Robopac Improves Structural Strength on Stretch Wrapping Machine Using Ansys Tools

"Ansys Mechanical helped us find the most accurate loading cases and scientifically calculate the load on our new stretch wrapping machine. Thanks to transient analysis, we could determine the forces and torques in circumstances for which we previously had no data, such as during machine start-up and emergency stopping. Using simulation, production time was reduced from 30 months to 18 months."

— Andrea Ridolfi, Senior Mechanical Engineer and CAE Specialist / Robopac S.p.A., Gualdicciolo, San Marino

Introduction

Robopac is a leading designer and manufacturer of stretch wrapping machines, which use stretch film to stabilize products for shipment. The company needed to develop an innovative rotating arm machine that was more durable and less costly than its existing product to be competitive in the industry.

Challenges

Robopac’s existing product, called Rotowrap, was constructed as a metal box with a lot of welding seams. These seams caused potential reliability issues during the rotation of the wrapping arm. Also, the complex design was more costly than competitors’ products. The challenge was to create a new product of higher quality, performance and reliability at lower cost.

Engineering Solution

Robopac engineers chose Ansys solutions to explore the design space and to focus on structural robustness. Using Ansys Mechanical for both static and dynamic analysis and Ansys SpaceClaim to model geometries for product design optimization, they were able to greatly improve the structural strength of the new wrapping machine by substituting metal tubes for the welded metal plates. This resulted in closed structures that have more resistance to twisting forces. Transient analysis enabled them to calculate forces and torques during machine start-up and emergency stopping — both critical phases for mechanical stress — especially near welding seams.

Benefits

• Eliminated structural problems.
• Increased wrapping speed from 12 revolutions per minute to 15 revolutions per minute.
• Reduced production cost by 30%.
• Compressed production time to 18 months instead of 30 months in the past.
• Increased sales by more than 150%.