The Benefits of Robotic Trimming

Flexibility, productivity, safety, quality and cost-competitiveness: these are the attributes that can make or break the business of a heavy gage thermoformer. The ability to have trimming processes that deliver all of these attributes can greatly enhance the thermoformer’s success. The goal of this article is to familiarize thermoformers with the attributes and benefits that can be achieved using robotic trimming systems over the other trimming choices available. Implementing robotic trimming automation requires a deep understanding of “path intensive” motion requirements and the other supporting technologies required to maximize the benefits that can be achieved with a robotic trimming system. Take care to select a System Integrator that fully understands the requirements of trimming applications to take full advantage of the potential benefits. This article is based upon KMT Robotic Solutions’ (KMT-RS) many years of success working with thermoforming companies to implement robotic trimming solutions.

Flexibility

The ability to easily program for a variety of parts, to be able to add in new parts over time and to efficiently implement part changeovers is key to the thermoformer’s production flexibility. Making this efficient requires a combination of off-line programming tools, system calibration features and program management tools that specifically address these flexibility requirements. With these features in place, changeovers between parts can typically be implemented in about a quarter of the time it takes to changeover a CNC machine.

Flexibility also comes from the ability to reprogram for part design changes. KMT-RS provided a production system to one thermoformer that used this equipment to implement a series of short prototype part runs for their customer. This allows their customer to work through an intensive product design change period in a fraction of the time that it took them when the parts were trimmed using trim dies. Now their customer is demanding that all future part programs be implemented with robotic trimming for prototyping and production so that they get the benefits of the part change flexibility available during the prototyping stage.

The ability to use a variety of tools on the same robot is another type of flexibility that can be provided. This can be more traditional with a variety of cutting tools being available to an automatic tool change routing spindle, or more advanced. An example of more advanced tool change would be a robot dropping off the routing spindle and picking up a compliant knife to facilitate fine edge finishing.

Flexibility is also delivered through having a wider range of motion with a 6-axis robot arm, providing the ability to process a wide range of part sizes, including taller parts. CNC machine pricing is heavily influenced by the Z stroke required while robots can often process tall parts at no added cost. Flexibility is also available with the option of adding capacity as production requirements increase. For example, adding another trimming position or another robot arm to a system can be accomplished to increase throughput.

And the ultimate flexibility also exists: if the need for the robot in its current process goes away, then the robot can be retooled and redeployed doing a totally different process, protecting your investment.

Productivity

Ease of changeover part to part was mentioned in the Flexibility section. The time savings over CNC changeovers using a robotic system equipped for fast changeover results in less labor per changeover, less part waste during set-up and more parts produced in a shift.

Another key attribute of productivity is the cycle time achievable per part. The process used to cut the part primarily governs the cutting speed, so CNC machines and robotic trimming typically will not vary significantly in cut time but the robot can implement faster tool changes and Tool Center Point (TCP) calibrations than on a CNC and make quicker motions between cuts, giving it a total cycle time advantage. For example, spindle alignment can be achieved automatically on the robot system within 90 seconds while this process takes up to four times longer on a CNC machine. Shorter per part cycle time plus faster worn tool changes means more productivity per shift.

The ability of the robot to reach all around the part, including from underneath the part, can impact the number of set-ups required to trim a part. KMT-RS has customers that have eliminated the second set-up required on a CNC machine to process the underside of the part and save the cost of the second part fixture along with increasing their productivity.

Reliable operation is also a key to high productivity. Today’s industrial robots have Mean Time Between Failure (MTBF) over 90K hours and never take a vacation day. The maintenance requirements for the FANUC robot arms are minimal consisting of annual lubrication and replacement of 4 D Cell batteries. In addition, the robot is able to protect itself and its tooling with Torque Overload Sensing (TOS), so it stops upon collision. This approach is superior to the mechanical break-away methods used on CNC machines and facilitates much quicker recovery from unexpected events, again improving productivity.

Safety

Operating a thermoforming business safely is essential to controlling risk and its associated cost. Keeping team members separated from high speed rotating equipment is a benefit of a robotic trimming solution implemented correctly with appropriate solid guards. In addition, removing team members from repetitive, manual trimming operations eliminates a major source of repetitive motion injuries and the associated insurance liability.

Quality

Robots deliver repeatable processes with consistent results. They don’t get bored or distracted and they can be programmed to insure that the right features get trimmed into every part. This is very important when there are lots of option choices that impact the features to be trimmed in a part. KMT-RS has had experience with a range of plastic and thermoformed parts that require tight tolerance trimming that is challenging due to the part distortion or variable shrink rates. To overcome this challenge, KMT-RS has developed patent-pending AccuFind® sensing technology that can be implemented to locate the part and specific key features and make 3D offsets to the robot’s trim path to the new position of the part and features. This unique approach minimizes additional cycle time required, protecting productivity while delivering part quality.

Cost Competitiveness

Reliable and repeatable processes lead to better control of the manufacturing critical path, predictability and reductions in manufacturing time, and more consistent high product quality. This provides the opportunity for the thermoformer to take a more aggressive pricing position at less risk when going after new business. KMT-RS has many customers that have revised their approach to quoting projects based on their new economics with robotic trimming and have won back business that was previously lost.

Flexible Robotic Trimming, implemented effectively, can offer your company the opportunity to improve process throughput, have more reliable and repeatable processes, improve product quality and consistency, remove your employees from potentially hazardous jobs and increase cost competitiveness. This can lead to a variety of benefits for the business, including improved relationships with customers, opportunities to win new business and improved financial results. Consider how your business can be impacted with the power of Flexibility, Productivity, Safety, Quality and Cost Competitiveness, and create a plan to add robotic trimming to your business model.

Written by Roberta Zald and Paul Schuch, KMT Robotic Solutions, Inc.