Hot rolling environments are unforgiving: heat, scale, water spray, vibration, and heavy intermittent loads all work together to destroy ordinary sleeve bearings. In a HOT MILL COMPLEX—from descaling and roughing to finishing and coiling—bushings are often the “quiet” components that decide whether a line runs smoothly or bleeds downtime.

One proven choice for demanding sliding applications is CuZn40Pb2 (European designation CW617N)—a leaded copper‑zinc alloy widely used where good load capacity + excellent machinability + reliable sliding behavior are required.

What is CuZn40Pb2 (CW617N)?

CuZn40Pb2 is a copper‑zinc alloy with a controlled lead addition. Typical composition range (per common EN datasheets) includes:

• Cu: 57.0–59.0%
• Pb: 1.6–2.5%
• Zn: balance
• With small limits on elements like Fe, Ni, Sn, Al

A key microstructural point: lead is insoluble in this alloy and appears as finely distributed particles (often along grain boundaries), which strongly improves machinability and helps stable sliding performance.

Why CuZn40Pb2 works in hot mill bushing duty

Hot mill bushings typically face combinations of:

• High radial loads and shock loads (impact, cobbles, acceleration/deceleration)
• Vibration and misalignment at pivots and linkages
• Contamination (mill scale, dust, coolant/water)
• Thermal cycling from radiant heat and hot product proximity

CuZn40Pb2 is commonly selected because it balances several practical requirements:

1) Excellent machinability (fast turnaround, tight tolerances)

CuZn40Pb2 is known for very good machinability compared with many bronzes. For hot mill maintenance teams and OEMs, that typically means:

• Faster machining for sleeves, flanges, thrust faces, grooves, and lubrication pockets
• More consistent surface finish on bearing IDs/ODs
• Easier customization for non-standard designs and urgent shutdown jobs

2) Solid strength range for sliding components

Typical mechanical-property ranges (depending on product form and condition) are often cited around:

• Tensile strength (Rm): ~360–500 MPa
• Yield strength (Rp0.2): ~220–350 MPa
• Hardness: roughly ~90–170 HB (condition dependent)

That spectrum allows designers to select a supply condition that supports load-carrying capacity while still keeping the alloy machinable for complex bushing geometries.

3) Helpful thermal behavior in a high-heat environment

While any bushing selection must be validated against the actual bearing temperature, CuZn40Pb2 offers practical thermal advantages for steel-plant duty:

• Good thermal conductivity (often reported around ~123 W/m·K at 20°C in common datasheets)
• Helps move heat away from the contact zone—especially valuable when lubrication is imperfect or intermittent

4) Stable sliding behavior under imperfect lubrication

In real hot mill service, lubrication can be disrupted by washdown, scale ingress, and high operating temperatures. A well-designed CuZn40Pb2 bushing (with correct clearance, finish, and lubrication system) can support stable operation in boundary/mixed lubrication regimes.

Note: Material choice can’t “solve” poor lubrication design. The best results come from matching alloy selection with grooves, oil/grease delivery method, sealing, and contamination control.

Typical HOT MILL COMPLEX applications

CuZn40Pb2 bushings are commonly specified for general engineering and heavy-duty sliding points in steel plants. Typical hot mill complex use locations include:

• Pivot points and hinge joints (linkages, guides, actuators)
• Tension system components and sliding supports
• Coiler/mandrel related sliding interfaces (depending on design)
• Guide bushings and alignment sleeves
• Worm gear / drive shaft support sleeves in auxiliary systems

Exact suitability depends on shaft material/hardness, lubrication method, speed, and temperature at the bearing.

Design & ordering checklist (what to specify)

To get predictable life in a hot mill complex, specify more than “bronze bushing”:

1. Alloy / standard: CuZn40Pb2 (CW617N), and the relevant product standard (commonly EN 12164 / EN 12165 depending on form)
2. Temper/condition: Required strength/hardness range based on load and installation method
3. Dimensions & tolerances: ID/OD, flange/thrust features, press-fit allowance
4. Surface finish targets: Especially for the bearing ID
5. Lubrication design:
   • Groove pattern (axial/spiral), oil pockets, feed holes
   • Grease vs oil, supply pressure/interval
6. Contamination control: Seals, wipers, shields, labyrinth features
7. Mating shaft info: Material, hardness, surface finish, and whether it’s chrome plated or coated
8. Operating conditions: Load range, speed, temperature, presence of water/scale

Practical note on lead content

CuZn40Pb2 contains ~2% lead to enhance machinability. For steel plant mechanical bushings, this is usually an acceptable and common engineering choice, but always confirm:

• Site EHS requirements
• Waste handling / recycling rules
• Any restricted-environment constraints for your project

Bottom line

For a HOT MILL COMPLEX, CuZn40Pb2 (CW617N) bushings are a practical, proven option when you need:

• A machinable alloy for fast maintenance and custom geometries
• Reliable sliding performance in harsh, contaminated environments
• Strength and hardness options that can be matched to real mill loads

If you share your load/speed/temperature, lubrication method, and bushing drawing (or just ID/OD/length + shaft material), the bushing design can be optimized with the right clearances, groove pattern, and supply condition.