Image source: HRABEC
Background
HARBEC is a manufacturing contractor which, for over 40 years, has aimed to provide effective solutions to customer problems and requests. HARBEC provides tight tolerance prototypes, tooling, machined components and injection molded parts, while keeping sustainability in mind and having a social conscience. HARBEC has been known to not only suffice requirements with their projects, but to exceed expectations, using cutting edge technology to proficiently accomplish their objectives.
Challenge
HARBEC utilizes robots to perform some of the tasks which are part of the daily manufacturing processes at the facility. A robot requires fitted tools to complete the duty for which it is called upon. These tools are called end of arm tools, which in many cases are multiple pneumatically actioned claws or grippers, attached to a bracket of the required shape. HARBEC owns many different 3D printing technologies which would be useful in creating the brackets for each job. Initially, a SLA printer was used to create the bracket. This bracket had decent mechanical properties, and worked well for the job at hand. Interest was shown to reduce the weight of the gripper brackets that are to be utilized by the robots.
Using SOLIDWORKS topology optimization technologies, a new design was created which reduced the weight as much as possible, considering the required preserved areas and the forces on the design during operation. This optimized part was grown in the SLA printer, and the resulting component wasn’t as rigid as what was hoped for. A solution was sought after to maintain the lightweight design, but to ensure a component with similar stiffness to that of the initial part.
Solution
Trials with the SLA printer weren’t successful, and alternate methods were analyzed to provide a solution. The other types of printing options available at HARBEC include FDM, Polyjet, and SLS. A part which is lightweight, stiff, and dimensionally accurate is desired for these end of arm tools. Knowing this, a decision to use the XYZprinting MfgPro230 xS selective laser sintering machine was made. A nylon material can be used in the machine, and this material was chosen to grow the end of arm tool. The resulting mechanical properties were exactly what was desired. After short inspection of the newly created part, it is easily noted that the part lost a significant amount of weight, while keeping a stiffness consistent with the original, non-optimized part. Shown below is a representation of a few different routes taken, to try and perfect this tool.
* Where UTS is an abbreviation for the Ultimate Tensile Strength, and YM stands for Young’s Modulus
It is notable that the PA 12 material has larger values for many important mechanical properties, which may have a relationship with the increased rigidity when using the polyamide material in the MfgPro230 xS. The PA 12 material has the properties that were desired for this project, and the XYZprinting MfgPro230 xS uses this material well, all while maintaining the directional accuracy required in this case. As a result, we have designed a lightweight, rigid, and accurate end of arm tool for the robot. The tool, fitted with the gripper mechanisms is imaged below.
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