Cold Drawn Round Steel Bar – Sizes, Grades and Tolerances

We draw round steel bar from Ø5 mm up to Ø100 mm on our cold drawing lines. Hot rolled round bar is pickled and pulled through a die, which tightens the diameter, straightens the bar and leaves a bright, scale-free surface. Common stock sizes are Ø10, Ø16, Ø20 and Ø25 mm. Larger diameters up to Ø150 mm can be produced on request.

How We Draw Round Bar

Hot rolled round bar has scale and a loose tolerance from the rolling mill. We pickle the bar to strip the scale, then pull it through a die that is slightly smaller than the nominal diameter. The die work-hardens the surface, pulls the diameter down to h9/h11 tolerance and leaves a bright finish with no scale. After drawing, bars are straightened on a roller straightener, cut to your length and deburred at both ends.

Sizes We Stock

Ø10, Ø16, Ø20 and Ø25 mm are our fastest-moving stock sizes, available in Q235 and C45. We also keep partial stock on Ø30, Ø32, Ø40 and Ø50 mm. If you need a size we do not stock, we draw it to order with the same tolerance and surface. Imperial sizes 3/8" to 4" can be matched to their metric equivalents.

Tolerance and Straightness in Practice

Cold drawn round bar holds a tighter diameter than hot rolled bar of the same nominal size. For a Ø20 mm bar, h9 holds the diameter to ±0.052 mm and h11 to ±0.13 mm. We check diameters with micrometers and straightness on the roller straightener before cutting. If your lathe or CNC feeds bar through a collet or guide bushing, the consistent diameter cuts down on chatter, tool wear and scrap.

Surface and Finish Options

Standard delivery is bright drawn: clean, scale-free and ready to machine. For rust protection on longer shipments we oil the bars. If your part is plated, induction hardened or used with a visible surface, we can supply peeled (WP) bar to remove the decarburized layer. Both options keep the h9/h11 tolerance.

Material Grades and What They Are Used For

Q235 is the general structural grade – good for pins, spacers and parts that are welded or machined without heavy wear. C45 is a medium carbon grade (0.42–0.50% carbon) with higher strength, used for shafts, spindles and parts that take load. 40Cr and 42CrMo4 are alloy grades for components that are hardened after machining – gears, pins and high-stress parts. Tell us the grade you need and we confirm stock or drawing time.

Where Customers Use Cold Drawn Round Bar

Most of our round bar goes into turned shafts, pins, dowels, bolts, rollers and machined components. Buyers in pumps, valves, fasteners, conveyors and general machine building order it because the bright surface and tight tolerance let them skip an extra machining pass. If your part is machined from round stock, cold drawn bar is the stock that feeds consistently.

Quality and Inspection

Every order comes with an EN 10204 3.1 mill test certificate showing chemical composition, mechanical properties and dimensional results. We check diameter, straightness and surface on the drawing line. Third-party inspection can be arranged on request.

Cutting, Packing and Lead Time

Stock sizes ship within 3–7 days. Custom diameters and non-standard lengths take 15–25 days depending on quantity. We cut to your length from 50 mm up to 6,000 mm with ±0.5 mm tolerance; cut pieces are deburred, bundled with steel strapping and protected for container loading.

Send us your diameter, grade, length and quantity for a quote. We also draw square steel and flat steel bar on the same lines.

Diameter Tolerance and Machining Allowance

Tolerance is the reason most shops switch to cold drawn round bar. Hot rolled round holds a loose diameter – often ±0.5 mm or more – so every bar has to be measured and the program offset adjusted. Drawn bar at h9/h11 holds the diameter within ±0.052 mm (Ø20 h9) or ±0.13 mm (h11). In practice that means the bar feeds through a collet or guide bushing without size checking, and the first part off each bar matches the last. The finish allowance for turning is typically 0.3–0.5 mm on diameter; on drawn bar you can reduce that because the surface is already clean and round.

Straightness and Bar Feed

Straightness of ≤ 0.5 mm/m matters on two fronts. In a lathe with a bar feeder, a bowed bar bounces in the guide bushing, marks the surface and wears the bushing. In a centreless or between-centres operation, a straight bar needs no pre-straightening and no extra setup. We straighten every bar after drawing and check it on the roller straightener before cutting, so the stock you receive is ready to feed.

Shaft, Pin and Roller Applications

Most drawn round bar ends up as a turned part: shafts, pins, dowels, rollers, bolts and studs. For a shaft, the drawn bar is the blank and the turned surface carries the tolerance – the drawn diameter just needs to be close enough for a stable first cut. For pins and dowels that are used as drawn or with light finishing, the h9 diameter can often serve directly as the finished size. If the part runs in a bearing or bushing, tell us the running fit and we confirm whether the drawn tolerance meets it.

Stock Program and Small Quantities

Our stock concentrates on Ø10, Ø16, Ø20 and Ø25 in Q235 and C45, with partial stock on Ø30, Ø32, Ø40 and Ø50. Stock sizes ship within 3–7 days, and we take small orders – the 500 kg MOQ applies per size, so a mixed order of several sizes can be combined. If you need a length between 50 mm and 6,000 mm, we cut it to size with ±0.5 mm tolerance and deburr both ends.

Export Packing

Bars for export are bundled with steel strapping, oiled on request for rust protection, and protected against container humidity. Cut pieces and small orders go into wooden crates with dunnage between layers. We quote delivered to your port and can arrange loading marks per your packing instruction.

Common Questions About Cold Drawn Round Bar

What is the minimum order quantity? 500 kg per size. Stock sizes combine across a mixed order, so the practical entry point for a first order is about one ton.

What are your lead times? Stock sizes in Q235 and C45 ship within 3–7 days. Custom diameters and special grades take 15–25 days depending on quantity and heat availability.

Do you issue mill test certificates? Yes. Each order carries an EN 10204 3.1 certificate with chemical composition, mechanical properties and dimensional results. Third-party inspection is available on request.

What tolerances can you hold? h9 and h11 per EN 10278. For Ø20 bar, h9 is ±0.052 mm and h11 is ±0.13 mm on diameter. Tighter tolerance is quoted per order.

Can you supply imperial sizes? Yes. 3/8" to 4" inch sizes are matched to their metric equivalents, and we confirm the exact metric dimension in the quotation.

Can you cut short lengths? Yes, from 50 mm up to 6,000 mm with ±0.5 mm tolerance, deburred. This suits blank supply for turned parts and keeps your sawing line free.

Where Cold Drawn Round Bar Ends Up

Motor and pump shafts. 45# drawn round in Ø20–Ø40 mm is the standard blank for motor shafts and pump spindles. The drawn diameter feeds the lathe at a stable size, and the bar's straightness keeps the turned shaft true over its length.

Hydraulic piston rods. Ø20–Ø50 mm 45# or 40Cr bar is supplied as the blank for piston rods that are turned, ground and chrome plated. The drawn stock removes the need for a straightening pass before machining.

Dowel and locating pins. Ø5–Ø12 mm h9 drawn bar cuts directly into dowel pins with only length machining. The diameter tolerance is the pin's working size, which is why h9 stock is specified for jig and fixture pins.

Rollers and bushings. C45 drawn round in Ø25–Ø60 mm is used for conveyor rollers, guide rollers and bushing blanks, turned and often hardened at the machinist's end. The scale-free surface means the bar is clean to machine from the first cut.