Pneumatic nailing tools are an integral part of any pallet company. Some nailing machines use pneumatic tools, and even companies that are equipped with automated pallet assembly systems that drive nails with hydraulics inevitably assemble or repair some custom pallets by hand.
Proper care and maintenance will not only extend the service cycle and life of a tool but can also increase operator productivity.
One of the most important aspects of maintaining pneumatic nailing tools has nothing to do with the tool itself but rather with the compressed air supply system that powers the tool. A better understanding of how the pneumatic tool works with the compressed air system can lead to more cost effective, efficient operations.
Air Supply System
A good air system must supply the correct volume of clean air at the required pressure to properly drive a nail or other fastener. The air supply also has to provide lubrication to the internal parts of the tool.
Air Volume
While maintaining proper air pressure (measured in pounds per square inch-psi) is often emphasized, having adequate, clean air flow is equally critical to proper tool operation. Due to friction, airflow and pressure are reduced if the air line is too small, too long or restricted in some way. Air flow or volume is measured in cubic feet per minute (cfm).
If a tool does not appear to be getting sufficient air, the first reaction often is to increase the pressure with little thought about air flow. Pneumatic nailing tools are designed to perform optimally with air at a lower pressure and a higher volume.
If an air supply system is improperly sized or designed for the number of tools and the pace of nailing, the tools will not work properly. For example, the Stanley-Bostitch N70C tool requires 4.3 cfm of free air at 80 psi to operate properly at the rate of driving 60 nails per minute. If another nailing tool is added to the system and is also driving 60 nails per minute, twice the volume of free air is needed.
A properly sized compressor and an unrestricted air supply system must provide enough air volume to maintain the correct air pressure during full speed operation. A good way to test if a tool is getting proper pressure and sufficient air flow is to hook up a pressure gauge right behind the tool on a T fitting and activate the tool action. If the pressure drops slightly and then recovers immediately, the air supply system is adequate. However, if the pressure drops 5 psi or more and takes a second or more to recover, the air flow is not adequate. Even though the system may pressurize the air to 100 psi, it cannot provide enough air to operate the tool properly if the air supply system is too small or is restricted in some way.
A symptom of an air supply system that is restricted is ‘laddering’ of nails. The first nail drives properly, but the air supply system cannot recover quickly enough, and the tool fails to completely drive the second or third nail. Rather than increasing the pressure, the air supply system should be checked for restrictions and to ensure the overall design provides adequate air volume and flow.
Air Restrictions
Condensed water is a by-product of compressed air. Water blockages can collect at a low point in an air pipe and greatly restrict air flow in a system that appeared to work well at first.
Other sources of restriction are narrow diameter fittings, hoses, or pipes that reduce air flow similar to a clogged artery. If an air supply system is constructed with 1-inch pipe but contains a ¾-inch fitting at a point in the main supply line, air flow in the entire system is restricted by the smaller fitting, and the pressure must be set higher to deliver the same air volume.
Often the last pneumatic nailing tool on a line gets the least amount of air. As tools are added in a shop, it becomes more critical for them to be connected to a looped air supply system rather than an air system supplied by a single pipe. (See accompanying diagram of a properly designed air supply system.)
Here are a few more recommendations to achieve optimum air supply system performance:
• Spur lines feeding individual tools should be tapped from the top of the pipe to avoid filling with condensed water, ensuring clean air flow.
• A secondary remote storage tank located at the far end of the loop can help increase air flow and maintain pressure, especially during high usage.
• Moisture traps and drain valves should be placed at low points and dead ends on the main pipes as well as spur lines; they should be drained daily to prevent condensed water blockage. Installation of airline dryers also can help eliminate moisture.
Air Pressure
Excessive air pressure costs money. A compressor struggling to maintain excessive high pressure wastes electricity, and excessive pressure also increases tool wear and downtime.
Pneumatic nailing tools generally should be operated with compressed air between 70 and 100 psi. Pressure beyond what is required to drive the fastener is absorbed by the tool, causing excessive wear and mechanical failure. Bumpers and parts that drive the nail will become highly stressed by excessive air pressure. (See accompanying diagram of a typical pneumatic nailing tool’s components.)
A pressure regulator must always be used with the air supply system to control pressure. Tools and regulators should never be attached to pressurized air sources that could potentially exceed 200 psi. Regulators must be correctly sized for the air flow. A regulator that is too small could restrict air flow and affect tool cycle rate and power. A regulator with a gauge, such as the Bostitch 86504, should be placed as close as possible to a tool or group of tools in order to get good pressure at the tool. Another benefit of properly pressurized tools is that they function more quietly: the lower the pressure, the quieter the exhaust from the tool.
Lubrication
Most pneumatic tools require frequent but not excessive lubrication by adding small amounts of oil to the air line. This can be done by squeezing a few drops of air tool oil (not detergent motor oil) daily to the male fitting on the end of the tool.
If in-line lubricators are used, they should be mounted as close to the tool as possible since the tool — not the air line — needs to be lubricated. In addition, placing the lubricator too far from the tool will create an oil sludge inside the piping, restricting air flow and provide little benefit to the tool. Remember: too much oil can be just as detrimental to the tool’s internal parts as no oil.
Winter Care
When not in use during winter, tools should be stored in a heated area. Compressors and airlines should be drained at least once a day. Winter air tool lubricant should be used. In cold weather it is a good practice to blow water out of the drop hose by opening the female disconnect at the end of the day.
Filters
Several corrosive materials can get into a pneumatic nailing tool and reduce its service cycle: water vapor, rust and pipe scale, dust and compressor oil vapor. Air filters clean the compressed air. Filters must be correctly sized for the air flow and located to catch the contaminants; ideally they should be placed close to the tool. Like the filters in a car, they must be properly maintained in order to be effective.
External Care
Another way to greatly prolong the life of a pneumatic nailing tool and its replacement parts is to mount the tool on a zero gravity balancer. (See accompanying photograph.) The balancer protects the tool from being repeatedly thrown or dropped onto a table. It also reduces worker fatigue, resulting in higher productivity and greater nailing accuracy.
If a balancer is not feasible, a simple holster may be built out of scrap wood and mounted to the side of a work bench; the worker places the tool in the holster temporarily when he handles the pallet. The holster can prolong the life of the body and nose of the tool. It also
increases productivity because the worker always reaches in the same place for the tool.
If pallets are being assembled or repaired on a metal table, put down plywood on the area where the tool is placed when not in use; this greatly cuts down on external wear on the tool over time.
A well designed and maintained compressed air supply system coupled with properly lubricated and handled tools can go a long way in reducing downtime and operating costs, ultimately increasing productivity of pallet assembly or repair operations.
(Editor’s Note: Pallet Enterprise wishes to thank Stanley-Bostitch and Paul Jacey for providing the above article. For more information or questions on this article, call Stanley-Bostitch at (800) 832-3080 and ask for the author or your local territory manager.)
