C38500 / CDA 385 Brass Screw Machine Components and Screw Machine Parts

Why C38500 suits profile-based machined components

C38500 is useful where the starting extrusion contributes important external geometry and machining adds the precise interfaces. A profile can contain flats, shoulders or an asymmetrical envelope that would be expensive to remove from a large round bar. Cutting the profile into blanks and machining the functional features can reduce stock removal. The value of that route depends on volume, extrusion availability, die requirements and the tolerance needed on the unfinished profile. It should be compared with round-bar machining on the actual drawing.

The alloy is frequently called architectural bronze, although it belongs to the leaded copper-zinc brass family. Use UNS C38500 in the purchase specification to avoid confusion with tin bronze or aluminum bronze. Descriptive terms such as bronze finish or architectural hardware are not chemical specifications. Where corrosion behavior or appearance is critical, state the environment, finishing process and acceptance method rather than assuming the trade name establishes a particular service life.

High-speed machining from extruded stock

The grade supports efficient machining, but a generic machinability rating does not prescribe a safe spindle speed for every component. Tool diameter, rigidity, engagement, chip removal and the required finish affect the practical cutting conditions. An interrupted cut across an extruded profile presents a different loading pattern from continuous turning of round rod. Clamping should locate the profile predictably without damaging surfaces that remain visible on the finished product.

A profile-based part often needs a datum strategy that separates as-extruded surfaces from machined reference faces. If a bore must align with a mounting face, use the actual functional relationship in the drawing. Small changes in extrusion straightness or twist can otherwise produce a part that passes separate size checks but assembles poorly. Where profile dimensions are only clearance features, allowing appropriate extrusion tolerances can avoid unnecessary secondary machining and reduce cost.

Profiles, connector bodies and decorative mechanical hardware

For a connector body, the extrusion can provide a wrenching surface while turning or milling establishes threads, bores and sealing lands. For mounting hardware, a non-round section can offer an integral anti-rotation feature. For a visible mechanical component, the exterior may be polished or plated after machining. These are distinct product requirements and should be described separately in the quotation. A decorative surface target does not define pressure integrity, electrical performance or structural capacity.

Inspection should identify which surfaces are machined, which are retained from the extrusion and where cosmetic limits apply. State whether die lines are acceptable on concealed surfaces. Specify the direction of brushing or polishing if it affects appearance, and identify rack marks allowed after plating. Masking a precision bore can preserve dimensional fit, but the coating transition must not interfere with sealing or assembly. Agreeing these details early prevents a purely cosmetic issue from disrupting a functional production order.

Forming limits and selection against other screw machining grades

C38500 is not the first choice for severe cold forming. If an extruded component later needs a rolled thread or deeply formed retention feature, review that operation specifically. It may be better to machine the feature, change local geometry or select another alloy. Hot-forming suitability does not establish cold-forming performance. Similarly, an extrusion alloy should not be treated as interchangeable with C36000 just because both can be machined rapidly.

For recurring profile components, retain the extrusion drawing alongside the finished part drawing. Define permissible die changes, profile orientation and machining allowances. A new extrusion supplier should be reviewed for chemistry, dimensional variation and surface condition before unrestricted production. This is especially valuable where a stock face becomes an assembly datum. The resulting supply specification links profile economics to reliable finished geometry instead of treating the raw extrusion as an uncontrolled intermediate material.

Drawing-based manufacture and specification review for C38500

A dependable screw machine component begins with a controlled drawing. The drawing should identify the part number, revision, units and applicable general tolerances. It should also show the interfaces that determine assembly: the seating face, locating diameter, thread axis and any sealing feature. A three-dimensional model helps explain geometry, but a model without tolerances does not establish acceptance limits. Where a sample is the starting point, material, hidden features and functional dimensions still need to be agreed before production.

During quotation, distinguish essential requirements from reference information. A close diameter tolerance may be justified by a bearing fit, while an adjacent clearance diameter may allow a wider limit. Applying the tightest tolerance everywhere increases machining and inspection effort without necessarily improving performance. Identify critical characteristics directly so the manufacturer can propose a practical sequence. If a drawing conflict appears between a model and a dimensioned view, resolve it before tooling or sample release rather than allowing a production operator to choose.

Stock form, temper and material traceability for C38500

The alloy designation defines a material family but does not define every property of the supplied stock. Rod, bar, extruded shapes and forging blanks can have different product specifications and conditions. State the stock form or approved manufacturing route where it affects performance. Mechanical properties depend on condition and section size; a single typical tensile value should not be treated as a guaranteed minimum for all components. If hardness or strength is essential, specify the required limit and test basis.

Material identification should continue from receiving to final shipment. Link the supplier certificate and heat or lot reference to the production batch. Keep different grades clearly separated where their color and appearance are similar. Where positive material identification is requested, define the method and acceptance criteria. Handheld screening, laboratory chemistry and a mill certificate are different sources of evidence. The purchase order should state which evidence is required and how it will be reported, especially for restricted elements or customer-specific material limits.

Turning, drilling, boring and secondary machining for C38500

Turning establishes concentric outside diameters, shoulders, grooves and faces. Drilling opens the internal passage, while boring or reaming can refine size and geometry where required. The selected operation depends on tolerance, depth, surface condition and access. A drilled hole should not automatically be assumed to have the same cylindricity or finish as a bored locating feature. State the required result rather than specifying a process that may be unnecessary for the function.

Secondary machining can add wrench flats, slots, cross holes, radial threads and mounting details. Plan these operations around stable datums so the relationship between features remains controlled. Intersecting holes need particular attention because an internal burr can survive exterior inspection. If a part carries fluid, wire or a seal, define the internal edge condition and cleanliness requirement. Where a feature cannot be reached by an ordinary gauge, agree an inspection approach during drawing review so acceptance remains practical and repeatable.

Thread standards, engagement and gauge control for C38500

Specify each thread by its complete designation. Metric threads require nominal diameter, pitch and tolerance class. Unified threads require size, series, pitch and class, such as a drawing-defined UNC or UNF connection. Pipe threads require the exact system: parallel and tapered forms perform different functions. BSPP, BSPT and NPT are not interchangeable merely because the nominal size sounds similar. Identify the sealing method and the applicable thread specification for the actual connection.

Thread length should distinguish full usable thread from drill depth, tap runout and entry chamfer. A blind hole needs room for the chosen tool and sufficient base thickness. On external threads, define the shoulder relief if engagement close to a face matters. Inspection should address the final supplied condition, particularly after plating. Go/no-go gauges check defined aspects of thread acceptance but do not replace the drawing requirements for position, engagement length or damage. State whether mating samples or special functional gauges are part of approval.

Tolerances, datums and surface roughness for C38500

Dimensional tolerances describe permitted size variation; geometric tolerances describe relationships such as position, runout, flatness or perpendicularity. Choose datums from how the part is located in its assembly. A sealing bore may need to run true to a seating face even where its diameter alone is easy to hold. Use the drawing convention specified by the customer and avoid mixing symbols or interpretation rules without agreement. A clear datum scheme can prevent unnecessary disputes during receiving inspection.

Surface roughness should be assigned where it affects sealing, friction, appearance or fatigue performance. A lower roughness value is not automatically better for every contact. Texture direction can matter on a sliding or sealing interface. Specify the surface concerned and whether the requirement applies before or after coating. A visual sample can support cosmetic acceptance but cannot reliably replace an instrumented roughness requirement. Where a very small feature cannot be measured with a standard stylus, agree a suitable method or functional alternative before production.

Knurls, grooves, thin walls and manufacturability for C38500

Retention geometry should be designed around the assembly method and the mating material. Knurl pitch, depth and pattern influence both the machining or forming operation and installation behavior. A groove for a retaining ring needs controlled width, root diameter and edge condition. A seal groove needs a design appropriate to the chosen seal and service conditions. A generic groove callout leaves too much undefined when the feature carries a functional load.

Thin walls require a review of clamping and machining forces. A flexible sleeve may measure differently while held in a fixture and after release. Define the inspection condition if that distinction matters. Long slender parts may require additional support, and deep narrow holes may need a different process sequence. Providing the functional requirement gives the manufacturer room to suggest a more stable design. Any proposed change to radius, relief or wall thickness should be approved before it becomes part of the production drawing.

Surface finish, plating and dimensional allowance for C38500

Natural machined brass can be specified where the application allows the base material surface. Tin, nickel or other finishes may be considered where the drawing requires them and the material and service are compatible. Define the coating system, thickness, coverage, adhesion requirement and any post-treatment. A phrase such as bright plated does not identify the engineering finish. If a particular area must remain uncoated, show the masking boundary and permitted transition.

Coating thickness changes effective dimensions. A close bore, external thread or contact surface may need a pre-coating allowance to achieve the final fit. Recesses and exposed edges can receive different local thicknesses, so define the measurement location when it affects acceptance. If an underplate is required, include it in the specification. Confirm whether inspection reports refer to the base-machined state or finished state. Packaging should then protect the coating from contact damage and prevent treated surfaces from being confused with unfinished parts.

Cleanliness, deburring and handling for C38500

Deburring is a functional operation when edges contact wires, seals, fluid passages or an operator. Specify edges that must remain sharp and edges that need a controlled break. A blanket instruction to remove all sharp edges can unintentionally damage a sealing land or alter a small retention feature. Internal burrs at cross holes should be included in the inspection plan. Where the component has a narrow passage, verify that the cleaning method can remove chips rather than simply move them farther inside.

Cleanliness requirements vary between a general mechanical spacer and a fluid-handling or sensitive electrical component. State whether residual oil, particles, moisture or cleaning agents are controlled. If a particle-count test or gravimetric method is required, define it explicitly. Do not assume ordinary commercial cleaning meets a specialized hydraulic or medical requirement. Once cleaned, protect the component during inspection, storage and packing so later handling does not undo the specified condition. Caps, separators or sealed bags can be reviewed for the actual design.

Inspection planning and first article approval for C38500

An inspection plan should connect each important characteristic to a method, frequency and acceptance limit. Micrometers, bore gauges, thread gauges and coordinate measurement serve different geometries. The method should have suitable resolution and access for the tolerance being checked. Where a customer specifies a measurement system study or capability evidence, agree the characteristics, sample size and production conditions. Capability cannot be inferred from a single good sample or from a machine brochure.

First article approval establishes that the proposed material and process can produce the reviewed drawing. A dimensional report should identify the drawing revision and link measured results to numbered characteristics. Material and finish records should accompany it when required. Approval of a sample does not authorize later changes to alloy, coating, tooling route or critical geometry. Define the notification and reapproval process for changes. For ongoing supply, agreed sampling and lot controls provide a more useful production framework than an undefined promise of perfect quality.

Electrical, fluid and mechanical application checks for C38500

A brass part may perform a mechanical, electrical, fluid-handling or decorative function, sometimes in the same assembly. Identify which function governs material and dimensional requirements. For electrical service, contact force, finish, resistance and temperature rise may matter more than exterior appearance. For a fluid connection, sealing geometry, material compatibility and pressure qualification need review. For a mechanical insert, pull-out strength, torque resistance and installation temperature may control the design.

A component supplied to a drawing does not automatically carry the certification of a finished cable gland, valve, connector or enclosure. If a listing, pressure test, ingress-protection result or hazardous-area approval is required, identify the exact product and scope. The component specification can then reflect the approved design and test requirements. This distinction helps buyers request the evidence they actually need and prevents a general material statement from being mistaken for a verified assembly performance claim.

Corrosion, environment and restricted-substance review for C38500

Define the service environment during material selection. Moisture, salts, ammonia, cleaning chemicals, temperature and contact with dissimilar metals can affect brass performance. A general claim of corrosion resistance is not an exposure assessment. Residual stress and chemical environment can matter for stress corrosion, while water chemistry and alloy selection affect dezincification considerations. Where a specific corrosion test is needed, state the method, exposure and acceptance criterion instead of relying on a broad grade description.

Restricted-substance requirements should be evaluated against the actual alloy, finish and destination. A conventional leaded brass should not receive an unqualified lead-free statement. Any compliance declaration must identify its scope and applicable requirements; available exemptions and customer restrictions require current review. Where a buyer requires low lead, request a defined composition limit and supporting evidence. A material certificate, a regulatory declaration and an application approval are separate documents, each answering a different purchasing or engineering question.

Production quantities, repeat supply and packaging for C38500

Quotation quantities should include the immediate order and expected annual demand. A prototype may use a different economical setup from a recurring production batch, so identify the intended stage. Tooling, special gauges and sample approval can affect the first order even when the finished component is small. Ask for a realistic production and inspection scope rather than assuming that every drawing is available from stock. The minimum order quantity and delivery schedule should be confirmed for the actual part.

Repeat orders should reference the approved part number, drawing revision, material and finish. Where variants look similar, use clear labels and separated packaging to reduce receiving errors. Packing can be specified by count, weight, tray, bag or another agreed arrangement. Fine threads and cosmetic surfaces may need protection against metal-to-metal contact. Export requirements should identify destination, shipment terms and any special documentation. Combining those details with the technical specification makes the quotation easier to compare and the resulting purchase order easier to execute.

Price, weight basis and a complete request for quotation for C38500

The listed product rate is US$ 14.50/kg. State the ordered weight basis and component scope in the quotation so that the price can be interpreted consistently. A per-kilogram rate should not be confused with a per-piece price. For an illustration only, a finished component weighing 20 grams represents 0.020 kilograms, giving a simple weight calculation of US$ 0.29 at the listed rate. This arithmetic does not independently define tooling, taxes, shipping, inspection or other commercial terms.

For a firm quotation, send the drawing and revision, required alloy, quantities, annual demand, thread specification, final finish and inspection documents. Include the destination and any sample approval, testing or special packaging. Identify whether the quoted weight refers to finished parts and how individual unit mass will be established. Where a complex component needs forging tooling, unusual machining or a special test, those requirements should be reviewed expressly. Written agreement on the complete scope protects both purchasing and production from assumptions.

Related Brass Alloy Product Pages

Compare the related brass grades and manufacturing routes below, or return to the main screw machine parts product family.

• C36000 / CDA 360 Brass Screw Machine Parts
• C35300 / CDA 353 Brass Screw Machine Parts and Screw Machine Components
• C69300 / CDA 693 Lead Free Brass Components and Screw Machine Parts
• C37700 / CDA 377 Forged and Machined Brass Parts and Components
• Brass Screw Machine Parts — Main Product Family