Electric Class A Truck Oven for Silicone-Jacketed Cable Heat Treatment

The project was developed for a medical interconnect manufacturing operation requiring controlled batch heat treatment of silicone-jacketed cable product. In this environment, the oven had to support repeatable thermal processing for cable-based product forms while fitting into a disciplined production setting serving critical medical applications.

APPLICATION REQUIREMENT

• The equipment had to process cable with a silicone jacket in a controlled batch format.
• The process had to support a medical cable and interconnect manufacturing environment where repeatability and process control are important.
• The project required a heat-treatment platform rather than a general-purpose storage or warming chamber.

WORK CHAMBER / LOADING REQUIREMENT

• Required work chamber: 48 in W × 48 in D × 60 in H.
• The process required a hanging-cart loading basis suitable for suspended product handling.
• The hanging cart was required to support 750 lb total load capacity.
• The cart included 2 loading positions.
• Hanger capacity was 200 lb per hanger, uniformly distributed.

OPERATOR / HANDLING REQUIREMENT

• Product had to be loaded and unloaded from the front of the oven through dual swing doors.
• The oven had to support cart-based movement into the chamber using floor guide tracks.
• The loading arrangement had to preserve workable access for repeated production cycles.

QUALITY / PROCESS-CONTROL REQUIREMENT

• The customer required repeatable thermal exposure across the work envelope.
• The process required ±10°F work-zone uniformity.
• The operating sequence had to include dependable purge completion, airflow verification, and excess-temperature protection before and during heating.

SAFETY / ENVIRONMENTAL REQUIREMENT

• The oven had to operate as a Class A system.
• The process required powered exhaust handling for the stated volatile-load basis.
• Heat could only be enabled when required safe operating conditions were satisfied.

UTILITY REQUIREMENT

• Required electrical service: 460V / 3PH / 60Hz.

The project required a controlled forced-convection heat-treatment process for suspended silicone-jacketed cable product. The thermal requirements centered on moderate-temperature batch heating, cross-chamber airflow, safe Class A ventilation, and controlled cooldown behavior.

TEMPERATURE REQUIREMENT

• Operating temperature range: 400°F to 500°F.
• Maximum temperature: 500°F.
• Required work-zone uniformity: ±10°F.

AIRFLOW / HEAT-TRANSFER REQUIREMENT

• Airflow direction basis: full horizontal airflow.
• The process required steady cross-chamber convection around suspended cable loads.
• Using the documented recirculation airflow and chamber cross-sectional area in the airflow direction, the first-pass average chamber crossflow is approximately 90 FPM.

HEAT-INPUT REQUIREMENT

• Heat source: electric resistance heat.
• Installed heat basis: 36 kW total.
• The process required controlled electric heat input matched to the stated operating range and uniformity requirement.

VENTILATION REQUIREMENT

• The oven required Class A exhaust and purge sequencing.
• Exhaust basis: 550 CFM.
• Maximum volatile-load basis: 0.44 gal/batch o-xylene equivalent.
• Design elevation basis: below 1,000 ft.

CONTROL / PROTECTION REQUIREMENT

• The thermal cycle required a dedicated work-area temperature controller and a separate excess-temperature limit.
• Airflow had to be proven for both the exhaust fan and recirculation fan before heat was enabled.
• The oven had to complete a timed purge cycle before entering heat.

COOLDOWN REQUIREMENT

• The process required continued fan operation during cooldown.
• Fans had to remain on until oven temperature fell below 250°F.

To satisfy those requirements, Precision Quincy configured the project as a 74-500 electric Class A truck oven with front-loading cart handling, horizontal airflow, electric resistance heat, and interlocked safety controls.

OVERALL CONCEPT

• One electric Class A truck oven.
• Front-loading batch configuration for suspended cable product.
• Hanging-cart process arrangement sized for repeatable batch loading and unloading.

HEATING ARCHITECTURE

• Heat source: electric resistance heat.
• Total installed heat: 36 kW.
• Heater package based on twelve 3,000 W heating elements.
• Heat output controlled through solid-state relays with a backup contactor.

AIRFLOW ARCHITECTURE

• Airflow pattern: full horizontal airflow.
• Recirculation system based on a Jan-Air 13.5 × 5 FC fan assembly.
• Recirculation performance: 1,800 CFM at 2 in. W.c..
• Recirculation motor: 1.5 HP.
• Integrated fresh-air inlet built into the oven body.

EXHAUST / VENTILATION ARCHITECTURE

• Class A exhaust based on a PQ1 exhauster.
• Exhaust performance: 550 CFM at 1 in. W.c..
• Exhaust motor: 0.75 HP.
• Exhaust, airflow proving, and purge timing are integrated into the heater-enable logic.

CHAMBER / SHELL ARCHITECTURE

• Internal work chamber: 48 in W × 48 in D × 60 in H.
• 4-inch insulated wall construction.
• Insulation: 4 in of 6 lb mineral wool.
• Interior material: aluminized steel.
• Front-loading floor built with cart guide tracks.
• Oven frame includes lifting lugs and floor anchors.

DOOR / LOADING ARCHITECTURE

• Two swing doors at the load face.
• Hanging cart designed for 750 lb total load capacity.
• Cart configured with 2 loading positions.
• Product handling is organized around suspended loading rather than fixed shelving.

CONTROLS ARCHITECTURE

• SSI 804 temperature controller for primary work-area temperature control.
• Gefran 650L for excess-temperature protection.
• NEMA 1 UL 508A open industrial control panel.
• Eagle purge timer and dual airflow switches integrated into the operating sequence.
• Panel layout includes dedicated controls and indication for exhaust fan, recirculation fan, purge complete, and heat bank on status.
• Control enclosure includes an enclosure cooling fan.

SAFETY ARCHITECTURE

• Applicable standards basis: NFPA 79, NFPA 86, UL 508A.
• Operating logic follows this sequence:
• Start exhaust fan
• Start recirculation fan
• Complete purge
• Enable heat
• Maintain heat only while required safe-operating conditions remain satisfied
• If a required safe-operating condition is lost, the oven turns heat off.
• Cooldown logic keeps the fans running until temperature falls below 250°F.

SERVICE / ACCESS ARCHITECTURE

• Control-enclosure door swing: 36 in.
• Oven door swing: 37 in.
• Heater-plug removal depth: 32 in.
• Fan-assembly removal depth: 10 in.