Cold Drawn Flat Steel – Sizes, Grades and Tolerances

We draw flat steel from 20×3 up to 200×40 mm on our 8-ton to 120-ton cold drawing lines. Flat bar comes off the line bright, scale-free, straight, and with a consistent cross-section that hot-rolled flat bar simply does not hold. If you machine flat blanks, guide rails, or stamped parts, this is the product that saves you straightening and surface cleanup downstream.

Available sizes and grades

What buyers use it for

Most of our flat steel goes into elevator guide rails, machine tool parts, agricultural machinery, transmission components, stamping blanks, and automation equipment frames. Because the drawn surface is smooth and the section is consistent, many customers skip secondary machining on the faces and go straight to cutting and drilling.

What to specify when you ask for a quote

Three things decide the price and lead time: the exact width × thickness, the grade, and the quantity in tons. Delivery marks and special surface requirements (oiled, painted, or VCI wrapped) can be added to the order. Standard sizes are drawn from stock in 3–7 working days; custom sections run 15–35 days depending on the heat schedule.

Request a quote: send us your flat bar size, grade and quantity via the contact form, or check our cold drawn steel size guide for reference. We reply with price and lead time within one working day.

Related pages: Cold Drawn Square Steel · Cold Drawn vs Hot Rolled Steel · How Cold Drawn Steel Is Made · About Our Factory

Tolerance Grades and What They Mean on Flat Bar

Flat bar is measured on width and thickness, and the tolerance grade decides how much of the bar is usable without machining. h9 holds a 50 mm width to ±0.062 mm and a 10 mm thickness to ±0.036 mm; h11 loosens those to ±0.16 mm and ±0.09 mm. For elevator guide rails and machine slides, the h9 width is often the running dimension itself – the drawn bar becomes the rail with only a light finish pass. For stamping blanks, h11 is usually enough because the blank is punched oversize and trimmed later. Tell us the finished tolerance at quoting; we confirm which grade we can hold on your section.

Grades Beyond Structural Steel

Beyond Q235, Q275 and the S235JR/S275JR structural grades, we draw flat bar in medium-carbon and alloy grades. 45# and 40Cr suit parts that are hardened after machining – rails, cams and wear strips. 42CrMo adds higher strength and toughness for load-bearing sections. 65Mn is a spring steel used for elastic strips and clamping elements. Stainless options such as SUS304 and SUS316 can be drawn on request. The grade changes the drawing reduction and heat treatment, so confirm it with the size – a quote on the wrong grade wastes everyone's time.

Flat Bar for Guide Rails and Stamping

Two applications take most of our flat steel. Guide rails need a straight, parallel-edged bar with a controlled width: the drawn bar is cut to length, drilled and mounted, and the width tolerance becomes the running accuracy of the slide. Stamping blanks need a consistent thickness and a clean surface so the die fills evenly and the blank edge is clean. Both are cases where the drawn product replaces a machining pass on the faces.

Surface Finish and Protection Options

Standard delivery is bright drawn – clean, scale-free and ready to machine or weld. On request we supply oiled bars for rust protection, peeled (WP) surface where a decarburized layer must be removed, painted edges for identification, or VCI wrapping for long sea freight and warehouse storage. State the protection level at ordering; the extra cost is small and the surface stays usable on arrival.

Processing: Cutting, Drilling and Chamfering

We supply flat bar cut to length with ±2 mm tolerance and deburred ends. For repetitive assembly parts we can drill hole patterns, chamfer edges and stamp or tag each piece to your drawing. Processing is quoted together with the material, so the delivered piece is closer to your finished blank – which shortens your line and reduces your scrap.

Common Questions About Cold Drawn Flat Steel

What tolerance can you hold on flat bar? h9 to h13 per GB/T 905, tighter on request. For guide rail sections we commonly hold h9 on width; for stamping blanks h11 is standard.

Can you draw flat bar in alloy or stainless grades? Yes. 45#, 40Cr, 42CrMo and 65Mn are drawn to order, and SUS304 / SUS316 on request. Grade availability is confirmed at quoting against heat schedule.

Do you provide mill certificates? Every order carries an EN 10204 3.1 certificate with chemical composition, mechanical properties and dimensional results on request.

Can you supply long lengths? Standard is 3–12 m; we cut to your length with ±2 mm tolerance and can supply full-length bars for your own cutting line.

What is the minimum order quantity? 500 kg per size, with mixed sizes combined toward the MOQ. First orders to validate our quality are practical at about one ton.

Do you offer surface protection for sea freight? Oiled, painted or VCI-wrapped options are available; we recommend VCI wrapping for long container shipments to humid regions.

Where Precision Flat Steel Goes

Elevator guide rails. The running face of an elevator guide rail is a flat drawn section – typically 16–30 mm wide – where the h9 width tolerance becomes the slide accuracy of the car. Rails are supplied in 5–10 m lengths, drilled and slotted to the mounting drawing at our side, so the installer mounts and aligns without machining on site.

Stamping and press blanks. Press blanking lives and dies on thickness consistency. Drawn flat steel holds the thickness within 0.03–0.05 mm across the width and along the length, which keeps the die fill even and the blank edge clean. 65Mn is a common choice for spring and clip blanks; Q235 and Q275 cover general press work.

Machine slide ways, spacers and shims. Drawn flat bar in Q275 or 45# is used for slide plates, spacers and shims where two parallel faces are the working surfaces. The drawn faces are flat and scale-free, so the part is often used with a single light machining pass – or as supplied, if the tolerance allows.

Transmission and conveyor components. 40Cr flat sections for hardened transmission parts, and straight drawn bars for conveyor side rails and scrapers, are standard orders. If the part is hardened, the drawn condition is the machining blank and the finishing hardness is confirmed at ordering.

Inspection and Certificates

Width, thickness, straightness and surface are checked on the drawing line before cutting. EN 10204 3.1 mill certificates with chemical composition and mechanical properties are issued per order, and third-party inspection is arranged on request. Surface protection level – oiled, painted or VCI – is confirmed in the packing specification.