Q Academy

There are a variety of curing and degassing ovens used in ophthalmic labs worldwide. No matter the brand or model, all ovens in this industry have the same or similar functionality. They will have similar components, such as heating elements, fans, temperature and air controls, timers, alarms, etc.

Purpose

There are two reasons to have an oven in your ophthalmic lab:

  • Degas lenses
  • Cure  dip hardcoat

Degassing Lenses

Lenses are baked in a degassing oven to remove all internal moisture and provide optimal conditions for a successful AR coating application. The lens substrate determines oven temperatures, varying from 50°C to 75°C, as well as processing time, varying from 1 to 4 hours.

NOTE: For the purpose of batch processing, the oven setpoint temperature needs to be 55°C for no less than 1 hour.

Curing Lens Coatings

There are two basic methods of curing ophthalmic coatings:

  • Thermal (heat) ovens
  • Ultraviolet (UV) light chambers

Thermal coatings are commonly used by lens manufacturers for the front side hard coat. Thermal curing tends to produce superior performance due to longer cure times allowing for more effective cross-linking.

Compared to UV curable coatings, thermally curable coatings usually have a higher concentration of “Colloidal Silica,” which increases coating hardness. Thermal coatings potentially have more effective curing throughout the coating layer because of the heat distribution in the curing oven.

Quick Reference

Know Your System

Read your user manual carefully. Make use of its instructions and explanations. The knowledge of safe, continuous, satisfactory, trouble-free operation depends primarily on the degree of your
understanding of the system and of your willingness to keep all parts in proper operating conditions.

Proper Line Voltage

Voltage must correspond to the nameplate requirements of motors and controls. Refer to the section on power connections in your user manual.

Proper Ventilation

Do not be careless about restrictions in and around the fresh air and exhaust openings. If your unit has adjustable vents, make sure the vent is adjusted properly by opening or closing the vent. Do not permit them to become filled with dirt or debris so that the contaminants interfere with the proper volume of flow. The proper ventilation clearances should be fulfilled at all times. Refer to the set-up instructions in your user manual.

Maintenance

Keep Equipment Clean

Gradual dirt accumulation retards airflow. A dirty oven can result in unsatisfactory operation, such as:

  • Unbalanced temperature in the work chamber
  • Reduced heating capacity
  • Reduced prodcution
  • Overheated components

Keep the walls, floor, and ceiling of the oven work chamber free from dirt and dust.

Keep all equipment accessible. Do not permit materials to be stored or piled on or against the oven.

NOTE: Never use the oven to heat or store food or any other item not intended for lens processing use.

Protect Controls Against Excessive Heat

This is particularly true of controls, motors, and other equipment containing electrical components. Temperatures in excess of 51.5°C (125°F) should be avoided.

Establish Maintenance & Check-Up Schedules

Do this promptly, and follow them faithfully. Careful operation and maintenance will result in continuous, safe, and economical operation.

  • Lubrication: All door latches, hinges, door operating mechanisms, bearings, or wear surfaces should be lubricated to ensure easy operation.
  • Repairs: Make repairs immediately. Delays may be costly in added expense for labor and materials and in prolonged shutdown time.

Practice Safety

Make it your primary policy to know what you are doing before you do it. Make CAUTION, PATIENCE, and GOOD JUDGEMENT the safety watchwords for the operation of your oven.

NOTE: DO NOT ATTEMPT ANY MAINTENACE OR REPAIR ON YOUR OVEN UNTIL YOU HAVE DISCONNECTED THE MAIN POWER.

Operation

NOTE: For fastest oven heat-up time, close fresh air vent. After desired temperature is reached, adjust vent as needed.

  1. Start oven.
    1. Open oven door.
    2. Press POWER ON or tutn dial to I (you should hear the fan start circulating).
    3. Close oven door.
    4. Adjust vent to desired opening (vents will need to be adjusted accordingly for maximum performance at various operating temperatures).
    5. Check that the LED for the POWER is illuminated.
  2. Enter temperature setpoint.
    1. This will vary depending on the unit that you have installed; see manufacturer’s manual.
  3. Set HI-LIMIT Instrument
    1. This temperature should be set slightly higher than the setpoint of the oven or to a temperature that should not be exceeded in the process.
  4. Turn heat switch on.
    1. If applicable, otherwise this is part of the “start oven” process.
    2. Note: Indicator LED should illuminate as the heater initially turns on to bring oven up to temperature and then cycles on/off while maintaining oven temperature through temperature control unit.
  5. Stop oven.
    1. Press POWER ON button or turn dial to 0 (you should hear the fan stop circulating).
    2. Open fresh air vent.
    3. Open door.

Warning

Do not use flammable solvents or materials in any oven.

Do not process closed containers containing any substance or liquid in this oven as they may explode under heat.