Custom Sealing Parts and O-Ring Manufacturing
From custom O-rings to drawing-based sealing parts, we support prototype to production with fast engineering feedback, MOQ from 1 piece, and no mold fees for standard circular profiles.
Overview
Not every sealing application fits a standard size chart. We support both custom O-rings and drawing-based sealing parts manufactured to your exact dimensional, material, hardness, and color requirements. Because we operate an in-house mold shop, we can move from your drawing or sample to a cured part in days, not weeks.
This service is designed for OEM buyers, maintenance teams, and engineers who need more than an off-the-shelf size. If the requirement is non-standard, under development, or tied to a specific groove or assembly condition, we can review it and recommend the most practical manufacturing approach.
Our custom manufacturing capability spans over two decades of elastomer processing experience. We work with high-precision CNC mold machining, vacuum compression molding, and liquid silicone injection systems to deliver parts that meet tight tolerances across a wide hardness and temperature range. Whether you need a single prototype for validation or a recurring production batch with lot traceability, our workflow adapts to your program requirements.
Many of our customers arrive with a failed seal, an obsolete part number, or a new assembly where no standard size exists. In these cases, our engineers evaluate the groove geometry, operating environment, and mechanical loads to propose a manufacturable design. We also cross-reference discontinued sizes and competitor specifications to minimize your redesign effort.
For R&D and product-development teams, we offer rapid prototyping with engineering feedback at every stage. This collaborative approach reduces the risk of costly redesigns later in the product lifecycle. We understand that a sealing component is often the last item specified but the first point of failure—so we treat custom projects with the urgency and precision they deserve.
All custom parts are produced under our ISO 9001 quality system, with optional material certifications, dimensional reports, and RoHS/REACH declarations available on request.
What We Can Customize
Custom Dimensions
Any inside diameter (ID) and cross-section (CS) combination is achievable through our cut-and-vulcanize or direct-molding processes. We manufacture from micro-size O-rings as small as 1 mm ID up to large-diameter flange seals exceeding 2 meters in diameter. For non-circular or irregular profiles, we machine cavity plates in-house to match your drawing exactly. Tolerances can be held to ±0.05 mm for precision applications, with tighter tolerances available on request for critical aerospace or medical assemblies.
Material Selection
NBR, FKM, EPDM, VMQ (Silicone), PTFE, and specialty compounds are available from our compound library. This includes FDA-compliant grades for food-contact equipment, USP Class VI elastomers for medical devices, NSF 61 certified compounds for potable water systems, and ultra-low-temperature grades capable of sealing at -60°C. We also stock conductive silicone, metal-detectable elastomers, and high-purity FFKM for semiconductor applications. If your specification references an ASTM D2000 line call-out, we can match it directly.
Hardness and Color
Standard hardness ranges from 40 to 90 Shore A, with intermediate grades available in 5-point increments. Colors can be specified for material identification, brand alignment, or visual leak-detection purposes. We offer black, brown, green, red, blue, white, yellow, orange, and translucent options, with custom Pantone matching available for silicone grades. Color consistency is monitored batch-to-batch using spectrophotometric measurement for applications where appearance is critical.
Special Profiles
Beyond circular O-rings, we manufacture square-cut rings, X-rings (quad rings), backup rings, D-rings, and custom cross-sections for unique groove geometries. Special profiles often deliver better sealing performance in reciprocating or rotary applications by reducing friction and improving lubricant retention. Our in-house mold shop can produce single-cavity prototype tools within 48 hours, allowing you to validate profile geometry before committing to production tooling.
Drawing-Based Parts
Send a 2D drawing in PDF or DWG format, a 3D model in STEP or IGES, or even a marked-up sample photo for non-standard sealing parts, OEM replacements, and development-stage components. Our engineering team reviews every submission for manufacturability, highlighting potential issues such as undercut geometry, insufficient draft angles, or compression-set risks. We respond with a formal feasibility assessment, recommended tolerance adjustments, and a detailed quotation within 24 hours.
Prototype and Small-Batch Runs
Low-volume production is ideal for validation builds, pilot runs, maintenance spares, and urgent replacements before full production quantities are released. Minimum order quantity starts at 1 piece for standard profiles, with no mold tooling required. This flexibility allows design engineers to test multiple design iterations without committing to high-volume tooling costs. Lead times for prototype batches are typically 3-5 days from drawing approval to shipment.
Typical Project Types
Custom O-Rings
Non-standard inside diameters, cross-sections, special tolerances, and low-volume prototypes for new projects or difficult replacements are manufactured using either cut-and-vulcanize cord or direct compression molding. Cut-and-vulcanize is cost-effective for large diameters and low volumes, while molded parts deliver superior dimensional consistency and surface finish for high-precision applications. Our engineers will recommend the optimal process based on your quantity, tolerance requirements, and lead-time constraints.
Special Sealing Profiles
Square rings, X-rings, backup rings, and other profile changes are produced to match groove geometry, pressure conditions, or installation constraints that standard O-rings cannot satisfy. X-rings, for example, provide dual-sealing surfaces and reduced breakout friction in dynamic reciprocating applications. Backup rings in PTFE or hard elastomer prevent extrusion gaps under high-pressure hydraulic conditions. Each special profile is reviewed for gland fill ratio and compression set before tooling begins.
OEM and Replacement Parts
Drawing-based parts for existing equipment, discontinued sizes, imported machinery, and private-label replacement programs are a core strength of our custom service. We routinely reproduce seals for machinery where the original supplier has gone out of business or the part number has become obsolete. Our process includes dimensional verification against the original sample, material property matching using FTIR spectroscopy when required, and production under full lot traceability for regulated industries.
Large-Diameter and Low-Volume Jobs
Practical support for flange seals, pressure vessel rings, and oversized parts where standard stock is not available is delivered through our specialized large-diameter vulcanizing equipment. Diameters exceeding 1 meter are produced by precision cutting and hot-vulcanizing extruded cord on CNC joining machines, achieving joint strength exceeding 80% of parent material. For critical static flange applications, we also offer spliced and bonded construction with 100% leak testing on request.
How to Order Custom Parts
Submit Drawing or Sample
Send us a CAD drawing, dimensional sketch, or physical sample. Include material, hardness, quantity, and application details such as operating temperature, pressure, fluid media, and motion type. The more complete your technical package, the faster we can assess feasibility and provide accurate pricing. If you are unsure about any parameter, our engineers will guide you through the minimum information required for a valid quotation.
Engineering Review
Our engineers review your specifications for manufacturability and recommend the most efficient molding approach. This includes evaluating compression rate, gland fill, draft angles, undercuts, and tolerance stack-up. If the design presents a risk of flash, trapped air, or insufficient cavity fill, we flag it early and propose corrective geometry. This review typically completes within 24 hours and is provided at no charge.
Tooling and Sampling
For standard circular cross-section profiles, no mold fee applies because our in-house mold shop can machine cavity plates quickly and cost-effectively. Custom profiles requiring unique tooling geometry are quoted with transparent mold cost and amortization options. First-article samples ship in 3-5 days and include a dimensional inspection report and material certificate. Sample approval can be conducted via video inspection or physical shipment.
Approval and Production
Once samples are approved, we schedule production with a standard lead time of 7-15 days depending on quantity and material availability. Production runs are monitored through our ISO 9001 process control system, with in-process dimensional checks and visual inspection at defined intervals. Final inspection reports, material batch certificates, and custom labeling are available on request to support your incoming quality procedures.
Custom Order Process
Input & Review
Submit your drawing, sample, or dimensional specification. Include operating conditions (temperature, pressure, fluid, motion) so our engineers can assess manufacturability and recommend the optimal process.
Deliverable: Feasibility assessment + formal quotation within 24 hours
Duration: 24 hours
Tooling & Sampling
For standard circular profiles, no mold fee applies. Custom profiles receive transparent tooling cost and amortization options. First-article samples are produced with full dimensional inspection and material certification.
Deliverable: First-article samples + dimensional report + material certificate
Duration: 3–5 days
Validation
Test samples in your actual application or accelerated conditions. Provide feedback on fit, function, and performance. Our engineers adjust compound, hardness, or groove recommendations based on validation results.
Deliverable: Revised specification + updated quotation if changes required
Duration: Customer-dependent
Production
Approved parts move to production under ISO 9001 process control. In-process checks, 100% visual inspection, and batch hardness testing ensure consistency. Full documentation is provided with every shipment.
Deliverable: Production batch + inspection report + CoC/MTC as required
Duration: 7–15 days standard
What You Can Customize
Almost every parameter of an O-ring can be tailored to your application. Use this matrix to identify which customizations are available and their typical lead-time impact.
| Parameter | Standard Range | Custom Range | Tooling Impact | Lead-Time Impact |
|---|---|---|---|---|
| Inside Diameter | AS568 / ISO 3601 catalog | Any ID from 1 mm to 2,000 mm | None for standard CS | No impact |
| Cross Section | 1.02–8.40 mm standard | Any CS from 0.5 mm to 20 mm | None for standard profiles | +2–3 days for non-standard |
| Material | NBR, FKM, EPDM, VMQ, PTFE | 200+ compounds including FDA, USP, aerospace | None | No impact if in stock |
| Hardness | 70 Shore A default | 40–90 Shore A in 5-point increments | None | No impact |
| Color | Black (NBR/FKM), Brown (FKM) | Any Pantone match for VMQ; standard pigments for others | None | No impact |
| Profile | Round O-ring | Square, X-ring, D-ring, backup ring, custom geometry | Required for non-circular | +3–5 days for mold |
| Tolerance | AS568 Class 1 / ISO Grade N | AS568 Class 2 / ISO Grade S or CS | None | +30–100% cost for CS |
| Certification | Standard CoC | USP Class VI, FDA, REACH, RoHS, PPAP, FAIR | None | +1–2 days documentation |
No Mold Fee Policy
For any O-ring with a standard circular cross-section, we do not charge a mold fee even for custom inner diameters. This is possible because our in-house mold shop can machine cavity plates quickly and cost-effectively. Mold fees apply only to complex non-standard profiles that require unique tooling geometry.
What to Send With Your RFQ
- Part drawing, sketch, or clear dimensions
- Material requirement or service media
- Operating temperature, pressure, and motion type
- Quantity, target lead time, and sample requirement
- Photos or sample notes for replacement parts
Frequently Asked Questions
Do you charge mold fees for custom sizes?
No mold fees apply to standard circular cross-section profiles with custom inner diameters. Mold fees apply only to special profiles, custom shapes, or tooling that requires a unique cavity geometry. For these cases, we provide a transparent mold cost quotation with amortization options for larger production volumes.
What is the minimum order quantity for custom parts?
MOQ starts at 1 piece. We accept prototype quantities for validation before you commit to larger production runs. This applies to standard circular profiles. For complex multi-cavity tooling, the practical minimum may be higher, but we will discuss this during the feasibility review stage.
How do I send you a drawing?
Email your drawing to yaoqingpu1983@gmail.com or upload the details through the quote request form. We accept PDF, DWG, DXF, STEP, IGES, and common image formats. If you only have a physical sample, send it by courier to our factory address with a note describing the application and operating conditions.
Can you match a competitor's material specification?
Yes. If you provide the compound specification or ASTM D2000 callout, we can match or exceed the required properties. We can also perform FTIR analysis on a competitor sample to identify the base polymer and fillers, then propose an equivalent or improved formulation from our certified compound library.
Do you provide samples before full production?
Yes. We strongly recommend first-article samples for new custom sizes and development-stage parts. Sample lead time is typically 3-5 days for standard profiles and 5-7 days for special profiles. Samples include a dimensional inspection report and material batch certificate. Approval can be by email confirmation or formal signed sample approval form.
Do you only make custom O-rings?
No. We supply both standard catalog sizes and custom-made parts. This page focuses on custom work, but many customers order standard and custom sealing parts together in the same project. Consolidating your purchase often reduces shipping costs and simplifies incoming inspection.
Can you review OEM replacement parts from a sample or photo?
Yes. If a drawing is not available, send a physical sample or clear photos with critical dimensions marked. Include any visible part numbers, color, hardness estimates, and a description of the equipment manufacturer and model. We can usually evaluate feasibility and suggest the best way to reproduce the part within 24 hours.
What tolerances can you hold on custom molded parts?
For standard O-ring profiles, we typically achieve tolerances per ISO 3601-1 Class B or AS568 standard. Tighter tolerances down to ±0.05 mm are achievable for precision applications in medical, aerospace, or semiconductor equipment. Tolerance capability is confirmed during the drawing review stage before any tooling is committed.
Can you produce custom parts with metal inserts or bonded components?
Yes. We offer rubber-to-metal bonding for applications requiring structural attachment or anti-rotation features. Metal inserts can be stainless steel, brass, or aluminum, prepared with chemical bonding agents and over-molded in a secondary operation. Bonded parts are 100% pull-tested to verify adhesion strength before shipment.
Do you support color matching for branding or material identification?
Yes. We offer custom color matching for silicone and many thermoset elastomers using Pantone references or physical color chips. Color consistency is monitored spectrophotometrically batch-to-batch. This service is popular for medical device manufacturers who need color-coded seals for different fluid lines, and for OEMs who want brand-aligned component aesthetics.
Ready to Start Your Custom Order?
Send us your drawing, sample, or standard size requirement for a fast technical quote and manufacturing review.