Benefits of Automated Robotic Systems for Screwdriving

Automated robotic systems for screwdriving and nut running offer manufacturers a great solution to alleviate repetitive, non-ergonomic tasks from their assembly lines while increasing the quality and consistency of their finished products. In this post we explore current trends in robotic screwdriving technology, and provide insight into cutting-edge models that are able to tackle unique applications previously untouchable by last-gen solutions.  

Robotic Screwdriving Overview 

No matter the industry, screwdriving and nut running are called upon as primary fastening methods used in all sorts of modern manufactured assemblies. Threaded fasteners play a pivotal role in industrial design, offering a very appealing combination of high strength at low costs on account of being available in seemingly countless options and styles. In early automated manufacturing days, threaded screws and nuts were mostly handled manually for all but the largest and highest volume production lines. Thankfully today, we see automated solutions for nearly any threaded fastener application of nearly any size. While the initial goal of automation in this arena was to free humans from the redundant and non-ergonomic task of threading in fasteners by hand, new technology advancements seek to improve the working conditions of human operators in even larger ways.  

For our purposes here, automated screwdriving can be defined as using a controller and a driving tool to repeatedly complete the work of threading a fastener into a component. The driver can be loaded by hand, the component set in place by hand and the controller engaged to run the screw into position until a preset torque or rotation value has been achieved, stopping when complete.  

Introducing motion and deterministic steps into this automated screwdriving process turns the system into a “robotic” system. In a robotic screwdriving arrangement, the component to be fastened is placed into the fastening machine by hand, and then all other steps are completed by the automated robot: pick up and orient the fastener, move the fastener to the appropriate location, align the fastener path with the target, confirm that all variables are acceptable, complete the screwdriving insertion and confirm that the fastening was successful. 

Modern screwdriving and nut running systems employ a host of additional sensors, adjustment actuators, safety devices and data management tools to further automate and streamline a fastening workflow. Common advanced features found in today’s systems include integral torque measurement, positioner tracer arms, automatic data tracking, operator safety sensors and automatic tooling change mechanisms.         

Automated Deployment Schemes 

We introduced above a few deployment options for automatic screwdriving and nut running systems. Let’s put specific names to these tiers of automation levels, which will help you differentiate systems and their benefits in better detail.  

Mounted Automated Fastening System

A fastening system consisting of a single or multiple screwdriving tools typically mounted on holding arms, along with a controller to start and stop the threading runs is referred to as a mounted fastening system. This type of system typically requires that an operator move the tool to the fastening position by hand, one task at a time. This machine utilizes hand-loaded fasteners and components, and runs screws or nuts downward until the desired torque value is met. The benefits of this design include:

• Mounting arms bear the weight of the screwdriving tool, not the operator.
• The screwdriver turns itself, and the operator does not need to perform the twisting insertion motion. Operators only push a button to engage the driver.
• The controller will monitor and stop the driver when the desired torque value is met, so that the operator does not need to feel or measure torque manually.

Mounted Robotic Fastening System

Adding automatic driver positioning and multiple fastening runs to the mix gives us a mounted robotic fastening system. The robotic element lays in the machine’s ability to load its own fasteners into the tool end, move the driver itself through the entire fastening process and to perform these tasks multiple times sequentially until a number of thread runs are completed on a single part. Only the initial part load is performed by hand, and the robotic machine does the rest. Benefits here include:

• Minimal manual operation: Operators only need to load the part and fasteners into the machine. 
• Driver motion is automatic, ranging from simple vertical motion of a single driver to multi-axis position seeking and orienting of multiple drivers via position or vision sensors.
• Automatic error detection.
• Automatic part adjustment in some systems (moving the part into position if a misalignment is detected).
• Completion of all fastening tasks and production of a finished part upon completion

Cobot Fastening 

An emerging deployment scenario for robotic fastening systems places the robot adjacent to humans in a shared workspace, each completing complementary assembly tasks simultaneously. For example, a part might be loaded into a machine with a human completing a series of initial preparation steps, then once the machine senses that these steps are complete, it automatically and safely proceeds to the next screwdriving steps itself.  This arrangement: 

• Greatly reduces overall assembly time by overlapping human and machine assembly tasks.
• Decreases reject parts by having the human and machine both double-check each other.
• Reduces manufacturing steps needed in the overall production line.
• Optimally splits the workflow between human and machine: Humans focus on judgement-based, subjective, variable tasks, while the machine completes repetitive, high precision, routine tasks.
• Uses smaller robots at lower costs to perform a portion of the work, presenting a great economical value between very expensive, fully automated equipment and entirely manual, slow, error-prone assembly.

Modular, Re-Deployable Robotic Fastening 

Automating highly variable, constantly changing production lines has always been a challenge to mounted robotic systems. In recent years, a new generation of robots has introduced small scale, movable, fully reconfigurable systems expressly designed to serve changing production demands. The value of these robots is found in their unique programming and interface software, allowing very easy, non-technical configuration for modified or entirely new workflows that the end user can set up without the need for software coding or re-engineering. In short, modular robots can be moved between dissimilar parts and stations as often as needed. Benefits include:

• Small, entirely customizable robots that are not limited to fixed locations or tasks.
• No need for special technical skills or software to program; they can be redeployed easily by plant staff.
• Reduced investment cost compared to separate dedicated machines.
• Improvement in new design launch time; they can be redeployed very quickly, even moved between dissimilar applications from day to day.
• Availability to rent or lease in some markets.

Common Applications 

To exemplify a few common automated screwdriving applications, we’ll use our line of Precision Fastening Systems as models.  

• AMS’s PF-201 is our basic, low entry cost precision fastening machine, designed to solve ergonomic and consistency demands in single tool, small scale applications. The screwdriver is mounted onto a manually positioned tool balancer arm, with controller-managed torque and quick-change tool ends. Our PF-201 is a great selection for entry-level automation of low volume, high precision applications such as automotive and industrial component assembly.   
• Our PF-301 offers expanded automation capabilities with an onboard PLC, color interface screen, safety sensors, reconfigurable tooling and error-proof positioning. This model introduces automatic driving, using actuated arms to pick up and position fasteners to multiple fastening points on a given part. Operators only need to load the part into the machine, and the rest of the fastening process happens automatically. Supporting up to 10 tools working simultaneously, the PF-301 is perfect for complicated, multi-fastener, high volume part assembly in plastic manufacturing, consumer goods and medical equipment applications.  
• AMS’s PF-401 is our flagship, large scale, multi-tool platform, offering robust PLC controls, real-time condition monitoring and adjustment and data logging for full job traceability. Similar to our PF-301, the PF-401 controls up to 10 simultaneously operating tools for completely automatic fastener load, positioning, driving and torque confirmation. Further, this system offers additional quality and compliance features for recording all fastening results, torque curves and system error data. For applications in regulated or high volume, high quality-controlled markets (hygienic, medical, health and beauty, aerospace, etc), the PF-401 offers the ideal combination of automated fastening and data management.

All models feature transducerized, DC electric torque control screwdrivers and nut runners managed by digital controllers, for applications covering a torque range of 10 to 310 in-lbs. (1.1 to 35 Nm). Our frame-mounted, reconfigurable single or multi-tool systems offer sophisticated torque and angle control at competitive costs, outstanding productivity and with many customization options to meet your exact needs.       

Automated Machine Systems (AMS) is an industrial automation integrator in Cincinnati, Ohio. We specialize in advanced automation solutions for medical, plastic processing, consumer goods and transportation industry manufacturers. With 99.5 percent on-time delivery, 97 percent customer satisfaction, 24/7 service and over 20 years of earning our customers’ trust, AMS is your partner for industrial automation. To talk about your fastening needs, reach us at (513) 771-3525, or by email at info@amsmachinesinc.com.