Electrically Heated Conveyor Oven with Cooldown Zone for Medical Device Lamination

The process requirement was to conveyorize a lamination operation joining a nylon outer jacket to an inner PTFE liner on elongated minimally invasive medical device components. The system was designed around customer-provided product racks and hanger geometry moving on an overhead conveyor through the full thermal and cooldown sequence.

APPLICATION REQUIREMENT

• The equipment had to thermally support a lamination process joining a nylon outer jacket to a PTFE inner liner on medical device components.
• The design was based on customer-provided racks with an envelope of approximately 73.5 in high by 19.25 in wide, carrying 30 parts per hanger at 25 total product hangers in the system.
• Production basis: approximately 600 parts per hour using a 10-minute dwell time.

CLEANLINESS AND CONTAMINATION-CONTROL REQUIREMENTS

• Food- and medical-grade lubrication was required for all moving parts. Specified conveyor lubricant: Schaeffer's 450 Food Grade H-1 Hi-Temp Chain Lube.
• A debris guard was required between the product hook and conveyor to prevent falling debris from reaching the product, with no direct line of sight between the conveyor and the product.
• Stainless materials and color-cleaned stainless welds were required in all product-exposed areas.

CONTAINMENT / ROOM-PROTECTION REQUIREMENT

• The oven internal pressure was required to be negative to help prevent exhaust or particulate from escaping into the surrounding area.
• The level of negative pressure was noted to require post-build adjustment, as excessive negative pressure can affect uniformity.

SAFETY / OPERATOR ACCESS REQUIREMENTS

• E-stops provided at the control enclosure, conveyor load side, and conveyor unload side — each affecting the oven conveyor only.
• Perimeter fencing, exhauster guarding, and safety laser scanners at the inlet and outlet were incorporated into the final configuration.

FACILITY / INSTALLATION CONSTRAINTS

• The system had to be divided into more and smaller sections than would normally be preferred due to constrained clean-room-related installation access.
• The equipment was designed to be lifted through an upper-level hatch and assembled in place without field welding. Heaviest expected shipped section: 3,000 lb.

UTILITY REQUIREMENT

• Required electrical service: 480V / 3PH / 60Hz.

These thermal process requirements were established from the need to laminate medical device components on hanging racks moving continuously through a controlled Class A conveyor system.

TEMPERATURE CAPABILITY

• Normal operating temperature: 390°F. Maximum temperature capability: 475°F.
• Required temperature uniformity: ±5°F, measured at 9 points off the supply filter outlet.
• Higher-temperature food-grade lubrication was required to support the 475°F maximum temperature capability.

DWELL / THROUGHPUT BASIS

• Process dwell basis: 10 minutes. Conveyor rate: approximately 0.667 ft/min.
• Production basis: approximately 600 parts per hour.

HEAT INPUT REQUIREMENT

• Heat source: electric resistance heat. Total installed heat: 108 kW across three heater banks.
• Heat control: SSR-controlled heat banks with backup contactors and Watlow F4T single set-point controller.

AIRFLOW DELIVERY REQUIREMENTS

• Airflow pattern: full vertical-up airflow through MERV 14 filtered supply ducts across the heated section.
• Heated-zone recirculation airflow: 2,400 CFM at 4 in. w.c.; 3 HP recirculation fan with VFD.
• Fan: NYB 128PLR plug fan.

EXHAUST / VENTILATION BASIS

• Heated-zone exhaust: 225 CFM at 1 in. w.c.; 0.75 HP exhauster. Exhauster capable of 550 CFM if required.
• Maximum VOC load: approximately 0.47–0.50 gal/hr on an o-xylene basis.
• Oven classification: NFPA 86 Class A. Internal pressure maintained negative.

VESTIBULE / ENERGY RECOVERY

• Inlet and outlet vestibules are each 68 in long.
• Each vestibule uses a PQ1 vestibule heat-recovery fan rated at 225 CFM at 1 in. w.c. to recover heat at the oven openings.

COOLDOWN REQUIREMENT

• An ambient cooldown zone is located downstream of the heated zone.
• Cooling zone airflow: two NYB 128PLR GP fans at 2,400 CFM each with 3 HP VFD-driven motors.
• The cooldown zone lowers product to a more manageable handling temperature before unload.

To deliver the thermal process requirements for this medical device lamination application, the following equipment concept and architecture was developed.

OVERALL CONCEPT

• One electrically heated overhead-conveyor Class A oven with filtered vertical-up airflow, stainless product-area construction, vestibule heat recovery, and an integrated post-heat ambient cooldown section.
• A Pacline overhead round-track conveyor carries hanging customer racks through load, heated process, cooldown, and unload positions within a guarded, fenced system.

HEATING ARCHITECTURE

• Heat source: electric resistance heat. Total installed heat: 108 kW across three heater banks.
• Heat control: solid-state relays with backup contactors. Process controller: Watlow F4T. Work-area thermocouple type: Type J.
• Work-area excess-temperature protection: Gefran 650L high-limit controller.

AIRFLOW / RECIRCULATION ARCHITECTURE

• Heated zone: NYB 128PLR plug fan — 2,400 CFM at 4 in. w.c.; 3 HP motor with VFD. Air delivered through MERV 14 filtered supply ducts in full vertical-up pattern.
• Cooldown zone: two NYB 128PLR GP fans at 2,400 CFM each; 3 HP motors with Allen-Bradley PowerFlex 525 VFDs.
• Exhaust: PQ1 exhauster ducted to outside the facility — 225 CFM nominal, 550 CFM maximum capability. Return and exhaust arrangement maintains negative internal pressure.
• Vestibule heat-recovery fans (PQ1, 225 CFM at 1 in. w.c.) at both the inlet and outlet vestibule to recover heat at the oven openings.

CONVEYOR / HANDLING ARCHITECTURE

• Conveyor type: Pacline round-track overhead conveyor with spring-loaded take-up.
• Drive: Nord right-angle helical-bevel gearmotor (or equivalent), 0.5 HP, VFD-controlled via Allen-Bradley PowerFlex 525.
• Load capacity: 15 lb per hanger; 300 lb total; 25 total product hangers.
• Dedicated product hanger with debris guard and no direct line of sight between the conveyor and the product.
• Two thru-beam sensors monitor part position at unload and overtravel locations. Conveyor oiler output included in controls wiring.

CHAMBER / CONSTRUCTION ARCHITECTURE

• Heated zone work area: 80 in length; 58.75 in wide oven body; 88 in work area height; 12 in work area width each side; 78 in product opening height.
• Overall equipment dimensions: approximately 287.75 in L × 148.90 in W × 110.48 in H.
• Interior heated-zone wall material: 20 ga 304 stainless steel. Supply duct material: 304 stainless steel. Vestibules: 304-2B stainless steel. All welded stainless color cleaned.
• Exterior wall material: 20 ga mild steel, finished PQ Blue. Insulation: 4 in of 6 lb mineral wool.
• Interior seams sealed with Sil-Bond RTV 6500. Gasketing: silicone / silicone-coated fiberglass.

SAFETY / COMPLIANCE ARCHITECTURE

• NFPA 86 Class A. Applicable standards: NFPA 79, NFPA 86, UL 508A.
• Access doors also serve the NFPA 86 explosion-relief function. Perimeter fencing, safety laser scanners at inlet and outlet, and exhaust heat shield/exhauster guard incorporated.
• E-stops at control enclosure, conveyor load side, and conveyor unload side — each affecting oven conveyor only.

CONTROLS ARCHITECTURE

• PLC: Allen-Bradley Micro850. HMI: 10 in Allen-Bradley PanelView 800.
• Controls split into a separate high-voltage enclosure and a low-voltage / operator enclosure.
• Ethernet switch: Allen-Bradley 1783-US8T unmanaged switch. VFDs: Allen-Bradley PowerFlex 525. Local EtherNet/IP-style addressing for PLC, HMI, controller, and VFDs.

SHIPPING / INSTALLATION ARCHITECTURE

• The oven is split into multiple shippable sections for constrained clean-room installation access.
• Designed to be lifted through an upper-level hatch and assembled without field welding. Heaviest expected shipped section: 3,000 lb.
• Equipment pre-assembled, pre-wired, pre-tested, and uniformity tested before shipment.