What is a Pre Gel Oven?
A Pre Gel, or Booster, oven is a short single, two or three section oven, that is placed directly in front of a conventional convection cure oven. Pre Gel ovens from Heraeus Vulcan utilize Gas Catalytic IR technology.
Where Are Pre Gel Ovens Used?
Pre Gel ovens can be used in the following instances:
- Curing powder on larger parts with thick cross-sections, a Pre-Gel oven may be necessary for that extra boost before the convection oven.
- Curing powder on any part where there is a need to increase line speed, but your current convection oven just isn’t long enough. A Pre Gel oven will ensure increased line speed whilst utilizing the same overall length of oven.
- If you are experiencing cross contamination of powder from the natural air movement associated with a convection oven, a Pre-Gel oven will gel the powder and reduce the problem.
- If frequent color changes are required, a pre gel oven will enable shorter spaces between parts. This is due to the reduced cross contamination of powder caused by air movement within a convection oven.
Quantifying the Advantages of a Pre Gel Oven
Consider a typical conventional convection oven:
- Overall length of 96 ft., with a line speed of 3 ft./min.
- The available cure time will be 33 min.
- By inserting a 12 ft. long Gas Catalytic Pre Gel oven in front of the convection oven, there are three possible scenarios to consider:
Option 1 – Maintain same line speed, but reduce overall oven footprint.
Using the 3:1 rule of thumb (for every 3 minutes in a convection oven, only 1 minute is required in a Gas Catalytic IR Oven), the parts will be in the Pre Gel oven for 4 minutes, which is the equivalent of 12 minutes in a convection oven.
- Therefore, in this case, the parts require only a further 21 min. (33 min. – 12 min. = 21 min.)
- The required length of convection oven is reduced to 61 ft. (21 ft. x 3 ft/min.)
- Therefore the total length of oven (Pre Gel + Convection) = 12 ft. + 61 ft. = 73 ft.
- This represents a 23 ft. (24%) reduction in overall length.
Option 2 – Increase line speed, but maintain same footprint
- In this case, the overall length of the oven is still 96 ft., however, the first 12 ft. will be Gas Catalytic IR.
- Again, using the 3:1 rule of thumb, this the equivalent of increasing the overall length of oven to 120 ft.
- But we still require a cure time of 33 min., so the line speed required = 120 ft. /33 min. = 3.6 ft. / min.
- This represents an increase in line speed of 20%.
Option 3 – Add Pre Gel oven to existing footprint
If space is not an issue, and a 12 ft. Pre Gel oven can be added directly in front of the convection oven.
- Thus the equivalent length (actual length = 108 ft.) of oven becomes 132 ft. (36 ft. + 96 ft.)
- We still require a cure time of 33 min., so the line speed would need to be 132 ft. / 33 min. = 4 ft./min.
- This represents an increase in line speed of 33%.
Of course, these results can be improved upon further by increasing the length of the Pre Gel oven, to suit the required aims of the installation .
Added Energy Savings
Customers using Gas Catalytic Pre Gel ovens from Heraeus Vulcan have found that once a pre gel oven has been added, the powder gels rapidly, and less heat is then required to complete the curing process. This means that the convection part of the oven can be operated at a lower temperature, thus making considerable savings on energy costs.
In conclusion, for any given situation, the advantages of using a Gas Catalytic IR Pre Gel oven from Heraeus Vulcan can be summarized as:
- Increased line speed
- Increased capacity and productivity
- Same or reduced footprint
- Reduced cross contamination