Urethane Casting for US Product Teams: Compare Bridge-Batch Options

For a short US urethane-casting batch, Xometry gives casting-specific quantity and US production guidance; Fathom lists casting among several bridge-production methods.[2][3] Compare those options first, then request quotes against the same master, resin, tooling and acceptance requirements.

Compare Xometry and Fathom

Xometry

• Process choices: A 3D-printed master pattern creates room-temperature-vulcanizing (RTV) silicone tooling, which is used to cast urethane or silicone parts.[2]
• Quantity guidance: Xometry identifies one to 100 parts as suitable and gives 50 pieces as an example of low-volume production.[2]
• US service coverage: The service page lists domestic US-based production and an international economy option.[2]

Fathom Manufacturing

• Process choices: Fathom lists urethane casting alongside additive manufacturing, sheet-metal fabrication/prototyping, photochemical machining, metal or plastic CNC machining, and rapid tooling for injection molding.[3]
• Quantity guidance: Its several-hundred or several-thousand-part guidance covers bridge production generally, not casting specifically.[3]
• US service coverage: Fathom describes itself as a U.S. contract manufacturer with eight U.S. locations; confirm which site would run the casting.[3]

Xometry provides a direct starting point for a casting-specific inquiry.[2] Fathom offers a broader process comparison if the manufacturing route remains undecided.[3] Ask both providers for comparative completed-part performance results before making an overall quality ranking.[2][3]

Separate cast-resin validation from production-resin approval

“ABS-like” and “polycarbonate-like” describe urethanes that mimic thermoplastic characteristics—not the intended injection-molded thermoplastics, as Xometry’s “-like” naming implies.[2] Ask Xometry and Fathom for evidence of equivalence in tensile strength, impact, creep, chemical resistance, UV aging, temperature cycling or long-term durability.[2][3]

Define what the batch must demonstrate:

• Appearance and assembly: Evaluate samples against agreed visual criteria and document fit with mating components. Keep those conclusions separate from production-resin approval.
• Material performance: Specify application-specific test evidence comparing the proposed cast resin with the intended production resin under relevant loads and exposures.

Ask the quote to identify the casting resin, technical data sheet, required properties and substitution-approval process. Xometry says equivalent materials may be used depending on availability and work location, so a material named on its page is not a project-specific commitment.[2]

Approve master-dependent finishes before tooling

Xometry describes the master as the final-part pattern, with the cured silicone cavity taking its shape.[2] Resolve these master-dependent finishes before authorizing tooling:

• High gloss: Polish the master before mold creation.[2]
• Matte/frosted: Use a bead-blasted matte master.[2]
• Texture: Apply paint and manual techniques to the master before making the tooling.[2]

Identify cosmetic faces, finish references and which treatments belong on the master versus the cast parts. Xometry also offers painting and secondary finishing, so not every appearance requirement is created in the mold.[2] Its page says polishing and custom finishes must be defined and agreed at order placement.[2]

Request a finish-approval gate before tooling rather than assuming it is part of the supplier’s workflow.

Set the controlling dimensional reference

Ask Xometry and Fathom to confirm precedence among customer CAD, drawings, the approved master, first articles or golden samples.[2][3] Agree on a revision-controlled hierarchy: identify each reference, its revision and what it controls. Specify who resolves discrepancies before affected work proceeds.

Xometry states expected shrinkage of +0.15%, not a universal acceptance tolerance.[2] It cautions that irregular or overly thick geometries may deviate or deflect, and its tolerance table assumes adequate draft, radii and coring. Sharp corners and text may appear slightly rounded.[2]

Ask the supplier to confirm critical dimensions, project-specific tolerances and inspection methods. Limit appearance approval to appearance; document dimensional approval separately.

Confirm ownership and control of the master

Ask Xometry and Fathom to confirm master ownership, return, custody, storage, reuse rights, intellectual-property assignment and destruction policies.[2][3] Request contract language covering:

• Who owns and holds the master, and how to obtain its return.
• Who may authorize reuse or transfer, and who controls the approved revision.
• What happens to the master and silicone tooling when the project ends, including storage, return or authorized destruction.

Address ownership and physical possession separately in the order.

Set mold-copy limits and replacement authorization

Xometry says silicone molds wear faster than CNC-machined metal injection molds, but its cited casting page gives no numerical mold life or guaranteed-copy figure.[2] Request a tooling allowance tied to the required accepted-part quantity:

• Define the allowance: Specify the planned number of molds, allowed casts or copies per mold, whether trials and rejects consume the allowance, retirement criteria, and who pays if usable yield falls short.
• Control replacements: Agree on replacement-mold pricing, ownership, lead time and authorization. Define any automatic-replacement permission and spending limit; otherwise, require written approval before replacement work begins.

Xometry says different materials can be tested in the same mold.[2] If proposed, ask the supplier to confirm compatibility, changeover conditions and effects on mold life before agreeing to the copy allowance.

Define first-article and batch acceptance

Ask Xometry and Fathom to confirm first-article procedures, inspection-report requirements, sampling plans and acceptance/rejection criteria.[2][3] Propose these purchase controls rather than assuming provider workflows:

• Master/finish approval: Identify the approved master and finish references; limit signoff to characteristics checked.
• First-article approval: Specify the resin, substitution restrictions, finish references, critical dimensions and inspection evidence required before releasing the remaining batch.
• Batch acceptance: Define the accepted quantity, resin and finish requirements, dimensional checks and delivery inspection records.

Include sampling, treatment of nonconforming parts, rework or replacement remedies, and the person authorized to release the remaining batch. Keep material-validation approval separate from visual and dimensional acceptance.

What to confirm with each provider

Ask Xometry and Fathom to confirm project-specific prices, payment schedules, quote validity and cancellation/refund terms.[2][3] Send both suppliers the same RFQ, covering:

• Accepted-part quantity, delivery location and schedule.
• Exact resin, required properties and permitted substitutions.
• Master revision, finish references and controlling dimensional reference.
• Master and tooling ownership, custody and reuse rights.
• Inspection, approval and batch-acceptance criteria.
• Mold-copy allowance, treatment of rejects and replacement authorization.
• Separate master/tooling, finishing, inspection, replacement and per-part charges.
• Quote validity, payment and cancellation terms.

Choose against the same written specification, resolving—or explicitly accepting—remaining unknowns before authorizing work.

References

2. Urethane Casting Parts on Demand – Cast Urethane and Silicone Parts Service (xometry.com)
3. Bridge Production – Fathom Manufacturing (fathommfg.com)