Continuous Cast Bronze
Legacy context
For over a century, the name Cannon has been linked to the craft of bronze manufacturing. Our preserved records trace this lineage to the late 1890s, when A.P. Cannon founded the Cannon Oiler, producing bronze pump oil cans from a site in Keithsburg, Illinois. By the mid-1940s, the company was reorganized as Cannon Precision Manufacturing, focusing on continuous cast bronze and custom bronze products.
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Today, this site serves as an independent educational reference on that legacy. We document the historical processes of bronze casting, machining, and the production of bearings, bushings, and thrust washers. Our content draws from archival excerpts, including details on vertical integration and material recycling, to illustrate past industry practices.
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We do not represent an active commercial entity. Instead, we preserve and share this technical heritage for researchers and enthusiasts. For current product availability or services, please consult contemporary manufacturers.
Continuous Cast Bronze: A Practical Specification Guide for Home DIY and B2B Sourcing
Continuous cast bronze is a manufacturing process, not a single alloy. It involves pouring molten bronze into a water-cooled die, typically graphite, and drawing the solidified bar or tube through the die at a controlled rate. This produces a dense, fine-grained, and porosity-free material compared to sand casting or centrifugal casting. For a home DIY builder or a small B2B buyer, understanding the specification table is the difference between a part that lasts decades and one that fails in months. This guide focuses on verifiable engineering data, decision criteria, and common mistakes, without referencing current inventory or pricing.
The Core Specification Table: Alloys and Their Properties
The most common continuous cast bronze alloys are grouped by their Copper Development Association (CDA) numbers. The table below is a baseline for room-temperature, as-cast properties. Always verify with a mill test report for your specific heat.
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| Alloy (CDA) | Common Name | Nominal Composition (wt%) | Tensile Strength (MPa) | Yield Strength (0.5% ext., MPa) | Elongation in 2 in (%) | Brinell Hardness (500 kg) | Typical Use Case |
|---|---|---|---|---|---|---|---|
| C93200 | Bearing Bronze (SAE 660) | Cu 83, Sn 7, Pb 7, Zn 3 | 240–310 | 125–170 | 15–25 | 60–75 | General bushings, thrust washers, light-duty gears |
| C95400 | Aluminum Bronze | Cu 85, Al 11, Fe 4 | 515–620 | 205–275 | 12–18 | 150–190 | Heavy-duty gears, wear plates, valve seats, marine hardware |
| C95500 | Nickel-Aluminum Bronze | Cu 81, Al 10, Ni 5, Fe 4 | 620–760 | 275–345 | 8–15 | 190–220 | High-strength structural parts, pump shafts, aerospace components |
| C90700 | Tin Bronze (Gear Bronze) | Cu 89, Sn 11 | 275–345 | 125–170 | 10–20 | 80–95 | Worm gears, high-load low-speed bearings, sliding parts |
| C90300 | Tin Bronze (Gunmetal) | Cu 88, Sn 8, Zn 4 | 275–345 | 125–170 | 20–30 | 70–85 | Fittings, valve bodies, pump housings, steam service |
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Key Reading of the Table: Notice the trade-off. C93200 has high elongation (ductility) but low hardness. C95400 has double the tensile strength but half the elongation. Do not select an alloy based on name alone; select based on the *stress* and *wear* environment.
Decision Criteria: How to Choose the Right Alloy
For a B2B buyer or a serious DIYer, the selection process is a series of engineering questions, not a price comparison.
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- Define the Load Type: Is the part under static load (holding a weight) or dynamic load (rotating, sliding, impacting)? For static loads, yield strength is your primary criterion. For dynamic loads, fatigue strength and elongation matter more. C90700 is superior for worm gears because its microstructure resists surface fatigue, even though its tensile strength is lower than C95400.
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- Assess the Counterface Material: Bronze is often paired with steel shafts. A hard bronze (C95400) will wear the steel shaft faster than a softer bronze (C93200). If you are rebuilding a vintage machine with an original hardened shaft, use C93200. If you are making a new shaft and bushing set, you can use C95400 and a hardened shaft. The rule: the softer material wears, the harder material survives. Decide which component you want to replace.
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- Consider the Environment: For saltwater or chemical exposure, aluminum bronze (C95400) is the default due to its protective oxide layer. For steam or hot water, tin bronze (C90300) is preferred. Leaded bronze (C93200) is *not* for food contact or high-temperature steam (above 200°C) because lead can leach.
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- Machinability vs. Wear Resistance: C93200 is the easiest to machine, producing short, broken chips. C95400 is gummy and requires sharp tooling and lower speeds. If you are making 100 parts on a manual lathe, C93200 will save hours. If you are making 10 parts for a high-load application, the machining time is irrelevant.
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- Size and Shape Availability: Continuous cast comes in standard rounds, tubes, and rectangles. If you need a complex profile (e.g., an I-beam shape), you will need to machine it from a solid round, which increases waste. Check the standard size chart from your supplier before finalizing your design. A 50 mm diameter rod is common; a 51 mm rod is a special order.
Common Mistakes in Specification and Use
These are the errors seen repeatedly in DIY and small-shop settings.
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- Mistake 1: Confusing "Bronze" with "Brass." Brass is copper-zinc (e.g., C36000). Bronze is copper-tin or copper-aluminum. Brass is cheaper but has poor wear resistance and will gall against steel. If you order "bronze" and receive "brass," your bushing will seize. Always specify the CDA number on your purchase order.
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- Mistake 2: Ignoring the Lead Content in C93200. Lead acts as a solid lubricant, which is excellent for low-speed, high-load bearings. However, lead also reduces impact strength. Do not use C93200 for a hammer head or a pry bar. It will crack under shock loading.
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- Mistake 3: Assuming Continuous Cast is the Same as Centrifugal Cast. Centrifugal cast is poured into a spinning mold, which is good for rings and cylinders. Continuous cast is drawn through a die, giving a more uniform grain structure along the length. For a long rod (over 300 mm) that will be machined into multiple bushings, continuous cast is superior. For a single large ring (over 300 mm diameter), centrifugal cast is often better. Do not substitute one for the other without checking the supplier's manufacturing method.
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- Mistake 4: Over-Tightening the Fit. Bronze has a higher thermal expansion coefficient than steel. A bushing that fits perfectly at 20°C will seize at 80°C. For a rotating shaft, use a clearance fit of 0.001 to 0.0015 inches per inch of shaft diameter. For a press-fit bushing, the interference should be 0.001 to 0.002 inches per inch of housing bore. Do not rely on "feel" – use a micrometer.
This independent educational reference summarizes general technical concepts. Verify current standards, dimensions, and manufacturer specifications before making a procurement or engineering decision.