Benefits of Efficient Racking
Posted on Monday, March 21, 2022
By Isaiah Haley
The past couple of years have been uncertain and we are all dealing with many of the same issues: increased material costs, supply chain delays, labor shortages, and the list continues to grow. In 2022, a primary challenge for powder coaters is to reduce costs to become more profitable.
Many factors impact the cost of coating: energy consumption, building costs, powder, labor, equipment, and maintenance, all of which are necessary. Most of these costs are fixed; the hourly overhead line cost is similar whether you coat 1,000 parts or 10,000 parts per hour. These factors combined make efficient racking more critical than ever. By implementing efficient racking, reducing handling, and increasing throughput, powder coaters can reduce their cost per part to become more profitable.
Many companies find that the paint line is the bottleneck of their manufacturing process; some even consider their paint system a “loss leader” to sell their finished product. Efficient, maximum density racking will reduce or eliminate bottlenecks to challenge those lines of thinking and increase profitability. So, what is efficient racking and how can you implement it into your system? The first step is to evaluate your current system to understand the type of racking that you need. Since there is no “one size fits all” solution for powder coating, a variety of factors must be considered before beginning rack design.
- Hanging method: How are you hanging parts? What is the size of your part window? (single hooks, daisy-chaining, welded racking, adjustable racking)
- Part density: Are you maximizing the amount of space on your line?
- Part variety: What types of parts are you hanging (small, large, or both), and what are the parts that can be coated more efficiently?
- Line speed: What is your current line speed? Can it be increased?
- Cleaning and maintenance: How do you clean your hooks/racking? (burn-off, acid dip, fluidized sand bed, no cleaning) How often do you replace your hooks/ racking?
The size and style of racking will change from system to system, depending on the parts you are finishing and the system style (batch or overhead conveyor line), but all efficient racking shares the same principles.
Hanging Method and Part Density
The first step is choosing the proper hook and hanging method. Successful hook designs will present the class A surface to your powder guns, minimize touch points, and ensure the part is angled properly for drainage.
The second step is to maximize density. Rack density has more impact on profitability than any other factor; increased density allows you to finish more parts per cycle, reassign the saved labor to other production areas, or reduce labor costs, further increasing throughput and profits.
Let’s look at an example:
Company A is currently coating 600 small parts per cycle by daisy-chaining single-use hooks under a load bar. There are currently 12 parts per load bar and 50 load bars in the system. By implementing adjustable racking, the company now hangs 40 parts per load bar and is finishing 2,000 parts per cycle—roughly a 233% increase in production. This example shows how racking increases throughput for one part, but what if you need to use the same racks to increase throughput for a variety of parts? This is where step three comes in.
Step three addresses the variety of parts you are painting. Efficient racking is often universal and adjustable to work within the scope of your parts. Adjustability is especially important for finishers who are painting large volumes of various-sized products.
The benefits of adjustable racking are:
- The same rack frame can hang a wide variety of parts.
- The maximum number of parts can be hung on each rack.
- The overall amount of racking stored off-line can be reduced.
Consider the following ways racking can be adjustable:
- The spacing of the horizontal crossbars can be adjusted to fit the specific parts being coated, minimizing the distance between part rows.
- The part hooks are not welded, which enables broken hooks to be replaced or the hook style to be changed for different parts. They can also be swapped out for clean hooks.
The fourth step is to evaluate line speed and improve it. Unfortunately, most lines run slower than designed because they are limited by “people speed,” and in the case of Company A, 233% more parts are now being hung per cycle. To hang the increased number of parts while the racks are continuously moving can be challenging and may require increased labor (more people hanging/removing parts) or even a slowdown in the line speed, both of which reduce profit.
Instead, off-line loading and unloading can resolve this issue and reduce cost. Off-line loading and unloading usually does not require additional labor and will increase line speed, further increasing throughput. Rather than hanging or removing parts one at a time, racks loaded off-line (lifted from staging carts) will allow larger quantities of parts to be loaded onto the line all at once.
Using carts for off-line loading can also increase efficiency in other areas of your process. The carts can be used for off- line transportation of parts on racks to and from the paint area, either by forklift or a rolling base. In a manufacturing plant, the parts can be installed on a rack in weld stations and transported directly to the paint line. They can also go to assembly after coating. This will often reduce the amount of handling by up to 50%, saving valuable time for production employees. The staging carts also provide organized rack storage when not in use. Rather than stacking racks on pallets or, more often than not, on the floor in the corner, floor space can be saved by hanging the racks in designated storage areas. This will also extend the lifespan of the racking. In addition, specifically designed staging carts are available for part hooks that are not in use. Rather than putting hooks in a box, where they become tangled, hanging them from a cart extends the lifespan of the hook and saves time in untangling hooks.
The last benefit of staging carts is that they can transport racking to cleaning and burn-off.
Cleaning and Maintenance
The fifth and final step is to reduce cleaning and maintenance. Although cleaning hooks and racks is unavoidable, frequency can be reduced by implementing internal grounding into your racking system. Using the Faraday cage effect, internally grounded racking shields the contact points on racks to stay clean of powder and maintain the proper electrostatic current for longer periods of time. To further reduce costs, operators can quickly replace hooks/contact points multiple times before cleaning entire racks. Once internally grounded racks have either lost their grounding or have excessive powder build-up, they can be cleaned through burn-off, chemical stripping, or a fluidized sand bed.
Reducing rack maintenance is another important step towards efficiency. Welded racking often wears out over time, resulting in damaged or missing hooks. Each broken hook reduces the amount of density on the paint line, and damaged racks must either be entirely replaced or sent to welding for repair—both of which are time-consuming and expensive. Modular racking with replaceable components allows quick repair of racks/hooks without the need for welding or rack replacement. If using welded racks, this method should be considered.
The implementation of efficient racking requires an investment of time and money, but when done correctly, the return on investment is often immediate. An efficient racking process will increase line density, enable increased line speed, reduce the amount of cleaning and maintenance needed, and decrease overhead cost per part—ultimately making you more profitable.
Isaiah Haley is senior account manager for Production Plus Corp.