How Smart is Your Screwdriver?
Most consumer goods are assembled with small screws by hand. This close hand-eye work is prone to error. SMAC Moving Coil Actuators, out of Carlsbad, CA, has a solution that removes human error and replaces fallible pneumatic screwdrivers with what they call the “Smart Screwdriver.”
Using a pneumatic handheld auto-feed screwdriver to install screws is dramatically more productive than manually picking up a screw, inserting it into a part, and driving it home, but simple pneumatic screwdrivers are not an ideal solution either. Workers using pneumatic tools with compressed air and dials to estimate the amount of torque for the screw can strip or misalign the threads if an incorrect torque or angle is used.
For some manufacturers, a misaligned critical screw could result in stopping an assembly line. There is little or no feedback on the work until the device goes to QA. If QA misses the critical screw, it could lead to faulty products, angry customers, and the one word no manufacturer wants to hear- particularly in the automotive and aerospace industries: recalls. When you add this all up, a small screw could cost big money.
A common problem with screws and lug nuts is cross-threading. Cross-threading means the threads on a lug nut or screw are not aligned with the threads on the stud when you start to screw them together. To avoid cross-threading, many assemblers will start lug nuts or screws by hand, turning the screw the wrong way until he feels a bump and hears a sound. This is the screw falling into position. The assembler would then turn the screw several rotations before using a wrench or screwdriver to "snug" it into place. Up until now, this process has been difficult to automate, performed by human operators only.
This is how the Smart Screwdriver automates the process. First, it performs a fast approach, then finds the surface with our patented Soft-Land capability. Then, it turns counter clock-wise and the screw moves up and drops as the first thread is found. This is, in effect, “thread matching” and prevents cross-threading. The linear rotary actuator then starts rotating clock-wise. A "snug" torque can be applied. This is useful when there are a number of screws holding a part on the clamping surface and they need to be snugged evenly, then a final torque is applied. The entire time, the Smart Screwdriver is monitoring the torque and pitch verification. Good, shallow, cross/no-threads, and the precision of the thread are detected through feedback of positon and torque off both axes.
The SMAC Smart Screwdriver performs the same work as a pneumatic auto-feed tool electronically. There is no compressed air, no mechanical parts, and no need for oil or recalibration. On top of being maintenance free, the Smart Screwdriver also has a high degree of programmability, so that you know the screw is correctly inserted when linear height, degrees of rotation and the desired torque have been reached. The smart screwdriver monitors the linear position and force, rotary torque and degree of rotation while simultaneously driving the screw. These parameters are all completely programmable with the capability to have feedback sent to a PLC or database in real time. This ability to perform work and verify all in one move eliminates the need for down-the-line quality checks that are costly and time consuming.
The SMAC Smart Screwdriver is intended for a wide range of screw sizes, including but not limited to 1.4 millimeter or less, like those found in watches, eyeglasses, cameras, consumer electronics, cell phones, power tools, etc. SMAC Moving Coil Actuators tend to be small but the Smart Screwdriver is so small that it could be attached to a larger robotic arm for special applications, providing 100 percent quality every time.
Of course, the reverse could also be done. The Smart Screwdriver could be used to automatically disassemble a device, quickly, efficiently, and carefully.