled Titanium Plate: The Tolerance Band, Springback and Forming Fit-Up Dimension Chain

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Reviewed and maintained by the Engineering Team, Shaanxi Qianyi Tuoda Technology Co., Ltd.

Cold-Rolled Titanium Plate: The Tolerance Band, Springback and Forming Fit-Up Dimension Chain

A cold-rolled Titanium Plate is thin, but thin does not mean dimensionally accurate: published charts place the cold-rolled and hot-rolled dividing thickness near 4.75 mm in some tables and 4.76 mm in others. The developed blank for a bend must be computed on the neutral axis and on the measured mean thickness, not the nominal gauge. Our ASTM B265 plate specification guide, our Grade 5 hot and cold rolled plate page and our Grade 1 AMS 4911 plate page settle identity, standard and condition; this article works the fit-up dimension chain when that plate is bent, stamped or welded.

Published charts disagree on the dividing thickness, the thickness band, the K factor and springback, so we publish the conflict, eight rejection triggers and one 14-line verification sheet instead of one invented number. Our B265 plate and sheet page gives the specification context and our plate ordering guide the buying context; the drawing revision and named standard edition govern.

At a Glance: Eight Decisions That Separate a Clean Cold-Rolled Fit-Up from a Rejected Bend

Item	What the decision turns on
The short answer	Thin does not guarantee dimensional accuracy; a nominal gauge is not a fit
The dividing line conflict	Published charts place the cold-rolled and hot-rolled boundary near 4.75 mm or 4.76 mm, and some mills quote thinner plate on request; no single value is given
The governing identity	Developed blank length is computed on the neutral axis at mean diameter; bend allowance uses R plus K times t
Where plus tolerance goes	Measured thickness above nominal shifts the mean diameter, then the flange and hole positions after forming
The width question	Crown, edge drop and a thickness wedge across the width change the bend from one edge to the other
The surface question	Finish, rolling direction and residual stress decide whether the outer fibre cracks or the weld stays clean
The conflict	Charts disagree on thickness band, K factor, springback and flatness; we publish the conflict, not one value
The one document	A 14-line Cold-Rolled Plate Fit-Up and Dimension Chain Verification Sheet: check, basis, method, criterion, who signs

Our Grade 2 B265 supplier page gives the grade context and our EN 10204 3.1 mill certificate page shows a traceable thickness record. A stockholder can certify a heat number, not a bend allowance it did not calculate for your drawing.

The Trap: Thin Does Not Mean Dimensional Accuracy Is Guaranteed

Cold rolling delivers a smoother surface, better flatness and a tighter thickness spread than hot-rolled plate, but that reputation is about material as delivered, not the geometry of the formed part. Our Grade 5 hot and cold rolled plate page describes the two routes and our plate thickness and form classification page separates the forms; treat the gauge as an input, not a fit-up result.

The specification pages already cover thickness ranges, widths, surface condition, chemistry and buying questions; this page starts once the purchase order has fixed a nominal thickness and asks whether the cumulative deviation still lets the part close on its partner. Our Titanium Plate range lists the product, but the drawing revision decides how the thickness is used.

A thin plate that passes its thickness tolerance can still fail fit-up; the band travels into the bend allowance, springback and mating hole.

What matters in a dimension chain is the measured mean thickness, the thickness across the width, the K factor, the bend deduction and the springback angle. Our zero-cutting and small-batch plate page covers non-standard blanks and our process equipment buyers guide gives the assembly context. Confirm the fit-up criterion against the drawing revision and named standard edition.

Where the Tolerance Goes: The Dividing Thickness That Published Sources Cannot Agree On

Ask several sources where cold-rolled sheet ends and hot-rolled plate begins and you get a spread: sheet from about 0.8 mm to just under 4.75 mm and plate from 4.76 mm in one chart, a 4.75 mm plate threshold in another, cold-rolled 0.8 to 4.75 mm and hot-rolled from 4.8 mm in a third, and thinner plate to 3.0 mm on request. Our thickness classification page and our B265 plate and sheet page give the product-form context; the controlling boundary is the edition named in the purchase order.

Condition codes matter too: a mill-annealed, hot-rolled and cold-worked condition are not interchangeable once the plate is formed, because cold work raises strength and lowers ductility. The relevant designations are ASTM B265, ASME SB-265, GB/T 3621 and AMS 4911, and our GB versus ASTM B265 comparison and our sheet strip and plate page give the buying context. Name the edition, grade and condition before any band is used as a fit-up input.

The thickness tolerance band is a second disagreement: charts quote symmetric and asymmetric bands and split strip, sheet and plate into different tables. Treat the measured mean thickness as the dimension-chain input. Our Grade 2 B265 plate page gives the product context and our coil and strip guide the thinner cold-rolled range; neither is a fit-up conclusion.

The Dimension Nobody Measures: Thickness Distribution Across the Plate Width

Incoming thickness is usually logged at one or two stations near the centre, but a bend uses the thickness at every station along the bend line. Cold rolling can leave a crown, an edge drop or a wedge from one side to the other, so a plate that passes a single-point check can carry a gradient that changes the bend allowance between flanges. Our plate sheet and coil page gives the form context and our coil and strip guide shows how width is produced; the drawing decides which edge becomes the bend line.

The remedy is a mapped ultrasonic survey with a written point layout, recording thickness at both edges, quarter width and centre, at head, middle and tail, and logging mean and spread. That map is a fit-up input, not a material-identity record; our mill certificate page shows what the mill record proves. Where the spread is large, develop the blank on the measured mean and hold outlying stations for the first-article bend.

A single thickness reading certifies a heat, not a bend line; map the width before calculating the developed length.

A tight nominal band is worth little if a thickness wedge across a 1000 mm width moves the neutral axis along the bend. Our bright surface coil page describes the finish route and our same-day cut-to-size plate page describes how the blank is cut; the measured width map, not the cut ticket, decides the forming allowance.

Before the Bend: Surface Condition, Residual Stress and Levelling

Surface condition and the bend, the weld and the die

Cold-rolled sheet arrives with a controlled finish that is a forming input: a bright face behaves differently in a press brake die than a pickled matte face, and a bend line parallel to the rolling direction is more prone to outer-fibre cracking than one across it. Surface cleanliness decides whether a weld root stays sound. Our pickling and iron contamination page covers cleanliness and our GTAW shielding guide covers the root. Name the finish and rolling direction on the cutting plan.

Cold rolling residual stress and levelling

Cold reduction leaves residual stress: a coil that has been tension levelled or annealed behaves differently from as-rolled material, and a blank cut from a stressed sheet can warp or spring open before it reaches the brake. Our Grade 1 AMS 4911 plate page gives the condition context and our WPS and NDT qualification guide shows a procedure is a signed record. Measure flatness after cutting.

What to record before the first bend

Before the first production bend, record the finish, rolling direction, levelling or annealing condition, mapped thickness, chosen K factor and measured springback from a first article. Our cut-to-size plate stock page describes how the blank is prepared and our bright surface coil page gives the finish route; the development sheet decides which is critical.

The Blank Dimension Chain: Mean Diameter, Bend Deduction and Springback

A blank is laid out from one identity: developed length is the arc at the neutral axis. For a rolled course L equals pi times the mean diameter Dm, with Dm equal to inside diameter plus measured thickness or outside diameter minus that thickness. For a press-brake bend the bend allowance equals the angle in radians times R plus K times t. Our Grade 2 B265 plate page gives the product context and our cut-to-size plate stock page describes the blank; the development sheet owns the calculation.

Bend deduction converts that allowance into a flat pattern: outside setback on both flanges minus the bend allowance. Published practice disagrees on the K factor and springback, so we will not print one as correct; close both against a measured first-article bend. Our WPS qualification guide and our what a dimensional standard hides make the parallel point that a standard leaves mating geometry to the drawing.

The developed length, bend deduction and springback accumulate into flange position, hole alignment and the gap at the mating part, and that cumulative offset is what the fit-up check must catch. Our zero-cutting plate page covers the non-standard sizes that make re-development common and our process equipment buyers guide gives the assembly context.

When Two Passing Numbers Still Fail at the Bend: Publish the Conflict, Not One Value

A thickness reading can pass and a formed part can still miss its mating hole, because the figures that decide the fit are the ones no chart agrees on. The table below collects secondary supplier charts, mill notes and our own pages, not the controlling edition. Our B265 specification page and our GB versus ASTM B265 comparison show why the edition must be named.

Quantity	Figures in conflict	Why they disagree	What to confirm
Dividing thickness	Near 4.75 mm for sheet and 4.76 mm for plate in one chart; a 4.75 mm plate threshold in another; cold-rolled 0.8 to 4.75 mm and hot-rolled from 4.8 mm in a third; thinner plate to 3.0 mm on request	Different band edges, imperial versus metric rounding, mill practice	Named edition, product form, condition and whether the order is sheet or plate
Thickness band near 2.0 mm	One chart quotes a symmetric band over a given range; another an asymmetric band with a larger plus side; strip and sheet tables use different values	Symmetric versus asymmetric, different editions and conditions	Named edition table and the measured mean thickness from a mapped survey
K factor and neutral axis	Rolling practice assumes near mid-thickness; press-brake work uses 0.35 to 0.45; some procedures add an elongation term	Forming method, machine type and temperature	First-article bend allowance against the qualified forming procedure
Springback and flatness	Published flatness figures use different reference lengths; springback depends on yield strength and radius-to-thickness ratio	Different bases, delivery conditions and grades	Governing drawing clause, levelling record and measured springback
Width and edge condition	Mill width, slit width and cut-to-size width carry different tolerances and camber bases	Rolling versus cutting operation	Whether the width is mill, slit or cut, and the named edition table

Six verification actions settle the disagreement:

1. Require every acceptance value to carry its document, revision and clause. Name the ASTM B265 or ASME SB-265 edition, the drawing revision, the grade and the condition code before quoting any band. Our B265 specification guide is a product reference, not the governing clause.
2. State the sample condition and measuring method: cold-rolled or hot-rolled, annealed or cold-worked, and the measured mean thickness from a mapped ultrasonic survey rather than the nominal gauge. Our plate ordering guide gives the buying baseline.
3. Publish the development calculation before cutting: the control diameter, L equals pi times Dm, the K factor, the bend allowance, the bend deduction and the cut length. Our plate weight calculator is a mass tool, not a layout tool.
4. Name who reviews the conflict: buyer quality, fabricator engineer, forming supervisor and, where the contract calls for it, a third-party surveyor, with authority to accept or hold. Our WPS qualification guide shows qualification is a signed decision.
5. Keep records independent with their own dates: purchase order and MTC, thickness map, development sheet, levelling and finish record, first-article bend survey and the signed verification sheet. Our EN 10204 3.1 certificate page covers what the mill record proves.
6. Use trigger-based re-verification: any re-cut, heat or thickness-band change, condition change, levelling change or opened hold forces reassessment. Our equipment leak repair guide and our equipment layup guide show the downstream cost.

Most of these cost little at planning and a great deal after a blank is bent and fitted to a partner. Our hydrostatic test guide is a later gate, not a substitute for the fit-up record; we are a stockholder, not the author of your drawing, and where figures disagree we give the disagreement and the action.

Two Independent Check Lines: What the Old Pages Certify, What This Page Calculates

What a cold-rolled plate is and which standard to buy it under is answered by our ASTM B265 plate specification guide, our Grade 5 hot and cold rolled plate page and our Grade 1 AMS 4911 plate page. That is the material-identity line; this page is the fit-up line, checked at different gates with different records.

The settlement line decides what the buyer pays, and our receiving-weight guide and our ordering-by-end-use page cover that gate. The fit-up line decides whether the blank, bend and springback close on the mating part. A plate can be on weight and still fail fit-up, because mass cannot see a crown, a K factor or a springback angle. Our process equipment buyers guide gives the assembly context.

Limitations and Failure Conditions: Eight Cold-Rolled Plate Fit-Up Rejection Triggers

(Geometry) Trigger 1 - Blank length computed from outside diameter or nominal thickness instead of measured mean thickness

The flat length must be computed on the neutral axis using the measured mean thickness from a mapped ultrasonic survey, not the nominal gauge or outside diameter; an unmeasured thickness is a hold. Our Grade 2 B265 plate page gives the product context.

(Geometry) Trigger 2 - Thickness logged at one station with no crown, edge drop or wedge survey across the width

Measure thickness at both edges, quarter width, centre, head, middle and tail; a single reading cannot describe a bend line across the width. Judge the spread against the drawing criterion. Our plate sheet and coil page gives the form context.

(Fit-up) Trigger 3 - Springback and bend deduction not closed against a measured first-article bend

Measure the flange angle and hole position on a first article after the brake load is released, then compare with the flat pattern; an assumed K factor or unmeasured springback moves the flange tip and mating hole. Our WPS qualification guide shows a procedure is a signed record.

(Fit-up) Trigger 4 - Plus thickness tolerance carried into the mean diameter without re-checking the ID or OD control basis

Confirm whether the drawing controls the inside or outside diameter and measure the formed part at several stations, because a thicker sheet on a fixed blank shifts the controlled diameter. Our B265 specification page names the edition.

(Process) Trigger 5 - Residual stress, levelling and condition code not recorded before cutting, so the blank warps

Measure flatness after cutting, not only on the delivered coil, and record the levelling, annealing or stress-relief condition, because a stressed blank that twists changes the stock the brake sees. Our Grade 1 AMS 4911 plate page gives the condition context.

(Process) Trigger 6 - Finish, rolling direction and surface cleanliness not matched to the bend line, the weld or the die

Examine the finish, the bend line relative to rolling direction and the cleanliness of the weld zone before forming; outer-fibre cracking, galling and root contamination are process failures, not thickness failures. Our GTAW shielding guide covers the root.

(Fit-up) Trigger 7 - Sheet substituted by another thickness band, lot or condition without re-development and re-cut

Any change of heat, thickness band, lot, width or condition resets the measured thickness feeding the bend allowance and flat pattern, so re-run the development and re-cut; a substitute cut to the old flat pattern is a reject. Our ordering-by-end-use page separates buying from fit-up.

(Process) Trigger 8 - Dimension chain reviewed with no signed verification sheet or lost heat-to-blank traceability

Reconcile every cut blank, bend and weld against the heat number, drawing revision and signed 14-line sheet; a part whose thickness map cannot be rebuilt is a reject regardless of a clean certificate. Our EN 10204 3.1 certificate page shows what the mill record proves.

The 14-Line Cold-Rolled Plate Fit-Up & Dimension Chain Verification Sheet

#	Fit-up check	Basis drawing or standard edition	Measurement method	Acceptance criterion	Who signs
1	Standard edition, grade and condition named	Purchase order and MTC	Document review	One designation with revision	Buyer QA
2	Cold-rolled or hot-rolled dividing thickness confirmed	B265 or SB-265 edition in the PO	Check the named edition table	Product form named as sheet or plate	Buyer QA
3	Measured mean thickness from a mapped survey	MTC and plate marking	Calibrated ultrasonic gauge, mapped points	Mean and spread logged and used in the layout	Fabrication inspector
4	Thickness band identified, symmetric or asymmetric	Named standard edition table	Check the edition table	Deviation carried into the calculation	Fabricator engineer
5	Thickness across the width, crown, edge drop and wedge	Drawing and inspection plan	Ultrasonic map at edges, quarter width, centre, head, mid, tail	Spread inside the drawing criterion	Fabrication inspector
6	Control diameter basis ID or OD, and bend line orientation	Equipment drawing revision	Drawing and nesting review	Basis and rolling direction stated	Design engineer
7	Developed length L equals pi times Dm	Approved development calculation	Independent recalculation	Formula, pi value and result agree	Fabricator engineer
8	Bend allowance on neutral axis, R plus K times t	Development sheet and forming procedure	Recalculation plus first-article bend	K factor closed against a measured first article	Forming supervisor
9	Bend deduction and flat pattern length	Cutting plan and development sheet	Tape or laser check against the cut blank	Cut length matches the flat pattern	Fabrication inspector
10	Springback angle and flange position	First-article bend record and drawing	Angle gauge and coordinate check of the flange	Flange and hole position inside criterion	Forming supervisor
11	Surface finish, cleanliness and rolling direction	Edge and finish procedure, nesting plan	Visual and surface check, PT where specified	Bend line and weld zone clean, direction recorded	Welding inspector
12	Residual stress, levelling and flatness after cutting	Drawing flatness clause and condition code	Surface plate with feeler or straightedge	Blank flat, machining allowance sufficient	Machining supervisor
13	Root gap, hi-lo and hole alignment at fit-up	WPS, joint detail and general arrangement	Angle gauge, feeler gauge and fit-up clamps	Gap, offset and hole alignment inside criterion	Welding inspector
14	Heat-to-blank traceability and signed verification sheet	Drawing revision and 14-line sheet	Reconcile every blank, bend and weld to the heat	Sheet signed per line before release	Quality lead and buyer

Line three is often answered with a nominal gauge instead of a mapped mean. Our mill certificate page and our receiving-weight guide separate material and settlement evidence from fit-up work, and our equipment leak repair guide shows the cost of an undocumented joint. A sheet without a signature column is a note, not a record.

Summary: Choose a Nominal Blank if, Escalate if, Choose a Re-Measured Blank if

Choose a nominal-thickness blank with a signed development sheet if:

• The purchase order names the standard edition, the grade, the condition code and the drawing revision, and the control diameter is stated as ID or OD.
• A mapped ultrasonic survey gives the measured mean thickness and the thickness spread, and the development calculation uses them.
• The K factor, bend deduction and springback are closed against a measured first-article bend, with the flat pattern reissued.
• The finish, rolling direction, levelling and flatness records and the 14-line sheet are signed per line before the blank is released.

Escalate to a fit-up hold or a drawing review if:

• A clean mill certificate or a clean weighbridge ticket is the only fit-up evidence offered.
• The blank length was computed from the outside diameter, from the nominal thickness or from an assumed K factor.
• Published charts disagree on the dividing thickness, the thickness band, the K factor or springback and no one has named the governing edition.
• Cumulative flange, hole or hi-lo offset at the mating part exceeds the drawing criterion.
• The heat-to-blank traceability, the first-article bend or a signed verification sheet is missing from the file.

Choose a re-measured blank and a re-cut if:

• The plate was substituted by another heat, thickness band, lot or condition; settle the dimension chain again before forming. Our zero-cutting plate page covers the non-standard sizes that make this common.
• The design controls an inside diameter for internals or a lining, so a plus thickness deviation cannot be absorbed. Our process equipment buyers guide gives the vessel context.
• The buyer cannot produce a thickness map, a development sheet or a signed verification sheet; set up the shop records first.
• Area-versus-weight settlement is in dispute; keep that on the receiving line and read our receiving-weight guide while the fit-up line stays independent.

The whole subject reduces to one sentence: a nominal size is not a fit, because the drawing tells you what to order while the tolerance chain tells you whether the formed part will assemble. Send the grade, standard edition, nominal and measured thickness, control diameter and bend detail. We are a Baoji China Titanium Valley titanium stockholder with roughly 800 tonnes in stock, about 400 tonnes of it in plate, zero-cutting non-standard and small-batch sizes from customer drawings and certifying to ASTM, ASME and GB standards. Send us the part drawing and the thickness map. Request a quote →

Frequently Asked Questions

Should the developed blank length for a cold-rolled bend use the nominal 2.0 mm or the measured mean thickness?

Use the measured mean thickness from a mapped ultrasonic survey, not the nominal gauge. The developed length is computed on the neutral axis, and for a rolled course L equals pi times the mean diameter, which equals the inside diameter plus the measured thickness. A cold-rolled sheet can carry a plus-side thickness deviation, so the measured value can sit above nominal. If you develop the blank from the nominal figure, the finished flange and hole positions move at fit-up. Confirm the control diameter and the measured thickness against the drawing revision and the standard edition named in the purchase order.

If a 2.0 mm cold-rolled sheet is substituted by a 2.5 mm lot, must every bend be re-developed and re-cut?

Yes. Any change of heat, thickness band, lot, width or condition resets the measured thickness that feeds the bend allowance and the flat pattern. Re-run the development with the new measured mean thickness, re-close the K factor and springback against a first-article bend, re-cut the blank and re-issue the 14-line verification sheet before forming. A substitute sheet cut to the old flat pattern is a reject even if the mill certificate is clean. Keep the heat number tied to the new calculation and photograph identity before and after cutting.

When two plates both pass the thickness tolerance, why does the formed part still fail fit-up?

Because the thickness band is only one input. A crown across the width, an assumed K factor, an unmeasured springback angle, a rolling direction that promotes cracking and residual stress that warps the cut blank all add deviation that a single gauge reading does not see. Those errors accumulate into flange position, hole alignment and the gap at the mating part. A plate can be inside its band and still produce a part that misses the drawing criterion. Rebuild the dimension chain from the measured map and the first-article bend rather than accepting the gauge pass.

Who signs off flatness, residual stress and levelling before the blank is released to the press brake?

The machining or forming supervisor signs the flatness, levelling and bevel or bend allowance check against the drawing clause, and the welding inspector signs the surface cleanliness and edge condition against the finish and joint procedures. Flatness is not cosmetic: a blank that warps after cutting changes the stock the brake sees, so the bend angle and flange drift along the part. Published flatness figures disagree, so name the governing drawing clause and the standard edition, measure out-of-flat after cutting and confirm that levelling was recorded.

When published charts disagree on the cold-rolled dividing thickness, which document decides our part at fit-up?

The standard edition named in the purchase order, read together with the drawing revision and the condition code. Secondary charts place the boundary near 4.75 mm or 4.76 mm, and some mills quote thinner plate on request; none of those is the governing value for your order. Do not pick one to size the blank. Name the edition and the product form, confirm whether the order is sheet or plate, and record the decision on the verification sheet. Where figures disagree, the measured plate and the signed sheet are the tie breakers.

How does springback move the flange position and the mating hole alignment after bending?

After the brake load is released, the flange opens by an angle that depends on yield strength, the radius-to-thickness ratio and the cold-worked or annealed condition. That angular error grows into a linear error at the flange tip, so a hole or a mating edge drilled to the nominal flat pattern no longer lines up with its partner. Do not print one springback angle as correct. Measure the first-article bend, adjust the flat pattern and the brake overbend, and confirm the hole alignment against the drawing criterion at fit-up.

Is the cold-rolled plate fit-up check the same as the receiving thickness check?

No. They are two independent check lines at two gates. The receiving line decides what the buyer pays, using the purchase order, the weighbridge ticket or area calculation and the certificate, and the area-versus-weight question belongs there. The fit-up line decides whether the formed part assembles, using the drawing revision, the measured thickness map, the development calculation, the bend and springback records and the signed verification sheet. A plate can be on weight and still fail fit-up, and a well-formed part can still be disputed at the weighbridge. A pass on one does not grant a pass on the other.

Cold-Rolled Titanium Plate: The Tolerance Band, Springback and Forming Fit-Up Dimension Chain

A cold-rolled Titanium Plate is thin, but thin does not mean dimensionally accurate: published charts place the cold-rolled and hot-rolled dividing thickness near 4.75 mm in some tables and 4.76 mm in others. The developed blank for a bend must be computed on the neutral axis and on the measured mean thickness, not the nominal gauge. Our ASTM B265 plate specification guide, our Grade 5 hot and cold rolled plate page and our Grade 1 AMS 4911 plate page settle identity, standard and condition; this article works the fit-up dimension chain when that plate is bent, stamped or welded.

Published charts disagree on the dividing thickness, the thickness band, the K factor and springback, so we publish the conflict, eight rejection triggers and one 14-line verification sheet instead of one invented number. Our B265 plate and sheet page gives the specification context and our plate ordering guide the buying context; the drawing revision and named standard edition govern.

At a Glance: Eight Decisions That Separate a Clean Cold-Rolled Fit-Up from a Rejected Bend

Item	What the decision turns on
The short answer	Thin does not guarantee dimensional accuracy; a nominal gauge is not a fit
The dividing line conflict	Published charts place the cold-rolled and hot-rolled boundary near 4.75 mm or 4.76 mm, and some mills quote thinner plate on request; no single value is given
The governing identity	Developed blank length is computed on the neutral axis at mean diameter; bend allowance uses R plus K times t
Where plus tolerance goes	Measured thickness above nominal shifts the mean diameter, then the flange and hole positions after forming
The width question	Crown, edge drop and a thickness wedge across the width change the bend from one edge to the other
The surface question	Finish, rolling direction and residual stress decide whether the outer fibre cracks or the weld stays clean
The conflict	Charts disagree on thickness band, K factor, springback and flatness; we publish the conflict, not one value
The one document	A 14-line Cold-Rolled Plate Fit-Up and Dimension Chain Verification Sheet: check, basis, method, criterion, who signs

Our Grade 2 B265 supplier page gives the grade context and our EN 10204 3.1 mill certificate page shows a traceable thickness record. A stockholder can certify a heat number, not a bend allowance it did not calculate for your drawing.

The Trap: Thin Does Not Mean Dimensional Accuracy Is Guaranteed

Cold rolling delivers a smoother surface, better flatness and a tighter thickness spread than hot-rolled plate, but that reputation is about material as delivered, not the geometry of the formed part. Our Grade 5 hot and cold rolled plate page describes the two routes and our plate thickness and form classification page separates the forms; treat the gauge as an input, not a fit-up result.

The specification pages already cover thickness ranges, widths, surface condition, chemistry and buying questions; this page starts once the purchase order has fixed a nominal thickness and asks whether the cumulative deviation still lets the part close on its partner. Our titanium plate range lists the product, but the drawing revision decides how the thickness is used.

A thin plate that passes its thickness tolerance can still fail fit-up; the band travels into the bend allowance, springback and mating hole.

What matters in a dimension chain is the measured mean thickness, the thickness across the width, the K factor, the bend deduction and the springback angle. Our zero-cutting and small-batch plate page covers non-standard blanks and our process equipment buyers guide gives the assembly context. Confirm the fit-up criterion against the drawing revision and named standard edition.

Where the Tolerance Goes: The Dividing Thickness That Published Sources Cannot Agree On

Ask several sources where cold-rolled sheet ends and hot-rolled plate begins and you get a spread: sheet from about 0.8 mm to just under 4.75 mm and plate from 4.76 mm in one chart, a 4.75 mm plate threshold in another, cold-rolled 0.8 to 4.75 mm and hot-rolled from 4.8 mm in a third, and thinner plate to 3.0 mm on request. Our thickness classification page and our B265 plate and sheet page give the product-form context; the controlling boundary is the edition named in the purchase order.

Condition codes matter too: a mill-annealed, hot-rolled and cold-worked condition are not interchangeable once the plate is formed, because cold work raises strength and lowers ductility. The relevant designations are ASTM B265, ASME SB-265, GB/T 3621 and AMS 4911, and our GB versus ASTM B265 comparison and our sheet strip and plate page give the buying context. Name the edition, grade and condition before any band is used as a fit-up input.

The thickness tolerance band is a second disagreement: charts quote symmetric and asymmetric bands and split strip, sheet and plate into different tables. Treat the measured mean thickness as the dimension-chain input. Our Grade 2 B265 plate page gives the product context and our coil and strip guide the thinner cold-rolled range; neither is a fit-up conclusion.

The Dimension Nobody Measures: Thickness Distribution Across the Plate Width

Incoming thickness is usually logged at one or two stations near the centre, but a bend uses the thickness at every station along the bend line. Cold rolling can leave a crown, an edge drop or a wedge from one side to the other, so a plate that passes a single-point check can carry a gradient that changes the bend allowance between flanges. Our plate sheet and coil page gives the form context and our coil and strip guide shows how width is produced; the drawing decides which edge becomes the bend line.

The remedy is a mapped ultrasonic survey with a written point layout, recording thickness at both edges, quarter width and centre, at head, middle and tail, and logging mean and spread. That map is a fit-up input, not a material-identity record; our mill certificate page shows what the mill record proves. Where the spread is large, develop the blank on the measured mean and hold outlying stations for the first-article bend.

A single thickness reading certifies a heat, not a bend line; map the width before calculating the developed length.

A tight nominal band is worth little if a thickness wedge across a 1000 mm width moves the neutral axis along the bend. Our bright surface coil page describes the finish route and our same-day cut-to-size plate page describes how the blank is cut; the measured width map, not the cut ticket, decides the forming allowance.

Before the Bend: Surface Condition, Residual Stress and Levelling

Surface condition and the bend, the weld and the die

Cold-rolled sheet arrives with a controlled finish that is a forming input: a bright face behaves differently in a press brake die than a pickled matte face, and a bend line parallel to the rolling direction is more prone to outer-fibre cracking than one across it. Surface cleanliness decides whether a weld root stays sound. Our pickling and iron contamination page covers cleanliness and our GTAW shielding guide covers the root. Name the finish and rolling direction on the cutting plan.

Cold rolling residual stress and levelling

Cold reduction leaves residual stress: a coil that has been tension levelled or annealed behaves differently from as-rolled material, and a blank cut from a stressed sheet can warp or spring open before it reaches the brake. Our Grade 1 AMS 4911 plate page gives the condition context and our WPS and NDT qualification guide shows a procedure is a signed record. Measure flatness after cutting.

What to record before the first bend

Before the first production bend, record the finish, rolling direction, levelling or annealing condition, mapped thickness, chosen K factor and measured springback from a first article. Our cut-to-size plate stock page describes how the blank is prepared and our bright surface coil page gives the finish route; the development sheet decides which is critical.

The Blank Dimension Chain: Mean Diameter, Bend Deduction and Springback

A blank is laid out from one identity: developed length is the arc at the neutral axis. For a rolled course L equals pi times the mean diameter Dm, with Dm equal to inside diameter plus measured thickness or outside diameter minus that thickness. For a press-brake bend the bend allowance equals the angle in radians times R plus K times t. Our Grade 2 B265 plate page gives the product context and our cut-to-size plate stock page describes the blank; the development sheet owns the calculation.

Bend deduction converts that allowance into a flat pattern: outside setback on both flanges minus the bend allowance. Published practice disagrees on the K factor and springback, so we will not print one as correct; close both against a measured first-article bend. Our WPS qualification guide and our

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