Daniel Afonso

Finding the Best Machine for SPIF Operations - a Brief Discussion

Single Point Incremental Forming (SPIF) given its easy implementation and absence of dedicated tooling is a promising manufacturing technology concerning the production of customized products, low batches or prototyping of ready-to-use parts. The range of application is wide, covering many materials and virtually unlimited geometries. Indeed, current process boundaries are more related to machine limitations than to the procedure itself. In this paper, research is carried out on the state-of-the-art of existing SPIF machine technology, in order to determine an appropriate configuration for an incremental forming equipment that overcomes such limitations. A comparative analysis is carried out to evaluate the different types of currently used equipment: adapted milling machines, serial robots and purpose built machines. Comparison parameters include among many others the maximum payload, tool path flexibility, stiffness and overall cost of the machine, based on information gathered on publications mainly from the last decade. Alternatively, other solutions used for different technological processes and assembly operations, such as precision positioning, are also taken into account. Based on the comparison of all solutions, and on the objectives of the current project carried out at the University of Aveiro, it is concluded that an equipment with parallel kinematics, driven by hydraulic servo-cylinders, could be the best choice to achieve the established goals.

Testing single point incremental forming molds for thermoforming operations

Low pressure polymer processing processes as thermoforming or rotational molding use much simpler molds then high pressure processes like injection. However, despite the low forces involved with the process, molds manufacturing for this operations is still a very material, energy and time consuming operation.The goal of the research is to develop and validate a method for manufacturing plastically formed sheets metal molds by single point incremental forming (SPIF) operation for thermoforming operation. Stewart platform based SPIF machines allow the forming of thick metal sheets, granting the required structural stiffness for the mold surface, and keeping the short lead time manufacture and low thermal inertia.

CAD/CAM Strategies for a Parallel Kinematics SPIF Machine

Single point incremental forming has attracted the interest of researchers in the last decade for the production of prototypes and small batch production of sheet-based parts [1, 2]. This technique allows the manufacture of parts without using expensive die sets. The SPIF (Single point incremental forming) process can be performed on different equipments such as adapted CNC milling machines, serial robots and built proposed machines [3]. Every solution has advantages and disadvantages. This work presents the CAD/CAM strategies for a parallel kinematics SPIF machine, designed and built at the University of Aveiro [3]. This machine brings a new approach to the SPIF industry. The machinery used to perform SPIF operations has limitations in their work volume with limited movements and in the magnitude of applicable forces. With that in mind, this machine was projected to overcome that obstacle, and was provided with a system with 6 degrees of freedom, while maintaining the ability to apply high loads. The disadvantage is the increase in volume occupied by the kinematic system. The manufacture of new parts could be reached out with more flexibility on the chosen tool path. The first step is the product design in the commercial CAD system. Next step is generating the tool path of the forming tool. This step is very important to achieve the desired part shape. It is used a commercial CAM system (EdgeCAM 2012®), which has resources from three up to five axis strategies. The last step is to send the information to the machine’s control system, based on real-time software. This paper will describe each step with more details.

Testing single point incremental forming moulds for rotomoulding operations

Low pressure polymer processes as thermoforming or rotational moulding use much simpler moulds than high pressure processes like injection. However, despite the low forces involved in the process, moulds manufacturing for these applications is still a very material, energy and time consuming operation. Particularly in rotational moulding there is no standard for the mould manufacture and very different techniques are applicable.The goal of this research is to develop and validate a method for manufacturing plastically formed sheet metal moulds by single point incremental forming (SPIF) for rotomoulding and rotocasting operations. A Stewart platform based SPIF machine allow the forming of thick metal sheets, granting the required structural stiffness for the mould surface, and keeping a short manufacture lead time and low thermal inertia. The experimental work involves the proposal of a hollow part, design and fabrication of a sheet metal mould using dieless incremental forming techniques and testing its o...

Numerical Studies and Equipment Development for Single Point Incremental Forming

This paper summarizes the achievements obtained so far in the context of a research project carried out at the University of Aveiro, Portugal on both numerical and experimental viewpoints concerning Single Point Incremental Forming (SPIF). On the experimental side, the general guidelines on the development of a new SPIF machine are detailed. The innovation features are related to the choice of a six‐degrees‐of‐freedom, parallel kinematics machine, with a high payload, to broad the range of materials to be tested, and allowing for a higher flexibility on tool‐path generation. On the numerical side, preliminary results on simulation of SPIF processes resorting to an innovative solid‐shell finite element are presented. The final target is an accurate and fast simulation of SPIF processes by means of numerical methods. Accuracy is obtained through the use of a finite element accounting for three‐dimensional stress and strain fields. The developed formulation allows for an unlimited number of integration point...