Bronze CNC Machining Services — Custom Bronze Parts & Alloys

Bronze is a family, not a single material. The alloying additions decide whether a part slides, resists seawater or carries load — so the grade you pick matters more than the machining itself. The table below compares the bronze grades we machine most often. Not sure which one fits? Send the application and we will recommend a grade before you commit to a drawing.

Alloy reference: Review Copper Development Association data for C93200, C95400 and C86300. These sources support material identification and selection discussions; the purchase specification and mill certificate control the order.

A note on naming: UNS C22000 is a copper–zinc alloy and is metallurgically a brass, even though it is sold commercially as “commercial bronze”. If a specification calls it out by that name, we will machine it — just be aware that it will not give you the wear or seawater performance of a true tin bronze.

These are the bronze grades that cover the large majority of custom part enquiries we receive. Values are typical figures for the standard temper or as-cast condition; forgings, continuous cast bar and centrifugal castings differ slightly.

All three are copper alloys, and that is where the similarity ends. The alloying element decides the mechanical behaviour, the corrosion performance and how easily the material machines — which in turn decides the cost of your part.

How to choose in three questions ？

• Does the part slide, rotate under load, or see seawater? Specify bronze. Start with C93200 for bearings and bushings, C95400 or C95500 for seawater, and C86300 where the load is high enough to break a tin bronze.
• Is it mainly a fitting, connector or decorative part that has to machine fast and cheap? Specify brass. It cuts faster than any bronze and costs less, as long as corrosion is not severe. See our brass material page for grades and finishes.
• Is conductivity or heat transfer the primary function? Specify copper. Bronze sacrifices conductivity for strength and wear resistance, so it is the wrong answer for a busbar or a heat sink.
• Still not sure? Send your drawing and application notes. We will tell you which grade gives the best cost-to-service-life ratio, and we will say so if a cheaper material would do the job.

Bronze is forgiving to machine, but a handful of design decisions separate a part that runs for a decade from one that starts wearing in weeks. These are the points our engineers raise most often in DFM reviews of bronze components.

• Choose a leaded bronze when machinability matters most. C93200 and C83600 cut cleanly at high feed rates and give the best surface finish per dollar. Reserve the harder aluminium and manganese bronzes for parts that genuinely need their strength.
• Plan for work hardening, not built-up edge. Bronze work-hardens readily, so use sharp, positive-rake carbide tooling and keep the feed steady. Dwelling on a bronze surface polishes it instead of cutting it, which dulls the finish and burns the tolerance.
• Review thin or unsupported walls early. Minimum practical wall thickness depends on the alloy, stock form, unsupported length and workholding. A rib or local thickness increase may reduce distortion and setup cost.
• Design bushings for running clearance, not a press fit. For a bronze sleeve bearing in continuous duty, allow roughly 0.001–0.002 in of clearance per inch of shaft diameter so the part can form a lubricating film instead of seizing.
• Round internal corners. A corner radius of at least one third of the pocket depth lets a standard end mill reach the floor. Sharp internal corners push the part into EDM and multiply the cost.
• Keep holes and threads standard. M, UNC, UNF, NPT and BSP threads are all available, but deep small-diameter holes are slow and prone to tool breakage. Where you can, keep hole depth to about four times the diameter.
• Mark the wear surface on the drawing. Bronze parts usually have one critical sliding face. Calling it out lets us control finish and tolerance exactly there and machine the rest economically — you get the same service life for less money.
• Flag any part that will be joined. Most bronzes are poor welding candidates, so tell us at quoting if the part is a weldment or an assembly. Brazing, silver soldering or a press-fit joint is usually the right answer, and it changes the design.

Four steps from CAD file to parts at your door. A complete RFQ lets the team return pricing, manufacturability notes and a realistic schedule with fewer clarification cycles.

Bronze is one of the many metals and plastics we machine every week. If your project spans several materials, we can quote and produce them together and ship as one batch.