Lean manufacturing is here to stay. It has been around for over 50 years and many companies have really started to implement Lean in a big way. Very often the results are immediate and when implemented correctly, gains continue to be made. Long term commitment and implementation delivers far reaching changes that ensure future competitiveness in an ever changing, more competitive business landscape. This article focuses on how Lean Manufacturing philosophy applies when considering powder curing technology. In particular gas catalytic infrared versus convection curing. It will be of interest to any company with powder coating ovens and is intending to or is already following the Lean path. Other aspects such as powder application, quick color changes and powder reclamation are extremely important but are already being addressed by the major providers in this field (Gema, Nordson, Wagner etc.).
Identifying the Lean Wastes – Continuous Flow and Batch Production
There are two main production systems for powder coating; continuous flow and batch production. The Lean wastes are generally common to both, except that there are other significant differences which require careful investigation and will be covered in a later article. This article focuses on the major differences between the leading technologies in curing, from a Lean Manufacturing perspective.
First let us consider what we are trying to achieve by reviewing the seven (eight including Energy) wastes identified by Lean.
The main aim is to reduce the following Lean Wastes within any manufacturing plant.
- Transport (moving products unnecessarily)
- Inventory (Work In Progress over and above what is actually needed to complete orders in hand)
- Motion (people or equipment moving or walking more than is required)
- Waiting (People or energy consuming processes waiting for parts or parts waiting for people or energy consuming processes)
- Overproduction (production ahead of demand)
- Over Processing (doing more to the product than is required)
- Defects (the effort involved in inspecting and fixing defects or scrapping parts)
- Energy (Unnecessary use of energy in the production process)
Implications for Lean Powder Coating
When the 8 wastes identified above are applied to conventional gas fired convection curing ovens, the following issues become obvious:
So, it is clear that there are significant drawbacks to using conventional gas fired convection oven in a Lean Manufacturing environment. They are inefficient, unresponsive to changes in production load or requirements and tend to be either on and consuming energy or off with no intermediate control available.
The Lean Powder Coating Curing Oven Solution
If convection oven curing is not the correct technology for companies serious about Lean, then what is the correct technology? Infrared technology has been available for over 20 years and is available in two forms.
Electric Infrared ticks all the Lean boxes in terms of controlability, but has two major drawbacks. Firstly cost; electricity is around four times as expensive as gas and can generally be ruled out on this fact alone. Secondly, the infrared that is emitted is short wavelength, which is not as easily absorbed by organic materials such as powder.
Gas Catalytic Infrared
Gas catalytic infrared is truly the lean powder coating solution:
- Catalytic infrared hits the “sweet spot” when it comes to absorption by organic materials
- Catalytic infrared is controllable.
- During production breaks the oven can be put into “Lo Fire” mode (20% of maximum output)
- The oven can be split into individually controlled zones to suit parts
- Each zone is infinitely variable between 20% – 100% output
- Size. A gas catalytic infrared oven has a footprint around 50% that of a convection oven.
- Efficiency. Gas Catalytic Infrared is around 85% efficient at converting energy into usable heat.
- Cure time is generally one third that of a convection oven.
- Less air movement within the oven means less powder blow off and improved finish quality
So in conclusion it is clear to see that gas catalytic infrared technology addresses all the Lean Waste issues that are raised by the use of a conventional convection oven, and why those companies involved in powder coating and wish to go Lean, should give serious consideration to a Gas Catalytic Infrared solution.