Hill Engineering’s machining process simulation service reduces uncertainty in machining planning and improves machining processes. By providing results from validated models, our services support the decision-making of contract machining vendors who want to efficiently produce high-quality parts and OEMs who want to maximize the productivity of their supply chain.
“Part distortion due to residual stress is an ongoing recurring manufacturing challenge in machining of large aerospace components which causes unexpected nonconformance parts, rework cost and delays. A study by Boeing, based on four aircraft programs, estimated the rework and scrap costs related to part distortion … to exceed the amount of 290 million dollars.” [Reference L. D’Alvise et al., 15th CIRP Conference on Modelling of Machining Operations]
What can be done about these distortion issues?
To reduce inefficiencies in the manufacturing sector, Hill Engineering provides machining modeling services, which can benefit many areas, including the following:
- Quickly provide upfront assessments of distortion risks to support machining planning
- Optimize an existing machining process to reduce distortion and improve outcomes
- Reduce the number of set-ups and steps for current machining processes
- Quantify residual stress in incoming material stock to improve consistency.
Our machining modeling capabilities enable us to quickly provide upfront assessments of distortion risks to support planning. Estimates for the initial residual stress in the raw material are developed from our library of existing measurement data, or process simulations, specific to your application. An initial assessment of the distortion upper limit (if unchecked) and likely hot spots can then be prepared. Following this, we can evaluate the machining plan you have in mind – providing estimates for distortion. In addition, we’re also able to perform sensitivity studies, which assess different machining approaches.
So, when is part distortion likely to occur?
Residual stress fields are generally symmetric for plate material and complex for forgings and extrusions. Symmetric residual stress combined with an asymmetric part geometry will lead to distortion. Through machining simulation, we can optimize an existing machining process to reduce distortion and improve outcomes. Analysis shows that part-placement within the stock material can affect distortion by up to 87% for typical large aluminum machining operations. Our models can assess distortion for different machining approaches including incremental steps and flips, clamping, fixture design, and part placement.
By reducing the number of set-ups and steps in the machining process, our machining modeling services can limit the time and money required for part production. Our standard process includes reviewing drawings/requirements, simulating the current machining process, simulating the impact of alternate approaches, and providing a well-documented report.
In one example, modeling showed that the number of operations could be reduced from 3 to 2 (33% reduction) while also reducing distortion by more than 50% by changing the part placement and order of operations.
Hill Engineering has extensive experience with residual stress measurement and modeling. Our in-house, ISO certified, commercial testing laboratory is one of the largest in the world and enables us to quickly test the residual stress levels in your incoming material stream and/or estimate it based on previously published results. In addition, we have the comprehensive skill necessary to model the incoming residual stress in your material due to processes like quench and cold work.