When confronted with a fastener that just won’t turn, most of us reach for an impact wrench. However, while impact wrenches are capable of high torque outputs, they lack precision. When loosening a stuck fastener, this doesn’t matter much. But the unpredictable torque of an impact wrench can leave a fastener too loose or too tight. As such, impact wrenches are unsuitable for tightening in some applications, and mixing up impact wrenches and pneumatic torque wrenches can waste a lot of materials and labor hours every single day.
The mechanism that drives pneumatic torque wrenches is far different than that of an impact gun. Inside an impact gun, an internal hammer releases built-up force in a strike against the driveshaft. The best pneumatic torque wrench for manufacturing and assembly will be one that keeps the driveshaft continuously engaged, allowing for precise control of the torque output.
Types of Pneumatic Torque Tools
Pneumatic torque tools can be divided into two types. The first has a relatively low torque output and is suitable for light joints and assemblies. These are not technically pneumatic torque wrenches and are better-termed “air-powered torque screwdrivers.” Air screwdrivers keep the drive shaft engaged at all times. When the specified torque limit is reached, a clutch disengages the power to prevent over-torquing. In a manufacturing environment where each product needs to be tightened exactly to specifications, air screwdrivers excel—at least in light assembly where torque values are relatively low and measured in inch-pounds (lbf.in) as opposed to foot-pounds (lbf.ft).
Heavy-duty manufacturing environments demand a similar high-speed output but require higher torque values. In these environments, the best pneumatic torque wrench for the job is actually a pulse tool. Like air screwdrivers, these provide steady torque control through a gear mechanism. However, they are capable of delivering much higher levels of torque—over 330 lbf.ft of torque compared to an air screwdriver’s approximate maximum of 95 lbf.ft of torque. That’s powerful enough to cause employee injury from high torque shut-off reaction if it wasn’t for the unique mechanism that helped give pulse tools their name.
Inside of pulse tools is a hydraulic mechanism between the driveshaft and the air motor. The mechanism allows the driveshaft of the tool to spin freely when the fastener is loose. When the fastener becomes snugger, the hydraulic pressure in the mechanism builds until it acts upon an internal anvil, causing an exertion of force. The exertion decreases the hydraulic pressure inside the mechanism, but it immediately starts building again. This is the pulsing action that gives pulse tools their name.
The pulse is similar to the effect of an impact wrench in that it isolates the user from kickback due to the high torque values. It is dissimilar in that the drive shaft is engaged the whole time, allowing for exacting torque control. Pulse tools are available both with automatic shut-off for when the specified torque values are reached and without the shut-off to allow the operator to better control the fastening. The best pneumatic torque wrench for manufacturing will be either one of these pulse tools or an air screwdriver with the form and functions that are suited to your fastening needs.
The Best Pneumatic Torque Wrenches for Manufacturing
Air screwdrivers and pneumatic pulse tools fulfill different purposes. Which one is the best depends on the type of products you’re assembling. In-line air screwdrivers and in-line pulse tools mount the air engine, drive shaft, gear box, and driver in a straight line. They have a form factor that is a cylinder, with the air line connection on one end and the fastener driver on the other with a side mounted lever that engages the power. With everything in a straight line, you don’t need additional gears to transfer power around an angle. In-line pneumatic tools excel at assembly done flat at a workstation and offer excellent speed and output. In other fastening situations, in-line pneumatic torque tools have disadvantages. If there isn’t enough space to fit the entire tool above a fastener, then they cannot be used. And when driving fasteners into a vertical surface perpendicular to the shop floor, the cylindrical form factor can be difficult to control and speed suffers as a result.
Fasteners in vertical joinings are best served by pistol grip air screwdrivers or pulse tools with a pistol grip. These are the tools most people really need when they confuse impact guns with pneumatic torque wrenches, even though neither is technically a torque wrench. Visually, it’s easy to see why. The pistol grip gives these torque tools a very similar profile to impact guns and, in the case of pistol grip pulse tools, a nearly identical one. The pistol grip, however, also gives the user a greater amount of leverage, allowing the tool to put out far more force than in-line torque tools without sacrificing control. In vertical fastening, the pistol grip form factor is easier to line up and maintain control over. The reduced fatigue speeds up production and makes these the best pneumatic torque wrench to use for vertical assembly work.
However, the pistol grip is quite bulky and can’t be easily maneuvered to assemble joints that are flat at a workstation, nor will it tighten fasteners in tight areas in the same way an in-line torque tool can. A right angle pneumatic torque tool with a ninety-degree bend between the driveshaft and the driver near the tip, though, can. These tools can be used to tighten fasteners in tight horizontal positions, but they also work well in the flat assembly position. Although it is less than ideal for vertical assemblies, the body of the torque tool serves as a very long handle that can provide leverage so they can be used in this manner, although they tend to have lower torque output ratings than pistol grip pneumatic torque tools. Right-angle pulse tools and right-angle air screwdrivers are some of the most versatile pneumatic torque tools available.
The best pneumatic torque wrench in a manufacturing environment technically isn’t going to be a torque wrench at all. In light industry, it will be an air screwdriver, and in heavier duty manufacturing, a pulse tool. They provide power that exceeds the impact wrenches they are often mistaken for and the level of precise torque control that your customers rely on.
Mountz, Inc. knows the importance of torque control. That’s why we sell precision torque screwdrivers, wrenches, and pulse drivers that fill any role in manufacturing and assembly. To see our full range of products, shop our store. Contact us anytime to ask a question. To inquire about price, request a quote. If you’d like to see our equipment in person, schedule an appointment.