In-Bay Automatics

Robotics - Wash Faster than an In-Bay or Conveyor

By Robert Roman |


According to the International Federation of Robotics, an estimated 200,000 industrial robots were installed worldwide in 2014, 15 percent more than in 2013.

An industrial robot is defined by ISO 8373 as an automatically controlled, reprogrammable, multipurpose manipulator programmable in three or more axes.

Shown in Figure 1 

Figure 1 – Gantry or X-Y-Z robot

is a gantry or X-Y-Z robot and car wash application. A gantry robot has the advantage of three or more axes of movement of almost any length. A gantry is flexible and efficient due to linear axes scalability. It can be sized according to range of motion and speeds, and it’s relatively inexpensive.

The major disadvantages associated with the gantry shown in Figure 2

Figure 2 – Standing frame gantry

are that it cannot vary reach into or around obstructions; linear slides, belts, and rails are not easily sealed against the environment; and it requires a stand, frame, or other mounting.

Another disadvantage of the standing frame gantry car wash systems is speed. For example, typical travel length of the gantry wash is 23’. Many gantries cover this distance in about 30 seconds or travel speed of 0.23 meters per second. Thus, a four-pass wash (detergent and wash) would take about two minutes, start-to-finish or an hourly capacity of roughly 30 cars.

If we add passes for wax and rinse, total time increases to three minutes and hourly capacity decreases to 20 cars. Add a minute to dry and capacity decreases to 15 cars.

This dilemma is resolved by installing a travelling axis on the floor so equipment can be positioned relative to conveying direction. The combination of travelling axis and automated equipment makes it possible to clean, shine, and dry and efficiency is maximized.

Hourly capacity is a function of conveyor length, roller spacing, and line operating speed. For example, at line speed of 60’ per minute or 0.3 m/sec, the conveyor is only 23 percent “faster” than the gantry but length allows it to process many more cars in an hour.

The major disadvantage of the travelling axis is expense. For example, minimum building length for in-bay gantry with freestanding dryer is 38’. Add 40’ at the entrance and exit ends for turning radii and property length of at least 118’ is required.

An in-bay system capable of processing 15 cars an hour cost $150,000. A short conveyor in the same building capable of 30 or more cars an hour costs $250,000. A conveyor capable of processing 100 or more cars an hour requires a 100’ building, property length of at least 180’, and equipment costing $450,000.

Arguably, technology will continue to drive innovation in car washing. For example, I wrote an article last year on the possibility of using robotic arms to wash cars (see Figure 3). 

Figure 3 – Robotic arm car wash

I came up with this idea based on my experience painting cars — a process that is similar to washing a car with a spray wand and trigger gun.

Here, finish quality is a function of coverage and maintaining a distance of 8” to 12” between the spray nozzle and the surface and a steady travel speed as vertical and horizontal surfaces are processed.

The difficulties in meeting these requirements includes recoil from the high-pressure spray wand, reaching up and down to get at high and low areas as the user walks around the vehicle, and anxiety as the timer counts down to zero.

Likewise, when auto painters encounter difficulties with application techniques, the result can be paint runs, paint lines, color mismatch, and other defects as well as overspray (waste).

In automobile manufacturing, robotic arms that open and close doors, hood and trunk lids, and apply paints have replaced people.

Robots are faster than humans. Arms have a high degree of accuracy and precision and there is less waste. Robots can support constant speed tracking (pedestal mount) and stop-and-go operation (move on rail or traveling axes). Robots keep employees out of aggressive environments.

Robotic arms also have high operational performance (20,000 hours, 93,000 miles). In addition to robot rotation, vertical and horizontal arm rotation, arms have hand rotation, axis and spray rotation. Moreover, a robotic arm moves seven times faster than an in-bay gantry and five times faster than a car wash conveyor.

There are several trends that may drive the development of robotic arm car wash systems.

• Today’s youth are increasingly adverse to the dirty and dull tasks that car wash operations sometimes require.
• Minimum wage, health care costs, and unionization of workers will continue to drive up the cost to wash cars.
• Automotive paints and applied protective surfaces will mostly likely be more durable in the future as well as a lot easier to clean and maintain.
• Higher real estate prices, increasing capital cost of automation technology, and increases in interest rates will continue to drive up the cost to build a wash.

So, robots may help put an end to companies needing to chase manpower, increase prices, clean with friction, and borrow more money.

In the final analysis, robotic arms can provide a wider range of motion and can be programmed for more complex tasks than either a gantry or a conveyor wash can. Robotics has the potential to use less energy than conventional automation with fewer errors and waste. 

Bob Roman is president of RJR Enterprises – Consulting Services ( You can reach Bob via e-mail at


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