Today’s manufacturers realize that relying on an operator’s brute strength to get the job done is not only dangerous, but counterproductive. This is especially the case with today’s high throughputs and the increasing emphasis on quality.
Manufacturers have also come to appreciate the importance of a well-organized workspace. More and more, manufacturing engineers are realizing that every tool should have its place. In electronics manufacturing, in particular, there can be a lot going on in a small area. No matter what the industry, hunting for tools is an obvious waste of time, even if an operator only spends a few seconds doing it.
To resolve these issues, manufacturers have the option of employing a variety of different tool support systems to both stabilize a tool and, in many cases, lift it out of the way when not in use.
At the most basic level, there are retractors, spring-loaded reels that exert an upward force on a tool, lifting it up and out of the way when it is not in use. (Some models also have a lock, which works like a window shade, allowing a tool to be held in place.) These come in two basic forms: wire reels that are clipped to the tool, which is then powered by a separate umbilical; and line reels, or hose reels, in which the pneumatic umbilical itself supports the tool and is wound and unwound in the retractor.
Although at first glance, the latter may seem the obvious choice for any kind of pneumatic tool, it has its downsides. For example, line reels have a bulkier feel to them, which can bother operators who are continually pulling them down and letting them go. They are also less flexible in that they can only be used with pneumatic tools and removing a tool for maintenance means detaching it from its umbilical.
Similar to retractors are balancers. Whereas retractors will lift a tool up and out of the way once it is released, a correctly sized and adjusted balancer will hold the tool at the exact point where it is released, essentially leaving it hanging in midair. The advantage to this approach is that the operator doesn't have to reach up to retrieve a tool. Obviously, if the tool is used in just one of a number of operations at a given workcell or station, the reaching action won’t be overly burdensome. However, if an operator is installing multiple fasteners with a single tool, having it immediately at hand can make a world of difference.
Of course, while hanging a tool from a hose or cable means an operator does not have to support its weight, this does nothing to control the tool once it is in use-a concern especially when attaching high-torque threaded fasteners. To solve this problem, manufacturers can implement an articulated or linear torque arm, to both support the tool’s weight and help protect operators from harm.
These systems, which can be used with either pneumatic or electric tools, generally hold the tool so that it remains in a vertical orientation, although adapters can be added to set the tool at an angle or even at horizontal.
In the case of a linear arm, a single-piece arm both revolves around, and travels up and down on a fixed shaft. In the case of an articulated arm, a jointed arm allows the tool to cover the entire area within the arm radius.
When looking at different arms, engineers need to be aware that not all arms are created equal, that, in fact, they can vary widely in terms of performance and quality. For example, some arms employ an adjustable pneumatic system to support the tool’s weight, while others depend on a sealed-gas cylinder, like those used in the hatchback of a car. This latter approach makes the arm less expensive and can still provide excellent performance. However, it can be trickier to fine-tune.
Similarly, while some arm joints are built with high-quality bearings, others use bushings or even stripper bolts, which wear much faster.
In terms of mounting a torque arm, the options are endless. In many workcells, the arms are simply bolted to the work surface. However, if space is tight, floor pedestals are available. Manufacturers can also mount an arm on an overhead rail system or to a nearby wall.
Finally, for those really big jobs, engineers have the option of going with a torque tube or vertical balancer. These devices move up and down with the aid of a pneumatic cylinder, and are generally moved to and from a workpiece using an overhead rail system. Vertical balancers are more lightly built and serve primarily to support a tool’s weight. Torque tubes, as the name implies, are much beefier and robust enough to absorb the forces involved in high-torque applications.