FRP Pultrusion Cases: Die & Puller Component Protection

A scratch inside a pultrusion die differs fundamentally from other transit damage: every mark in the cavity is reproduced continuously along the whole profile. Pultrusion is a continuous process. Fibre tows pass through the same cavity length without interruption, so any raised burr or depression on the cavity wall is stamped onto the product surface at a frequency tied to the pulling speed, producing regular longitudinal defects. These cannot be corrected downstream; the die must be re-polished or replaced. The priority in a glass reinforced plastic equipment case is therefore not load capacity but whether the cavity stays clear of every hard surface. Around it, puller pads, clamping cylinders, metering pumps and ceramic guide eyes each carry their own sensitive face, and the packing system has to protect all of them while keeping the load path in the structure.

This article is written for equipment and process teams at FRP profile plants, pultrusion line integrators, die makers and spare parts distributors. It covers cavity surface protection, die straightness and lifting, puller and drive components, creel and guide parts, resin bath and metering systems, heating and cutting parts, case structure and ocean-freight moisture protection, and acceptance criteria, closing with a selection matrix, cost structure, FAQs and further reading.

Contents

• Process layout and where the components sit
• Pultrusion dies: why the cavity tolerates nothing
• Cavity protection and end plug design
• Support, lifting and straightness of long dies
• Puller pads, belts and clamping assemblies
• Puller gearboxes and drive chains
• Creels, guide plates and tension parts
• Resin bath and metering systems
• Heating platens, controls, cutting and electrical parts
• Case structure, sealing and moisture protection at sea
• Testing and acceptance criteria
• Selection guidance and cost structure
• Customisation workflow and handover
• Frequently Asked Questions
• Conclusion and related reading

Process layout and where the components sit

A complete pultrusion line starts at the creel, runs through guide and tension control into the resin bath, then through a preforming plate into the heated die. The cured profile leaves the die and is pulled continuously before entering the cutting and post-cure sections. The components fall into five functional groups with clearly different transit risks.

Creel and guiding covers spindle shafts, guide hole plates, ceramic guide eyes and tension bars. Ceramics are hard but brittle; a chipped edge sitting in the fibre path abrades the tow and builds up debris. Impregnation and metering covers the resin bath, doctor blade, preforming plate and metering pumps, where the risks are bath distortion and contaminated fits. The die group covers the pultrusion die body, preforming die and mandrels for hollow profiles, with risk concentrated at the cavity and the parting face. Puller and drive covers pads, belts, clamping cylinders, gearboxes and couplings, where cover compression, bent cylinder rods and corroded shaft extensions are the concerns. Heating and cutting covers platens, thermocouples, diamond blades and clamping devices, with risks of panel distortion, damaged ports and chipped teeth.

A common thread runs through the table. Most pultrusion components have a functional face and a structural face, and the packing must protect every functional face while loading only the structural one. On a die, the functional faces are the cavity and the parting face. On the puller, they are the clamping face of each pad and the sealing surface of each cylinder. On a guide eye, it is the bore. Identify those faces and half the design work is done.

Pultrusion dies: why the cavity tolerates nothing

A pultrusion die is usually a long steel block, between roughly 0.8 and 1.2 m, sometimes longer where preforming and forming sections are machined in one piece. The cavity is finish machined and polished, often to a roughness of Ra 0.2 to 0.4 micrometres, with chrome plating or nitriding applied on some dies to raise wear resistance. The cavity entry carries a chamfer and transition, and the exit end carries a sizing section.

Why scratches matter so much here. In injection moulding or compression moulding, a small surface defect affects only the parts formed at that position. In pultrusion, fibre and resin pass the same cavity length continuously, so any raised feature is stamped repeatedly at a rate tied to line speed, creating a longitudinal mark that runs the length of the profile. Structural or visible profiles in this condition are usually rejected as a batch, and the loss far exceeds the cost of die repair.

Three scratch mechanisms. Direct contact damage follows from wire rope slings around the die, tools or hardware bearing on the cavity during packing, or metal chips inside the liner. Relative movement damage occurs when the die is inadequately restrained, so vibration lets it slide in its cavity and hard particles roll across the contact face. Parting face damage occurs when the split faces are struck and raised a burr, which opens a gap during closing and produces flash while the burr itself marks the cavity edge.

A layered defence. Cavity protection, parting face protection and structural support should all be present. The cavity is protected by soft end plugs or sleeves so the internal passage stays clear, resting on centring supports at both ends. The parting face is covered by a guard strip with a rigid isolation layer outside it. Structural support is taken by the die base or by dedicated support pads, which carry the whole mass. Separating load carrying from surface protection is the key point. A single soft liner asked to do both jobs will fail at one of them.

Cavity protection and end plug design

The design sequence runs from how the cavity is kept clear, to where the supports sit, and only then to case structure and hardware.

Plugs and sleeves. End plugs serve two purposes. They close the passage against dust, debris and moisture, and they act as an end cushion that absorbs axial shock before the die face reaches the case. Soft polyurethane, expanded PE or silicone are suitable, with external diameters graded to the cavity taper and insertion depth set by the axial load to be carried. Hard materials are unsuitable, and so are materials that shed particles or leach plasticiser, because the plug then becomes the contamination source. For mandrels used on hollow profiles, the outer diameter is a fit surface, so use a full-length or segmented sleeve with end caps.

Parting face treatment. Most pultrusion dies split into upper and lower halves, and the parting face is the closing datum. Fit a soft guard strip, slightly narrower than the face so that the strip edge does not press on the cavity chamfer, and add a rigid cover outside it against external loads. Where locating pins or keys are present, cut reliefs in the cover so these features never become load paths.

Location inside the case. The die needs location in three directions. Vertical support comes from the cradle, horizontal restraint from side blocks, and axial restraint from the end plugs together with an end stop. Axial restraint is frequently forgotten, yet longitudinal acceleration makes a long die creep along its length, striking the case wall repeatedly, which damages the end face and can roll the cavity entry edge.

Access for loading and removal. Because the die is heavy, the case should allow either vertical lifting out or horizontal sliding out on guides. If horizontal removal is chosen, fit internal rails and rollers so the cavity never rubs on the case. If vertical lifting is chosen, leave headroom above the open case and keep the die's lifting threads serviceable. Where cavities are die cut, check that no hard burr remains at the cut edge; process details are described in the custom EVA insert process.

Support, lifting and straightness of long dies

A pultrusion die can weigh several hundred kilograms to over two tonnes, and above about a metre long, self-weight deflection is no longer negligible.

Support layout. Use at least three supports on the two-ends-plus-middle principle, located at the die support pads or designed load faces rather than on the cavity edge. Spacing should be calculated from section inertia and permitted deflection, with permitted deflection taken as no more than half the straightness requirement and a dynamic factor of 1.5 to 2.0 applied. Long dies need four or more supports, with an internal support beam where the case length limits the options.

Lifting. Dies normally have lifting threads, so use matching eye bolts or dedicated gear. Never sling directly around the die body, and never apply a sling load across the cavity or parting face. Keep sling angles within 60 degrees to avoid horizontal components squeezing the die body. If no lifting points exist, agree additional ones with the die maker at design stage rather than improvising a sling route on site.

Preventing bending and twist. Beyond vertical support, watch torsion. A long die supported only at mid-length cantilevers at both ends and deflects visibly; asymmetric supports introduce twisting that harms parting face fit. Keep supports symmetrical and add auxiliary support at the ends to limit cantilever deflection. Store the die in a stable attitude, vertical or horizontal, rather than at an angle where restraint becomes uncertain.

Shipping with the die closed. Where upper and lower halves ship clamped together, confirm that the bolt count and pattern can resist relative movement under vibration, and keep a soft guard strip in the parting gap. Where halves ship separately, design a cavity for each half based on its own centre of gravity and support points. Simply stacking the two halves is a poor choice: one cavity faces up, the other faces down, and if the intermediate protection fails the two cavities touch directly.

Puller pads, belts and clamping assemblies

The puller sets line speed and pulling force stability, and its parts are mostly covered contact elements plus pneumatic or hydraulic actuators.

Pads and covers. Caterpillar pullers use rubber or polyurethane covers to generate friction without crushing the profile. These covers suffer compression set, oil contamination and heat ageing. Avoid stacking pads on top of each other, because sustained compression can leave permanent indentations. Lay each pad flat in its own cell with the clamping face clear of hard objects. Where pads ship mounted on the chain, coil and secure the chain so links cannot press on each other, and wrap the assembly against oil.

Puller belts. Belts are flexible components at risk from creases, oil and edge wear. Coil them to no less than the maker's minimum bend diameter, since long-term small-radius storage fatigues the inner layers, and protect the edges against rubbing on the case wall.

Clamping cylinders. These are usually slender pneumatic cylinders with fragile piston rods. Support horizontally at both ends and at mid-length, never through the rod, fit a rod guard and plug the air or oil ports. Where magnetic switches or position sensors are fitted, leave clearance in the cavity so nothing bears on them.

Reciprocating clamp jaws. Reciprocating pullers use two jaw sets alternately, and the jaws carry both covered clamping faces and guide rails with sliders. Sliders are precision items and should not take lateral shock. Coat the rail surfaces with protective oil and anti-rust film, and secure the sliders inside their cavities so they cannot run off the end of the rail.

For fixed and side-load practice on linear motion components, see packing notes for linear actuator components.

Puller gearboxes and drive chains

Gearboxes, couplings and drive chains are the heavy-duty parts of a pultrusion line, and their risks differ from precision items: oil seals, shaft extensions and fits.

Gearbox attitude. Ship gearboxes in their normal mounting attitude or as the maker specifies, so that oil does not stand against one seal, and handle the breather as instructed, replacing it with a plug where oil loss is a risk. If the breather is left open, road vibration will push lubricant out of the breather and over everything else in the case.

Shaft extensions and output flanges. Cap the shaft extension, and guard the spigot and bolt holes on the output flange. Lift only from the housing eyes, never through the extension or the output flange. Where a coupling is already assembled to the gearbox, add support under the coupling so its mass is not carried by the bearings.

Chains and chain cases. Chains are flexible transmission elements. Clean them, coat with anti-rust oil and coil them securely so they cannot swing against other components. Where a chain case ships filled with oil, confirm the sealing state with the maker before dispatch to avoid leakage in transit.

Packing sequence against installation order. On a full line project, the puller usually arrives mid-installation, so it pays to number cases in installation order. This is particularly valuable for line integrators, because matching case numbers to workstations cuts site inventory time sharply.

Creels, guide plates and tension parts

Creel-area components are small, numerous, and the easiest to overlook, yet they cause disproportionate downtime on site.

Ceramic guide eyes. Ceramics are hard and brittle, and a fall or impact chips the bore edge. A chipped edge abrades fibre and gradually collects debris, eventually breaking single tows. Give every eye its own cell with soft padding, insert a soft plug into the bore, and never pack several ceramics loose in one compartment where they touch. Limit stack height so that nothing presses down on ceramic parts.

Guide and splitter plates. These are usually stainless or coated steel plates with regular hole patterns, at risk from face distortion and hole edge rolling. Store them upright or suspended so the plate face carries no load, guard the hole edges, and separate multiple plates with soft dividers to prevent face-to-face fretting.

Tension bars and sensors. Tension bars are slender and should not be stored unsupported at mid-length. Tension sensors follow the same rules as any precision measuring item: individual cavity, load path away from the sensing face, and a coiled cable with a service loop.

Spindle shafts. Spindle shafts have very large length-to-diameter ratios and bend easily. Support horizontally at several points, cap both ends, and fit anti-roll features inside the case.

Resin bath and metering systems

Impregnation and metering components contact resin, so the packing design has to handle distortion, contamination and leakage at the same time.

Bath bodies. Typically welded stainless structures with relatively thin walls, their main transit risk is wall buckling and rim distortion. Fit temporary internal bracing, clearly marked as a transit item with removal instructions before installation, or use a cradle with straps that limits rim distortion. The interior should be clean and dry, with a protective film where appropriate. If resin remains inside, temperature changes in transit will move it and then cure it, and removal becomes extremely expensive. Cleaning out uncured residue before dispatch is therefore a required operation, not an optional one.

Doctor blades and preforming plates. These parts have precision slots or holes whose dimensions set resin content. Protect slot edges from impact with a cover, separate each plate, and apply corrosion protection to the faces so that a long sea voyage does not leave rust in the slots.

Metering pumps. Gear and plunger pumps run with small clearances and are sensitive to particulate contamination. Use one cavity per pump, plug and label the inlet and outlet ports, cap the shaft extension, and seal the unit in a clean bag before fixing it in place. Do not put a pump in the same cavity as a die, because a heavy die that shifts will strike the pump directly.

Piping and hoses. Clean and plug resin lines before dispatch. Fix rigid pipes at their existing bend radius with guarded ends, and coil hoses without small-radius bends or long-term contact with hard surfaces. Where cured resin remains on internal walls, clean to the process requirement so that on-site commissioning is not delayed.

Heating platens, controls, cutting and electrical parts

Pultrusion dies are heated electrically or by oil, and the associated components and temperature control loops are numerous.

Heating platens. Platens are usually aluminium or steel with embedded heater cartridges, and the risks are face distortion and damaged cartridge ends. Store vertically or carry load on the back face so the heated face touches nothing, protect the terminals, and fit end guards on cartridges, since impact damage there is an electrical safety issue rather than a tolerance issue. Where oil channels are present, drain, dry and plug them before packing, following the same logic as cavity closure on the die.

Thermocouples and control elements. Leads are the weak point and should be coiled and secured. Measuring junctions are fine and should not be squeezed, and threaded mounting bosses need caps to protect the threads so that contact at the measuring point is not compromised at installation.

Cutting section parts. Diamond blades are hard and brittle, and chipped teeth degrade cut quality immediately. Ship blades in rigid round boxes or dedicated covers with the teeth touching nothing. Clamping and pneumatic pressing devices follow the cylinder rules above.

Electrical and control components. Control cabinets, drives and temperature modules fear moisture, conductive dust and free-fall drops. Glass fibre dust is less conductive than carbon dust but still contaminates cooling paths and terminals. Keep original packaging inside the outer case, or use a clean bag with desiccant and maintain low humidity. Where resin and hardener travel in the same consignment, keep them in separate cases so that a leak cannot reach the electrical items.

Case structure, sealing and moisture protection at sea

Structural choice follows component mass and length, while sealing and dehumidification follow voyage duration.

Structural forms. Die cases generally need high structural strength: thick plywood cases, framed timber cases or steel-timber hybrids, with reinforced longitudinal beams in the base and corner protectors outside. Puller and wear parts can travel in rotomoulded or aluminium frame cases. Keep case height moderate, because dies and pads have a low but concentrated mass, and excessive height reduces handling stability.

Internal load path. The load path must be continuous, from die cradle to base panel, from base panel to longitudinal beams, and from beams to fork pockets or lifting points. Load must not pass through thin panels or through hardware alone. Cavities and dividers are best designed as replaceable modules, so damaged sections can be swapped after transit.

Sealing and breathing. Aim for at least IP65, and IP67 for long ocean voyages. One caution: a fully airtight case creates a pressure problem. Internal air expands and contracts with temperature, and without equalisation the case draws in dust when opened. Fit and verify a hydrophobic breather valve.

Moisture and corrosion. Dies and steel components corrode readily in a humid sea voyage. Apply a thin anti-corrosion film or tape to exposed metal and close the cavity with plugs. Resin and hardener are separate compliance questions, and if they must travel with the equipment they should be sealed independently with temperature control considered. Maintain internal relative humidity at 45 to 55 percent, sizing desiccant from net volume with at least 30 percent margin.

Glass fibre dust. Fibre dust irritates skin and airways, so unpacking and cleaning should be done with protective equipment and with filtered vacuum extraction rather than blowing. Where a liner is contaminated with fibre and cannot be cleaned, replace the module.

Testing and acceptance criteria

Verification covers structure, dynamics and environment, with projects and criteria agreed in the technical protocol.

Making criteria measurable. The core criterion for a pultrusion die is the visible condition of the cavity and parting face, supported by surface inspection records before dispatch and after arrival, with roughness spot checks and straightness re-measurement where the die demands it. For puller pads the criterion is an uncompressed, uncontaminated cover; for metering pumps it is undamaged fits, intact port plugs and unbroken clean packaging.

Basis for environmental testing. MIL-STD-810H may be used to select vibration, shock, temperature and humidity methods, on the understanding that in this project the standard is a method reference only and does not constitute military certification or qualification. Domestic shipments can follow the GB/T 4857 series, and cross-border orders can apply distribution cycle simulation, with the project mix and sequence set by destination and carriage mode.

Selection guidance and cost structure

Component form, mass, transport mode and re-use cycles drive the selection. The table gives recommended schemes for common combinations.

Pultrusion is a continuous die process, so the material - continuous roving and thermoset resin - dominates cost, while the pultrusion die is a one-off steel tool amortised over volume; labour is mostly creel handling, cutting and finishing, so its share stays low. A typical breakdown is resin and reinforcement 42 to 55 percent, pultrusion die and forming tooling 8 to 15 percent, liner and cradles 20 to 30 percent, surface treatment and corrosion protection 8 to 15 percent, and hardware with marking 4 to 8 percent. Die cost tracks the profile cross-section and cavity count: a wider section or more cavities raises the tool price, so boxing long profiles in sections is usually cheaper than one oversized case and easier to lift on site.

Customisation workflow and handover

Work proceeds in five stages, each ending in a confirmable deliverable.

1. Technical input: parts list and drawings, die length and mass, cavity and parting face locations, surface roughness requirements, pad dimensions and cover condition, transport mode and route, handling equipment and re-use cycles.
2. Design and calculation: support points and cavity layout, deflection and load calculation, liner materials and guard faces, corrosion and dehumidification design, issued as drawings with the calculation note.
3. First article build: pack, lift and open-close rehearsal with the real die or an equivalent weight, plus drop screening where required.
4. Approval and trial run: confirm fit and workflow, then lock parameters and the cleaning sequence.
5. Production and pre-dispatch audit: check to the agreed sampling plan, issuing a packing list, cleaning sheet and audit sheet.

Two steps deserve separate attention on pultrusion projects. The first is a cavity inspection record: a complete inspection of cavity and parting face before dispatch, with images retained, then repeated on arrival. This is the most effective evidence when a scratch is disputed. The second is a cover condition record: any pre-existing indentation or mark on puller pads should be documented before packing, otherwise it will be attributed to transport on arrival.

On supply models, standard returnable cases come from stock, while die cases and full-line packing cases are built to drawing. For pultrusion line integrators, complete packing schemes can be matched to the installation schedule with supporting process documents. Pultrusion equipment cases are designed and manufactured by Kexin New Materials (Guangdong) Co., Ltd., and wholesale, agency, OEM/ODM production and global supply all fall within its remit. Test reports and material documentation required for dies and puller components can be issued item by item as agreed in the contract.

Frequently Asked Questions

Q: Why does the cavity of a pultrusion die suffer more than the outside of the die? A: Because pultrusion copies a defect continuously. In injection moulding or compression moulding, a small surface defect affects only the parts formed at that position, so the consequence is limited and measurable. In pultrusion, fibre and resin travel through the same cavity section without interruption, so any raised feature is stamped onto the profile at a rate set by the pulling speed, producing a longitudinal mark along the entire length of the section. Such marks cannot be corrected in later operations. On a structural or visible profile this can mean downgrading or scrapping the batch, and the cost runs far beyond repairing the die. The cavity is also finish machined and polished, often to Ra 0.2 to 0.4 micrometres, so local repair rarely restores the original finish and the die usually has to be re-polished or re-plated. By contrast, minor marks on the die body usually do not affect function, provided the parting face and locating features are intact.

Q: What liner material suits a die case, and how do you avoid scratching the cavity? A: Split load carrying and surface protection into two layers, and never ask one material to do both. The load-bearing layer can be denser EVA, cross-linked PE or a timber structure, positioned between the die base and the support pads. The protective layer covers the cavity ends, the parting face and the end faces, using soft polyurethane, expanded PE or flocked material that contains no hard filler, does not shed and carries no plasticiser. Inside the cavity, protection comes from end plugs graded to the cavity taper, and soft materials are preferable to hard ones. Three practices to avoid: using one hard foam to both carry load and touch the cavity; using ordinary open-cell foam as the contact layer, since it absorbs and slowly releases dust; and putting metal tools or hardware in the same cell as the die. Before closing the case, confirm no metal chips or grit remain inside the cavity, because a small hard particle under vibration is enough to leave a visible mark at the cavity entry.

Q: Pultrusion dies are long. How do you keep them from bending in transit? A: Control the number of supports and the spacing between them. Self-weight deflection in a long steel die varies with the fourth power of support spacing, so supporting only the two ends can produce mid-span deflection well beyond the permitted value. Use at least three supports on the two-ends-plus-middle principle, and four or more for very long dies. Supports should sit on the die's support pads or designed load faces, never on the cavity edge. Take permitted deflection as no more than half the straightness requirement and apply a dynamic factor of 1.5 to 2.0. Beyond vertical support, watch torsion: keep the supports symmetrical, avoid leaving the ends cantilevered for long, and add auxiliary supports where necessary. If case length limits the number of support positions, fit an internal support beam to break the long span into shorter ones, with the beam deflecting no more than one fifth of the die's permitted deflection. For lifting, use the designed lifting threads with matching gear and keep sling angles within 60 degrees.

Q: What matters when packing puller pads and clamping assemblies? A: The critical risks are compression set and oil contamination on the pads, and bent rods plus contaminated ports on the clamping cylinders. Pads carry a rubber or polyurethane clamping face, and stacking them leaves permanent indentations under sustained load, so lay each pad flat in its own cell with the clamping face clear of hard objects. Where the pads are already mounted on the chain, coil and secure the chain and wrap the assembly against oil, so links do not press on each other. Clamping cylinders are slender, so support them horizontally at both ends and mid-length and never through the piston rod; fit rod guards and plug the air or oil ports; where magnetic switches or position sensors are fitted, leave clearance in the cavity. It is also worth recording the existing condition of each pad cover before packing, because marks that were present at dispatch are otherwise attributed to transport on arrival and turn into avoidable disputes.

Q: Can the resin bath travel in the same case as the metering pumps? A: Not in the same cavity, though they can share a case if they are properly separated. Metering pumps run with very small clearances and are highly sensitive to particulate contamination, while a resin bath is a large thin-walled welded structure that can shift in transit and strike the pump directly, with relatively sharp rim edges that can score a pump body. The better arrangement is to place bath and pumps in different cavities of the same case with a rigid divider between them. Each pump gets its own cavity and clean packaging, plugged and labelled ports, and a capped shaft extension. The bath gets temporary internal bracing to limit rim distortion, with the bracing clearly marked as a transit item to be removed before installation. Both must be cleaned before packing: residual resin in a bath flows and cures under transit temperature changes and is extremely costly to remove, while residual resin inside a pump directly affects metering accuracy at first commissioning. If they must travel together, separate cases are still preferable to one case.

Q: What does glass fibre dust mean for packing and for electrical components? A: It matters at two levels. For people, glass fibre dust irritates skin and airways, so unpacking, cleaning and liner handling should be done with gloves and a dust mask in a ventilated area. For the case interior, fibre debris contaminates electrical items and cooling paths. Glass fibre is less conductive than carbon fibre, but once it enters a drive cooling path or a terminal area it raises fault risk, particularly when mixed with resin or oil, which makes it far harder to remove. Zone electrical items away from fibre-generating components with a dust barrier between them. Clean with filtered vacuum equipment rather than compressed air, because blowing lifts fibre into the whole work area and lets it settle into any open precision cavity. On the liner itself, fibre debris embeds in foam and fabric and resists cleaning, so reusable cases should use replaceable liner modules that can be swapped out once contaminated, and the removed module should go to the appropriate waste route rather than general refuse.

Q: What problems typically appear after an ocean shipment of pultrusion line components? A: Four groups. Cavity and parting face scratches or witness marks, most often caused by a cavity that was not fully clear, hard debris in the liner, or a die that slid within its cavity. Rust on steel parts, concentrated at cavity entries, parting face edges and exposed fits, linked to inadequate humidity control, continuous moisture release from untreated timber and negative-pressure moisture uptake where no pressure equalisation is fitted. Compression damage to covers and flexible parts, including pad indentations, belt creases and small-radius hose kinks, which are often invisible at unpacking and appear only once the line runs. And moisture in electrical items and instruments, showing up as reduced insulation resistance or signal faults. The countermeasures are cleaning and plugging before dispatch, holding internal humidity at 45 to 55 percent, fitting desiccant and a hydrophobic breather valve, closing cavities with plugs, and keeping photo records of condition before dispatch and after arrival. Addressing these four groups before the shipment leaves avoids the situation where a line is fully installed but cannot be commissioned.

Q: Are there special packing requirements for heating platens and control elements? A: Two requirements drive them: panel face accuracy and electrical safety. If a platen face distorts, contact with the die and heat transfer uniformity suffer, so store platens vertically or carry load on the back face so the heated face touches nothing, and separate multiple platens with soft dividers to prevent face-to-face fretting. The electrical side is equally important. Terminals and cartridge ends must be protected, because impact damage at a cartridge end can compromise insulation and create a shock risk, which makes this a safety item rather than a tolerance item. Where a platen contains oil channels, drain and dry it before dispatch and plug the ports, so that no residual medium seeps out or corrodes the interior during a voyage; the logic matches cavity closure on a die. Thermocouple and control element leads should be coiled and secured with slack, measuring junctions kept uncompressed, and threaded mounting bosses capped, so that a damaged thread does not compromise contact at the measuring point.

Conclusion and related reading

The central difficulty in a pultrusion equipment case is that functional faces outrank structural strength in the priority order. The cavity must stay clear, the parting face must be covered, the pad covers must avoid sustained compression, and pump fits must be clean and shielded from heavy items. The route to that result is to design the load path and the protective layers separately, then use multi-point support to control self-weight deflection in long dies, and finally isolate each functional face with plugs, guard strips and dividers. For buyers, recording the state of cavity, parting face and covers before dispatch, then comparing on arrival, catches genuine transit damage while preventing existing marks from being blamed on the packing.

For cavity protection logic on moulds generally, read injection mould component transport protection. For divider and removable structure design, see configuring a removable case divider system. Where equipment involves baths and chemicals, compare the practice in electroplating equipment component protection.

Related reading

• Matching impact cushion liners with restraint structures
• Running an ASTM D4169 distribution cycle
• Rubber mould component transport and distortion control