The four levels of fastener automationMarch 02, 2021
As production ramps up, manufacturing engineers, managers and process improvement specialists are called upon to squeeze more and more efficiency out of an assembly operation. Fastener automation is an effective way to get more out of a process, while enhancing reliability and increasing tracking abilities. While some class of automation is an obvious solution, the question then becomes just how much automation is appropriate?
Automation: But how much?
To properly consider the level of automation needed, there are a number of factors that must be considered. First, and likely foremost, is product volume. If a company only makes 10 parts per day, it is a much different scenario than if it is making 1,000 parts, or 10,000 for that matter. On a related note, if the daily volume is high, but each unit must be customized to a different specification, this changes the scenario of whether it is worth purchasing, tooling up and programming a fully automated robotics cell to handle every possibility. A “lower level” automation scenario, as discussed further on in this article, might be more appropriate.
Automation complexity must also be taken into account, as some designs lend themselves to robotic operation better than others. Consider, for instance, a rigid machined metal gearbox that can be dropped into a part fixture versus an electric dryer where the back cover is made out of flexible stamped metal. If the dryer is attached with screws while the operator simultaneously pushes its sides together, a robotic operation may be impractical. Something like the metal gearbox, however, with ready-made features for fixturing, could be an ideal scenario for more advanced Visumatic automated screw fastening.
Ideally, manufacturing and design engineering can work together to implement an assembly that is easy to automate, but this is not always possible, especially for a long-established product. Visumatic is able to help out on the front end of the design process, making automation integration easier and more reliable when a product is actually being assembled. More about what makes an ideal part for automation, and the challenges in making a good finished part for the end customer, is discussed in the whitepaper: Designing Fastened Parts for Automation — What You Need to Know.
Other factors that must also be considered include the potential for repetitive stress injuries, operator training and the need for process tracking (a particular strength of robotic systems). Finally, from a business standpoint, one must consider the product lifecycle. Heavy automation may not be worth the investment if the product itself is only going to be around for a short time. Conversely, if a fully automated system is flexible enough to accommodate similar parts or part revisions, this could help justify more advanced fastener automation.
Success example: Inline conveyor screwdriving station increases productivity fifteen-fold
One Visumatic customer, a manufacturer of traffic barrel safety lights, received large bulk batch orders that required quick turnaround. Hand assembly of these orders required repeated cycles of hiring and layoffs, so to speed up the process the customer installed a five spindle assembly machine with a conveyor system to produce the lights. This automation took production from two parts a minute to producing one part every two seconds — a fifteen-fold increase in productivity.
The system moves partially assembled lights down a conveyor into the driving position, where each is lifted and located. The Visumatic Power Driver assembly installs all five screws simultaneously, driving each one to the correct depth and torque. The completed assembly is then placed back on the conveyor, where it progresses down the assembly line. Throughput using this new system is so fast that the process bottlenecks were moved all the way to the end of the line, where the product is packed.
The four levels of fastener automation
Broadly speaking, fastener automation — wherein Visumatic handles everything from clips to nuts and more — can be divided up into four levels (with “Level 0” being no automation). Each Visumatic solution involves a vibratory bowl or other feed mechanism, as well as an automated driver that is applied to the part under human or robot power.
“Level 0, No Automation”
Level 0 is a very basic assembly operation with personnel inserting fasteners manually. Such an operation is not only expensive labor-wise, but it can also subject operators to a variety of repetitive stress injuries. Precise process tracking is also difficult or impossible. The benefits of Level 0 include the low cost of set up, and, with highly qualified operators, flexibility.
“Level 1, Handheld System”
For a dramatic improvement in operator throughput, while still maintaining a high degree of versatility, a Level 1 handheld solution can be an excellent fit. Visumatic’s handheld systems (such as the VLB-900 discussed in the success example below) allow an operator to manually position assemblies via fastener insertion, while automating the actual fastening process, such as driving a screw.
“Level 2, Tabletop Machine”
Tabletop machines are the next step up in process automation from a handheld system. These machines feature custom tooling that holds each workpiece and a screwdriver that moves into position for driving. An operator places the assembly in position and starts the process, which can involve multiple fasteners in tandem where needed.
“Level 3, Cobot Workstation”
Cobots, or collaborative robots, and automation cells combine the manual fixturing concept of a tabletop machine with the versatility of a robotic arm. An operator puts the part in place, then initiates the process. A six-axis robot arm then moves to pre-programmed fastening locations for attachment. Once the fastening procedure is started, the operator can use this process time to prepare a new part, or to accomplish other tasks. Such a workstation can be ideal for physically large or awkward parts, which can be difficult to transport on an assembly line, and may feature broadly positioned screws.
“Level 4, Viper Fastening Robot”
For the ultimate in process automation, Visumatic Viper Fastening Robots feature a four-axis selective compliance articulated robot arm (SCARA) that can be adjusted to a wide variety of assembly configurations with custom jigs. In its stock configuration, the machine is only 30 sq in, allowing it to be easily integrated into an existing floorspace. It can also be moved as needed, with integrated casters and integrated automatic height adjustment. Machines can be highly customized, even employing multiple SCARAs in one cell. Finally, high-speed Viper robots can also be integrated into a “lights out” assembly line, with no operator involvement required.
Visumatic stands ready to offer their expertise to potential and existing customers on what level of automation is appropriate for a particular need. Customers include well-known precision manufacturers like Sony, Tesla, Caterpillar and more. Visumatic is also able to partner with systems integrators to provide the critical fastening automation in overall assembly cell builds.
Success example: VLB-900 driver enhances production for decades
A Visumatic customer manufacturing laundry hampers had been experiencing sustained sales growth. Production was given the task of nearly doubling production at their facility, driving two #6 flat head screws into a metal lid hinge.
This company purchased their first VLB-900 automatic screwdriver for this application in 2002, and since then the unit has successfully driven millions of screws. Fifteen years later, a new duplicate assembly work cell was approved to add line capacity next to the original system, while the original system was upgraded and refurbished to current design standards. This allowed both to share common spare parts, facilitating maintenance.
The VLB-900 was the right fit for this hinge attachment application, largely because the bit stays engaged behind the screw, allowing the operator to positively locate the through hole and align the hinge for driving. The feeder system takes care of screw handling, enabling the operator to drive the two screws in seconds.
It is a great example of how Visumatic can help enhance production now and of their level of support available years — even decades — into the future.
Visumatic: Enhanced efficiency for U.S.-based production and beyond
With relatively high labor costs, keeping production in the U.S. depends in large part on employing the appropriate level of automation to be competitive. Visumatic is ready and willing to work with customers to determine what level of automation is needed to keep operations competitive. They are also able to work with product designers to help easily create automated assemblies, or improve on hard to automate existing designs.
With production kept close to home with the help of automation, monitoring of part quality is easier, intellectual property can be more closely guarded and a faster response to product upgrade cycles is possible. Automation can also help lower scrap rates and failure in the field. When there is a failure, the proper record keeping can help trace errors back to the source, thereby eliminating future defects.
Whether the chosen automation is Level 1, 2, 3 or 4, Visumatic has a wide variety of product options from which to choose, and can customize a solution for a specific customer’s needs. Visumatic can help ramp up fastener assembly production speeds and process tracking now, while continuing to be an important manufacturing partner for many years to come. For more information, visit the Visumatic website.