TORQUE CONTROL AUTOMATIC SCREWDRIVERS *** PNEUMATIC AND ELECTRIC *** TOOLED TO ACCEPT FASTENERS FROM AUTOMATIC VIBRATORY PARTS FEEDER BOWLS.
From simple hand-held electric, pneumatic, and torque control screwdrivers to nut runners, Lean Manufacturing Cells and beyond, we can quote a complete package that will be an exact match to your needs. We can help you with individual torque control screwdrivers or entire systems. We're uniquely suited to helping you to achieve your specific system requirements. We hold numerous patents and trademarks on the processes and equipment needed to perform the many functions involved in creating assemblies to the highest of industry standards. At MCI we are equipped to handle all of your needs for torque control screwdrivers and fasteners. Please contact one of our consultants by E-mail, or call us at (317) 776-1970, to discuss your applications for torque control screwdrivers today.
MCI/SCREWDRIVER SYSTEMS TORQUE MONITORING AND CONTROL DEVICES FEATURING QUICK STEP, TWO STEP TIGHTENING, PREVAILING TORQUE COMPENSATION AND TRANSDUCER INTEGRITY MONITORING.
Designing and manufacturing affordable and easy-to-use Pneumatic and DC electric automatic screwdriver and nut driver systems for tightening threaded fasteners is one of MCI/Scrwedriver Systems' major objectives. Our goal is to deliver a robust assembly system with precise torque control comparable to today’s state-of-the-art DC assembly systems, at an affordable price. In our efforts to meet these goals, we considered several choices for the MCI/Screwdriver Systems' torque control method. Today’s most accurate DC assembly systems use a torque transducer to continuously monitor the dynamic torque delivered to the fastener during the tightening process. The controller electronically monitors this dynamic torque signal to control the precise shut-off point. In our efforts to reduce the overall system costs, MCI Screwdriver Systems considers several alternative torque control methods when making recomendations base upon your production conditions and requirements.
TORQUE CONTROL - CLUTCH METHOD:
One choice is to simply use our mechanical clutch directly from the CT pneumatic tool line. This provides torque control comparable to that of a pneumatic tool, and requires the need for manual torque adjustment. This is a very low cost method of torque control.
BASIC CURRENT CONTROL:
Rather than use the torque transducer method another option that is available is a lower-cost DC electric systems. Instead of measuring the actual dynamic torque delivered to the fastener during the fastening process, these measure the power consumption of the motor. The most basic example simply monitors the electric current used by the motor, and when this current reaches a certain level, the motor is shut off. This method of controlling torque is not a accrurate as the torque transducer because “current controlled” systems monitor the flow of current into the motor which is not directly related to the torque delivered to the fastener. Many other factors can affect "current contolled" automatic screwdrivers. First, as the temperature of the motor increases, less torque is produced for a given amount of current. Shutting off the tool at a preset current level will produce less torque when the tool is hot. Secondly, the inertia of the rotating parts within a tool, combined with the response time of the control system will cause torque overshoot that is not at all related to the amount of current used by the motor. The amount of torque overshoot can be negligible when the tool is operated at a slow speed or on a soft joint, but it will be higher when the tool is at a high speed or on a hard joint. Simply measuring the current into the motor will not differentiate between these conditions. A third factor is the efficiency of the entire gear system. While a torque sensing transducer will automatically compensate for any change in efficiency of the planetary gear system, a system based on current control requires re-calibration as the efficiency of the gear system changes throughout the life of the tool.
ADVANCED CURRENT CONTROL:
Additional comprehensive software algorithm utilizing (advanced current control), may be integrated to arrive at a more accurate control of torque, in the above described power consumption method, by sensing the motor temperature thus compensating for the difference in torque output with changing temperature. Operating the system in a “learn mode” on a specific test joint while sensing the joint rate and then reducing the tool’s speed to a level where the torque overshoot produced by the rotating inertia becomes negligible, can help reduce the effects of inertia and can reduce torque overshoot. But this is only effective on production joints that are consistently similar to the sample joint. When these systems are used on production joints of varying torque rates, they fail to meet expectations. And when used on multiple joints of different torque rates, they require a joint type selector, which adds cost and complexity to the fastening system. One of the basic requirements of the ISO 5393 test method for torque capability over a wide range of joints is that tools be tested on both hard and soft joints without any adjustment to the control system. Systems that must “re-learn” or have control parameters changed for either type of joint will violate this basic requirement of this industry standard performance test. Advanced current control systems can help compensate for some of the shortcomings of the basic current control method, and under certain conditions, can actually produce fairly consistent torque control. But data from these systems can not be used to document process control capability because the data is merely a target, or a calculation based on a number of measured properties, not the actual dynamic torque delivered to the fastener. When compared to a reference master torque transducer, the indicated torque can differ substantially from the actual torque. Some tool users who purchased these systems have rejected them once they realized this deficiency. For all of these reasons, Stanley decided that a current control system was not the preferred torque control method for the Kappa system.
After considering the above alternatives, MCI/Screwdriver Systems will determine the benefits of using either the torque transducer, clutch method or other alternatives as described above as the heart of our torque control system. We strive to provide a clear, simple, and direct and most accurate torque control method based on the most reliable and affrodable methods.