Powder Coating Ovens: Industrial Box Oven vs Tunnel Oven | Ultrimax

box oven vs tunnel oven

Which Powder Coating Oven? Industrial Box Oven vs Tunnel Oven

There are three main deciding factors when it comes to choosing the best type of powder coating oven for your business – production rate, budget and space. In short, an industrial box oven will serve the needs of any metal finishing outfit that doesn’t require mass production. As soon as high production rates become your primary concern, a tunnel oven is the way to go.

Here we explain the difference between the two types of curing oven and the things to consider before upgrading to a tunnel-type system.

What is an industrial box oven?

Box ovens are designed for batch-curing powder coated items or for curing something that is too big to go through a tunnel oven, such as plant or machinery. Because it works on a batch process as opposed to a conveyorised system, it is suited to businesses that operate with lower production rates.

Box oven working principle

A box-type oven achieves maximum temperatures of around 180 – 200 ºC using the same recirculation system as a tunnel oven. Air enters the oven through ductwork at the bottom. It is then partially recirculated via a burner box in the ceiling, with some air being extracted via a high-level extraction system. Together, the ducting, burner box and extraction system keep the baking chamber at a constant and even temperature.

A box system differs to a tunnel oven in two ways:

A box oven has doors (and no air seals). You simply open the oven, put the product inside and close the doors again. When the product has cured, you remove it from the oven.
It's not conveyorised. Your technicians will need to transfer freshly powder coated items into the oven and then remove them once the baking process has finished.

Box oven price

Because industrial box ovens don’t require the mechanics of a conveyor system, they’re significantly cheaper than tunnel ovens. You can expect to buy a standard size box oven for around £20K through to £50K+ for a large oven.

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What is a tunnel oven?

Tunnel ovens work at high temperatures and produce a constant production line, so they are ideal for any business curing powder coating on a large scale. They are also commonly used at lower temperatures for drying wet-spray products where you need high production rates.

Tunnel oven working principle

A tunnel oven is essentially an insulated stainless steel box that fits over a conveyor system. It usually has two open ends, with an air seal at each end to stop the cold air from entering the baking chamber and the hot air from escaping.

As with a box oven, air enters from ductwork beneath the oven and is recirculated via a burner box in the ceiling with some air being extracted out through the exhaust system to maintain a constant temperature. The product exits the oven fully cured (powder coating) or fully dried (wet-spray coating).

Product temperature

A tunnel system needs a data-packing system in place to achieve the correct product temperature for curing according to the thickness of the metal. In layman's terms, this means using a specially designed thermometer that monitors and records hotspots as the product passes through the oven. Data-packing gives your technicians the information they need to adjust the dampers inside the oven and reduce the likelihood of hotspots.

Tunnel oven design

Tunnel ovens are designed to the client's requirements for two main reasons:

They use both heat and a conveyor system, so the oven must be a set length according to the production speed requirements.

box oven vs tunnel oven calculation

They need to be a specific size according to the products being cured.

Tunnel oven price

Any plant with a conveyorised system comes with a decent price tag. You can expect to pay £50K through to £200K + for a tunnel oven, depending on size and customisation requirements.

The bottom line

There are three main considerations when it comes to deciding whether you need a box oven or tunnel oven for your powder coating operations: production rate, cost and space.

Production rate

If you have a problem with getting enough stock out the door with a box oven and you are running the most efficient production line possible, it may be time to consider upgrading to a tunnel oven.

Cost

If you need to up your production rate but haven't got a budget of at least £50K to spend on a tunnel oven, your best bet is to work on your production line efficiency and start putting the budget aside for an upgrade.

Space

It's not just the budget that you need to accommodate a tunnel oven. Get your supplier to work out the necessary oven dimensions and working space required for your production needs. You may need to factor in expanding or moving premises to accommodate a tunnel oven.

What next?

Talk to an Ultrimax expert advisor to identify your powder coating oven needs. We can work with you to:

Improve your production rate efficiency
Design a box or tunnel oven system that meets your production needs and budget
Plan for an upgrade to a tunnel oven if this is the next stage for your business