Ordering a standard FRP pultruded section — a channel, angle, or square tube in a stocked size — is a relatively straightforward procurement transaction. The manufacturer has existing tooling, published load data, and known lead times. Ordering a custom section is a different kind of engagement. The buyer is asking the manufacturer to produce tooling that doesn’t exist, to verify structural performance for a geometry that hasn’t been tested before, and to commit production capacity to a part that may have no secondary market if the relationship ends. Getting this process right requires a different level of preparation on the buyer’s side.
The following covers what manufacturers actually need to process a custom section request, where miscommunication most commonly occurs, and how to structure the initial submission to get a usable quotation.
What “custom” means in pultrusion
Pultrusion is a continuous manufacturing process — fiber reinforcement is pulled through a resin bath and then through a heated die that shapes the cross-section. The die is the tooling. Every unique cross-section requires its own die, and dies for structural FRP profiles are precision-machined steel tools that cost real money to produce. A simple custom angle or channel die runs in the range of several thousand dollars depending on complexity; a multi-cavity die or a complex hollow section with internal webs can be significantly more.
This tooling cost is typically charged to the buyer as a one-time setup fee, amortized across the first order or held separately depending on the manufacturer’s commercial terms. It’s not negotiable in the same way that unit pricing is, because the tooling is a physical asset the manufacturer must produce regardless of order volume. Understanding this upfront prevents the common situation where a buyer receives a quotation, sees the tooling line item, and treats it as a negotiating point rather than a fixed cost of the engagement.
Custom also means that the mechanical properties of the finished section must be verified rather than assumed from published data. Standard sections have tested load tables. A new section profile has the same fiber and resin inputs as an equivalent standard section, but the geometry affects structural performance in ways that require calculation — or in some cases, physical testing — before the data can be stated with confidence. Buyers who need certified structural data for a custom section should raise this requirement at the inquiry stage, not after tooling is committed.
What to include in the initial drawing package
The drawing package for a custom FRP pultruded section should include the following:
Cross-section geometry. A dimensioned drawing of the cross-section with all critical dimensions called out explicitly: overall height and width, wall thickness at each face, internal fillet radii at corners, and the location of any holes, slots, or features that are part of the pultruded form (as opposed to secondary machining). Dimensions should be in metric or imperial consistently throughout — mixed units in a drawing create conversion errors that persist through tooling production.
Length and tolerances. The required cut length of each piece, and the acceptable tolerance on that length. Standard pultrusion cut tolerances are typically ±3mm on length; tighter tolerances require secondary machining and add cost. Cross-section dimensional tolerances should also be stated — standard wall thickness tolerance in pultrusion is approximately ±10% of nominal thickness, and overall dimension tolerance is typically ±0.5mm to ±1mm depending on the section size.
Quantity. Both the initial order quantity and the anticipated ongoing volume. Tooling economics look different at 50 meters per year versus 500 meters per year. Some manufacturers set minimum order quantities for custom sections that reflect the setup cost relative to the production run; knowing the buyer’s volume expectation upfront allows the manufacturer to quote the tooling cost appropriately.
Material specification. The resin system required — polyester, vinyl ester, or epoxy — and any flame retardancy or UV resistance requirements. If the section will be used in electrical applications, the dielectric specification should be stated. If chemical exposure is a factor, the specific chemicals and concentrations the section will contact should be listed so the manufacturer can confirm resin compatibility.
Surface finish. Whether the section needs a veil layer on exterior surfaces (which improves UV resistance and surface quality but adds cost), and any color requirements. FRP pultrusions can be produced in colors by adding pigment to the resin, but standard colors vary by manufacturer and custom colors may carry a minimum quantity requirement.
Where the drawing review stage matters
Most manufacturers will review a submitted drawing before confirming quotation, specifically to identify features that create production difficulties or that the buyer may not have intended. Common issues that surface at this stage:
Wall thicknesses that are inconsistent across the section. Pultrusion achieves its mechanical properties partly through consistent fiber density across the cross-section. A section with one face significantly thinner than others may have fiber architecture problems during processing. Manufacturers who flag this are doing the buyer a service, not creating obstacles.
Internal corners with no fillet radius. Sharp internal corners in a pultruded section are a stress concentration point and can create fiber bridging problems during production. A minimum internal fillet radius — typically 3–5mm for most structural sections — should be assumed unless the design specifically requires otherwise.
Features that require secondary operations. Holes, slots, and cutouts that appear on the cross-section drawing may be interpretable as either pultruded-in features (machined into the die and present in every linear meter of the section) or as secondary machined features (cut into individual pieces after pultrusion). These are very different in cost and lead time. The drawing should make clear which features are part of the cross-section geometry and which are applied to specific pieces.
Tooling ownership and terms
The question of who owns the tooling — and what happens to it if the commercial relationship ends — should be addressed in the purchase order or supply agreement, not left to assumption. Standard practice varies: some manufacturers retain ownership of custom tooling as a condition of the low tooling charge; others transfer ownership to the buyer upon payment.
Tooling ownership matters if the buyer wants to move production to a different manufacturer, or if they want to store the tooling and restart production after a gap. A manufacturer who retains tooling ownership is not obligated to maintain or store it indefinitely if the buyer stops ordering. For FRP pultruded profiles that are components in long-term infrastructure or equipment, tooling continuity is a supply chain risk worth addressing contractually before the first order.
Lead time expectations for custom sections
Tooling production is the long pole in a custom section project. Die manufacture for a simple profile typically takes 4–8 weeks from drawing approval; complex multi-cavity or hollow section dies can take longer. First article samples — the initial production run to verify that the section meets dimensional and performance requirements — add additional time before full production begins.
Buyers who treat custom FRP section procurement like standard catalog purchasing, and expect delivery timelines equivalent to standard sections, consistently have problems. The timeline for a new custom section from drawing submission to first production delivery is realistically 10–16 weeks for a simple profile, and longer for anything with elevated complexity. This needs to be built into the project schedule at the outset, not discovered when the quote comes back with a lead time the buyer wasn’t expecting.
The alternative — sizing the design to use a standard stocked section rather than a custom profile — eliminates the tooling cost and the extended lead time entirely. It’s worth asking at the design stage whether a standard section can be made to work before committing to custom tooling.
