Dual-Oven Natural Gas-Fired Convection Curing System for Laboratory Sink Mold Partial Cure

The customer required a curing system to support production of chemically resistant laboratory sinks (e.g., drop-in and undermount styles) used in laboratory countertops, where parts are produced using a sand + proprietary resin system placed in aluminum molds. This equipment performs a partial-cure step before parts proceed to a separate post-cure process in other equipment.

PROCESS OBJECTIVE (PARTIAL CURE)

• Advance molded sink parts to the required partial-cure state (stable for handling and downstream post-cure).
• Maintain consistent results across multiple sink styles and mold geometries.

CAPACITY / PRODUCTION CONCEPT

• Capacity basis: 8 cavities total (implemented as (2) ovens, each with (1) 4-cavity chamber).

PRODUCT INTEGRITY CONSTRAINT

• Airflow must provide heat transfer without disturbing the product surface (basis for avoiding high-intensity impingement).

LOAD HANDLING / MATERIAL HANDLING

• Molds are placed onto built-in carts/trolleys that ride on V-groove rails with V-groove casters.
• Carts/trolleys are moved by hand in and out of each oven.

WORK ENVELOPE BASIS (PER CAVITY)

• Work area: 36 in H × 36 in W × 60 in D.

VOC / SAFETY-DRIVEN REQUIREMENTS

• The curing process produces VOC; equipment must safely manage VOC in accordance with NFPA 86 and applicable codes.
• The system must tolerate possible resin drips/spills and support safe containment/cleanup.

OPERATING TEMPERATURE ENVELOPE

• Typical operating temperature (partial cure): 265°F.
• Maximum equipment temperature capability: 450°F.

HEATING CAPACITY (THERMAL INPUT BASIS)

• Heat source: natural gas.
• Heat input basis: 1.5 MMBTU/hr per 4-cavity oven.
• Total installed heat input for the full system: 3.0 MMBTU/hr (2 ovens × 1.5 MMBTU/hr; basis: 8 cavities total).

TEMPERATURE CONTROL / UNIFORMITY

• Air temperature uniformity requirement: ±10°F.
• Control temperature measurement: control thermocouple located in the middle of the supply duct.
• High-limit temperature: 450°F maximum (Partlow high limit controller).

AIRFLOW DELIVERY (CONVECTION PERFORMANCE)

• Airflow direction: vertical downflow (top-down) into each cavity.
• Supply distribution: slot-nozzle supply ducting over the cavities.
• Discharge air velocity basis: ~2,800 FPM.
• Recirculation airflow basis: 14,000 CFM @ 4.0 in. w.c.
• Return air path basis: return air flows up the sides back toward the burner/heat section.

VOC MANAGEMENT (PROCESS-OFFGAS CONTROL)

• Dedicated exhaust for VOC control: 1,065 CFM total per oven.
• Exhaust device: PQ15 exhaustor.
• VOC ventilation basis: exhaust/hooding maintained per NFPA 86 requirements.
• Purge and safety interlocks: provided per NFPA 86 Class A compliance requirements.

SPILL / DRIP TOLERANCE (RESIN HANDLING REALITY)

• The system must tolerate resin drips/spills without creating an unsafe condition; containment/cleanup provisions are addressed in the equipment architecture.

To deliver the thermal process requirements (which deliver the customer process requirements), Precision Quincy implemented a natural gas-fired, recirculating convection curing oven system with 8 total cavities (implemented as (2) ovens, each with (1) 4-cavity chamber), where each oven includes its own vertical lift door for loading/unloading.

MATERIAL HANDLING (HOW LOADS MOVE THROUGH THE SYSTEM)

• Carts/trolleys ride on V-groove rails (with V-groove casters) and are moved by hand.
• Rail/track arrangement: four tracks with spacing basis of 15 in / 20 in / 25 in.
• Cart/rail load height: 38 in above floor.
• Loading rail extension outside oven: 78 in.
• Internal track length: 72.5 in.
• Oven is mounted on a stand to establish the rail height and loading interface.

AIRFLOW ARCHITECTURE (HOW THE OVEN ACHIEVES THE REQUIRED CONVECTION)

• Airflow direction: vertical downflow (top-down) into each cavity.
• Recirculation fan arrangement: roof-mounted New York Blower (NYB) 27 PLR recirculation fan with a vertical shaft (15 HP).
• Fan discharge path: fan discharges horizontally, then airflow is turned 180° and delivered vertically downward through slot-nozzle supply ducting above the cavities.
• Return path: air returns up the sides of the duct/chamber and is routed back to the heat section (burner inlet region).
• Recirculation basis: 14,000 CFM @ 4.0 in. w.c., with discharge velocity basis ~2,800 FPM.

HEATING SYSTEM

• Burner basis: (1) Eclipse AH150 burner per oven.
• Heat input basis: 1.5 MMBTU/hr per 4-cavity oven.
• Total installed heat input: 3.0 MMBTU/hr (2 ovens × 1.5 MMBTU/hr; basis: 8 cavities total).

VOC EXHAUST / SAFETY

• Exhaust for VOC control: PQ15 exhaustor, 1,065 CFM total per oven.
• Explosion relief in the roof.

DOOR SYSTEM

• Door type: vertical lift door per oven.
• Low-headroom actuation: four pneumatic cylinders mounted horizontally with an engineered chain and sprocket mechanism to achieve door travel with reduced ceiling height.
• Pneumatic supply: 80 PSI.

SPILL / DRIP MANAGEMENT

• Removable drip pans located beneath the load path to capture resin drips/spills.

CONSTRUCTION / SHELL

• Construction: structurally reinforced insulated wall panels.
• Panel thickness: 4 in.
• Insulation: 6 lb/ft³ mineral wool.
• Overall dimensions: 270 in W × 172 in D × 168 in H.

CONTROLS

• Temperature controller: SSI 804.
• PLC: Allen-Bradley Micro850.
• Operator interface: 10 in touchscreen HMI for door operation and system interaction.