Dual-Zone Continuous Curing Oven for High-Volume Trim Finishing

A major North American building-products manufacturer required a continuous curing module to be integrated inline as part of a larger, two-machine production cell (the curing system mechanically and controls-wise interfaces with upstream/downstream equipment).

MATERIAL FLOW & LAYOUT

• Product travels lengthwise (boards oriented parallel to direction of travel; "skinny way in").
• Two parallel product paths run through the curing system.
• The customer required a specific fixed center-to-center spacing between the two paths to match their production layout.

THROUGHPUT REQUIREMENT (PRIMARY)

• The key requirement was mass throughput (≈152,000 lb/hr target). Line speed is secondary and is simply whatever speed is required to achieve lb/hr given product mix.

PRODUCT + UPSTREAM CONTEXT

• Trim boards are wood/composite.
• Upstream, the trim is wrapped on the top and bottom surfaces.
• After trim is cut, the exposed edges must be painted; this system's job is to dry/cure the edge paint.

ENERGY FOCUS / EDGE-ONLY HEATING CHALLENGE

• The customer's process requires concentrating heat transfer on the edges without wasting energy heating surfaces that do not need it.
• The system must accommodate a wide product width range (~1.5 in to 12 in) while still directing airflow/heat where needed (edge-focused) without disturbing product.

CONVEYOR/BELT REQUIREMENT + BELT TEMPERATURE CONSTRAINT

• The customer required a specific belt standard.
• The belt is not rated for the oven's maximum design temperature.
• Although the equipment is configured for up to 450°F max, the customer operates to keep the belt around ~212°F.
• A belt return/vestibule region is maintained cooler (as needed) to help protect the belt while still supporting production throughput.

LOW-NOX BURNER CORPORATE STANDARD

• The customer requires low-NOx burners.
• This creates a control/turndown challenge, especially at low heat-load conditions (e.g., empty/lightly loaded operation) where it is difficult to maintain low temperatures while preserving needed high-temperature capability.

ACCESS / MAINTAINABILITY REQUIREMENT

• The customer required side access so operators can quickly remove broken boards inside the oven (open side access rather than full disassembly).

PRODUCT STABILITY REQUIREMENT

• Boards must remain stable and properly guided—no lateral drift, hopping, or airflow-induced movement—while still achieving the required edge paint cure.

FOOTPRINT CONSTRAINT

• The customer provided a very limited installation envelope; the full solution had to fit within ~800 inches total length.

These thermal process requirements were jointly developed to meet the customer's process needs, based on a combination of Precision Quincy testing, customer experience, and Precision Quincy's prior experience with similar product lines.

TEMPERATURE REQUIREMENTS

• Normal operating temperature: 212°F.
• Maximum capability: 450°F (future flexibility for product line changes; may require belt retrofit).

CONVEYOR EXPOSURE / TIME-IN-HEAT

• Conveyor speed must be adjustable to achieve different time-in-heat values based on product size.
• Speed range includes up to ~350 ft/min.

EDGE-FOCUSED AIRFLOW DELIVERY

• Airflow must be delivered vertically downward at the board edges.
• Target nozzle discharge velocity: 5,800 FPM, with allowable variation ±870 FPM.
• Nozzle geometry: 3/8-inch-wide slots.

EXHAUST REQUIREMENTS (TEMPERATURE CONTROL + PROCESS REMOVAL)

• Minimum exhaust: 5,250 CFM (water removal from drying + products of combustion).
• Maximum exhaust capability: 17,200 CFM to support stable low-temperature operation given low-NOx turndown limitations.

HEAT INPUT REQUIREMENT

• Required heat input: 5,000,000 BTU/hr.

MOISTURE LOAD

• Maximum water load capacity: 8 gallons/hr.

TEMPERATURE UNIFORMITY

• ±10°F from setpoint at the nozzle discharge (sufficient to meet even-heating requirement)

To deliver the thermal process requirements (which deliver the customer process requirements), Precision Quincy settled on the following equipment concept and architecture.

OVERALL CONCEPT

• Two-zone, dual-path conveyor oven.
• Top-mounted recirculation with burners located upstream of each recirculation fan.
• Conditioned air is directed down from nozzles above each conveyor, then returns down the sides back to the heat source/fan loop.

AIRFLOW/DUCTING ARCHITECTURE

• Return air flows back to a heat source located upstream of the recirculation fan.
• The recirculation fan pressurizes a duct with outlets to each side, feeding a supply plenum directly over each conveyor.
• Nozzles above each conveyor deliver the required edge-focused vertical-down airflow.

ZONE ARCHITECTURE (ONE FAN + ONE BURNER PER ZONE)

• Recirculation fan: 40-inch fan, 33,000 CFM @ 3 in. w.c. (concept-point), 25 HP motor (selected via fan curve analysis).
• Heating: Burners fire into a diffuser that mixes burner heat with incoming return air prior to fan pressurization. (2) Maxon OvenPak LE25 burners (one per zone), each 2.5 MMBtu/hr (5.0 MMBtu/hr total). SmartLink MRV servo-driven emissions control (NOx <30 ppm).

EXHAUST CONCEPT

• Exhaust system located at the center of the oven.
• Equipped with modulating dampers to support the required exhaust turndown/capability.

SERVICEABILITY / ACCESS

• Two independently operable conveyors run side-by-side with a central walk-through pathway for service.
• The center pathway also serves as part of the return-air space.
• Explosion relief incorporated, with as much relief area as practical placed in the roof.
• Total of 10 access doors. Large side access openings supported by an overhead truss concept enabled by the shell architecture.

SHELL / STRUCTURAL ARCHITECTURE

• Shell built around a structural steel frame that integrates the conveyor support structure.
• Interior construction uses free-floating sheet-metal pans designed to accommodate thermal expansion/contraction while minimizing through-metal.
• Construction: 16-gauge interior pans (aluminized), insulation outside the interior pans, 16-gauge exterior cladding (mild steel), two-part epoxy paint, light gray specified by the customer.

SHIPPING ARCHITECTURE

• The oven ships as two main pieces (two zones).
• Full assembly supported on bolt-on stands removed for shipment to maintain legal over-the-road shipping height.

CONVEYOR / MECHANICAL CONCEPT HIGHLIGHTS

• Belt return runs through a vestibule and can be configured for additional cooling air (if needed) to protect the belt.
• Belt tracking uses a V-guide / V-groove on the back of the belt (no active tracking system).
• Drive: Each conveyor has its own gearbox on a torque arm. Drive motor: 2 HP per conveyor, VFD-controlled. Lag pulleys used to grip/drive the belt.
• Take-up: Rack-and-pinion synchronized take-up with pneumatic cylinders (one system per conveyor/zone). Bearing blocks on slides maintain pulley shaft alignment.

CONTROLS ARCHITECTURE

• Controls are remotely located.
• Allen-Bradley CompactLogix PLC controls this curing module and the adjacent paired equipment.
• VFDs are Yaskawa (customer-specified).
• Burner safety hardware uses a Karl Dungs-based safety system with Maxon/Honeywell burner control components.

OTHER NOTED ATTRIBUTES

• Coating is non-VOC.
• Roof areas not occupied by explosion relief are outfitted with guard rails for service access.
• Equipment was fully tested and accepted via FAT at Precision Quincy; a future widening retrofit was requested by the customer but has not been executed.