Heat Treatment Furnace Manufacturer: Annealing, Burnout and Thermal Processing Systems
OPDEL builds heat treatment furnaces for jewellery manufacturers, precious-metal refiners and casting houses that need controlled, repeatable thermal cycles on gold, silver, copper and their alloys. The range covers batch annealing under a reducing atmosphere (FR series), continuous belt annealing for chain, wire and blanks (FN series), and muffle burnout furnaces that dewax and fire investment cylinders before casting (FRC series). Machines are built and supported from Vadodara, Gujarat, India, with export supply.
This page is the hub for the thermal-processing range. If you already know which process you need, go straight to the FR series batch annealing furnaces, the FN series continuous belt annealing furnaces, or the FRC series muffle burnout furnaces.
What these furnaces are used for
Annealing restores ductility to metal that has work-hardened during drawing, rolling, chain-making or stamping. Without it, wire cracks, chain snaps at the link, and blanks split when struck. Burnout does a different job: it melts wax out of an investment flask and fires the plaster so the cavity is clean, dry and at the right temperature when metal enters it.
Typical users are chain manufacturers, findings and blank producers, coin and medal minters, bullion and refining operations, and contract jewellery factories running lost-wax lines.
The range at a glance
| Series | Type | Process | Models |
|---|---|---|---|
| FR | Batch annealing furnace with cooling chamber | Annealing under reducing atmosphere, water quench or slow cool | aD 010 – aD 050 |
| FN | Continuous belt (tunnel) annealing furnace | Non-stop annealing of chain, wire, plate and blanks | bD 020 – bD 050 |
| FRC | Electric muffle furnace | Wax dissolution and plaster firing for casting cylinders | — |
| ETNA | Continuous casting furnace | Continuous casting of rod, plate and tube, 10–140 kg crucible | cD range |
| VULCANO | Continuous casting furnace, reduced capacity | Bench and floor continuous casting | cD 3, cD 5, cD 7, cD 12 |
ETNA and VULCANO are continuous casting furnaces rather than heat treatment equipment. They are grouped here because they sit in the same thermal-processing decision for most buyers, and because the profiles they cast are usually annealed on an FN belt furnace afterwards.
FR series: batch annealing furnaces
The FR range is built from a tubular frame with louvred panels for air exchange. The tubular system keeps general maintenance interventions straightforward. Heating muffles are formed by resistances and special refractory insulating panels with high thermal properties, and the heating chamber is stainless steel so it can take sharp temperature swings.
Protective gas enters through nozzles inside the chamber. A burner in front of the chamber blocks oxygen ingress and improves de-oxidation, which is what keeps annealed surfaces bright instead of scaled. A stainless steel shovel sits inside the chamber; once the metal is annealed the operator pushes the shovel to the bottom of the cooling chamber and tips the load into the water tub for instantaneous cooling, or leaves it in the cooling chamber for a slower cool. Treated material is recovered from the tub by hand or by an optional pneumatic piston.
FR series specifications
| Model | Power (kW) | Power with NH3 dissociator (kW) | Chamber (mm) | Heated zones | Heated zone length (mm) | Cooling chamber (mm) | N+3H atmosphere (l/min) | Overall size (mm) / weight (kg) |
|---|---|---|---|---|---|---|---|---|
| aD 010 | 8.0 | 10.5 | 200 x 110 x 875 | 1 | 400 | 475 | 15–20 | 923 x 1800 x 1380 / 290 (350 with diss.) |
| aD 020 | 10.5 | 13.0 | 250 x 150 x 1185 | 1 | 720 | 559 | 16–20 | 1094 x 2200 x 1560 / 420 (480) |
| aD 030 | 12.0 | 14.5 | 290 x 150 x 1185 | 1 | 720 | 559 | 17–20 | 1094 x 2200 x 1560 / 440 (500) |
| aD 040 | 18.0 | 20.5 | 450 x 150 x 1185 | 2 | 720 | 684 | 18–20 | 1480 x 2620 x 1890 / 663 (720) |
| aD 050 | 24.0 | 26.5 | 450 x 210 x 1185 | 2 | 720 | 684 | 19–20 | 1480 x 2800 x 1950 / 730 (790) |
| Supply voltage | — | |||||||
| Maximum temperature | — |
Options across the FR range: ammonia, nitrogen and hydrogen pressure regulators; N+3H mixer; NH3 dissociator (60 kg, 2.5 kW, supplied to order); pneumatic unloading on aD 020 and above.
FN series: continuous belt annealing furnaces
The FN belt furnaces run product continuously through a tunnel instead of treating it in batches. Each machine carries two heating chambers working as separate heating zones with independent temperature settings, so the soak and the taper can be set separately. Construction is the same tubular frame with louvred panels. Internal sliding blocks stop the belt wearing the chamber, and the cooling chamber is water cooled. A flange holds the chambers together and carries the gas nozzle; two burners at each end of the tunnel keep oxygen out and improve de-oxidation.
The FN range is aimed at jewellery chain, coin blanks, rectangular plate and wire — anywhere output is continuous and the metallurgical result has to be identical at the end of a shift and the start of it.
FN series specifications
| Model | Power (kW) | Power with NH3 dissociator (kW) | Belt chamber (mm) | Heated zones | Heated zone length (mm) | Cooling chamber (mm) | Overall size (mm) / weight (kg) |
|---|---|---|---|---|---|---|---|
| bD 020 | 11.5 | 13.5 | 80 x 40 (100 x 50 optional) | 1 | 600 | 985 | 700 x 3050 x 1530 / 390 (450 with diss.) |
| bD 030 | 13.3 | 15.8 | 80 x 40 (100 x 50 optional) | 2 | 800 | 1600 | 700 x 4030 x 1530 / 580 (640) |
| bD 040 | 16.8 | 19.3 | 80 x 40 (100 x 50 optional) | 2 | 1000 | 1600 | / 600 (660) |
| bD 050 | 20.3 | 22.8 | 80 x 40 (100 x 50 optional) | 2 | 1200 | 1800 | 700 x 5030 x 1530 / |
Common to the FN range: supply 3 x 400 V, with 3 x 230 V optional; maximum temperature 950°C, with 1100°C optional; reducing atmosphere N+3H at 10–20 l/min. Options include the NH3 dissociator, a chain loader and alternative belt types.
FRC series: burnout furnaces for casting cylinders
The FRC range is a set of electric muffle furnaces used to prepare casting cylinders. Adjustable temperature up to 850°C allows the wax to be dissolved out and the plaster inside the hollow cylinder to be fired. The bottom of the chamber carries a grill and a drawer, so wax is collected rather than lost into the furnace — this matters when the wax carries reclaimable metal or when soot in the chamber would spoil later flasks.
Where these furnaces sit in the line
A heat treatment furnace rarely stands alone. Upstream, metal is melted in an OPUMelt 12/16 induction melting furnace or, for heavier industrial charges, an OPUM ITC modular induction melting furnace. Cylinders fired in an FRC feed straight into casting: the OPCS Digital universal centrifugal casting system or the OPC F1000, F2000 and A03 lost-wax casting machines. Cast rod and plate from an ETNA or VULCANO continuous casting furnace is rolled and drawn, then annealed on an FN belt furnace before the next forming pass.
Related thermal equipment includes the Opdel Heat S5 induction heating power supply and induction brazing machines for localised joint heating. Crucibles and furnace consumables are covered under graphite crucibles and furnace spares. For the wider equipment range, see all OPDEL furnaces.
Buying considerations
Throughput before power rating. On a belt furnace, the useful number is kilograms per hour at your target temperature and belt speed, not installed kW. Ask for it against your own product.
Atmosphere running cost. Cracked ammonia (N+3H) at 10–20 l/min is a consumable. An NH3 dissociator generates the atmosphere on site instead of buying bottled gas, which is why it appears as an option on every model — and why it adds 2.0–2.5 kW to the load and 50–60 kg to the machine.
Batch or continuous. FR batch furnaces suit mixed work, short runs and operations that quench. FN belt furnaces suit a single product family running all shift. Buying a belt furnace for varied small lots usually costs more in changeover than it saves in labour.
Metal loss and consistency. The burner and gas nozzle arrangement exists to keep oxygen away from hot metal. Less oxidation means less surface scale, less pickling, and less metal lost in cleaning — the recurring cost that dominates the economics on precious metal work.
Installation, training and after-sales
OPDEL runs an after-sales service covering installation, replacement parts, and repair after breakage or accidental damage, and it also advises on production difficulties and process choices. A melting and casting laboratory (Cast-Lab) is used for start-up courses and for instructing operating personnel on belt furnaces, static furnaces and melting machines, and for running trials on customer samples before purchase. Full details are on the services and support page.
Frequently asked questions
Which furnace do I need for annealing gold chain? For continuous chain production, the FN belt furnaces are the intended machine: two independently set heating zones, a water-cooled cooling chamber, and burners at both tunnel ends to suppress oxidation. For mixed or intermittent work, an FR batch furnace with a cooling chamber and water tub is usually the better fit.
How do I select a size? Match the chamber to the product, then check throughput. FR chamber sizes increase across the range, and FN belt chambers are offered in a standard and an optional larger size. If your product does not fit the standard belt chamber, say so at enquiry stage rather than assuming a larger model solves it.
What electrical supply is required? FN furnaces are supplied for 3 x 400 V, with 3 x 230 V available as an option. FR series supply voltage is not stated in the published specification table.
What temperature can these furnaces reach? FN belt furnaces are rated to 950°C standard with 1100°C optional. FRC burnout furnaces are adjustable up to 850°C. The FR series maximum temperature is not published.
Do I need to buy protective gas separately? Both FR and FN run a reducing N+3H atmosphere. You can feed it from bottled gas with the optional ammonia, nitrogen or hydrogen pressure regulators, or generate it on site with the optional NH3 dissociator, which is built to order and rated at 60 kg and 2.5 kW.
Can the FRC burnout furnace take my flask sizes? The FRC is a muffle furnace for casting cylinders with a wax-recovery grill and drawer, adjustable to 850°C. Cylinder capacity per load varies by model.
What spares should I stock? On belt furnaces the wear items are the belt, the sliding blocks that protect the chamber, and thermocouples. On FR furnaces, the stainless shovel, muffle resistances and gas nozzles.
What is the lead time and warranty? and
Is training included? Operator start-up courses are run in the Cast-Lab on belt furnaces, static furnaces and melting machines, and customer samples can be trialled there.
Request a quote
Tell us the metal and alloy, the product form (chain, wire, plate, blanks or flasks), your target output per shift and your available electrical supply, and we will recommend a model and confirm the specification. Reach the sales team by phone or email using the details on the OPDEL contact page, or write to us with a drawing or sample specification for a trial in the Cast-Lab before you commit.