June 5, 2020
By using the correct equipment in your assembly you can greatly speed up the production and at the same time increase quality, decrease operator dependence, find defects in components or screws, store data from the tightening and keep track if there is need of improved assembly procedure or extra operator training. In this article we will go through some of the common challenges and the solution to handle them in production. Here is a customer of ours that has greatly improved productivity in production by switching to our MicroTorque assembly system and explains how and what benefit they experience with their new tools.
One of the major challenges in assembly parts and components in electronic and medical equipment is the low torques and self-threading screws in plastic. Tightening a screw to a pre-define torque in a plastic hole or in another material has to tackle a large variation in friction due to the imperfections of the hole and variation in the plastic material. The friction itself can vary a lot from hole to hole and from component to component and in order to achieve a safe and high-quality product you want to have a correct final torque. Other challenges include floating screw, where the screw is not run down completely, missed screws, thread out, screws look like they are assembled but the clamp force in the joint is wrong or missing.
Most of these challenges have in common that an operator can’t see it has happened or can miss faults due to human error, meaning a potential quality issue is missed and a product with potential problem is released to the customer. Another issue is re-work or damaged component taking resources from production.
By stepping away from click wrenches or traditional clutch tools and using more advanced tools the tool itself will be a means of checking for quality issues, verifying the assembly has been performed correctly, giving feedback to the operator and making sure you have an even and high quality in your assembled joints.
Advanced tightening tools have torque and angle monitoring and a number of ways to control the tightening to ensure a good result. By tightening on both torque and angle and using pre-set functions in our tools you can make sure the tool runs the screw down completely and then measures the clamp force from when the screw has run all the way down. By using this tightening strategy, you are not dependent on exact hole size or friction during rundown, the variation in friction will not affect the end result as this variation is not part of the final result, only clamp force/torque is measured. The tool will say the tightening was failed if the screw gets stuck on the way down before the rundown is complete, if threads are damaged, if the tool has stripped threads and cannot build toque etc.
Other features with advanced tools are the possibility to count screws, making sure all screws in an assembly is mounted and re-hit detection prevents the operator from tightening one screw twice. A positioning system or jig can be used to start the tool with the correct tightening program only when you tighten the correct screw in a sequence, guiding the operator to tighten screws in a specific order and the tool will use correct toque for the correct screw in the correct order. A smart vacuum pump can be used to pick screws or to tell a robot the screw is correctly aligned on the tool to perform the tightening without risk of damaging the threads. Of course the tools comes either as handheld or fixtured for robot/automated applications.
By monitoring your tightening's in a software, you can see if there is an issue in a batch of components, if an operator needs training or if there is an issue with latest batch of screws.
The MicroTorque assembly system is designed to tighten screws below 2.5 Nm and tools are available both in handheld and fixtured versions meaning they can easily be but in an automated assembly station or a robot as well as being used by an operator. The system is modular meaning the same controller and software is used for all tools, you pick what torque suits your application, what level of functionality you want in the control, length of cable, if you need a torque arm or if you want to be able to pick your screws with a vacuum nozzle on the tool. The MicroTorque assembly system can be controlled by RFID, barcode scanners or remotely programmed and monitored.
The MicroTorque system monitors the tightening and the data and result can be stored matched with a product serial number. This is done by a software allowing our customer full traceability which is required by the new MDR legislation on medical equipment. There are different needs in storing data and of course we can help defining what data should be stored and how to ensure a satisfactory traceability in production although the customer is always responsible in keeping and safeguarding its own data.
The MicroTorque assembly system can be used with a robot and communicate with I/O or open protocol. A number of successful automated or semiautomated assembly stations are used globally in a variety of industries.
For any questions regarding MicroTorque and tightenings (also for torques above 2.5Nm) please contact us and we will help you map out how to assembly quicker and smarter and with more quality.
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