Error budget and uncertainty analysis of portable machines by mixed experimental and virtual techniques

•Main error sources of using portable machines are studied.•Error-budget of a particular portable machine is performed.•Error values are obtained from experimentation and a virtual machine model.•Uncertainty in the use of the studied portable machines is below 0.06 mm.•Main areas for error improvement are identified.

This paper analyzes the error sources of portable machines, which can move along large parts to perform machining operations and defines a mixed virtual-experimental model to quantify such errors. The method combines three different aspects of particular relevance in portable machines: a process force and machine stiffness model, a geometric error model and a machine and work piece inter-referencing error model. The combination of these models helps to control and define the effects of different errors in the virtual mobile machine, before a real prototype is built. An application to a particular portable machine is presented where error values are either simulated or experimentally obtained from a conventional three-axis milling machine where typical strategies of mobile machines are implemented and tested. The research shows that portable machines can be a solution for automatic and unattended machining operations with accuracy requirements below 0.1 mm.