Power tools offer maintenance and engineering managers a way to meet both portability and heavy power challenges involved in getting maintenance work done effectively and at low cost. When starting a work order requiring a power tool, the technician wants to grab the right tool and go to the job site without delay and work productively to minimize operations downtime.
To achieve these goals, managers need to ensure the tool has the latest features for the job and be in good repair, and the technician must know how to use it to the best advantage.
By understanding the latest advances in power tool technology and materials, managers can specify tools that meet these needs and address user safety, productivity, and ergonomics demands.
Spotlight on batteries
Battery choice is a complex decision because of the many choices available. Features to consider include the metals used, power density, weight, size, self-discharge, and memory effect. Because of their use of low toxicity metals, energy density, and low self-discharge when not in use, lithium-ion batteries have become the power source for a range of power tools. And since lithium-ion batteries have been used for a long time, their cost is lower.
Battery options for power tools include nickel cadmium, lithium phosphate, and lithium polymer. Nickel metal hydride batteries are large, due to their low energy density, but they cost less. Generic replacement batteries will lose power as charge is used up, while better batteries retain the same power as they discharge.
Quality is crucial. Better batteries fully charge every time, while low-cost batteries acquire a memory effect, meaning they only partially charge after many charges. Multiplying amps by volts equals watts, which is the best way to measure power output. Six amps will deliver more power and run time than four amps of the same voltage.
Batteries come in many sizes and shapes, so it is especially important for managers to match the replacement battery with the model and make of the power tool. Replacement batteries are available online using battery finders by entering the tool model number and battery model number.
Battery-powered tools need no connection to the building’s power distribution system. Since maintenance work can be in remote areas, such as at high overhead, parking lots, storage buildings, and landscaped areas where no power source is close to the work, battery-powered tools are the ideal choice. Landscaping power tools have higher voltages of 40, 56, 60, and 80 volts. While they are more environmentally friendly than gasoline, some models have limited power and run time and can take about an hour to charge.
Material upgrades
Magnets composed of rare earth metals are a critical component in brushless motors in power tools. Cost-sharing research and development projects from the U.S. Department of Energy Include $19 million for advanced production methods for rare earth metals from abandoned coal mines.
These metals are quite abundant but occur in small amounts that are widely dispersed, so they challenge manufacturers to extract them at a reasonable cost. Nickel metal hydride batteries contain 7 percent of rare earth elements, such as cerium, lanthanum, neodymium, and praseodymium, or at least 2 ounces in a power tool battery.
An increasingly wide range of tools use brushless motors, but many brushed-motor power tools remain in use. To effectively use brushed motors, users need to stock proper materials, such as motor brushes, brush sets, and two spare batteries. Brush mechanisms must be available in inventory and replaced in a timely way to avoid on-the-job delays.
Since the brushes and commutator make physical contact in brushed motors, the brushes wear out and must be replaced regularly. The commutator will become grooved from abrasion of the copper brushes and require removal of scratches with emery cloth or replacement. A popular brand of power drill that features brushless motors has heavy-duty nylon or polypropylene housings and aluminum polymer capacitors. Opening the housing is simple, requiring removal of 12 screws and sliding off an alignment pin.
The inner assemblies consist of subassemblies — the brushless motor, switch sub-assembly and steel planetary gearbox. It requires less maintenance because it has an air gap between the rotor and fixed magnets, so there is no physical contact to cause wear. For this reason, this type of power tool tends to last longer with fewer repairs. Even though the initial cost is higher, the life-cycle cost is lower since it requires fewer repairs.
Brushless motors have become the motor of choice for power tools. These motors are the basis for a range of innovative, heavy-duty power tools. In addition to saws, drills, chippers, and grinders, numerous tools are manufactured to handle heavier loads with longer run times:
• A collated screwdriver feeds screws into driving position from a clip and has a rotating head.
• A miter saw works against the wall using two 18-volt batteries.
• A rotating-head rebar cutter uses a single chopping action.
• A sheet metal nibbler uses a rotating head and variable speed.
• A circular saw uses two 18-volt batteries and offers eight amp-hours power.
• A chainsaw kit includes two batteries, two chains, charger, and tools.
• A worklight features eight hours of run time, low-battery warning, and a threaded base for tripod.
Portable welders are a special case. Among the most common types are: electric arc (stick); oxy-acetylene gas; tungsten inert gas (TIG) and metal inert gas (MIG). Oxy-acetylene does not require an electric outlet. Oxy-acetylene cylinders provide the oxygen and gas for cutting and welding steel, brass, and bronze. TIG welding joins aluminum and stainless steel, and MIG welds steel faster.
Safety, productivity and ergonomics
Power tool users can gain benefits in safety and productivity from the higher power that new-generation tools offer. For example, upgrades to higher voltages for landscaping tools and double batteries increase work done and battery life to give users more productivity with less physical effort and fewer recharges. The lower the physical effort needed, the better control the user has.
For example, 36-volt tree branch cutters provide 17,000 continuous cuts and are adjustable for two sizes — 0.5 inch and 1.25 inch. Another innovative safety feature is torque control designed to prevent jamming, which can injure the user and damage the power tool. Also, innovative three-ring tool lights give users a clearer view of the work site.
Power tools enable users to be more productive than with manual tools, but they also get dirtier, wear out, and become dull faster. As a result, they become less safe because the user has to put more muscle into the work to get the same results as with a clean tool and sharp tooling. Productivity and safety both decline.
Managers can use a regular maintenance program to keep the power tools in top condition. By rotating this duty among users, managers can improve the understanding of the important role of preventive maintenance, and the users gain an understanding of the way the tool works, which improves productivity.
The focus on safety also extends to tool specification, where managers can pay attention to such features as retractable guards above and below the workpiece, well-designed grips, and two-handed operation. With cordless power tool technology, users do not have the added safety challenge of needing to keep the cord behind them and working away from the cord to avoid causing a shock or damaging the cord.
In the age of COVID-19 and its variants, safety managers also must pay continuous attention to changing federal guidelines and standards about safe work environments for power tool users. They also need to watch for newer advice and upgrades about washing hands and surfaces, using masks, and proper distancing. Some work environments, such as healthcare facilities, still require wearing masks, and more are likely to if the variants continue to spread.
Thomas A. Westerkamp is a maintenance and engineering management consultant and president of the work management division of Westerkamp Group LLC.
