Product Overview
A custom-formed element is an Accutherm tubular heating element — a nickel-chrome coil in a compacted-magnesium-oxide metal sheath — bent and formed to the customer’s profile and supplied at the electrical rating the application needs, rather than picked from a straight-element catalog. The reference build is the AccuTherm plate heater: the element serpentined into a flat-surface emitter and clamped to a cast-iron crucible to hold the metal at temperature on a die-casting machine. Choose a custom-formed element when the heat has to follow a plate, platen, drum, mold, or marine fixture — the diameter, sheath alloy, geometry, watt density, and terminations are engineered to fit.
Related Accutherm element & marine-duty lines
Tubular & Finned Tubular Elements — the straight / standard-figure OEM element this one is formed from
Finned-Tubular Marine Heaters — marine-duty finned elements in copper-nickel / Monel sheaths
Monel Marine-Duty Circulation — an assembled inline heater with Monel wetted parts for seawater and brine
Key Features & Benefits
- Made to your part, not the catalog — the element is bent and formed to your plate, platen, drum, mold, or crucible profile and supplied at the rating the application needs — so the heat lands where the part needs it instead of being approximated by a standard straight element. Start from the part; the element is engineered to fit it.
- A flat-surface emitter for crucible and die-casting heat — serpentined into a plate, the metal-sheathed element gives the even heat transfer of a flat surface, so a crucible or platen is held at temperature uniformly — the AccuTherm plate-heater pattern for die-casting machines. Even surface heat where a point or rod source would leave cold spots.
- A sheath alloy for the duty, including Monel for marine — the alloy is matched to the medium and temperature — copper for cool service up through Incoloy and Inconel for high-temperature work, and Monel for marine / chloride and shipboard elements — so the formed sheath survives where it has to live. The right metal for the environment, formed to the right shape.
- Engineered from a drawing, sketch, or the fixture — send the part, the temperature, and the rating and the element comes back engineered to fit — no forcing a standard heater onto a non-standard part. The custom-engineering work is the product.
Specifications
- Operating principle
- Electric resistance (Joule) heating — a coil of nickel-chrome resistance wire is centered in a metal sheath packed with compacted magnesium oxide, so the MgO insulates electrically while transferring heat rapidly from the coil to the sheath. The element is then bent and formed to your profile and supplied at the electrical rating the application needs — on a plate heater the element is serpentined into a flat-surface emitter so it can be clamped to the part being heated.
- Formable shapes
- Formed to the part rather than picked off a straight-element list: a flat plate / platen (serpentine layout for an even flat-surface emitter), a drum or ring, a mold or crucible profile, or any special bend — including custom-formed shipboard elements. Plate heaters can be designed to fit various crucible configurations and electrical ratings. The final geometry is engineered from your drawing or fixture.
- Forming & bending
- Straight single-pass elements are bent to virtually any configuration on CNC bending equipment; submit a drawing for a configuration outside the standard figure set. To protect the magnesium-oxide insulation, bends are repressed (recompacted) when the center-to-center spacing falls below a diameter-specific value, and the minimum bend radius is material- and diameter-specific. Tight or compound profiles are confirmed against the element diameter at order entry.
- Element construction
- Built on the standard Aspeq tubular element — nickel-chrome coil, compacted-MgO fill, heavy-gauge metal sheath, with cold (unheated) pins at the terminal ends to keep the heat away from the connection. One-pass (a terminal at each end) or two-pass (both terminals at one end, opposite end sealed) construction is chosen to suit the formed shape and how it mounts.
- Sheath materials
- Selected by the heated medium and the maximum temperature, each with its own maximum sheath temperature: Copper, Steel, Titanium, Monel (for marine / chloride and shipboard work), 304 / 316 / 321 stainless steel, Incoloy 800, and Inconel 600. The alloy is matched to the application so the sheath does not corrode out; not every alloy is offered in every diameter.
- Temperature range
- Set by the sheath alloy and the watt density — copper sheaths run cool service while the stainless and nickel alloys (Incoloy / Inconel) carry high-temperature air, gas, and metal heating. State the maximum part or medium temperature with the inquiry so the alloy and density are matched to it.
- Watt density
- Watt density (W/in² of sheath surface) is the single most important life factor and is set to the application — the maximum part / medium temperature, the heat-transfer path (clamped, cast in, or in a machined groove), and the fit. The lowest practical watt density gives the longest element life; on clamped and cast-in metal heating the achievable density also depends on how tightly the element seats and on the metal thickness. The final value is engineered at quote time, not picked from a fixed list.
- Mounting & heat transfer
- Custom-formed elements transfer heat by direct surface contact: clamped to the part (as on a plate heater bolted to a crucible), inserted into drilled holes or machined grooves, or cast into metal for the most uniform heat. The formed geometry is laid out so the heated surface matches the area to be heated; leave a clamped or straight element free to expand lengthwise as it heats.
- Terminations & moisture seals
- Threaded-stud, quick-connect, or weld-nut terminations with silicone-rubber, mica, or ceramic insulators chosen for the terminal-end temperature and voltage. Element ends are sealed against moisture — an epoxy or RTV barrier, or a hermetic seal for an absolute moisture seal — matched to whether the terminal end runs wet, dry, or hot. The terminal end is the first thing to fail, so it is specified for the worst case it will see.
- How to order
- Custom-formed elements are engineered from a drawing, sketch, sample, or the fixture itself — the more geometry we have, the tighter the fit. From the part, its maximum temperature, the electrical rating, and how it mounts, we set the element diameter, sheath alloy, formed geometry, watt density, and terminations. The full parameter list is in the quote request below.
- Build & lead time
- Custom build-to-order — no published price list, quote-only. Lead time depends on the formed geometry, sheath material, electrical rating, and any forming-tool or certification requirements.
Common Applications
- Plate heaters clamped to cast-iron crucibles — holding the metal at temperature on die-casting machines
- Platen, die, and mold heating — the element formed to the cavity or surface and clamped, inserted, or cast in
- Drum, ring, and vessel-wall heating — the element formed to the curvature of the part
- Custom-formed shipboard elements — formed to a marine fixture in a Monel or stainless sheath
- Special-profile OEM sub-assemblies — a formed element built to a customer drawing or fixture
Fit note: a custom-formed element is engineered to a specific part or fixture. For a straight or standard-figure OEM element, see the tubular & finned tubular element line; for a packaged, ready-to-install immersion, circulation, or tank heater, see those assembled-heater series.
Design & Selection Considerations
- Watt density and sheath alloy are the two life-or-death picks — too high a watt density burns the element out or damages the part; the wrong alloy corrodes the sheath through. Both follow from the heated part, its maximum temperature, and the heat-transfer path — give us those and we work back to a safe density and alloy. Almost every early failure on a formed element traces to one of these two.
- The drilled-hole or clamped fit sets the safe density — on clamped, cast-in, or grooved metal heating, a loose hole or a poor clamp leaves the sheath unable to dump its heat into the part, so it runs hot — the achievable density is governed by the contact, not the catalog. Hold the recommended clearance and lubricate on assembly. The fit, not the catalog number, decides how hard you can drive it.
- Let a clamped or straight element expand — a heated sheath grows lengthwise, so a formed element that is clamped or fixed has to be free to move as it heats; pin it rigidly at both ends and the thermal growth works the terminal seal loose over time. Plan the expansion path before you fix the mounting.
- Match the terminal seal to the wet-and-hot reality — an epoxy barrier suits a modest, dry terminal; a wet or washdown end needs a tougher barrier or a hermetic seal; a high-temperature terminal needs the RTV or hermetic seal with a mica or ceramic insulator. Pick for the worst case the terminal end sees. Moisture into the MgO is the classic slow death — seal for it.
- Megger and bake before energizing after storage — the magnesium-oxide insulation is hygroscopic, so an element off the shelf can read low insulation resistance. Megger it with a 500 VDC tester; if it reads under 1 megohm, bake at 250°F or energize at reduced voltage in air until it recovers. A “bad” new element is usually just damp MgO.
- A formed element is a component — the safety controls are the integrator’s job — on its own the element has no thermostat, high-limit, or ground-fault protection; the equipment builder must add a disconnect, branch-circuit and short-circuit protection, backup temperature limiting, and proper grounding per the IOM and the NEC. The element is engineered to fit; the protected system is built around it.
To engineer the right Accutherm custom-formed element:
Use the input form to send a drawing, sketch, sample, or the fixture itself, the part or surface to be heated and its maximum temperature, the required wattage and voltage, any size or clearance limits, and the mounting / heat-transfer method (clamped, inserted, or cast in) — and we’ll engineer the right Accutherm formed element for your part.
Electric Heating Application Sheet ›Talk to an engineer directly — Scott Prater, Principal · 917-580-0878 · scott@pratertechnical.com
Specifications compiled by Prater Technical Partners from Aspeq Heating Group product datasheets.