Powder coating on wood - a practical method for developing your system
By Lou McGough

Making a commitment to install a powder-on-wood system requires more than just your OK on the proposals from the equipment and chemical suppliers.

Before you even contact a vendor you should have clear expectations and some solid numbers as a guide to both your present requirements and future needs. While no one can predict the future, planning for it must be done before finalizing the system.

Obviously, you know what you want to make today, but consider where you will be in three to five years. This has a tremendous bearing on the design of your system because it is easier for the equipment supplier to create an expandable line that will allow you to maintain the highest possible productivity for the lowest possible capital expenditure.

For example, if you are in the kitchen cabinet business and don't plan to expand into other product areas, your primary concern will be handling increased production volume of similar parts. Conversely, if you plan on expanding into a wide variety of different product areas such as store fixtures, work surfaces, etc., a single line designed for and dedicated to a single part, size or configuration may not be the most economical approach.

Two other options, in this case, may be well worth considering:

  1. Plan for a second line. You may want to consider an additional line at some point in the future to handle those larger-size pieces you anticipate making, a different chemical formulation or a different grade of MDF.
  2. Plan your single line for a high level of flexibility and expandability in terms of speed, sizes of parts that can be processed, etc.

Establishing parameters

Start by determining your current production requirements (for example, 400 parts per day.) This determines minimum line speed. Then estimate your future production requirements, such as 1,000 parts/day in three years. This determines maximum line speed. Now, determine if the increase can be accomplished internally.

For example, could you schedule two shifts or three shifts, or could you improve the part staging or pre-coating processes? This investigation is a critical factor in reducing your initial capital expenditure because every reduction of the maximum line speed reduces the total system cost.

Once you have established the maximum required line speed, the equipment supplier will be able to size the conveyor for future requirements. At this point, make certain the equipment builder can provide modular components. You want to initially size the ovens and cooling capacity for a lower line speed, and then add components as required.

Unfortunately, today's application equipment has maximum line speed limitations, meaning you can make incremental speed changes up to a point, but not beyond that maximum. Since application equipment can run 1/4 to 1/3 the cost of the system, choose your application equipment for a shorter projected time frame.

To maximize your investment, make certain you can get features, such as quick-change color cartridges. Initially, this may not contribute to productivity, but as the line speed increases, features that enhance the operation of the equipment will more than pay for themselves.

In calculating potential increases in production capacity, many people overlook the significant difference in production throughput with a highly automated powder coating line. 

Line speed

Wet painting and vinyl wrapping can be highly time- and labor-intensive methods, so when you are determining present and future line speed requirements, don't base them on your existing production capacity. Powder coating lines have significantly lower labor requirements by their very nature. Additionally, because an automated line can significantly reduce your labor costs, you should factor these savings into your equipment payback calculations.

Start by calculating the amount of time a part spends at each production stage, including work-in-process time. For comparison, if it takes 1-1/4 hours to fill, paint, sand and finish coat a board with a machined edge, it will take only about 20 minutes with an automated powder-on-wood line. Plus, the only labor required is for loading and unloading parts off the conveyor and making a color changeover.

If you are vinyl wrapping, calculate your scrap cost. With powder coating there is virtually no scrap since the overspray can be captured and reused.

What's best?

There are two ways to apply powder, hanging parts from an overhead conveyor and placing them flat on a horizontal conveyor. Each has strengths and weaknesses that will guide you in your decisions.

The overhead conveyor line allows all sides to be covered simultaneously. This enables you to achieve a full wrap. Additionally, there are no shape limitations. The horizontal conveyor permits coating only one surface at a time. As such, it is recommended only when the other side will have a different material applied, such as laminate.

The horizontal conveyor does give you better control over the mil thickness of coating and better load efficiency for slightly higher line speeds and greater system capacity.

Putting it together

The actual system design and layout is critical to the ultimate success of any powder coating line. As mentioned, the conveyor should be designed to accommodate future requirements. But how and where the various components are placed can impact more than just production capacity.

An automated line is highly flexible, but system design involves more than just assembling individual pieces of equipment. In a properly designed system all components must work together.

While the equipment can fit almost anywhere, loading and unloading points should be positioned close to their respective staging areas and the conveyor should be designed to maximize space utilization, not just horizontal but vertical. When calculating the total cost of your system, it pays to consider the hidden cost of the unused vertical space in your plant, especially if you are considering constructing a new facility.

Unlike a labor-intensive production line, a powder-on-wood automated conveyor can be designed to make use of vertical space, with ovens placed overhead and the cooling zone stacked underneath. Systems designed in this manner can cut floor space requirements up to 90 percent compared to a traditional paint or vinyl wrap line.


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