Corner radii and thin sections are easy to overlook on a custom silicone profile drawing. A section may appear clear in CAD, yet the same geometry can behave differently during extrusion, cooling, handling and installation. Sharp internal corners can concentrate deformation, while a thin web beside a heavy section may respond differently from the rest of the profile. These details deserve review before a supplier prices tooling or prepares samples.
The objective is not to apply one universal minimum radius or wall value. It is to show which geometry is functional, explain how the profile fits the assembly, and let the supplier review the complete section. Buyers can use the questions below when preparing an RFQ for custom silicone profiles.
Mark functional and non-functional corners
Start by identifying what each corner does. An outside corner may locate the profile against a housing, provide a visible edge, or simply connect two surfaces. An inside corner may clear a mating feature, form the base of a sealing lip, or create a hinge-like area during installation.
Do not assume every corner must remain perfectly sharp. If a radius can be adjusted without affecting fit, mark it as non-critical or invite a supplier proposal. If a corner controls assembly clearance or sealing contact, provide the mating geometry and explain the acceptable contact region. This helps the supplier distinguish a drawing convention from a functional requirement.
Review thin sections in context
A thin feature cannot be evaluated from its nominal thickness alone. Its length, orientation, neighboring mass, material hardness, and role during installation all matter. A short flexible lip may behave differently from a long unsupported web with the same thickness.
For each thin section, clarify:
- whether it seals, flexes, wipes, covers, or only connects larger features;
- whether it is stretched, folded, compressed, or pulled during assembly;
- the available clearance around the feature;
- whether the free-state shape or installed shape controls acceptance;
- which edge, tip, or surface is critical to function.
Ask the supplier to review the transition between thin and thick areas. A gradual transition may be easier to evaluate than an abrupt step, but any change must still respect the assembly. The supplier should respond to the actual cross-section rather than offer a generic wall-thickness statement.
Show the complete mating interface
A profile drawing is more useful when it includes the channel, groove, cover, clamp, panel, or other surfaces that constrain it. Provide an assembly section or a separate interface drawing with the relevant dimensions. Indicate insertion direction, compression direction, and any movement expected in service.
If only part of the interface can be shared, describe the functional envelope and the intended contact points. State whether the profile must remain in a groove before final assembly, whether lubricant or adhesive is considered, and whether corners must pass around bends. These details often explain why a radius or thin lip is present.
Avoid conflicting dimension chains
Crowded profile drawings sometimes define the same feature through several linked dimensions. Individual values may appear reasonable while their combined limits create an inconsistent section. Thin walls and small corner regions are especially vulnerable to this problem because adjacent dimensions can consume the available space.
Choose dimensions from stable datums and identify which values control. Mark reference dimensions clearly. If a corner radius is defined together with both tangent locations and an overall width, explain which feature takes precedence if the numbers do not reconcile exactly. Ask the supplier to flag closed or conflicting tolerance chains before tooling.
General title-block tolerances may also be inappropriate for every feature in a flexible extrusion. Separate critical interface requirements from informational geometry and supplier-review dimensions. This creates a more useful discussion than assigning a tight default tolerance to the whole section.
Define how the section will be inspected
Flexible profiles can deform under contact pressure, cutting, lighting, or sample preparation. A thin lip may move when a caliper touches it, and a cut section may not represent the profile in its free, unstrained state. Corner radii can also be difficult to compare without an agreed viewing or measurement method.
Before sample approval, discuss:
- whether inspection uses a profile projector, optical method, fixture, gauge, or another agreed approach;
- how samples are cut and conditioned;
- where along the extrusion measurements are taken;
- how the section is supported without unwanted deformation;
- how many readings or sections are reviewed;
- how visual observations and dimensional records are documented.
The appropriate method depends on the section and project. The RFQ should request a proposed method rather than assume that every corner and thin feature can be verified with the same handheld tool.
Use samples to confirm handling and fit
Sample review should cover more than a flat dimensional report. Check how the profile is identified, uncoiled, cut, routed and installed. Observe whether a thin feature folds, twists, sticks to an adjacent surface, or becomes trapped during assembly. Confirm that corner geometry clears the mating parts and that the intended contact surfaces engage as expected.
Record the drawing revision, material description, sample length, lot or sample identification, and agreed inspection method. If fit trials lead to a geometry change, update the controlled drawing instead of relying on an annotated email or unlabeled sample. A reference sample can support communication, but it should not silently replace the specification.
Prepare a supplier-review package
A practical profile RFQ should include:
- A complete, scaled cross-section with units and revision control.
- Functional notes for corner radii, thin lips, webs and transitions.
- Mating geometry or an assembly envelope.
- Critical datums, controlling dimensions and clearly marked references.
- Installation direction, bending, stretching and compression conditions.
- Material and hardness questions for project review.
- Proposed inspection, sampling and approval expectations.
- Supply length, joint, packaging, labeling and quantity-stage information.
Clear geometry and application context allow engineering, quality, procurement and the extrusion supplier to review the same section. They also reduce the risk that a supplier interprets a sharp CAD corner or thin wall as a universal requirement that cannot be discussed.
To request a project-specific drawing review, submit the cross-section, mating interface, quantity stage and inspection questions through the Forvard Tech RFQ form.